High-boost isolated DC converter with parallel input and series output
阅读说明：本技术 一种并联输入串联输出的高升压隔离型直流变换器 (High-boost isolated DC converter with parallel input and series output ) 是由 张善路 李磊 于 2020-04-13 设计创作，主要内容包括：本发明公开了一种并联输入串联输出的高升压隔离型直流变换器。该变换器拓扑结构由电流型推挽电路模块和有源钳位反激电路模块构成了具有输入电压可调、输出电压高增益的隔离型直流变换器；电气连接为电流型推挽电路模块、有源钳位反激电路模块输入侧并联和输出侧串联,并联输入连接可以承受大电流输入减小了电流纹波,串联输出连接增加了输出电压增益；其中电流型推挽电路模块实现了零电压开通和零电流关断,减少了开关损耗,提高了工作效率和降低了电磁干扰；有源钳位反激电路模块则辅助输出电压的调节,实现最大功率分配下的最高效率转换。本发明输入电压可调、可宽负载运行,具有电路结构简单、开关损耗小、转换效率高、输出电压增益高等优点。(The invention discloses a high-boost isolated direct current converter with parallel input and series output. The converter topological structure is characterized in that an isolated direct current converter with adjustable input voltage and high output voltage gain is formed by a current type push-pull circuit module and an active clamping flyback circuit module; the electric connection is that the input sides of the current type push-pull circuit module and the active clamping flyback circuit module are connected in parallel and the output side is connected in series, the parallel input connection can bear heavy current input to reduce current ripples, and the series output connection increases output voltage gain; the current type push-pull circuit module realizes zero-voltage switching-on and zero-current switching-off, reduces switching loss, improves working efficiency and reduces electromagnetic interference; the active clamp flyback circuit module assists in adjusting output voltage, and maximum efficiency conversion under maximum power distribution is achieved. The invention has the advantages of adjustable input voltage, wide load operation, simple circuit structure, small switching loss, high conversion efficiency, high output voltage gain and the like.)
1. A high-boost isolated direct current converter with parallel input and series output is characterized by comprising a current type push-pull circuit module and an active clamp flyback circuit module, wherein the input sides of the current type push-pull circuit module and the active clamp flyback circuit module are connected in parallel, and the output sides of the current type push-pull circuit module and the active clamp flyback circuit module are connected in series;
the current-mode push-pull circuit module comprises a first DC input voltage source (V)in) A first input inductor (L)in) A first input capacitor (C)in) A second resonant capacitor (C)r) A first transformer (T)1) A first excitation inductance (L)m1) A second excitation inductor (L)m2) A first leakage inductance (L)k1) A second leakage inductance (L)k2) The first MOSFET (S)1) And a second MOSFET (S)2) A first diode (D)1) A second diode (D)2) A third diode (D)3) A fourth diode (D)4) A first output capacitor (C)o1) A first output voltage source (V)o) (ii) a The current type push-pull circuit module is used for zero voltage switching-on and zero current switching-off;
the active clamping flyback circuit module comprises a third clamping capacitor (C)L) And the third MOSFET (S)3) And the fourth MOSFET (S)4) And the fifth MOSFET (S)5) A second transformer (T)2) A third excitation inductor (L)m3) A third leakage inductance (L)k3) A second output capacitor (C)o2) (ii) a The active clamp flyback circuit module is used for assisting in the regulation of the output voltage.
2. The high-boost isolated DC converter according to claim 1, wherein the first DC input voltage source (V) isin) Simultaneously with the first input inductor (L)in) One terminal of (1), a first input capacitance (C)in) Positive electrode of (2), third clamping capacitance (C)L) Positive electrode of (2), third leakage inductance (L)k3) One end of the two ends are connected; a first DC input voltage source (V)in) Is simultaneously connected with the first input capacitor (C)in) Negative electrode of (2), second resonance capacitor (C)r) Negative electrode of (1), first MOSFET (S)1) Source electrode, firstTwo MOSFET tubes (S)2) Source electrode, third MOSFET tube (S)3) Source connected, first drain inductive reactance (L)k1) A second leakage inductance (L)k2) And a first transformer (T)1) Series, a first excitation inductance (L)m1) A second excitation inductor (L)m2) And a first transformer (T)1) Parallel connection; first MOSFET tube (S)1) A drain and a first drain reactance (L)k1) One end of the two ends are connected; second MOSFET tube (S)2) A drain and a second drain reactance (L)k2) Is connected to one end of the first drain inductive reactance (L)k1) And the other end of the first excitation inductor (L)m1) Is connected to a second drain inductive reactance (L)k2) And the other end of the second excitation inductor (L)m2) Is connected to a first excitation inductance (L)m1) And the other end of the second excitation inductor (L)m2) Is connected to the other end of the first input inductor (L)in) And the other end of the first resonant capacitor (C) and a second resonant capacitor (C)r) Is connected with the positive pole of the first excitation inductor (L) and the common terminal is connected with the first excitation inductorm1) A second excitation inductor (L)m2) A common terminal of (a);
the first diode (D)1) And a third diode (D)3) Are connected in series; second diode (D)2) And a fourth diode (D)4) Are connected in series; a first diode (D)1) An anode and a third diode (D)3) The negative electrode is connected with one end of the secondary side of the transformer; second diode (D)2) An anode and a fourth diode (D)4) The negative pole is connected with the other end of the secondary side of the transformer, and a third leakage inductance (L)k3) And a second transformer (T)2) Series, third excitation inductance (L)m3) And a second transformer (T)2) Parallel, third clamping capacitance (C)L) Positive electrode and third leakage inductance (L)k3) Is connected to a third drain inductive reactance (L)k3) And the other end of the third excitation inductor (L)m3) One end of the two ends are connected; fourth MOSFET (S)4) Drain and third clamp capacitor (C)L) The negative electrodes are connected; fourth MOSFET (S)4) The source electrode is respectively connected with a third MOSFET (S)3) Drain, third driving inductance (L)m3) The other ends of the two are connected; fifth MOSFET (S)5) And the second transformer (T)2) One end of the secondary side is connected; first, theFive MOSFET tubes (S)5) Source and second output capacitor (C)o2) The negative electrodes are connected; second output capacitance (C)o2) The positive pole is connected with a second transformer (T)2) The other end of the secondary side of (C), a first output capacitor (C)o1) The negative electrodes are connected; a first output capacitor (C)o1) A second output capacitor (C)o2) Connected in series with a first output voltage source (V)o) And (4) connecting in parallel.
3. The high-boost isolated DC converter according to claim 2, wherein the first to fifth MOSFET transistors (S)1～S5) The MOSFET tubes are respectively added with a first anti-parallel diode (D) to a fifth anti-parallel diode (D)s1～Ds5) And first to fifth parallel parasitic capacitances (C)s1～Cs5) And has the follow current capability.
4. The high-boost isolated DC converter according to claim 2 or 3, wherein the first to fifth MOSFET transistors (S)1～S5) The grid electrode and the source electrode of the MOSFET are respectively provided with a control driving signal provided by an external circuit, and the control driving signal of each MOSFET is a sine modulation wave emSame amplitude and same frequency triangular carrier wave eiAnd (5) comparing and determining.
5. The high-boost isolated DC converter according to claim 4, wherein the current-type push-pull circuit module has 8 operating states in one switching cycle, let tiThe time points are represented as follows, i is 0,1,2,3,4,5,6,7 and 8:
at t0～t1First MOSFET (S)1) Opening; the current passes through a first transformer (T)1) The primary winding transfers energy to the secondary side, and the current passes through the first MOSFET tube (S)1) At the first drain inductance (L)k1) And a second resonance capacitor (C)r) In the first transformer (T) is resonant when the first transformer (T) is in use1) First excitation inductance (L)m1) Charging, with linearly increasing exciting currentUntil t1Ending the moment;
at t1～t2First MOSFET (S)1) Turning off; first excitation current Im1Begins to decrease while the second excitation current I is simultaneously decreasedm2Begins to increase, according to kirchhoff's law, when the resonant current IrEqual to the first excitation current Im1And a second excitation current Im2Difference of difference, when t is reached2At the moment according to the first transformer (T)1) Flux balance relationship, first excitation current Im1And a second excitation current Im2Crossing to an intermediate value of maximum exciting current Im(max)Half of (1); resonant current IrDrops to zero, switch S1Switching off at zero current, namely ZCS; first excitation current Im1A second exciting current Im2Respectively, a first excitation inductance (L)m1) A second excitation inductor (L)m2) The generated excitation current;
at t2～t3When resonance is complete, the first excitation inductance (L)m1) A second excitation inductor (L)m2) The generated exciting current is the first MOSFET tube (S)1) First parallel parasitic capacitance (C)s1) Charging to make the second MOSFET tube (S)2) Second parallel parasitic capacitance (C)s2) Discharging; therefore, when the first MOSFET is on (S)1) Charging to a second resonant capacitor (C)r) At twice the voltage, the second MOSFET (S)2) The voltage drop over is zero;
at t3～t4When the second MOSFET is on (S)2) Second parallel parasitic capacitance (C)s2) When the discharge is complete, the second MOSFET tube (S)2) Realize zero voltage turn-on, second anti-parallel diode (D)s2) Conducting in the forward direction;
at t4～t5Second MOSFET (S)2) Opening; the current passes through a first transformer (T)1) The primary winding transmits energy to the secondary winding; the current passes through the second MOSFET tube (S)2) At the second drain reactance (L)k2) And a second resonance capacitor (C)r) Resonance is generated between the two; at this time, the first transformer (T)1) Second excitation ofInductor (L)m2) Charging, the exciting current linearly increasing until t5Ending the moment;
at t5～t6Second excitation current Im2Begins to decrease while the first excitation current Im1Starting to increase; from kirchhoff's law, when the resonant current IrEqual to the first excitation current Im1And a second excitation current Im2The difference between the two; when t is reached6At the moment according to the first transformer (T)1) Flux balance relationship, first excitation current Im1And a second excitation current Im2Crossing to an intermediate value of maximum exciting current Im(max)Half of (1); resonant current IrDrops to zero, switch S2Turn off at Zero Current (ZCS);
at t6～t7When resonance is complete, the first excitation inductance (L)m1) A second excitation inductor (L)m2) The generated exciting current is a second MOSFET (S)2) Second parallel parasitic capacitance (C)s2) Charging to make the first MOSFET (S)1) First parallel parasitic capacitance (C)s1) Discharging; therefore, when the second MOSFET is used (S)2) Charging to a second resonant capacitor (C)r) At twice the voltage, the first MOSFET (S)1) The voltage drop over is zero;
at t7～t8When the first MOSFET is on (S)1) First parallel parasitic capacitance (C)s1) When the discharge is complete, the first MOSFET tube (S)1) Realizing zero voltage switching-on (ZVS), a first anti-parallel diode (D)s1) And conducting in the forward direction.
6. The parallel-input series-output high-boost isolated DC converter according to claim 2,3 or 5, characterized in that the whole converter input voltage range is set to 24V-32V, the switching frequency is fixed to 500kHz, and the first transformer (T) is set1) The voltage transformation ratio is 1:12, and the output voltage is 400V;
the active clamping flyback circuit module enables a self circuit to work in a boosting or voltage-reducing mode by controlling the duty ratio according to different input voltages so as to compensate the whole output voltage set value of 400V; if the input voltage is 24V, the output voltage of the current type push-pull circuit module is 288V, at the moment, the active clamping flyback circuit module enables the active clamping flyback circuit module to work in a boost mode by adjusting the duty ratio, and the output voltage is 112V; if the input voltage is 32V, the output voltage of the current type push-pull circuit module is 384V, at the moment, the active clamping flyback circuit module enables the active clamping flyback circuit module to work in a step-down mode by adjusting the duty ratio, and the output voltage is 16V.
Technical Field
The invention relates to the technical field of power electronics, in particular to a high-boost isolated direct current converter with parallel input and series output.
Background
With the rapid development of scientific technology and social economy, the problems of energy consumption and environmental protection are increasingly prominent, and the problems of environmental pollution such as haze, greenhouse effect and the like caused by the use of fossil fuels are increasingly serious. The large-scale development and utilization of new energy sources such as solar energy, wind energy, hydrogen energy, biomass energy, ocean energy and the like is an effective way for solving the problems. The direct current converter is a key component of a new energy power generation system such as solar energy, wind energy and a fuel cell, and the performance of the direct current converter is directly related to the overall technology, the input return rate and the sustainable development of the new energy power generation system. The transmission efficiency and the reliability of the converter are further improved, the size is reduced, and the cost is reduced.
The switching frequency of a power tube of the japanese scholars AlsbachW, and the like, needs to be less than the resonant frequency to ensure that the voltages at two ends of S1 and S2 are resonated to zero before the power tube is switched on, and zero voltage switching-on (ZVS) is realized.
The push-pull direct-current converter has the advantages of simple structure, electrical isolation, high transformer utilization rate and the like, is often applied to a distributed power generation system, has the problems of large hard switching loss, high electrical stress and the like of the traditional push-pull converter, still has the problems of variable frequency regulation, difficult optimization design of magnetic elements, complex structure of a clamping absorption circuit, large bidirectional conversion circulating current loss, limitation of a multi-phase structure to hard switching work, large switching loss and the like of the traditional voltage and current optimization push-pull converter.
Disclosure of Invention
The invention aims to provide a high-boost isolated direct current converter which is connected in parallel, input and output in series, has a simple circuit structure, small switching loss, high conversion efficiency, high output voltage gain, adjustable input voltage and wide-load operation.
The technical solution for realizing the purpose of the invention is as follows: a high-boost isolated direct current converter with parallel input and series output comprises a current type push-pull circuit module and an active clamp flyback circuit module, wherein the input sides of the current type push-pull circuit module and the active clamp flyback circuit module are connected in parallel, and the output sides of the current type push-pull circuit module and the active clamp flyback circuit module are connected in series;
the current type push-pull circuit module comprises a first direct current input voltage source, a first input inductor, a first input capacitor, a second resonant capacitor, a first transformer, a first excitation inductor, a second excitation inductor, a first leakage inductance, a second leakage inductance, a first MOSFET, a second MOSFET, a first diode, a second diode, a third diode, a fourth diode, a first output capacitor and a first output voltage source; the current type push-pull circuit module is used for zero voltage switching-on and zero current switching-off;
the active clamping flyback circuit module comprises a third clamping capacitor, a third MOSFET, a fourth MOSFET, a fifth MOSFET, a second transformer, a third excitation inductor, a third leakage inductance and a second output capacitor; the active clamp flyback circuit module is used for assisting in the regulation of the output voltage.
Furthermore, the positive electrode of the first direct current input voltage source is simultaneously connected with one end of the first input inductor, the positive electrode of the first input capacitor, the positive electrode of the third clamping capacitor and one end of the third leakage inductance; the negative electrode of the first direct current input voltage source is simultaneously connected with the negative electrode of the first input capacitor, the negative electrode of the second resonant capacitor, the source electrode of the first MOSFET, the source electrode of the second MOSFET and the source electrode of the third MOSFET; the first leakage inductance and the second leakage inductance are connected with the first transformer in series; the first excitation inductor and the second excitation inductor are connected with the first transformer in parallel; the drain electrode of the first MOSFET is connected with one end of the first drain inductive reactance; the drain electrode of the second MOSFET is connected with one end of the second drain inductive reactance; the other end of the first leakage inductance is connected with one end of the first excitation inductor, the other end of the second leakage inductance is connected with one end of the second excitation inductor, and the other end of the first excitation inductor is connected with the other end of the second excitation inductor; the other end of the first input inductor is connected with the anode of the second resonant capacitor, and the common end of the first input inductor is connected to the common ends of the first excitation inductor and the second excitation inductor;
the first diode and the third diode are connected in series; the second diode and the fourth diode are connected in series; the anode of the first diode and the cathode of the third diode are connected with one end of the secondary side of the transformer; the anode of the second diode and the cathode of the fourth diode are connected with the other end of the secondary side of the transformer; the third leakage inductance is connected with the second transformer in series, the third excitation inductance is connected with the second transformer in parallel, the anode of the third clamping capacitor is connected with one end of the third leakage inductance, and the other end of the third leakage inductance is connected with one end of the third excitation inductance; the drain electrode of the fourth MOSFET is connected with the negative electrode of the third clamping capacitor; the source electrode of the fourth MOSFET is respectively connected with the drain electrode of the third MOSFET and the other end of the third excitation inductor; the drain electrode of the fifth MOSFET is connected with one end of the secondary side of the second transformer; the source electrode of the fifth MOSFET is connected with the cathode of the second output capacitor; the positive electrode of the second output capacitor is respectively connected with the other end of the secondary side of the second transformer and the negative electrode of the first output capacitor; the first output capacitor and the second output capacitor are connected in series and then connected in parallel with the first output voltage source.
Furthermore, the first to fifth MOSFET tubes are respectively added with first to fifth anti-parallel diodes and first to fifth parallel parasitic capacitors, and have a follow current capability.
Furthermore, control driving signals provided by an external circuit are received between the grid electrode and the source electrode of the first MOSFET, the control driving signal of each MOSFET is a sine modulation wave emSame amplitude and same frequency triangular carrier wave eiAnd (5) comparing and determining.
Furthermore, the current-type push-pull circuit module comprises 8 working states in one switching period, and t is setiThe time points are represented as follows, i is 0,1,2,3,4,5,6,7 and 8:
at t0～t1The first MOSFET is turned on; energy is transmitted to the secondary side by the current through the primary winding of the first transformer, resonance is generated between the first leakage inductance and the second resonance capacitor when the current passes through the leakage source electrode of the first MOSFET, at the moment, the first excitation inductance of the first transformer is charged, and the excitation current isLinearized rising until t1Ending the moment;
at t1～t2The first MOSFET is turned off; first excitation current Im1Begins to decrease while the second excitation current I is simultaneously decreasedm2Begins to increase, according to kirchhoff's law, when the resonant current IrEqual to the first excitation current Im1And a second excitation current Im2Difference of difference, when t is reached2At the moment, the first excitation current I is based on the flux balance relation of the first transformerm1And a second excitation current Im2Crossing to an intermediate value of maximum exciting current Im(max)Half of (1); resonant current IrDrops to zero, switch S1Switching off at zero current, namely ZCS; first excitation current Im1A second exciting current Im2The excitation currents are respectively generated by the first excitation inductor and the second excitation inductor;
at t2～t3After the resonance is finished, the exciting currents generated by the first exciting inductor and the second exciting inductor charge the first parallel parasitic capacitor of the first MOSFET tube, so that the second parallel parasitic capacitor of the second MOSFET tube is discharged; therefore, when the first MOSFET is charged to twice the voltage of the second resonant capacitor, the voltage drop on the second MOSFET is zero;
at t3～t4When the second parallel parasitic capacitor of the second MOSFET is completely discharged, the second MOSFET realizes zero-voltage switching-on, and the second anti-parallel diode is conducted in the forward direction;
at t4～t5The second MOSFET is turned on; the current transmits energy to a secondary side through a primary winding of the first transformer; when the current passes through the drain and the source of the second MOSFET, resonance is generated between the second drain inductive reactance and the second resonance capacitor; at the moment, the second exciting inductor of the first transformer is charged, and the exciting current rises linearly until t5Ending the moment;
at t5～t6Second excitation current Im2Begins to decrease while the first excitation current Im1Starting to increase; from kirchhoff's law, when the resonant current IrEqual to the first excitationStream Im1And a second excitation current Im2The difference between the two; when t is reached6At the moment, the first excitation current I is based on the flux balance relation of the first transformerm1And a second excitation current Im2Crossing to an intermediate value of maximum exciting current ImHalf of (1); resonant current IrDrops to zero, switch S2Turn off at Zero Current (ZCS);
at t6～t7After the resonance is finished, the exciting currents generated by the first exciting inductor and the second exciting inductor charge the second parallel parasitic capacitor of the second MOSFET tube, so that the first parallel parasitic capacitor of the first MOSFET tube is discharged; therefore, when the second MOSFET is charged to twice the voltage of the second resonant capacitor, the voltage drop on the first MOSFET is zero;
at t7～t8When the first parallel parasitic capacitor of the first MOSFET is completely discharged, the first MOSFET realizes zero voltage turn-on, and the first anti-parallel diode is conducted in the forward direction.
Further, setting the input voltage range of the whole converter to be 24V-32V, fixing the switching frequency to be 500kHz, setting the voltage transformation ratio of a first transformer to be 1:12, and outputting the voltage to be 400V;
the active clamping flyback circuit module enables a self circuit to work in a boosting or voltage-reducing mode by controlling the duty ratio according to different input voltages so as to compensate the whole output voltage set value of 400V; if the input voltage is 24V, the output voltage of the current type push-pull circuit module is 288V, at the moment, the active clamping flyback circuit module enables the active clamping flyback circuit module to work in a boost mode by adjusting the duty ratio, and the output voltage is 112V; if the input voltage is 32V, the output voltage of the current type push-pull circuit module is 384V, at the moment, the active clamping flyback circuit module enables the active clamping flyback circuit module to work in a step-down mode by adjusting the duty ratio, and the output voltage is 16V.
Compared with the prior art, the invention has the remarkable advantages that: (1) the input sides of the current type push-pull circuit module and the active clamping flyback circuit module are connected in parallel, and the output sides of the current type push-pull circuit module and the active clamping flyback circuit module are connected in series, the parallel input connection can bear heavy current input, current ripples are reduced, and the series output connection increases output voltage gain; (2) the current source type push-pull converter can realize zero voltage switching-on (ZVS) and zero current switching-off (ZCS), reduces switching loss, improves working efficiency and reduces electromagnetic interference; (3) the active clamping flyback circuit module can assist in achieving output voltage regulation, and ensures that energy transmitted when input voltage is minimum is maximum and energy transmitted when input voltage is maximum is minimum, so that maximum efficiency conversion under maximum power distribution is achieved.
Drawings
Fig. 1 is a schematic structural diagram of a high-boost isolated dc converter with parallel input and series output according to the present invention.
Fig. 2 is a theoretical analysis diagram of the waveform of the steady-state operation mode of the present invention.
Detailed Description
The invention relates to a high-boost isolated direct current converter with parallel input and series output, which comprises a current type push-pull circuit module and an active clamp flyback circuit module, wherein the input sides of the current type push-pull circuit module and the active clamp flyback circuit module are connected in parallel, and the output sides of the current type push-pull circuit module and the active clamp flyback circuit module are connected in series.
The current type push-pull circuit module comprises a first direct current input voltage source VinFirst input inductor LinA first input capacitor CinA second resonant capacitor CrA first transformer T1First excitation inductor Lm1A second excitation inductor Lm2First leakage reactance Lk1A second leakage reactance Lk2The first MOSFET S1A second MOSFET S2A first diode D1A second diode D2A third diode D3A fourth diode D4A first output capacitor Co1A first output voltage source Vo(ii) a The current type push-pull circuit module is used for zero voltage switching-on and zero current switching-off;
the active clamping flyback circuit module comprises a third clamping capacitor CLAnd a third MOSFET S3And a fourth MOSFET S4The fifth MOSFET S5A second transformer T2A third excitation inductor Lm3Third leakage reactance Lk3Second, secondOutput capacitor Co2(ii) a The active clamping flyback circuit module is used for assisting in adjusting output voltage, and ensures that transmitted energy is maximum when input voltage is minimum and transmitted energy is minimum when input voltage is maximum, so that maximum efficiency conversion under maximum power distribution is achieved.
The first DC input voltage source VinIs simultaneously coupled to the first input inductor LinOne terminal of (1), a first input capacitor CinPositive electrode of the third clamping capacitor CLPositive electrode of (2), third leakage inductance Lk3One end of the two ends are connected; a first DC input voltage source VinWith the negative pole of the first input capacitor CinNegative electrode of (1), and second resonance capacitor CrNegative electrode of (1), first MOSFET1Source electrode, second MOSFET tube S2Source electrode, third MOSFET S3Source connected, first leakage reactance Lk1A second leakage reactance Lk2And a first transformer T1Series, first excitation inductor Lm1A second excitation inductor Lm2And a first transformer T1Parallel connection; first MOSFET tube S1Drain and first drain reactance Lk1One end of the two ends are connected; second MOSFET tube S2Drain and second drain reactance Lk2Is connected to one end of the first leakage inductance Lk1And the other end of the first excitation inductor Lm1Is connected to a second leakage reactance Lk2And the other end of the second excitation inductor Lm2Is connected to a first excitation inductor Lm1And the other end of the second excitation inductor Lm2Is connected to the other end of the first input inductor LinAnd the other end of the first resonant capacitor CrIs connected with the anode of the first excitation inductor L and the common terminal is connected with the first excitation inductor Lm1A second excitation inductor Lm2A common terminal of (a);
the first diode D1And a third diode D3Are connected in series; second diode D2And a fourth diode D4Are connected in series; first diode D1Anode and third diode D3The negative electrode is connected with one end of the secondary side of the transformer; second diode D2Positive and fourth diodes D4The negative electrode is connected with the other end of the secondary side of the transformer;third leakage reactance Lk3And a second transformer T2Series, third excitation inductor Lm3And a second transformer T2Parallel, third clamping capacitance CLPositive electrode of (2) and third leakage inductance Lk3Is connected to the third leakage reactance Lk3And the other end of the third excitation inductor Lm3One end of the two ends are connected; fourth MOSFET S4Drain and third clamp capacitor CLThe negative electrodes are connected; fourth MOSFET S4The source electrode is respectively connected with a third MOSFET3Drain, third excitation inductor Lm3The other ends of the two are connected; fifth MOSFET S5And the second transformer T2One end of the secondary side is connected; fifth MOSFET S5Source and second output capacitor Co2The negative electrodes are connected; second output capacitor Co2The positive electrodes of the two transformers are respectively connected with the second transformer T2The other end of the secondary side and a first output capacitor Co1The negative electrodes are connected; a first output capacitor Co1A second output capacitor Co2Connected in series and then connected with a first output voltage source VoAnd (4) connecting in parallel.
Further, first to fifth MOSFET S1～S5The MOSFET tubes are respectively added with a first anti-parallel diode D to a fifth anti-parallel diode Ds1～Ds5And first to fifth parallel parasitic capacitances Cs1～Cs5And has the follow current capability.
Further, first to fifth MOSFET S1～S5The grid electrode and the source electrode of the MOSFET are respectively provided with a control driving signal provided by an external circuit, and the control driving signal of each MOSFET is a sine modulation wave emSame amplitude and same frequency triangular carrier wave eiAnd (5) comparing and determining.
Furthermore, the current-type push-pull circuit module comprises 8 working states in one switching period, and t is setiThe time points are represented as follows, i is 0,1,2,3,4,5,6,7 and 8:
at t0～t1First MOSFET tube S1Opening; the current passes through the first transformer T1The primary winding transfers energy to the secondary side, and the current passes through the first MOSFET tube S1At the first drain-source impedance Lk1And a second resonant capacitor CrGenerates resonance therebetween when the first transformer T1First excitation inductor Lm1Charging, the exciting current linearly increasing until t1Ending the moment;
at t1～t2First MOSFET tube S1Turning off; first excitation current Im1Begins to decrease while the second excitation current I is simultaneously decreasedm2Begins to increase, according to kirchhoff's law, when the resonant current IrEqual to the first excitation current Im1And a second excitation current Im2Difference of difference, when t is reached2At the moment according to the first transformer T1Flux balance relationship, first excitation current Im1And a second excitation current Im2Crossing to an intermediate value of maximum exciting current ImmaxHalf of (1); resonant current IrDrops to zero, switch S1Switching off at zero current, namely ZCS; first excitation current Im1A second exciting current Im2Respectively, first excitation inductor Lm1A second excitation inductor Lm2The generated excitation current;
at t2～t3When resonance is complete, the first excitation inductor Lm1A second excitation inductor Lm2The generated exciting current is the first MOSFET tube S1First parallel parasitic capacitance Cs1Charging to make the second MOSFET tube S2Second parallel parasitic capacitance Cs2Discharging; therefore, when the first MOSFET S1Charging to a second resonant capacitor CrAt twice the voltage, the second MOSFET S2The voltage drop over is zero;
at t3～t4When the second MOSFET tube S2Second parallel parasitic capacitance Cs2When the discharge is complete, the second MOSFET tube S2Realize zero voltage turn-on, second anti-parallel diode Ds2Conducting in the forward direction;
at t4～t5Second MOSFET tube S2Opening; the current passes through the first transformer T1The primary winding transmits energy to the secondary winding; the current passes through the second MOSFET tube S2Second leakage inductance of sourceAnti Lk2And a second resonant capacitor CrResonance is generated between the two; at this time, the first transformer T1Second excitation inductor Lm2Charging, the exciting current linearly increasing until t5Ending the moment;
at t5～t6Second excitation current Im2Begins to decrease while the first excitation current Im1Starting to increase; from kirchhoff's law, when the resonant current IrEqual to the first excitation current Im1And a second excitation current Im2The difference between the two; when t is reached6At the moment according to the first transformer T1Flux balance relationship, first excitation current Im1And a second excitation current Im2Crossing to an intermediate value of maximum exciting current ImmaxHalf of (1); resonant current IrDrops to zero, switch S2Turn off ZCS at zero current;
at t6～t7When resonance is complete, the first excitation inductor Lm1A second excitation inductor Lm2The generated exciting current is a second MOSFET tube S2Second parallel parasitic capacitance Cs2Charging to make the first MOSFET S1First parallel parasitic capacitance Cs1Discharging; therefore, when the second MOSFET is used2Charging to a second resonant capacitor CrAt twice the voltage, the first MOSFET S1The voltage drop over is zero;
at t7～t8When the first MOSFET tube S1First parallel parasitic capacitance Cs1When the discharge is complete, the first MOSFET tube S1Realizing zero-voltage turn-on ZVS with a first anti-parallel diode Ds1And conducting in the forward direction.
The invention relates to a high-boost isolated DC converter with parallel input and series output, which has the working principle that: setting the input voltage range of the whole converter to be 24V-32V, fixing the switching frequency to be 500kHz, and setting the first transformer T1The voltage transformation ratio is 1:12, and the output voltage is 400V. The current type push-pull circuit module is responsible for transmission and conversion of most energy due to high voltage transformation ratio, so that the fluctuation of an output voltage range is large. In order to ensure that the output voltage is stable,at the moment, the active clamping flyback circuit module can enable the circuit to work in a boosting or voltage-reducing mode by controlling the duty ratio through software according to different input voltages so as to compensate the whole set value of the output voltage of 400V. If the input voltage is 24V, the output voltage of the current type push-pull circuit module is 288V, and at the moment, the active clamping flyback circuit module enables the active clamping flyback circuit module to work in a boost mode by adjusting the duty ratio, and the output voltage is 112V; if the input voltage is 32V, the output voltage of the current-type push-pull circuit module is 384V, and at this time, the active-clamp flyback circuit module operates in a buck mode by adjusting the duty ratio, and the output voltage is 16V. Thus, it is achieved that the energy transferred is maximal when the input voltage is minimal and minimal when the input voltage is maximal, thereby achieving a high efficiency high boost conversion at maximum power distribution.
The invention is described in further detail below with reference to the figures and the specific embodiments.
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