阅读说明：本技术 一种具有升压和降压功能的双向变换器及方法 (Bidirectional converter with boosting and reducing functions and method ) 是由 陈景文 郑乃文 于 2021-09-18 设计创作，主要内容包括：本发明公开了一种具有升压和降压功能的双向变换器及方法；电路结构包括第一直流源、第二直流源,第一开关管、第二开关管、第三开关管和第四开关管,第一电感、第二电感、第三电感和第四电感,第二电容、第三电容和第三电容以及第一二极管、第二二极管和第三二极管。具有升压功能和降压功能具有相同的电路拓扑,通过低压侧耦合电感并联及高压侧耦合电感串联,以及对零电压开通的软开关技术,实现其双向变换器的升压与降压功能。同时,本发明在效消除开关管体二极管的反向恢复问题,减少了器件数量的同时,提高了电路的效率,通过DSP芯片和PWM控制器实现升压变换电路中开关管的控制,技术成熟,便于实现,结构简单,成本低。(The invention discloses a bidirectional converter with boosting and reducing functions and a method; the circuit structure comprises a first direct current source, a second direct current source, a first switch tube, a second switch tube, a third switch tube, a fourth switch tube, a first inductor, a second inductor, a third inductor, a fourth inductor, a second capacitor, a third capacitor, a first diode, a second diode and a third diode. The bidirectional converter has the same circuit topology as the boosting function and the voltage reduction function, and realizes the boosting and voltage reduction functions of the bidirectional converter through the parallel connection of the coupling inductors at the low voltage side, the series connection of the coupling inductors at the high voltage side and the soft switching technology for switching on zero voltage. Meanwhile, the invention effectively eliminates the problem of reverse recovery of the diode of the switching tube body, reduces the number of devices, improves the efficiency of the circuit, realizes the control of the switching tube in the boost conversion circuit through the DSP chip and the PWM controller, and has mature technology, convenient realization, simple structure and low cost.)

1. A bidirectional converter with the functions of boosting and reducing voltage is characterized by comprising a first direct current source, a second direct current source, a first switching tube, a second switching tube, a third switching tube, a fourth switching tube, a first inductor, a second inductor, a third inductor, a fourth inductor, a first capacitor, a second capacitor, a third capacitor, a first diode, a second diode and a third diode;

one end of the first inductor is connected with the positive electrode of the first direct current source, and the other end of the first inductor is connected with the drain electrode of the first switching tube, the positive electrode of the first diode and the source electrode of the third switching tube;

one end of the second inductor is connected with the anode of the first direct current source, the other end of the second inductor is connected with the drain electrode of the second switching tube, the anode of the second diode and one end of the third inductor, the other end of the third inductor is connected with one end of the fourth inductor, and the other end of the fourth inductor, the cathode of the second capacitor and the anode of the third capacitor are connected;

the anode of the first capacitor is respectively connected with the cathode of the first diode, the cathode of the second diode and the anode of the third diode; the negative electrode of the first capacitor is grounded;

the anode of the second direct current source is respectively connected with the drain electrode of the third switching tube, the cathode of the third diode and the anode of the second capacitor;

the negative electrode of the second direct current source, the negative electrode of the third capacitor and the source electrode of the fourth switching tube are connected; the drain electrode of the fourth switching tube is grounded;

and the cathode of the first direct current source, the source electrode of the first switching tube and the source electrode of the second switching tube are all grounded.

2. The bi-directional converter with voltage boosting and reducing functions as claimed in claim 1, wherein said first inductor is connected in parallel with its coupled inductor in the same direction, said second inductor is connected in parallel with its coupled inductor in the opposite direction, said third inductor is connected in series with its coupled inductor in the same direction, and said fourth inductor is connected in series with its coupled inductor in the opposite direction.

3. The bidirectional converter with voltage boosting and dropping functions as claimed in claim 1, wherein said first dc source voltage has a value of 48V and said second dc source voltage has a value of 400V.

4. The bidirectional converter with the voltage boosting and reducing functions as claimed in claim 1, wherein said first and second switching tubes are N-channel power MOSFET switching tubes with model number IRF200P223, and said third and fourth switching tubes are N-channel power MOSFET switching tubes with model number IPW65R041 CFD.

5. The bidirectional converter with the voltage boosting and reducing functions as claimed in claim 1, wherein the magnetic core models of the first inductor, the second inductor, the third inductor and the fourth inductor are High Flux C058110a2, the transformation ratios are 0.67, the inductance values of the first inductor and the second inductor coupling inductor are 17.3uH, and the inductance values of the third inductor and the fourth inductor coupling inductor are 2.8 uH.

6. The bidirectional converter with the voltage boosting and reducing functions as claimed in claim 1, wherein the first capacitor model adopts a capacitor of 4.7uF with a withstand voltage of MKT1820547165 and 160V, and the second capacitor and the third capacitor model are both capacitors of 68uF with a withstand voltage of 250V of B32526R3686K 000.

7. The bidirectional converter with the voltage boosting and reducing functions as recited in claim 1, wherein the first diode, the second diode and the third diode are fast recovery diodes of type IDW100E 60.

8. The bidirectional converter with the voltage boosting and reducing functions as claimed in claim 1, further comprising a DSP chip and a PWM driver.

9. A bidirectional conversion method with a step-up and step-down function, based on any one of claims 1 to 8, comprising the steps of:

and (3) boosting:

s1: the first switch tube and the second switch tube are switched on, the third switch tube and the fourth switch tube are switched off, the second switch tube is switched on in the working mode, the second switch tube is switched on under the condition of zero voltage switching-on due to the existence of a diode of the second switch tube body, in the period, the first direct current forms a loop with the first switch tube through the coupling inductor of the first inductor and a loop with the coupling inductor of the second inductor, so that the current flowing through the coupling inductor of the first inductor is linearly increased, the current flowing through the coupling inductor of the second inductor is linearly reduced, and at the moment, no current flows through the first inductor and the second inductor;

s2: the second switching tube is switched on, the first switching tube, the third switching tube and the fourth switching tube are switched off, and compared with the step S1, the first switching tube is switched off; at this time, the junction capacitor between the drain and the source of the first switching tube starts to charge, the junction capacitor between the drain and the source of the third switching tube starts to discharge, and the inductor L_lkCharging the junction capacitor between the drain and the source of the fourth switch tube, and generating resonance;

s3: the second switching tube is switched on, and the first switching tube, the third switching tube and the fourth switching tube are switched off, and the working mode in the step S2 is kept unchanged; the voltage of the junction capacitor between the drain and the source of the first switching tube reaches V_CWhen the first diode is naturally conducted, the voltage of the junction capacitor between the drain and the source of the first switch tube is stabilized to be V_CThe first capacitor starts to charge; in the last operating mode, the inductor L_lkThe junction capacitance between the fourth switch tube and the drain-source electrode is changed into an inductance L through resonance_lkThe junction capacitance between the drain and the source of the third switching tube and the junction capacitance between the drain and the source of the fourth switching tube resonate; the voltage of the junction capacitor between the drain and the source of the third switch tube is changed from V through resonance_H1Discharge to zero and the voltage of the junction capacitor between the drain and the source of the fourth switch tube is from V_H2Charging to V_H-V_C；

S4: the second switching tube and the third switching tube are switched on, the first switching tube and the fourth switching tube are switched off, and compared with the working mode in the step S3, the third switching tube is switched on; the body diode of the third switching tube is naturally conducted, so that the third switching tube is conducted by zero voltage; this mode is until the charging current of the first capacitor drops to 0;

s5: the second switching tube and the third switching tube are switched on, the first switching tube and the fourth switching tube are switched off, and the working mode in the step S4 is kept unchanged; as the charging current of the first capacitor is reduced to 0, the first diode is naturally turned off, and at the moment, the first capacitor is discharged through the third diode; the current flowing through the coupling inductor of the first inductor is linearly reduced, and the current flowing through the coupling inductor of the second inductor is linearly increased;

s6: the second switching tube is turned on, the first switching tube, the third switching tube and the fourth switching tube are turned off, and compared with the working mode in the step S5, the third switching tube is turned off; under the action of the coupling inductor of the first inductor, the junction capacitor between the drain and the source of the first switching tube starts to discharge, and the junction capacitor between the drain and the source of the third switching tube starts to charge; inductor L_lkThe resonant capacitor resonates with the junction capacitor between the drain and the source of the fourth switching tube to discharge the junction capacitor between the drain and the source of the fourth switching tube; in this mode, the voltage of the junction capacitor between the drain and the source of the fourth switch tube is from V_H-V_CDown to V_H2The junction capacitance between the drain and the source of the first switch tube is discharged to 0, and the junction capacitance between the drain and the source of the third switch tube is charged to V_H1；

S7: the first switching tube and the second switching tube are switched on, the third switching tube and the fourth switching tube are switched off, and compared with the working mode in the step S6, the first switching tube is switched on; the junction capacitance between the drain and the source of the first switch tube is discharged to 0, and the first switch tube is turned on and conducted at zero voltage; during the period, the first direct current source flow forms a loop with the first switch tube through the coupling inductor of the first inductor and forms a loop with the second switch tube through the coupling inductor of the second inductor, so that the current flowing through the coupling inductor of the first inductor is linearly reduced, and the current flowing through the coupling inductor of the second inductor is linearly increased; at this time, no current flows through the first inductor and the second inductor;

s8: the first switching tube is turned on, the second switching tube, the third switching tube and the fourth switching tube are turned off, and compared with the working mode in the step S7, the second switching tube is turned off; at the moment, the junction capacitor between the drain and the source of the second switching tube starts to charge, and the junction capacitor between the drain and the source of the fourth switching tube starts to discharge; inductor L_lkCharging the junction capacitance between the drain and the source of the third switching tube to generate resonance;

s9: the first switching tube is switched on, and the second switching tube, the third switching tube and the fourth switching tube are switched off, and the working mode in the step S8 is kept unchanged; the voltage of the junction capacitor between the drain and the source of the second switching tube reaches V_CWhen the second diode is naturally conducted, the voltage of the junction capacitor between the drain and the source of the second switch tube is stabilized to be V_CThe first capacitor starts to charge; in the operation mode of step S8, the inductor L_lkThe junction capacitance between the third switch tube and the drain-source electrode is changed into an inductance L_lkThe junction capacitance between the drain and the source of the third switching tube and the junction capacitance between the drain and the source of the fourth switching tube resonate; the voltage of the junction capacitor between the drain and the source of the third switch tube is changed from V through resonance_H1Charging to V_HAnd the voltage of the junction capacitor between the drain and the source of the fourth switch tube discharges to 0;

s10: the first switching tube and the fourth switching tube are switched on, the second switching tube and the third switching tube are switched off, and compared with the working mode in the step S9, the fourth switching tube is switched on; the body diode of the fourth switching tube is naturally conducted, so that the fourth switching tube is conducted by zero voltage; this mode is until the charging current of the first capacitor drops to 0;

s11: the first switching tube and the fourth switching tube are switched on, the second switching tube and the third switching tube are switched off, and the working mode in the step S0 is kept unchanged; the second diode is naturally turned off because the charging current of the first capacitor is reduced to 0; the current flowing through the coupling inductor of the first inductor is increased linearly, and the current flowing through the coupling inductor of the second inductor is decreased linearly;

s12: the first switching tube is turned on, the second switching tube, the third switching tube and the fourth switching tube are turned off, and compared with the working mode in the step S1, the fourth switching tube is turned off; under the action of the coupling inductor of the second inductor, the junction capacitor between the drain and the source of the second switching tube starts to discharge, and the junction capacitor between the drain and the source of the fourth switching tube starts to charge; inductor L_lkThe resonant capacitor resonates with the junction capacitor between the drain and the source of the third switching tube, so that the junction capacitor between the drain and the source of the third switching tube is discharged; in this mode, the junction capacitance voltage between the drain and the source of the third switch tube is from V_HDown to V_H1The junction capacitance between the drain and the source of the second switch tube is discharged to 0, and the junction capacitance between the drain and the source of the fourth switch tube is charged to V_H2Realizing the boosting process of the converter;

and (3) a pressure reduction process:

b1: the first switching tube and the second switching tube are switched on, the third switching tube and the fourth switching tube are switched off, and the second switching tube is switched on in the working mode; due to the existence of the diode of the second switch tube body, the second switch tube is switched on under the condition of zero voltage switching-on; during the period, the first direct current source flow forms a loop with the first switch tube through the coupling inductor of the first inductor and forms a loop with the second switch tube through the coupling inductor of the second inductor, so that the current flowing through the coupling inductor of the first inductor is linearly increased in the reverse direction, the current flowing through the coupling inductor of the second inductor is linearly decreased in the reverse direction, and the current flows into the first direct current source flow; at this time, no current flows through the first inductor and the second inductor;

b2: the second switching tube is switched on, the first switching tube, the third switching tube and the fourth switching tube are switched off, and compared with the working mode in the step B1, the first switching tube is switched off; at the moment, the junction capacitor between the drain and the source of the first switching tube starts to charge, and the junction capacitor between the drain and the source of the third switching tube starts to discharge; inductor L_lkCharging the junction capacitor between the drain and the source of the fourth switch tube, and generating resonance;

b3: the second switching tube is switched on, and the first switching tube, the third switching tube and the fourth switching tube are switched off and keep unchanged from the working mode in the step B2; the voltage of the junction capacitor between the drain and the source of the fourth switch tube reaches V_H-V_CThe third diode is naturally conducted, and the first capacitor starts to discharge; in the last operating mode, the inductor L_lkThe junction capacitance between the fourth switch tube and the drain-source electrode is changed into an inductance L through resonance_lkThe junction capacitance between the drain and the source of the first switching tube and the junction capacitance between the drain and the source of the third switching tube resonate; through resonance, the voltage of the junction capacitor between the drain and the source of the first switch tube is charged to V_CAnd the voltage of the junction capacitor between the drain and the source of the third switch tube discharges to 0;

b4: the second switching tube and the third switching tube are switched on, the first switching tube and the fourth switching tube are switched off, and compared with the working mode in the step B3, the third switching tube is switched on; the body diode of the third switching tube is naturally conducted, so that the third switching tube is conducted by zero voltage; this mode is until the discharge current of the first capacitor is reduced to 0;

b5: the second switching tube and the third switching tube are switched on, the first switching tube and the fourth switching tube are switched off, and the working mode in the step B4 is kept unchanged; the third diode is naturally turned off because the charging current of the first capacitor is reduced to 0; the current flowing through the coupling inductor of the first inductor increases in a reverse linear manner, the current flowing through the coupling inductor of the second inductor decreases in a reverse linear manner, and the current flowing through the inductor L_lkThe current of (2) decreases linearly;

b6: the second switching tube is switched on, the first switching tube, the third switching tube and the fourth switching tube are switched off, and compared with the working mode in the step B5, the third switching tube is switched off; under the action of the coupling inductor of the first inductor, the junction capacitor between the drain and the source of the first switching tube starts to discharge, and the junction capacitor between the drain and the source of the third switching tube starts to charge; inductor L_lkThe resonant capacitor resonates with the junction capacitor between the drain and the source of the fourth switching tube to discharge the junction capacitor between the drain and the source of the fourth switching tube; in this mode, the junction capacitance between the drain and source of the first switch is discharged to 0, and the junction capacitance between the drain and source of the third switch is charged to V_H1The voltage of the junction capacitor between the drain and the source of the fourth switch tube is from V_H-V_CDown to V_H2；

B7: the first switching tube and the second switching tube are switched on, the third switching tube and the fourth switching tube are switched off, and compared with the working mode in the step B6, the first switching tube is switched on; the junction capacitance between the drain and the source of the first switch tube is discharged to 0, and the first switch tube is turned on and conducted at zero voltage; during the period, the first direct current source flow forms a loop with the first switch tube through the coupling inductor of the first inductor and forms a loop with the second switch tube through the coupling inductor of the second inductor, so that the current flowing through the coupling inductor of the first inductor is linearly reduced in the reverse direction, the current flowing through the coupling inductor of the second inductor is linearly increased in the reverse direction, and the current flows into the first direct current source flow; at this time, no current flows through the first inductor and the second inductor;

b8: a switching tube is switched on, the second switching tube, the third switching tube and the fourth switching tube are switched off, and compared with the working mode in the step B7, the second switching tube is switched off; at this time, due to the effect of the coupling inductance of the second inductor, the junction capacitance between the drain and the source of the second switch tube starts to charge, and the fourth switch tube starts to chargeThe junction capacitance between the drain and the source of the switching tube begins to discharge; inductor L_lkCharging the junction capacitance between the drain and the source of the third switching tube to generate resonance;

b9: the first switching tube is switched on, and the second switching tube, the third switching tube and the fourth switching tube are switched off, and the working mode in the step B8 is kept unchanged; the voltage of the junction capacitor between the drain and the source of the second switching tube reaches V_CWhen the second diode is naturally conducted, the voltage of the junction capacitor between the drain and the source of the second switch tube is stabilized to be V_CThe first capacitor starts to charge; in step B8, inductor L_lkThe junction capacitance between the third switch tube and the drain-source electrode is changed into an inductance L_lkThe junction capacitance between the drain and the source of the third switching tube and the junction capacitance between the drain and the source of the fourth switching tube resonate; through resonance, the voltage of the junction capacitor between the drain and the source of the third switch tube is charged to V_HAnd the voltage of the junction capacitor between the drain and the source of the fourth switch tube discharges to 0;

b10: the first switching tube and the fourth switching tube are switched on, the second switching tube and the third switching tube are switched off, and compared with the working mode in the step B9, the fourth switching tube is switched on; the body diode of the fourth switching tube is naturally conducted, so that the fourth switching tube is conducted by zero voltage; this mode is until the charging current of the first capacitor drops to 0;

b11: the first switching tube and the fourth switching tube are switched on, the second switching tube and the third switching tube are switched off, and the working mode in the step B10 is kept unchanged; the second diode is naturally turned off because the charging current of the first capacitor is reduced to 0; the current flowing through the coupling inductor of the first inductor decreases in a reverse linear manner, the current flowing through the coupling inductor of the second inductor increases in a reverse linear manner, and the current flowing through the inductor L_lkThe current of (2) increases linearly;

b12: the first switching tube is turned on, the second switching tube, the third switching tube and the fourth switching tube are turned off, and compared with the working mode in the step B11, the fourth switching tube is turned off; under the action of the coupling inductor of the second inductor, the junction capacitor between the drain and the source of the second switching tube starts to discharge, and the junction capacitor between the drain and the source of the fourth switching tube starts to charge; inductor L_lkIs tuned with the junction capacitance between the drain and the source of the third switch tubeVibrating to discharge the junction capacitor between the drain and the source of the third switching tube; in the mode, the junction capacitance between the drain and the source of the second switching tube is discharged to 0, and the voltage of the junction capacitance between the drain and the source of the third switching tube is from V_HDown to V_H1And charging the junction capacitor between the drain and the source of the fourth switch tube to V_H2Realizing the voltage reduction process of the converter;

the V is_HIs the voltage across the first capacitor, V_H1Is the voltage across the second capacitor, V_H2Is the voltage across the third capacitor;

the coupling inductance of the third inductor and the coupling inductance of the fourth inductor are equivalent to a coupling inductance L_lk。

Technical Field

The invention belongs to the field of direct-current power supplies, and particularly relates to a bidirectional converter with boosting and reducing functions and a method.

Background

The development of renewable energy, electric vehicles and uninterruptible power supplies has been one of the most attractive topics in the power electronics field over the past decades, with DC-DC bi-directional converters being a key component for its applications.

However, since the dc voltage level on the renewable energy source side, the electric vehicle side, and the uninterruptible power supply side is low, it is necessary to realize this by a bidirectional converter that steps up and down. The existing buck-boost bidirectional converter has the following defects: 1. the single converter voltage gain is low; 2. the use of a coupled inductor can improve gain, but can increase current ripple; 3. the body diode of the switching tube can cause a strong reverse recovery problem, so that the circuit loss is large; 4. to solve the above problems, new problems are brought about, and circuit devices are made too many. These disadvantages are solved by adding extra devices or circuits, which increase the cost and volume of the existing bidirectional converter, thus limiting its application.

Disclosure of Invention

In order to solve the problems in the prior art, the invention provides a bidirectional converter with boosting and reducing functions and a method.

The invention is realized by the following technical scheme:

a bidirectional converter with the functions of boosting and reducing voltage is characterized by comprising a first direct current source, a second direct current source, a first switching tube, a second switching tube, a third switching tube, a fourth switching tube, a first inductor, a second inductor, a third inductor, a fourth inductor, a first capacitor, a second capacitor, a third capacitor, a first diode, a second diode and a third diode;

one end of the first inductor is connected with the positive electrode of the first direct current source, and the other end of the first inductor is connected with the drain electrode of the first switching tube, the positive electrode of the first diode and the source electrode of the third switching tube;

one end of the second inductor is connected with the anode of the first direct current source, the other end of the second inductor is connected with the drain electrode of the second switching tube, the anode of the second diode and one end of the third inductor, the other end of the third inductor is connected with one end of the fourth inductor, and the other end of the fourth inductor, the cathode of the second capacitor and the anode of the third capacitor are connected;

the anode of the first capacitor is respectively connected with the cathode of the first diode, the cathode of the second diode and the anode of the third diode; the negative electrode of the first capacitor is grounded;

the anode of the second direct current source is respectively connected with the drain electrode of the third switching tube, the cathode of the third diode and the anode of the second capacitor;

the negative electrode of the second direct current source, the negative electrode of the third capacitor and the source electrode of the fourth switching tube are connected; the drain electrode of the fourth switching tube is grounded;

and the cathode of the first direct current source, the source electrode of the first switching tube and the source electrode of the second switching tube are all grounded.

Furthermore, the first inductor is connected with the coupling inductor in parallel in the same direction, the second inductor is connected with the coupling inductor in parallel in the reverse direction, the third inductor is connected with the coupling inductor in series in the same direction, and the fourth inductor is connected with the coupling inductor in series in the reverse direction.

Further, the first dc source voltage value is 48V, and the second dc source voltage value is 400V.

Further, the first switch tube and the second switch tube are N-channel power MOSFET switch tubes with the model of IRF200P223, and the third switch tube and the fourth switch tube are N-channel power MOSFET switch tubes with the model of IPW65R041 CFD.

Furthermore, the magnetic core models of the first inductor, the second inductor, the third inductor and the fourth inductor are High Flux C058110a2, the transformation ratios are all 0.67, the inductance values of the first inductor and the second inductor are all 17.3uH, and the inductance values of the third inductor and the fourth inductor are all 2.8 uH.

Furthermore, the first capacitor model adopts a capacitor with a voltage withstanding value of MKT1820547165 of 4.7uF of 160V, and the second capacitor and the third capacitor model are both capacitors with a voltage withstanding value of 250V of 68uF of B32526R3686K 000.

Further, the first diode, the second diode and the third diode are all fast recovery diodes with the type IDW100E 60.

Further, the system also comprises a DSP chip and a PWM driver.

A bidirectional conversion method with the functions of boosting and reducing voltage comprises the following steps:

and (3) boosting:

s1: the first switch tube and the second switch tube are switched on, the third switch tube and the fourth switch tube are switched off, the second switch tube is switched on in the working mode, the second switch tube is switched on under the condition of zero voltage switching-on due to the existence of a diode of the second switch tube body, in the period, the first direct current forms a loop with the first switch tube through the coupling inductor of the first inductor and a loop with the coupling inductor of the second inductor, so that the current flowing through the coupling inductor of the first inductor is linearly increased, the current flowing through the coupling inductor of the second inductor is linearly reduced, and at the moment, no current flows through the first inductor and the second inductor;

s2: the second switching tube is switched on, the first switching tube, the third switching tube and the fourth switching tube are switched off, and compared with the step S1, the first switching tube is switched off; at this time, the junction capacitor between the drain and the source of the first switching tube starts to charge, the junction capacitor between the drain and the source of the third switching tube starts to discharge, and the inductor L_lkCharging the junction capacitor between the drain and the source of the fourth switch tube, and generating resonance;

s3: the second switching tube is switched on, and the first switching tube, the third switching tube and the fourth switching tube are switched off, and the working mode in the step S2 is kept unchanged; the voltage of the junction capacitor between the drain and the source of the first switching tube reaches V_CWhen the first diode is naturally conducted, the voltage of the junction capacitor between the drain and the source of the first switch tube is stabilized to be V_CThe first capacitor starts to charge; in the last operating mode, the inductor L_lkThe junction capacitance between the fourth switch tube and the drain-source electrode is changed into an inductance L through resonance_lkAnd the junction capacitance between the drain and the source of the third switching tube and the junction capacitance between the drain and the source of the fourth switching tube resonate. The voltage of the junction capacitor between the drain and the source of the third switch tube is changed from V through resonance_H1Discharge to zero and the voltage of the junction capacitor between the drain and the source of the fourth switch tube is from V_H2Charging to V_H-V_C；

S4: the second switching tube and the third switching tube are switched on, the first switching tube and the fourth switching tube are switched off, and compared with the working mode in the step S3, the third switching tube is switched on; and the body diode of the third switching tube is naturally conducted, so that the third switching tube is conducted by zero voltage. This mode is until the charging current of the first capacitor drops to 0;

s5: the second switching tube and the third switching tube are switched on, the first switching tube and the fourth switching tube are switched off, and the working mode in the step S4 is kept unchanged; since the charging current of the first capacitor is reduced to 0, the first diode is naturally turned off, and at the moment, the first capacitor is discharged through the third diode. The current flowing through the coupling inductor of the first inductor is linearly reduced, and the current flowing through the coupling inductor of the second inductor is linearly increased;

s6: the second switching tube is turned on, the first switching tube, the third switching tube and the fourth switching tube are turned off, and compared with the working mode in the step S5, the third switching tube is turned off; under the action of the coupling inductor of the first inductor, the junction capacitor between the drain and the source of the first switching tube starts to discharge, and the junction capacitor between the drain and the source of the third switching tube starts to charge; inductor L_lkThe resonant capacitor resonates with the junction capacitor between the drain and the source of the fourth switching tube to discharge the junction capacitor between the drain and the source of the fourth switching tube; in this mode, the voltage of the junction capacitor between the drain and the source of the fourth switch tube is from V_H-V_CDown to V_H2The junction capacitance between the drain and the source of the first switch tube is discharged to 0, and the junction capacitance between the drain and the source of the third switch tube is charged to V_H1；

S7: the first switching tube and the second switching tube are switched on, the third switching tube and the fourth switching tube are switched off, and compared with the working mode in the step S6, the first switching tube is switched on; the junction capacitance between the drain and the source of the first switch tube is discharged to 0, and the first switch tube is turned on and conducted at zero voltage; during the period, the first direct current source flow forms a loop with the first switch tube through the coupling inductor of the first inductor and forms a loop with the second switch tube through the coupling inductor of the second inductor, so that the current flowing through the coupling inductor of the first inductor is linearly reduced, and the current flowing through the coupling inductor of the second inductor is linearly increased; at this time, no current flows through the first inductor and the second inductor;

s8: the first switching tube is turned on, the second switching tube, the third switching tube and the fourth switching tube are turned off, and compared with the working mode in the step S7, the second switching tube is turned off; at the moment, the junction capacitor between the drain and the source of the second switching tube starts to charge, and the junction capacitor between the drain and the source of the fourth switching tube starts to discharge; inductor L_lkCharging the junction capacitance between the drain and the source of the third switching tube to generate resonance;

s9: the first switch tube is turned on, the second switch tube,The third switching tube and the fourth switching tube are turned off, and the working mode in the step S8 is kept unchanged; the voltage of the junction capacitor between the drain and the source of the second switching tube reaches V_CWhen the second diode is naturally conducted, the voltage of the junction capacitor between the drain and the source of the second switch tube is stabilized to be V_CThe first capacitor starts to charge; in the operation mode of step S8, the inductor L_lkThe junction capacitance between the third switch tube and the drain-source electrode is changed into an inductance L_lkAnd the junction capacitance between the drain and the source of the third switching tube and the junction capacitance between the drain and the source of the fourth switching tube resonate. The voltage of the junction capacitor between the drain and the source of the third switch tube is changed from V through resonance_H1Charging to V_HAnd the voltage of the junction capacitance between the drain and the source of the fourth switch tube is discharged to 0.

S10: the first switching tube and the fourth switching tube are switched on, the second switching tube and the third switching tube are switched off, and compared with the working mode in the step S9, the fourth switching tube is switched on; the body diode of the fourth switching tube is naturally conducted, so that the fourth switching tube is conducted by zero voltage; this mode is until the charging current of the first capacitor drops to 0;

s11: the first switching tube and the fourth switching tube are switched on, the second switching tube and the third switching tube are switched off, and the working mode in the step S0 is kept unchanged; the second diode is naturally turned off because the charging current of the first capacitor is reduced to 0; the current flowing through the coupling inductor of the first inductor is increased linearly, and the current flowing through the coupling inductor of the second inductor is decreased linearly;

s12: the first switching tube is turned on, the second switching tube, the third switching tube and the fourth switching tube are turned off, and compared with the working mode in the step S1, the fourth switching tube is turned off; under the action of the coupling inductor of the second inductor, the junction capacitor between the drain and the source of the second switching tube starts to discharge, and the junction capacitor between the drain and the source of the fourth switching tube starts to charge; inductor L_lkThe resonant capacitor resonates with the junction capacitor between the drain and the source of the third switching tube, so that the junction capacitor between the drain and the source of the third switching tube is discharged; in this mode, the junction capacitance voltage between the drain and the source of the third switch tube is from V_HDown to V_H1The junction capacitance between the drain and the source of the second switch tube discharges to 0, and the junction capacitance between the drain and the source of the fourth switch tube discharges to 0Capacity charge to V_H2Realizing the boosting process of the converter;

and (3) a pressure reduction process:

b1: the first switching tube and the second switching tube are switched on, the third switching tube and the fourth switching tube are switched off, and the second switching tube is switched on in the working mode; due to the existence of the diode of the second switch tube body, the second switch tube is switched on under the condition of zero voltage switching-on; during the period, the first direct current source flow forms a loop with the first switch tube through the coupling inductor of the first inductor and forms a loop with the second switch tube through the coupling inductor of the second inductor, so that the current flowing through the coupling inductor of the first inductor is linearly increased in the reverse direction, the current flowing through the coupling inductor of the second inductor is linearly decreased in the reverse direction, and the current flows into the first direct current source flow; at this time, no current flows through the first inductor and the second inductor;

b2: the second switching tube is switched on, the first switching tube, the third switching tube and the fourth switching tube are switched off, and compared with the working mode in the step B1, the first switching tube is switched off; at the moment, the junction capacitor between the drain and the source of the first switching tube starts to charge, and the junction capacitor between the drain and the source of the third switching tube starts to discharge; inductor L_lkCharging the junction capacitor between the drain and the source of the fourth switch tube, and generating resonance;

b3: the second switching tube is switched on, and the first switching tube, the third switching tube and the fourth switching tube are switched off and keep unchanged from the working mode in the step B2; the voltage of the junction capacitor between the drain and the source of the fourth switch tube reaches V_H-V_CThe third diode is naturally conducted, and the first capacitor starts to discharge; in the last operating mode, the inductor L_lkThe junction capacitance between the fourth switch tube and the drain-source electrode is changed into an inductance L through resonance_lkThe junction capacitance between the drain and the source of the first switching tube and the junction capacitance between the drain and the source of the third switching tube resonate; through resonance, the voltage of the junction capacitor between the drain and the source of the first switch tube is charged to V_CAnd the voltage of the junction capacitor between the drain and the source of the third switch tube discharges to 0;

b4: the second switching tube and the third switching tube are switched on, the first switching tube and the fourth switching tube are switched off, and compared with the working mode in the step B3, the third switching tube is switched on; the body diode of the third switching tube is naturally conducted, so that the third switching tube is conducted by zero voltage; this mode is until the discharge current of the first capacitor is reduced to 0;

b5: the second switching tube and the third switching tube are switched on, the first switching tube and the fourth switching tube are switched off, and the working mode in the step B4 is kept unchanged; the third diode is naturally turned off because the charging current of the first capacitor is reduced to 0; the current flowing through the coupling inductor of the first inductor increases in a reverse linear manner, the current flowing through the coupling inductor of the second inductor decreases in a reverse linear manner, and the current flowing through the inductor L_lkThe current of (2) decreases linearly;

b6: the second switching tube is switched on, the first switching tube, the third switching tube and the fourth switching tube are switched off, and compared with the working mode in the step B5, the third switching tube is switched off; under the action of the coupling inductor of the first inductor, the junction capacitor between the drain and the source of the first switching tube starts to discharge, and the junction capacitor between the drain and the source of the third switching tube starts to charge; inductor L_lkThe resonant capacitor resonates with the junction capacitor between the drain and the source of the fourth switching tube to discharge the junction capacitor between the drain and the source of the fourth switching tube; in this mode, the junction capacitance between the drain and source of the first switch is discharged to 0, and the junction capacitance between the drain and source of the third switch is charged to V_H1The voltage of the junction capacitor between the drain and the source of the fourth switch tube is from V_H-V_CDown to V_H2；

B7: the first switching tube and the second switching tube are switched on, the third switching tube and the fourth switching tube are switched off, and compared with the working mode in the step B6, the first switching tube is switched on; the junction capacitance between the drain and the source of the first switch tube is discharged to 0, and the first switch tube is turned on and conducted at zero voltage; during the period, the first direct current source flow forms a loop with the first switch tube through the coupling inductor of the first inductor and forms a loop with the second switch tube through the coupling inductor of the second inductor, so that the current flowing through the coupling inductor of the first inductor is linearly reduced in the reverse direction, the current flowing through the coupling inductor of the second inductor is linearly increased in the reverse direction, and the current flows into the first direct current source flow; at this time, no current flows through the first inductor and the second inductor;

b8: a switch tube is switched on, the second switch tube, the third switch tube and the fourth switch tube are switched off,the second switch tube is turned off compared with the working mode in the step B7; at the moment, due to the action of the coupling inductor of the second inductor, the junction capacitor between the drain and the source of the second switching tube starts to be charged, and the junction capacitor between the drain and the source of the fourth switching tube starts to be discharged; inductor L_lkCharging the junction capacitance between the drain and the source of the third switching tube to generate resonance;

b9: the first switching tube is switched on, and the second switching tube, the third switching tube and the fourth switching tube are switched off, and the working mode in the step B8 is kept unchanged; the voltage of the junction capacitor between the drain and the source of the second switching tube reaches V_CWhen the second diode is naturally conducted, the voltage of the junction capacitor between the drain and the source of the second switch tube is stabilized to be V_CThe first capacitor starts to charge; in step B8, inductor L_lkThe junction capacitance between the third switch tube and the drain-source electrode is changed into an inductance L_lkThe junction capacitance between the drain and the source of the third switching tube and the junction capacitance between the drain and the source of the fourth switching tube resonate; through resonance, the voltage of the junction capacitor between the drain and the source of the third switch tube is charged to V_HAnd the voltage of the junction capacitor between the drain and the source of the fourth switch tube discharges to 0;

b10: the first switching tube and the fourth switching tube are switched on, the second switching tube and the third switching tube are switched off, and compared with the working mode in the step B9, the fourth switching tube is switched on; the body diode of the fourth switching tube is naturally conducted, so that the fourth switching tube is conducted by zero voltage; this mode is until the charging current of the first capacitor drops to 0;

b11: the first switching tube and the fourth switching tube are switched on, the second switching tube and the third switching tube are switched off, and the working mode in the step B10 is kept unchanged; the second diode is naturally turned off because the charging current of the first capacitor is reduced to 0; the current flowing through the coupling inductor of the first inductor decreases in a reverse linear manner, the current flowing through the coupling inductor of the second inductor increases in a reverse linear manner, and the current flowing through the inductor L_lkThe current of (2) increases linearly;

b12: the first switching tube is turned on, the second switching tube, the third switching tube and the fourth switching tube are turned off, and compared with the working mode in the step B11, the fourth switching tube is turned off; by the effect of the coupling inductance of the second inductance,the junction capacitor between the drain and the source of the second switching tube starts to discharge, and the junction capacitor between the drain and the source of the fourth switching tube starts to charge; inductor L_lkThe resonant capacitor resonates with the junction capacitor between the drain and the source of the third switching tube, so that the junction capacitor between the drain and the source of the third switching tube is discharged; in the mode, the junction capacitance between the drain and the source of the second switching tube is discharged to 0, and the voltage of the junction capacitance between the drain and the source of the third switching tube is from V_HDown to V_H1And charging the junction capacitor between the drain and the source of the fourth switch tube to V_H2Realizing the voltage reduction process of the converter;

the V is_HIs the voltage across the first capacitor, V_H1Is the voltage across the second capacitor, V_H2Is the voltage across the third capacitor;

the coupling inductance of the third inductor and the coupling inductance of the fourth inductor are equivalent to a coupling inductance L_lk。

Compared with the prior art, the invention has the following beneficial technical effects:

the invention discloses a bidirectional converter with the functions of boosting and reducing voltage; the circuit structure comprises a first direct current source, a second direct current source, a first switch tube, a second switch tube, a third switch tube, a fourth switch tube, a first inductor, a second inductor, a third inductor, a fourth inductor, a second capacitor, a third capacitor, a first diode, a second diode and a third diode. The bidirectional converter has the same circuit topology as the boosting function and the voltage reduction function, and realizes the boosting and voltage reduction functions of the bidirectional converter through the parallel connection of the coupling inductors at the low voltage side, the series connection of the coupling inductors at the high voltage side and the soft switching technology for switching on zero voltage. Meanwhile, the invention effectively eliminates the problem of reverse recovery of the diode of the switching tube body, reduces the number of devices, improves the efficiency of the circuit, realizes the control of the switching tube in the boost conversion circuit through the DSP chip and the PWM controller, and has mature technology, convenient realization, simple structure and low cost.

The invention discloses a bidirectional conversion method with the functions of boosting and reducing voltage, which improves the gain of a bidirectional converter by arranging a coupling inductor and can effectively solve the problem of iron core reset; the zero-voltage switching-on soft switching technology is realized by using leakage inductance energy and a passive clamping circuit, the reverse recovery problem of a diode of a switching tube body is effectively solved, the number of devices is reduced, the efficiency of the circuit is improved, the cost is reduced, the power density is improved, and the application field is wider.

Drawings

FIG. 1 is a schematic diagram of a bidirectional converter circuit with step-up and step-down functionality in an embodiment of the present invention;

FIG. 2 is an equivalent circuit diagram with coupled inductors and reference directions in an embodiment of the invention;

FIG. 3 is a schematic diagram of a first operating state in a boost operating mode according to an embodiment of the present invention;

FIG. 4 is a diagram illustrating a second operating condition in the boost operating mode according to an embodiment of the present invention;

FIG. 5 is a schematic diagram of a third operating state in the boost operating mode according to an embodiment of the present invention;

FIG. 6 is a diagram illustrating a fourth operating state of the boost operating mode according to the embodiment of the present invention;

FIG. 7 is a diagram illustrating a fifth operating state of the boost operating mode according to the embodiment of the present invention;

FIG. 8 is a diagram illustrating a sixth operating state of the boost operating mode according to the exemplary embodiment of the present invention;

FIG. 9 is a diagram illustrating a seventh operating state of the boost operating mode according to the embodiment of the present invention;

FIG. 10 is a diagram illustrating an eighth operating state of the boost operating mode according to the exemplary embodiment of the present invention;

FIG. 11 is a diagram illustrating a ninth operating mode of the boost operating mode according to the embodiment of the present invention;

FIG. 12 is a diagram illustrating a tenth operating state in the boost operating mode according to the exemplary embodiment of the present invention;

FIG. 13 is a schematic diagram illustrating an eleventh operating condition in the boost operating mode according to an embodiment of the present invention;

FIG. 14 is a diagram illustrating a twelfth operating mode of the boost operating mode according to the embodiment of the present invention;

FIG. 15 is a schematic diagram illustrating a first operating state in a buck mode of operation in accordance with an embodiment of the present invention;

FIG. 16 is a diagram illustrating a second operating mode in the buck mode of operation in accordance with an embodiment of the present invention;

FIG. 17 is a diagram illustrating a third operating state in the buck mode of operation in accordance with an embodiment of the present invention;

FIG. 18 is a diagram illustrating a fourth operating state in a buck mode of operation in accordance with an exemplary embodiment of the present invention;

FIG. 19 is a diagram illustrating a fifth operating mode in a buck mode of operation according to an exemplary embodiment of the present invention;

FIG. 20 is a diagram illustrating a sixth operating state in the buck mode of operation according to an exemplary embodiment of the present invention;

FIG. 21 is a diagram illustrating a seventh operating mode in a buck mode of operation according to an exemplary embodiment of the present invention;

FIG. 22 is a diagram illustrating an eighth operating state of the buck mode of operation in accordance with an exemplary embodiment of the present invention;

FIG. 23 is a diagram illustrating a ninth operating mode in a step-down mode according to an embodiment of the present invention;

FIG. 24 is a diagram illustrating a tenth operating mode in a buck mode of operation in accordance with an exemplary embodiment of the present invention;

FIG. 25 is a schematic diagram illustrating an eleventh operating state in the buck mode of operation according to an embodiment of the present invention;

fig. 26 is a schematic diagram illustrating a twelfth operating state in the step-down operating mode according to the embodiment of the present invention.

Detailed Description

The present invention will now be described in further detail with reference to specific examples, which are intended to be illustrative, but not limiting, of the invention.

In order to make the technical solutions of the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that the terms "first," "second," and the like in the description and claims of the present invention and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the invention described herein are capable of operation in sequences other than those illustrated or described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

It should be noted that V shown in the drawings of the present invention_LIs a first DC source, V_HIs a second direct current source, S₁Is a first switch tube, S₂Is a second switching tube, S₃Is a third switching tube, S₄Is a fourth switching tube, L₁Is a first inductance, L₂Is a second inductance, L₃Is a third inductance, L₄Is a fourth inductance, L_M1A corresponding coupling inductance, L, of the first inductance_M2A corresponding coupling inductance of the second inductance, L_K1A corresponding coupling inductance, L, of the third inductance_K2A corresponding coupling inductance, C, of the fourth inductance_CIs a first capacitor, C₁Is a second capacitor, C₂Is a third capacitance, C_S1Is the junction capacitance between the drain and the source corresponding to the first switch tube, C_S2A junction capacitance between drain and source corresponding to the second switch tube, C_S3Is the junction capacitance between the drain and the source corresponding to the third switch tube, C_S4The junction capacitance between the drain and the source corresponding to the fourth switch tube, D_C1Is a first diode, D_C2Is a second diode, D_C3Third two polesA tube.

The invention discloses a bidirectional converter with voltage boosting and reducing functions, which comprises a first direct current source, a second direct current source, a first switch tube, a second switch tube, a third switch tube, a fourth switch tube, a first inductor, a second inductor, a third inductor, a fourth inductor, a second capacitor, a third capacitor, a first diode, a second diode and a third diode, as shown in fig. 1 and fig. 2;

one end of the first inductor is connected with the positive electrode of the first direct current source, and the other end of the first inductor is connected with the drain electrode of the first switching tube, the positive electrode of the first diode and the source electrode of the third switching tube;

one end of the second inductor is connected with the anode of the first direct current source, the other end of the second inductor is connected with the drain electrode of the second switching tube, the anode of the second diode and one end of the third inductor, the other end of the third inductor is connected with one end of the fourth inductor, and the other end of the fourth inductor, the cathode of the third capacitor and the anode of the third capacitor are connected;

the anode of the second capacitor is respectively connected with the cathode of the first diode, the cathode of the second diode and the anode of the third diode; the negative electrode of the second capacitor is grounded;

the anode of the second direct current source is respectively connected with the drain electrode of the third switching tube, the cathode of the third diode and the anode of the third capacitor;

the negative electrode of the second direct current source, the negative electrode of the third capacitor and the source electrode of the fourth switching tube are connected; the drain electrode of the fourth switching tube is grounded;

and the cathode of the first direct current source, the source electrode of the first switching tube and the source electrode of the second switching tube are all grounded.

In a preferred embodiment of the present invention, the first inductor is connected in parallel with its coupling inductor in the same direction, the second inductor is connected in parallel with its coupling inductor in the opposite direction, the third inductor is connected in series with its coupling inductor in the same direction, and the fourth inductor is connected in series with its coupling inductor in the opposite direction.

In another preferred embodiment of the present invention, the first dc source voltage is 48V, and the second dc source voltage is 400V.

Another preferred embodiment of the present invention is that the first switching tube and the second switching tube are N-channel power MOSFET switching tubes with a model number of IRF200P223, and the third switching tube and the fourth switching tube are N-channel power MOSFET switching tubes with a model number of IPW65R041 CFD.

In another preferred embodiment of the present invention, the magnetic core types of the first inductor, the second inductor, the third inductor and the fourth inductor all adopt High Flux C058110a2, the transformation ratios are all 0.67, the inductance values of the first inductor and the second inductor are all 17.3uH, and the inductance values of the third inductor and the fourth inductor are all 2.8 uH.

In another preferred embodiment of the invention, the second capacitor model adopts a capacitor with a voltage withstanding value of MKT1820547165 of 4.7uF and a voltage withstanding value of 160V, and the third capacitor model are both capacitors with a voltage withstanding value of 250V of 68uF and B32526R3686K 000.

In another preferred embodiment of the present invention, the first diode, the second diode and the third diode are all fast recovery diodes with the type IDW100E 60.

Another preferred embodiment of the present invention further comprises a DSP chip and a PWM driver.

The invention discloses a bidirectional conversion method with boosting and reducing functions, which comprises the following steps:

the boosting process comprises the following steps and corresponding working modes:

the first mode of operation: corresponding to step S1, as shown in fig. 3, the first switch and the second switch are turned on, the third switch and the fourth switch are turned off, and in this operation mode, the second switch is turned on, and the second switch is turned on under the condition of zero voltage turning on due to the existence of the diode of the second switch body, during this period, the first direct current forms a loop with the first switch through the coupling inductor of the first inductor, and the coupling inductor of the second inductor forms a loop with the second switch, so that the current flowing through the coupling inductor of the first inductor is linearly increased, the current flowing through the coupling inductor of the second inductor is linearly decreased, and at this time, no current flows through the first inductor and the second inductor.

The second working mode is as follows: corresponding to step S2, as shown in FIG. 4, secondThe switching tube is switched on, the first switching tube, the third switching tube and the fourth switching tube are switched off, and compared with the step S1, the first switching tube is switched off; at this time, the junction capacitor between the drain and the source of the first switching tube starts to charge, the junction capacitor between the drain and the source of the third switching tube starts to discharge, and the inductor L_lkAnd charging the junction capacitor between the drain and the source of the fourth switch tube to generate resonance.

The third mode of operation: corresponding to step S3, as shown in fig. 5, the second switch tube is turned on, and the first switch tube, the third switch tube and the fourth switch tube are turned off, which is the same as the operation mode in step S2; the voltage of the junction capacitor between the drain and the source of the first switching tube reaches V_CWhen the first diode is naturally conducted, the voltage of the junction capacitor between the drain and the source of the first switch tube is stabilized to be V_CThe first capacitor starts to charge; in the last operating mode, the inductor L_lkThe junction capacitance between the fourth switch tube and the drain-source electrode is changed into an inductance L through resonance_lkAnd the junction capacitance between the drain and the source of the third switching tube and the junction capacitance between the drain and the source of the fourth switching tube resonate. The voltage of the junction capacitor between the drain and the source of the third switch tube is changed from V through resonance_H1Discharge to zero and the voltage of the junction capacitor between the drain and the source of the fourth switch tube is from V_H2Charging to V_H-V_C。

A fourth mode of operation: corresponding to step S4, as shown in fig. 6, the second switching tube and the third switching tube are turned on, the first switching tube and the fourth switching tube are turned off, and the third switching tube is turned on compared with the operation mode in step S3; and the body diode of the third switching tube is naturally conducted, so that the third switching tube is conducted by zero voltage. This mode is until the charging current of the first capacitor drops to 0.

The fifth working mode: corresponding to step S5, as shown in fig. 7, the second switching tube and the third switching tube are turned on, and the first switching tube and the fourth switching tube are turned off, which remains unchanged from the operation mode in step S4; since the charging current of the first capacitor is reduced to 0, the first diode is naturally turned off, and at the moment, the first capacitor is discharged through the third diode. The current flowing through the coupling inductor of the first inductor decreases linearly and the current flowing through the coupling inductor of the second inductor increases linearly.

Sixth mode of operation: corresponding to step S6, as shown in fig. 8, the second switching tube is turned on, the first switching tube, the third switching tube and the fourth switching tube are turned off, and the third switching tube is turned off compared with the operation mode in step S5; under the action of the coupling inductor of the first inductor, the junction capacitor between the drain and the source of the first switching tube starts to discharge, and the junction capacitor between the drain and the source of the third switching tube starts to charge; the inductor Llk resonates with the junction capacitor between the drain and the source of the fourth switching tube to discharge the junction capacitor between the drain and the source of the fourth switching tube; in this mode, the voltage of the junction capacitor between the drain and the source of the fourth switch tube is from V_H-V_CDown to V_H2The junction capacitance between the drain and the source of the first switch tube is discharged to 0, and the junction capacitance between the drain and the source of the third switch tube is charged to V_H1。

Seventh mode of operation: corresponding to step S7, as shown in fig. 9, the first switch tube and the second switch tube are turned on, the third switch tube and the fourth switch tube are turned off, and the first switch tube is turned on compared with the operation mode in step S6; the junction capacitance between the drain and the source of the first switch tube is discharged to 0, and the first switch tube is turned on and conducted at zero voltage; during the period, the first direct current source flow forms a loop with the first switch tube through the coupling inductor of the first inductor and forms a loop with the second switch tube through the coupling inductor of the second inductor, so that the current flowing through the coupling inductor of the first inductor is linearly reduced, and the current flowing through the coupling inductor of the second inductor is linearly increased; at this time, no current flows in the first inductor and the second inductor.

The eighth mode of operation: corresponding to step S8, as shown in fig. 10, the first switch tube is turned on, the second switch tube, the third switch tube and the fourth switch tube are turned off, and the second switch tube is turned off compared with the operation mode in step S7; at the moment, the junction capacitor between the drain and the source of the second switching tube starts to charge, and the junction capacitor between the drain and the source of the fourth switching tube starts to discharge; inductor L_lkAnd charging the junction capacitance between the drain and the source of the third switching tube to generate resonance.

Ninth mode of operation: corresponding to step S9, as shown in fig. 11, the first switch tube is turned on, the second switch tube, the third switch tube and the fourth switch tube are turned off, and the same procedure as that in step S8 is performedThe operation mode is kept unchanged; the voltage of the junction capacitor between the drain and the source of the second switching tube reaches V_CWhen the second diode is naturally conducted, the voltage of the junction capacitor between the drain and the source of the second switch tube is stabilized to be V_CThe first capacitor starts to charge; in the operation mode of step S8, the inductor L_lkThe junction capacitance between the third switch tube and the drain-source electrode is changed into an inductance L_lkAnd the junction capacitance between the drain and the source of the third switching tube and the junction capacitance between the drain and the source of the fourth switching tube resonate. The voltage of the junction capacitor between the drain and the source of the third switch tube is changed from V through resonance_H1Charging to V_HAnd the voltage of the junction capacitance between the drain and the source of the fourth switch tube is discharged to 0.

The tenth operating mode: corresponding to step S10, as shown in fig. 12, the first switching tube and the fourth switching tube are turned on, the second switching tube and the third switching tube are turned off, and the fourth switching tube is turned on compared with the operation mode in step S9; the body diode of the fourth switching tube is naturally conducted, so that the fourth switching tube is conducted by zero voltage; this mode is until the charging current of the first capacitor drops to 0.

An eleventh operating mode: corresponding to step S11, as shown in fig. 13, the first switching tube and the fourth switching tube are turned on, and the second switching tube and the third switching tube are turned off, which remains unchanged from the operation mode in step S0; the second diode is naturally turned off because the charging current of the first capacitor is reduced to 0; the current flowing through the coupling inductor of the first inductor increases linearly and the current flowing through the coupling inductor of the second inductor decreases linearly.

The twelfth operating mode: corresponding to step S12, as shown in fig. 14, the first switch tube is turned on, the second switch tube, the third switch tube and the fourth switch tube are turned off, and the fourth switch tube is turned off compared with the operation mode in step S1; under the action of the coupling inductor of the second inductor, the junction capacitor between the drain and the source of the second switching tube starts to discharge, and the junction capacitor between the drain and the source of the fourth switching tube starts to charge; inductor L_lkThe resonant capacitor resonates with the junction capacitor between the drain and the source of the third switching tube, so that the junction capacitor between the drain and the source of the third switching tube is discharged; in this mode, the junction capacitance voltage between the drain and the source of the third switch tube is from V_HDown toV_H1The junction capacitance between the drain and the source of the second switch tube is discharged to 0, and the junction capacitance between the drain and the source of the fourth switch tube is charged to V_H2Realizing the boosting process of the converter;

the step-down process comprises the following steps and corresponding working modes: (ii) a

The first mode of operation: corresponding to step B1, as shown in fig. 15, the first switching tube and the second switching tube are turned on, the third switching tube and the fourth switching tube are turned off, and the second switching tube is turned on in this operation mode; due to the existence of the diode of the second switch tube body, the second switch tube is switched on under the condition of zero voltage switching-on; during the period, the first direct current source flow forms a loop with the first switch tube through the coupling inductor of the first inductor and forms a loop with the second switch tube through the coupling inductor of the second inductor, so that the current flowing through the coupling inductor of the first inductor is linearly increased in the reverse direction, the current flowing through the coupling inductor of the second inductor is linearly decreased in the reverse direction, and the current flows into the first direct current source flow; at this time, no current flows in the first inductor and the second inductor.

The second working mode is as follows: corresponding to step B2, as shown in fig. 16, the second switch tube is turned on, the first switch tube, the third switch tube and the fourth switch tube are turned off, and the first switch tube is turned off compared with the operation mode in step B1; at the moment, the junction capacitor between the drain and the source of the first switching tube starts to charge, and the junction capacitor between the drain and the source of the third switching tube starts to discharge; inductor L_lkAnd charging the junction capacitor between the drain and the source of the fourth switch tube to generate resonance.

The third mode of operation: corresponding to step B3, as shown in fig. 17, the second switching tube is turned on, and the first switching tube, the third switching tube and the fourth switching tube are turned off, which remains unchanged from the operation mode in step B2; the voltage of the junction capacitor between the drain and the source of the fourth switch tube reaches V_H-V_CThe third diode is naturally conducted, and the first capacitor starts to discharge; in the last operating mode, the inductor L_lkThe junction capacitance between the fourth switch tube and the drain-source electrode is changed into an inductance L through resonance_lkThe junction capacitance between the drain and the source of the first switching tube and the junction capacitance between the drain and the source of the third switching tube resonate; by resonance, the first switching tube is leakyThe voltage of the junction capacitor between the source electrodes is charged to V_CAnd the voltage of the junction capacitor between the drain and the source of the third switch tube is discharged to 0.

A fourth mode of operation: corresponding to step B4, as shown in fig. 18, the second switching tube and the third switching tube are turned on, the first switching tube and the fourth switching tube are turned off, and the third switching tube is turned on compared with the operation mode in step B3; the body diode of the third switching tube is naturally conducted, so that the third switching tube is conducted by zero voltage; this mode is until the discharge current of the first capacitor drops to 0.

The fifth working mode: corresponding to step B5, as shown in fig. 19, the second switching tube and the third switching tube are turned on, and the first switching tube and the fourth switching tube are turned off, which remains unchanged from the operation mode in step B4; the third diode is naturally turned off because the charging current of the first capacitor is reduced to 0; the current flowing through the coupling inductor of the first inductor increases in a reverse linear manner, the current flowing through the coupling inductor of the second inductor decreases in a reverse linear manner, and the current flowing through the inductor L_lkThe current of (2) decreases linearly.

Sixth mode of operation: corresponding to step B6, as shown in fig. 20, the second switching tube is turned on, the first switching tube, the third switching tube and the fourth switching tube are turned off, and the third switching tube is turned off compared with the operation mode in step B5; under the action of the coupling inductor of the first inductor, the junction capacitor between the drain and the source of the first switching tube starts to discharge, and the junction capacitor between the drain and the source of the third switching tube starts to charge; inductor L_lkThe resonant capacitor resonates with the junction capacitor between the drain and the source of the fourth switching tube to discharge the junction capacitor between the drain and the source of the fourth switching tube; in this mode, the junction capacitance between the drain and source of the first switch is discharged to 0, and the junction capacitance between the drain and source of the third switch is charged to V_H1The voltage of the junction capacitor between the drain and the source of the fourth switch tube is from V_H-V_CDown to V_H2。

Seventh mode of operation: corresponding to step B7, as shown in fig. 21, the first switch tube and the second switch tube are turned on, the third switch tube and the fourth switch tube are turned off, and the first switch tube is turned on compared with the operation mode in step B6; the junction capacitance between the drain and the source of the first switch tube is discharged to 0, and the first switch tube is turned on and conducted at zero voltage; during the period, the first direct current source flow forms a loop with the first switch tube through the coupling inductor of the first inductor and forms a loop with the second switch tube through the coupling inductor of the second inductor, so that the current flowing through the coupling inductor of the first inductor is linearly reduced in the reverse direction, the current flowing through the coupling inductor of the second inductor is linearly increased in the reverse direction, and the current flows into the first direct current source flow; at this time, no current flows in the first inductor and the second inductor.

The eighth mode of operation: corresponding to step B8, as shown in fig. 22, the first switch tube is turned on, the second switch tube, the third switch tube and the fourth switch tube are turned off, and the second switch tube is turned off compared with the operation mode in step B7; at the moment, due to the action of the coupling inductor of the second inductor, the junction capacitor between the drain and the source of the second switching tube starts to be charged, and the junction capacitor between the drain and the source of the fourth switching tube starts to be discharged; and the inductor Llk charges the junction capacitor between the drain and the source of the third switching tube, so that resonance occurs.

Ninth mode of operation: corresponding to step B9, as shown in fig. 23, the first switch tube is turned on, and the second switch tube, the third switch tube and the fourth switch tube are turned off, which remains unchanged from the operation mode in step B8; the voltage of the junction capacitor between the drain and the source of the second switching tube reaches V_CWhen the second diode is naturally conducted, the voltage of the junction capacitor between the drain and the source of the second switch tube is stabilized to be V_CThe first capacitor starts to charge; and in the working mode of the step B8, the inductor L_lkThe junction capacitance between the third switch tube and the drain-source electrode is changed into an inductance L_lkThe junction capacitance between the drain and the source of the third switching tube and the junction capacitance between the drain and the source of the fourth switching tube resonate; through resonance, the voltage of the junction capacitor between the drain and the source of the third switch tube is charged to V_HAnd the voltage of the junction capacitance between the drain and the source of the fourth switch tube is discharged to 0.

The tenth operating mode: corresponding to step B10, as shown in fig. 24, the first switching tube and the fourth switching tube are turned on, the second switching tube and the third switching tube are turned off, and the fourth switching tube is turned on compared with the operation mode in step B9; the body diode of the fourth switching tube is naturally conducted, so that the fourth switching tube is conducted by zero voltage; this mode is until the charging current of the first capacitor drops to 0.

An eleventh operating mode: corresponding to step B11, as shown in fig. 25, the first switching tube and the fourth switching tube are turned on, and the second switching tube and the third switching tube are turned off, which remains unchanged from the operation mode in step B10; the second diode is naturally turned off because the charging current of the first capacitor is reduced to 0; the current flowing through the coupling inductor of the first inductor decreases in a reverse linear manner, the current flowing through the coupling inductor of the second inductor increases in a reverse linear manner, and the current flowing through the inductor L_lkThe current of (2) increases linearly.

The twelfth operating mode: corresponding to step B12, as shown in fig. 26, the first switch tube is turned on, the second switch tube, the third switch tube and the fourth switch tube are turned off, and the fourth switch tube is turned off compared with the operation mode in step B11; under the action of the coupling inductor of the second inductor, the junction capacitor between the drain and the source of the second switching tube starts to discharge, and the junction capacitor between the drain and the source of the fourth switching tube starts to charge; inductor L_lkThe resonant capacitor resonates with the junction capacitor between the drain and the source of the third switching tube, so that the junction capacitor between the drain and the source of the third switching tube is discharged; in the mode, the junction capacitance between the drain and the source of the second switching tube is discharged to 0, and the voltage of the junction capacitance between the drain and the source of the third switching tube is from V_HDown to V_H1And charging the junction capacitor between the drain and the source of the fourth switch tube to V_H2。

The V is_HIs the voltage across the first capacitor, V_H1Is the voltage across the second capacitor, V_H2Is the voltage across the third capacitor;

the coupling inductance of the third inductor and the coupling inductance of the fourth inductor are equivalent to a coupling inductance L_lk。