阅读说明：本技术 一种推挽串联谐振软开关切换电路及其切换方法和芯片 (Push-pull series resonance soft switch switching circuit and switching method and chip thereof ) 是由 曹龙 杨昌军 张大华 彭显征 于 2021-09-02 设计创作，主要内容包括：本发明涉及一种推挽串联谐振软开关切换电路,属于电子电路的技术领域,其包括原边推挽电路、变压器T1、整流电路、输出电路、控制电路、开关切换电路和谐振电路；其中,控制电路,用于检测直流电源DC输入的直流电压所表征的电压值,基于预设映射表,根据所述直流电压的电压值确定对应的预设控制策略,根据所述预设控制策略生成对应的控制信号并发送至开关切换电路；开关切换电路,响应于控制信号切换变压器T1副边绕组的对应抽头接入电路,以调节至相应的档位。本发明具有降低电路损耗的效果。(The invention relates to a push-pull series resonance soft switch switching circuit, which belongs to the technical field of electronic circuits and comprises a primary side push-pull circuit, a transformer T1, a rectifying circuit, an output circuit, a control circuit, a switch switching circuit and a resonance circuit; the control circuit is used for detecting a voltage value represented by direct-current voltage input by a direct-current power supply DC, determining a corresponding preset control strategy according to the voltage value of the direct-current voltage based on a preset mapping table, generating a corresponding control signal according to the preset control strategy and sending the control signal to the switch switching circuit; and the switch switching circuit responds to the control signal to switch the corresponding tap access circuit of the secondary winding of the transformer T1 to adjust to the corresponding gear. The invention has the effect of reducing circuit loss.)

1. A push-pull series resonance soft switch switching circuit comprises a primary side push-pull circuit (101), a transformer T1, a rectifying circuit (102) and an output circuit (103), wherein a middle tap point of a primary side of the transformer T1 is connected to a DC positive electrode of a direct-current power supply, the primary side push-pull circuit (101) is used for converting direct-current voltage input by the direct-current power supply into alternating-current voltage, and the transformer T1 is used for boosting the alternating-current voltage; the rectification circuit (102) is connected to a secondary winding of the transformer T1, and is used for full-wave rectification of the boosted alternating-current voltage and outputting direct-current voltage; the output circuit (103) is used for storing the direct-current voltage output by the rectifying circuit (102); the method is characterized in that:

the circuit also comprises a control circuit (104), a switch switching circuit (105) and a resonance circuit;

the control circuit (104) is used for detecting a voltage value represented by a direct-current voltage input by a direct-current power supply DC, determining a corresponding preset control strategy according to the voltage value of the direct-current voltage based on a preset mapping table, generating a corresponding control signal according to the preset control strategy and sending the control signal to the switch switching circuit (105); the preset mapping table comprises a corresponding relation between a plurality of groups of voltage intervals and a preset control strategy;

the switch switching circuit (105) comprises a control signal input terminal, a first input terminal, a second input terminal and an output terminal; the resonant circuit comprises a first resonant unit, a second resonant unit and a third resonant unit; the secondary winding of the transformer T1 comprises a first tap, a second tap, a third tap and a fourth tap; a first tap of a secondary winding of the transformer T1 is connected to the first input end, a second tap of the secondary winding is connected to the second input end, and a third tap and a fourth tap of the secondary winding are both connected to the rectifying circuit (102); the first resonance unit is connected between a first tap and a first input end, the second resonance unit is connected between a second tap and a second input end, and the third resonance unit is connected between a third tap and the rectifying circuit (102);

the output end of the switch switching circuit (105) is connected with the voltage output end Hv of the output circuit (103), and the control signal input end is connected with the control signal output end of the control circuit (104); the switch switching circuit (105) responds to a control signal to switch corresponding tap access circuits of the secondary winding of the transformer T1 to adjust to corresponding gears.

2. The push-pull series resonant soft-switching circuit of claim 1, wherein: the control circuit (104) comprises a control chip U5, the voltage input end of the control chip U5 is connected to the positive pole of the direct current power supply DC, and the control signal output end of the control chip U5 is connected to the control signal output end of the control circuit (104).

3. The push-pull series resonant soft-switching circuit of claim 1, wherein: the switch switching circuit (105) comprises a first resistor R1, a first photocoupler U1, a second resistor R2, a third resistor R3, a first NMOS transistor Q1, a first NPN triode Q2, a first diode D1, a second diode D2, a fourth resistor R4, a second photocoupler U2, a fifth resistor R5, a sixth resistor R6, a second NPN triode Q4, a second NMOS transistor Q3, a third diode D3 and a fourth diode D4;

the control signal inputs of the switching circuit (105) comprise a first control signal input CTL1 and a second control signal input CTL 2;

one end of the first resistor R1 is connected to the first control signal input end CTL1, and the other end is connected to the anode of the first photocoupler U1; the cathode of the first photocoupler U1 is grounded, the collector of the first photocoupler U1 is respectively connected to one end of a first power supply VCC1 and one end of a second resistor R2, and the emitter of the first photocoupler U1 is connected to one end of a third resistor R3; the other end of the second resistor R2 is respectively connected to the grid of a first NMOS tube Q1 and the collector of a first NPN triode Q2, the other end of the third resistor R3 is connected to the base of a first NPN triode Q2, and the emitter of the first NPN triode Q2 is respectively connected to the source of the first NMOS tube Q1 and the output end of the switch switching circuit (105); the drain of the first NMOS transistor Q1 is connected to the cathode of a first diode D1, the anode of the first diode D1 is respectively connected to the cathode of a second diode D2 and the second input end of the switch switching circuit (105), and the anode of the second diode D2 is connected to the reference end;

one end of the fourth resistor R4 is connected to the second control signal input terminal CTL2, and the other end is connected to the anode of the second photocoupler U2; the cathode of the second photocoupler U2 is grounded, the collector of the second photocoupler U2 is connected to one end of the first power supply VCC1 and one end of the fifth resistor R5 respectively, and the emitter of the second photocoupler U2 is connected to one end of the sixth resistor R6; the other end of the fifth resistor R5 is respectively connected to the gate of the second NMOS transistor Q3 and the collector of the second NPN triode Q4, the other end of the sixth resistor R6 is connected to the base of the second NPN triode Q4, and the emitter of the second NPN triode Q4 is respectively connected to the source of the second NMOS transistor Q3 and the output of the switching circuit (105); the drain of the second NMOS transistor Q3 is connected to the cathode of the third diode D3, the anode of the third diode D3 is connected to the cathode of the fourth diode D4 and the first input terminal of the switch switching circuit (105), respectively, and the anode of the fourth diode D4 is connected to the reference terminal.

4. The push-pull series resonant soft-switching circuit of claim 1, wherein: the first resonance unit comprises a first inductance module and a first capacitance module, wherein a first end of the first inductance module is connected to a first tap of a secondary winding of a transformer T1, a second end of the first inductance module is connected to a first end of the first capacitance module, and a second end of the first capacitance module is connected to a first input end of the switch conversion circuit;

the second resonance unit comprises a second inductance module and a second capacitance module, a first end of the second inductance module is connected to a second tap of a secondary winding of the transformer T1, a second end of the second inductance module is connected to a first end of the second capacitance module, and a second end of the second capacitance module is connected to a second input end of the switch conversion circuit;

the third resonance unit comprises a third inductance module and a third capacitance module, a first end of the third inductance module is connected to a third tap of a secondary winding of the transformer T1, a second end of the third inductance module is connected to a first end of the third capacitance module, and a second end of the third capacitance module is connected to the rectification circuit (102).

5. The push-pull series resonant soft-switching circuit of claim 4, wherein: the first inductance module, the second inductance module and the third inductance module all adopt equivalent leakage inductance of a secondary side of a transformer T1.

6. The push-pull series resonant soft-switching circuit of claim 4, wherein: the rectifying circuit (102) comprises a fifth diode D5, a sixth diode D6, a seventh diode D7 and an eighth diode D8;

the anode of the sixth diode D6 is connected to the cathode of the eighth diode D8 and the second end of the third capacitor module, the anode of the eighth diode D8 is connected to the anode of the seventh diode D7 and the reference terminal, the cathode of the seventh diode D7 is connected to the fourth tap of the secondary winding of the transformer T1 and the anode of the fifth diode D5, and the cathode of the fifth diode D5 is connected to the cathode of the sixth diode D6 and the voltage output terminal Hv of the output circuit (103).

7. The push-pull series resonant soft-switching circuit of any of claims 1 to 6, wherein: the output circuit (103) comprises a storage capacitor EC1 and a fourth nonpolar capacitor C4, the positive pole of the storage capacitor EC1 is respectively connected to one end of the fourth nonpolar capacitor C4 and the voltage output end Hv of the output circuit (103), and the negative pole of the storage capacitor EC1 is respectively connected to the reference end and the other end of the fourth nonpolar capacitor C4.

8. The push-pull series resonant soft-switching circuit of claim 7, wherein: further comprising a bleeding circuit (106), the bleeding circuit (106) comprising a seventh resistor R7, an eighth resistor R8, a ninth resistor R9 and a tenth resistor R10;

one end of the seventh resistor R7 is connected to the voltage output terminal Hv of the output circuit (103) and one end of the eighth resistor R8, and the other end is connected to one end of the ninth resistor R9, the other end of the ninth resistor R9 is connected to the reference terminal, the other end of the eighth resistor R8 is connected to one end of the tenth resistor R10, and the other end of the tenth resistor R10 is connected to the reference terminal.

9. A switching method of a push-pull series resonance soft switch switching circuit is characterized in that: the push-pull series resonant soft switching circuit applied to any one of claims 1 to 8, the switching method comprising,

detecting a voltage value represented by direct-current voltage input by a direct-current power supply DC, determining a corresponding preset control strategy according to the voltage value of the direct-current voltage based on a preset mapping table, and generating a corresponding control signal according to the preset control strategy; the preset mapping table comprises a corresponding relation between a plurality of groups of voltage intervals and a preset control strategy; and the number of the first and second groups,

and sending the control signal to a switch switching circuit (105), and controlling the switch switching circuit (105) to switch a corresponding tap access circuit of a secondary winding of the transformer T1 so as to adjust to a corresponding gear.

10. A chip, characterized by: comprising a push-pull series resonant soft switching circuit as claimed in any one of claims 1 to 8.

Technical Field

The invention relates to the technical field of electronic circuits, in particular to a push-pull series resonance soft switch switching circuit, a switching method and a chip thereof.

Background

With the development of power electronics technology, there are demands for miniaturization, weight reduction, and high efficiency of power supply products. At present, a push-pull converter is one of basic topologies of a DC-DC converter, has a simple structure, and is suitable for a situation of low-voltage input and high-voltage output, in order to meet the above requirements, the push-pull converter needs to increase the switching frequency, but the high frequency directly causes the efficiency of the hard-switching push-pull converter to be reduced and the electromagnetic interference to be increased, so a push-pull series resonance soft-switching converter is proposed.

Compared with the traditional push-pull converter, the push-pull series resonance soft switching converter has the advantages of small size and low cost. In a circuit in practical application, because the input voltage of a battery can change within a certain range, the push-pull series resonance soft switching converter often needs to adopt a control mode of pulse frequency modulation or pulse width modulation, thereby achieving the purpose of stabilizing the output voltage and soft switching.

In view of the above-mentioned related technologies, the inventor believes that when the input voltage is input in a wide voltage range, the input voltage of the battery fluctuates greatly, and it is necessary to change the frequency or change the duty ratio in order to maintain the output voltage in a stable range, but both of the two methods change the series resonance point, so that the switching tube is still in a hard switching state, and the circuit loss is increased.

Disclosure of Invention

In order to reduce circuit loss, the invention provides a push-pull series resonance soft switch switching circuit, a switching method thereof and a chip.

The invention provides a push-pull series resonance soft switch switching circuit, a switching method and a chip thereof, which adopt the following technical scheme:

in a first aspect, the present invention provides a push-pull series resonance soft switch switching circuit, a switching method thereof and a chip, and adopts the following technical scheme:

a push-pull series resonance soft switch switching circuit and a switching method and a chip thereof comprise a primary side push-pull circuit, a transformer T1, a rectifying circuit and an output circuit, wherein a middle tap point of a primary side of the transformer T1 is connected to a DC positive electrode of a DC power supply, the primary side push-pull circuit is used for converting DC voltage input by the DC power supply into AC voltage, and the transformer T1 is used for boosting the AC voltage; the rectification circuit is connected with a secondary winding of the transformer T1 and used for performing full-wave rectification on the boosted alternating-current voltage and outputting direct-current voltage; the output circuit is used for storing the direct-current voltage output by the rectifying circuit;

the control circuit, the switch switching circuit and the resonance circuit are also included;

the control circuit is used for detecting a voltage value represented by direct-current voltage input by the direct-current power supply DC, determining a corresponding preset control strategy according to the voltage value of the direct-current voltage based on a preset mapping table, generating a corresponding control signal according to the preset control strategy and sending the control signal to the switch switching circuit; the preset mapping table comprises a corresponding relation between a plurality of groups of voltage intervals and a preset control strategy;

the switch switching circuit comprises a control signal input end, a first input end, a second input end and an output end; the resonant circuit comprises a first resonant unit, a second resonant unit and a third resonant unit; the secondary winding of the transformer T1 comprises a first tap, a second tap, a third tap and a fourth tap; a first tap of a secondary winding of the transformer T1 is connected to the first input end, a second tap of the secondary winding is connected to the second input end, and a third tap and a fourth tap of the secondary winding are both connected to the rectifying circuit; the first resonance unit is connected between a first tap and the first input end, the second resonance unit is connected between a second tap and the second input end, and the third resonance unit is connected between a third tap and the rectifying circuit;

the output end of the switch switching circuit is connected with the voltage output end Hv of the output circuit, and the control signal input end is connected with the control signal output end of the control circuit; the switch switching circuit responds to the control signal to switch the corresponding tap access circuit of the secondary winding of the transformer T1 to adjust to the corresponding gear.

By adopting the technical scheme, the control circuit is used for detecting the direct-current voltage input by the direct-current power supply DC, the corresponding preset control strategy is determined according to the voltage value of the direct-current voltage based on the preset mapping table, the control signal is generated and sent to the switch switching circuit, the switch switching circuit responds to the control signal to switch the corresponding tap access circuit of the secondary winding of the transformer T1, the turn ratio of the secondary winding of the transformer T1 is further changed, different voltage output gears are adjusted according to different input voltages, namely, the output voltage can be maintained in a stable range when the wide voltage range is input, the adjustment of the output voltage is realized while the resonance point is not changed, and the circuit loss is reduced.

Optionally, the control circuit includes a control chip U5, a voltage input terminal of the control chip U5 is connected to the positive electrode of the DC power supply DC, and a control signal output terminal of the control chip U5 is connected to a control signal output terminal of the control circuit.

By adopting the technical scheme, the control chip U5 is utilized to detect the direct current voltage input by the direct current power supply DC, and corresponding control signals are output according to different input voltages, so that the adjustment control of the voltage output gear is realized.

Optionally, the switch switching circuit includes a first resistor R1, a first photocoupler U1, a second resistor R2, a third resistor R3, a first NMOS transistor Q1, a first NPN triode Q2, a first diode D1, a second diode D2, a fourth resistor R4, a second photocoupler U2, a fifth resistor R5, a sixth resistor R6, a second NPN triode Q4, a second NMOS transistor Q3, a third diode D3, and a fourth diode D4;

the control signal inputs of the switching circuit comprise a first control signal input CTL1 and a second control signal input CTL 2;

one end of the first resistor R1 is connected to the first control signal input end CTL1, and the other end is connected to the anode of the first photocoupler U1; the cathode of the first photocoupler U1 is grounded, the collector of the first photocoupler U1 is respectively connected to one end of a first power supply VCC1 and one end of a second resistor R2, and the emitter of the first photocoupler U1 is connected to one end of a third resistor R3; the other end of the second resistor R2 is respectively connected to the gate of the first NMOS transistor Q1 and the collector of the first NPN triode Q2, the other end of the third resistor R3 is connected to the base of the first NPN triode Q2, and the emitter of the first NPN triode Q2 is respectively connected to the source of the first NMOS transistor Q1 and the output of the switching circuit; the drain of the first NMOS transistor Q1 is connected to the cathode of a first diode D1, the anode of the first diode D1 is connected to the cathode of a second diode D2 and the second input terminal of the switch switching circuit, respectively, and the anode of the second diode D2 is connected to the reference terminal;

one end of the fourth resistor R4 is connected to the second control signal input terminal CTL2, and the other end is connected to the anode of the second photocoupler U2; the cathode of the second photocoupler U2 is grounded, the collector of the second photocoupler U2 is connected to one end of the first power supply VCC1 and one end of the fifth resistor R5 respectively, and the emitter of the second photocoupler U2 is connected to one end of the sixth resistor R6; the other end of the fifth resistor R5 is connected to the gate of the second NMOS transistor Q3 and the collector of the second NPN triode Q4, respectively, the other end of the sixth resistor R6 is connected to the base of the second NPN triode Q4, and the emitter of the second NPN triode Q4 is connected to the source of the second NMOS transistor Q3 and the output of the switching circuit, respectively; the drain of the second NMOS transistor Q3 is connected to the cathode of the third diode D3, the anode of the third diode D3 is connected to the cathode of the fourth diode D4 and the first input terminal of the switch switching circuit, respectively, and the anode of the fourth diode D4 is connected to the reference terminal.

By adopting the technical scheme, when the input voltage of the direct-current power supply DC reaches the highest gear, the first control signal input end CTL1 and the second control signal input end CTL2 are both connected with a high-level signal, the first photoelectric coupler U1 is connected, the first NPN triode Q2 is connected, the grid of the first NMOS tube Q1 is connected with a low level and is cut off, the second photoelectric coupler U2 is connected, the second NPN triode Q4 is connected, the grid of the second NMOS tube Q3 is connected with a low level and is cut off, the third tap of the secondary winding of the transformer T1 is connected with a circuit, and at the moment, the output voltage gear is adjusted to the lowest gear;

when the input voltage of the direct current power supply DC reaches a middle gear, a first control signal input end CTL1 is connected with a low level signal, a second control signal input end CTL2 is connected with a high level signal, a first photoelectric coupler U1 is cut off, a first NPN triode Q2 is cut off, the grid electrode of a first NMOS pipe Q1 is connected with a high level and conducted, a second photoelectric coupler U2 is conducted, a second NPN triode Q4 is conducted, the grid electrode of a second NMOS pipe Q3 is connected with a low level and cut off, a first diode D1 is conducted in the forward direction, a second tap of a secondary winding of a transformer T1 is connected with a circuit, and at the moment, the output voltage gear is adjusted to the middle gear;

when the input voltage of the direct current power supply DC reaches the lowest gear, a first control signal input end CTL1 is connected with a high level signal, a second control signal input end CTL2 is connected with a low level signal, a first photoelectric coupler U1 is conducted, a first NPN triode Q2 is conducted, the grid of a first NMOS pipe Q1 is connected with the low level and is cut off, a second photoelectric coupler U2 is cut off, a second NPN triode Q4 is cut off, the grid of a second NMOS pipe Q3 is connected with the high level and is conducted, a first tap of a secondary winding of a transformer T1 is connected with a circuit, and at the moment, the output voltage gear is adjusted to the highest gear.

Optionally, the first resonance unit includes a first inductance module and a first capacitance module, a first end of the first inductance module is connected to a first tap of a secondary winding of the transformer T1, a second end of the first inductance module is connected to a first end of the first capacitance module, and a second end of the first capacitance module is connected to a first input end of the switch conversion circuit;

the second resonance unit comprises a second inductance module and a second capacitance module, a first end of the second inductance module is connected to a second tap of a secondary winding of the transformer T1, a second end of the second inductance module is connected to a first end of the second capacitance module, and a second end of the second capacitance module is connected to a second input end of the switch conversion circuit;

the third resonance unit comprises a third inductance module and a third capacitance module, a first end of the third inductance module is connected to a third tap of a secondary winding of the transformer T1, a second end of the third inductance module is connected to a first end of the third capacitance module, and a second end of the third capacitance module is connected to the rectification circuit.

By adopting the technical scheme, the first resonance unit, the second resonance unit and the third resonance unit are utilized to enable the secondary side of the transformer T1 to generate resonance current and resonance voltage, the soft switch design of the push-pull series resonance circuit is realized, and the switching loss of a switching tube in the primary side push-pull circuit is reduced.

Optionally, the first inductance module, the second inductance module, and the third inductance module all use equivalent leakage inductance of a secondary side of the transformer T1.

By adopting the technical scheme, the secondary side leakage inductance of the transformer T1 is directly used as the resonance inductance, so that the separately wound inductance is omitted, and the size and the cost are reduced.

Optionally, the rectifying circuit includes a fifth diode D5, a sixth diode D6, a seventh diode D7 and an eighth diode D8;

an anode of the sixth diode D6 is connected to a cathode of the eighth diode D8 and the second end of the third capacitor module, an anode of the eighth diode D8 is connected to an anode of the seventh diode D7 and the reference terminal, a cathode of the seventh diode D7 is connected to the fourth tap of the secondary winding of the transformer T1 and an anode of the fifth diode D5, and a cathode of the fifth diode D5 is connected to a cathode of the sixth diode D6 and the voltage output terminal Hv of the output circuit.

By adopting the above technical solution, the full-wave rectification circuit on the secondary side of the transformer T1 is formed by the fifth diode D5, the sixth diode D6, the seventh diode D7 and the eighth diode D8, and the boosted ac voltage is full-wave rectified to generate the dc high voltage.

Optionally, the output circuit includes a storage capacitor EC1 and a fourth non-polar capacitor C4, an anode of the storage capacitor EC1 is connected to one end of the fourth non-polar capacitor C4 and the voltage output terminal Hv of the output circuit, respectively, and a cathode of the storage capacitor EC1 is connected to the reference terminal and the other end of the fourth non-polar capacitor C4, respectively.

By adopting the technical scheme, the fourth nonpolar capacitor C4 is used as a high-frequency capacitor to filter a high-frequency interference part in the circuit, and the energy storage capacitor EC1 is used for storing the direct-current voltage output by the rectifying circuit, so that the load can be conveniently supplied with power.

Optionally, the electronic device further comprises a bleeding circuit, wherein the bleeding circuit comprises a seventh resistor R7, an eighth resistor R8, a ninth resistor R9 and a tenth resistor R10;

one end of the seventh resistor R7 is connected to the voltage output terminal Hv of the output circuit and one end of the eighth resistor R8, and the other end is connected to one end of the ninth resistor R9, the other end of the ninth resistor R9 is connected to the reference terminal, the other end of the eighth resistor R8 is connected to one end of the tenth resistor R10, and the other end of the tenth resistor R10 is connected to the reference terminal.

By adopting the technical scheme, the seventh resistor R7, the eighth resistor R8, the ninth resistor R9 and the tenth resistor R10 form a bleeder circuit which is used for quickly discharging residual charges on the energy storage capacitor EC1 after power failure, so that the safety is improved.

In a second aspect, the present invention provides a switching method for a push-pull series resonance soft switch switching circuit, which adopts the following technical scheme:

a switching method of a push-pull series resonant soft-switching circuit, applied to the push-pull series resonant soft-switching circuit of any one of the first aspect, the switching method comprising,

detecting a voltage value represented by direct-current voltage input by a direct-current power supply DC, determining a corresponding preset control strategy according to the voltage value of the direct-current voltage based on a preset mapping table, and generating a corresponding control signal according to the preset control strategy; the preset mapping table comprises a corresponding relation between a plurality of groups of voltage intervals and a preset control strategy; and the number of the first and second groups,

and sending the control signal to a switch switching circuit, and controlling the switch switching circuit to switch a corresponding tap access circuit of a secondary winding of the transformer T1 so as to adjust the corresponding tap access circuit to a corresponding gear.

By adopting the technical scheme, the direct-current voltage input by the direct-current power supply DC is detected, the corresponding preset control strategy is determined according to the voltage value of the direct-current voltage based on the preset mapping table, the control signal is generated and sent to the switch switching circuit, the switch switching circuit is controlled to switch the corresponding tap access circuit of the secondary winding of the transformer T1, the turn ratio of the secondary winding of the transformer T1 is further changed, different voltage output gears are adjusted according to different input voltages, the output voltage can be maintained in a stable range when the wide voltage range is input, the adjustment of the output voltage is realized while the resonance point is not changed, and the circuit loss is reduced.

In a third aspect, the present invention provides a chip, which adopts the following technical solutions:

a chip comprising a push-pull series resonant soft-switching circuit as in any one of the first aspect.

In summary, the invention includes at least one of the following beneficial technical effects: the control circuit is used for detecting the direct-current voltage input by the direct-current power supply DC, a corresponding preset control strategy is determined according to the voltage value of the direct-current voltage based on a preset mapping table, a control signal is generated and sent to the switch switching circuit, the switch switching circuit responds to the control signal to switch a corresponding tap access circuit of the secondary winding of the transformer T1, the turn ratio of the secondary winding of the transformer T1 is changed, different voltage output gears are adjusted according to different input voltages, the output voltage can be maintained in a stable range when the wide voltage range is input, adjustment of the output voltage is achieved while the resonance point is not changed, and circuit loss is reduced.

Drawings

Fig. 1 is a schematic diagram of a connection structure of a push-pull series resonant soft switching circuit according to an embodiment of the present invention.

Fig. 2 is a flow chart of a switching method of a push-pull series resonant soft switching circuit according to an embodiment of the present invention.

Description of reference numerals: 101. a primary side push-pull circuit; 102. a rectifying circuit; 103. an output circuit; 104. a control circuit; 105. a switch switching circuit; 106. a bleeding circuit.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to fig. 1-2 and the embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

When the voltage fluctuation is small, namely within a narrow voltage range, the stability of the output voltage can be adjusted by changing the duty ratio or changing the frequency; however, for a common energy storage power supply, the battery mostly adopts a lithium battery as an energy storage battery, the fluctuation of the battery voltage from full charge to emptying voltage is large, and at the moment, the switching tube is in a hard switching state by changing the frequency or changing the duty ratio for regulation, so that the switching loss is large.

The embodiment of the invention discloses a push-pull series resonance soft switch switching circuit.

Referring to fig. 1, the push-pull series resonance soft switching circuit includes a primary push-pull circuit 101, a transformer T1, a rectifying circuit 102, and an output circuit 103; a middle tap point of a primary side of the transformer T1 is connected to a DC positive electrode of the DC power supply, the primary side push-pull circuit 101 is used for converting DC voltage input by the DC power supply into AC voltage, and the transformer T1 is used for boosting the AC voltage; the rectifier circuit 102 is connected to the secondary winding of the transformer T1, and configured to full-wave rectify the boosted ac voltage and output a dc voltage; the output circuit 103 is used for storing the direct-current voltage output by the rectifying circuit 102;

the device also comprises a control circuit 104, a switch switching circuit 105 and a resonance circuit;

the control circuit 104 is configured to detect a voltage value represented by a DC voltage input by the DC power supply DC, determine a corresponding preset control strategy according to the voltage value of the DC voltage based on a preset mapping table, generate a corresponding control signal according to the preset control strategy, and send the control signal to the switch switching circuit 105; the preset mapping table comprises a corresponding relation between a plurality of groups of voltage intervals and a preset control strategy;

the switch switching circuit 105 includes a control signal input terminal, a first input terminal, a second input terminal, and an output terminal; the resonant circuit comprises a first resonant unit, a second resonant unit and a third resonant unit; the secondary winding of the transformer T1 includes a first tap, a second tap, a third tap and a fourth tap; a first tap of the secondary winding of the transformer T1 is connected to the first input end, a second tap is connected to the second input end, and a third tap and a fourth tap are both connected to the rectifying circuit 102; the first resonance unit is connected between the first tap and the first input end, the second resonance unit is connected between the second tap and the second input end, and the third resonance unit is connected between the third tap and the rectifying circuit 102;

a switch switching circuit 105, an output terminal of which is connected to the voltage output terminal Hv of the output circuit 103, and a control signal input terminal of which is connected to the control signal output terminal of the control circuit 104; the switch switching circuit 105 switches the corresponding tap access circuit of the secondary winding of the transformer T1 in response to the control signal to adjust to the corresponding gear.

As an embodiment of the DC power supply DC, the DC power supply DC may be a common energy storage power supply, such as a battery pack composed of energy storage batteries such as lithium batteries.

In the above embodiment, the control circuit 104 is used to detect the DC voltage input by the DC power supply DC, determine a corresponding preset control strategy according to the voltage value of the DC voltage based on a preset mapping table, generate a control signal and send the control signal to the switch switching circuit 105, the switch switching circuit 105 switches the corresponding tap access circuit of the secondary winding of the transformer T1 in response to the control signal, further change the turn ratio of the secondary winding of the transformer T1, and adjust different voltage output gears according to different input voltages, i.e. the output voltage can be maintained in a stable range when the wide voltage range is input, thereby achieving the adjustment of the output voltage without changing the resonance point, and reducing the circuit loss.

As an implementation mode for determining a corresponding preset control strategy according to a voltage value of a direct current voltage based on a preset mapping table, the preset mapping table includes a corresponding relationship between a plurality of groups of voltage intervals and the preset control strategy, each voltage interval has no intersection, and each voltage interval corresponds to one preset control strategy; the preset control strategy is an optimal control strategy when the voltage value of the direct-current voltage is in the voltage interval, and the optimal control strategy can be preset and adjusted.

As an embodiment of the primary side push-pull circuit 101, referring to fig. 1, the primary side push-pull circuit 101 includes a third NMOS transistor U3, a fourth NMOS transistor U4, a fifth nonpolar capacitor C5, and a sixth nonpolar capacitor C6; the primary side of the transformer T1 includes a first winding N1 and a second winding N2; a drain of the third NMOS transistor U3 is connected to one end of the fifth non-polar capacitor C5 and a synonym end of the primary first winding N1 of the transformer T1, and a source is connected to the other end of the fifth non-polar capacitor C5 and a source of the fourth NMOS transistor U4; the other end of the fifth nonpolar capacitor C5 is grounded, the positive electrode of the direct current power supply DC is connected to the center tap point of the primary side of the transformer T1, the negative electrode of the direct current power supply DC is grounded, the drain of the fourth NMOS tube U4 is connected to the synonym terminal of the secondary winding N2 on the primary side of the transformer T1 and one end of the sixth nonpolar capacitor C6, respectively, and the other end of the sixth nonpolar capacitor C6 is grounded.

As an embodiment of the control circuit 104, referring to fig. 1, the control circuit 104 includes a control chip U5, a voltage input terminal of the control chip U5 is connected to the DC positive pole of the direct current power supply, and a control signal output terminal of the control chip U5 is connected to a control signal output terminal of the control circuit 104; in this embodiment of the application, the control chip U5 may be an MCU, and the MCU detects the DC voltage input from the DC power supply DC, and outputs a corresponding control signal according to different input voltages, thereby implementing adjustment control of the voltage output stage.

As an embodiment of the switch switching circuit 105, referring to fig. 1, the switch switching circuit 105 includes a first resistor R1, a first photo coupler U1, a second resistor R2, a third resistor R3, a first NMOS transistor Q1, a first NPN transistor Q2, a first diode D1, a second diode D2, a fourth resistor R4, a second photo coupler U2, a fifth resistor R5, a sixth resistor R6, a second NPN transistor Q4, a second NMOS transistor Q3, a third diode D3, and a fourth diode D4;

the control signal inputs of the switch switching circuit 105 include a first control signal input CTL1 and a second control signal input CTL 2; the control signal output end of the control chip U5 comprises a first control signal output end and a second control signal output end, wherein the first control signal output end is connected to the first control signal input end CTL1, and the second control signal output end is connected to the second control signal input end CTL 2;

a first resistor R1 having one end connected to the first control signal input terminal CTL1 and the other end connected to the anode of the first photocoupler U1; a first photocoupler U1 with a grounded cathode, a collector connected to one end of a first power supply VCC1 and one end of a second resistor R2, and an emitter connected to one end of a third resistor R3; the other end of the second resistor R2 is connected to the gate of the first NMOS transistor Q1 and the collector of the first NPN transistor Q2, respectively, the other end of the third resistor R3 is connected to the base of the first NPN transistor Q2, and the emitter of the first NPN transistor Q2 is connected to the source of the first NMOS transistor Q1 and the output of the switch switching circuit 105, respectively; the drain of the first NMOS transistor Q1 is connected to the cathode of the first diode D1, the anode of the first diode D1 is connected to the cathode of the second diode D2 and the second input terminal of the switch switching circuit 105, respectively, and the anode of the second diode D2 is connected to the reference terminal;

a fourth resistor R4, one end of which is connected to the second control signal input terminal CTL2 and the other end of which is connected to the anode of the second photo-coupler U2; a second photo-coupler U2 having a cathode grounded, a collector connected to one end of the first power supply VCC1 and one end of the fifth resistor R5, respectively, and an emitter connected to one end of the sixth resistor R6; the other end of the fifth resistor R5 is connected to the gate of the second NMOS transistor Q3 and the collector of the second NPN transistor Q4, respectively, the other end of the sixth resistor R6 is connected to the base of the second NPN transistor Q4, and the emitter of the second NPN transistor Q4 is connected to the source of the second NMOS transistor Q3 and the output of the switch switching circuit 105, respectively; the drain of the second NMOS transistor Q3 is connected to the cathode of the third diode D3, the anode of the third diode D3 is connected to the cathode of the fourth diode D4 and the first input terminal of the switch switching circuit 105, respectively, and the anode of the fourth diode D4 is connected to the reference terminal.

In the above embodiment, when the input voltage of the DC power supply DC reaches the highest level, the first control signal input terminal CTL1 and the second control signal input terminal CTL2 both receive a high level signal, the first photocoupler U1 is turned on, the first NPN transistor Q2 is turned on, the gate of the first NMOS transistor Q1 is turned on at a low level and is turned off, the second photocoupler U2 is turned on, the second NPN transistor Q4 is turned on, the gate of the second NMOS transistor Q3 is turned on at a low level and is turned off, and the third tap of the secondary winding of the transformer T1 is connected to the circuit, and at this time, the output voltage level is adjusted to the lowest level;

when the input voltage of the direct current power supply DC reaches a middle gear, a first control signal input end CTL1 is connected with a low level signal, a second control signal input end CTL2 is connected with a high level signal, a first photoelectric coupler U1 is cut off, a first NPN triode Q2 is cut off, the grid electrode of a first NMOS pipe Q1 is connected with a high level and conducted, a second photoelectric coupler U2 is conducted, a second NPN triode Q4 is conducted, the grid electrode of a second NMOS pipe Q3 is connected with a low level and cut off, a first diode D1 is conducted in the forward direction, a second tap of a secondary winding of a transformer T1 is connected with a circuit, and at the moment, the output voltage gear is adjusted to the middle gear;

when the input voltage of the direct current power supply DC reaches the lowest gear, a first control signal input end CTL1 is connected with a high level signal, a second control signal input end CTL2 is connected with a low level signal, a first photoelectric coupler U1 is conducted, a first NPN triode Q2 is conducted, the grid of a first NMOS pipe Q1 is connected with the low level and is cut off, a second photoelectric coupler U2 is cut off, a second NPN triode Q4 is cut off, the grid of a second NMOS pipe Q3 is connected with the high level and is conducted, a first tap of a secondary winding of a transformer T1 is connected with a circuit, and at the moment, the output voltage gear is adjusted to the highest gear.

Therefore, in the present embodiment, the highest gear, the middle gear, and the lowest gear of the input voltage correspond to three preset voltage intervals; for example, the voltage interval corresponding to the highest level of the input voltage is configured to [ u1, u2], and the corresponding control strategy is configured to input a high-level signal to both the first control signal input terminal CTL1 and the second control signal input terminal CTL 2; the voltage interval corresponding to the middle gear of the input voltage is configured to be (u2, u 3), the corresponding control strategy is configured to input a low-level signal to the first control signal input end CTL1 and input a high-level signal to the second control signal input end CTL2, the voltage interval corresponding to the lowest gear of the input voltage is configured to be (u3, u 4), the corresponding control strategy is configured to input a high-level signal to the first control signal input end CTL1 and input a low-level signal to the second control signal input end CTL2, u1< u2< u3< u4, different voltage output gears are correspondingly adjusted according to different gears of the input voltage, and therefore the output voltage can be maintained in a stable range when the wide voltage range is input.

In the actual detection process, the opening and closing of the end points of each voltage interval, the length of each voltage interval and the number of voltage intervals can be set and adjusted according to the actual situation.

As an embodiment of the resonant circuit, referring to fig. 1, the first resonant unit includes a first inductance module and a first capacitance module, a first end of the first inductance module is connected to a first tap of a secondary winding of a transformer T1, a second end of the first inductance module is connected to a first end of the first capacitance module, and a second end of the first capacitance module is connected to a first input end of the switch conversion circuit;

the second resonance unit comprises a second inductance module and a second capacitance module, wherein the first end of the second inductance module is connected to a second tap of the secondary winding of the transformer T1, the second end of the second inductance module is connected to the first end of the second capacitance module, and the second end of the second capacitance module is connected to the second input end of the switch conversion circuit;

the third resonant unit comprises a third inductance module and a third capacitance module, a first end of the third inductance module is connected to a third tap of the secondary winding of the transformer T1, a second end of the third inductance module is connected to a first end of the third capacitance module, and a second end of the third capacitance module is connected to the rectifying circuit 102.

In the above embodiment, the first resonant unit, the second resonant unit, and the third resonant unit are used to enable the secondary side of the transformer T1 to generate resonant current and resonant voltage, so that the soft switch design of the push-pull series resonant circuit is implemented, and the switching loss of the switching tube in the primary side push-pull circuit 101 is reduced.

As an implementation manner of the first capacitor module, the second capacitor module and the third capacitor module, the first capacitor module, the second capacitor module and the third capacitor module can all adopt polypropylene capacitors with better high-frequency characteristics; in the embodiment of the present application, the first capacitance module is a first non-polar capacitor C1, the second capacitance module is a second non-polar capacitor C2, and the third capacitance module is a third non-polar capacitor C3.

As an implementation manner of the first inductance module, the second inductance module, and the third inductance module, the first inductance module, the second inductance module, and the third inductance module may adopt an equivalent leakage inductance of a secondary side of the transformer T1, or may adopt independent inductances; in the embodiment of the application, the first inductance module, the second inductance module and the third inductance module all adopt equivalent leakage inductance of the secondary side of the transformer T1, and the leakage inductance of the secondary side of the transformer T1 is directly used as resonance inductance, so that separately wound inductance is omitted, and the size and the cost are reduced.

As an embodiment of the rectifier circuit 102, referring to fig. 1, the rectifier circuit 102 includes a fifth diode D5, a sixth diode D6, a seventh diode D7, and an eighth diode D8;

an anode of the sixth diode D6 is connected to a cathode of the eighth diode D8 and the second end of the third capacitor module, an anode of the eighth diode D8 is connected to an anode of the seventh diode D7 and the reference terminal, a cathode of the seventh diode D7 is connected to the fourth tap of the secondary winding of the transformer T1 and an anode of the fifth diode D5, and a cathode of the fifth diode D5 is connected to a cathode of the sixth diode D6 and the voltage output terminal Hv of the output circuit 103.

In the above embodiment, the full-wave rectifier circuit 102 on the secondary side of the transformer T1 is configured by the fifth diode D5, the sixth diode D6, the seventh diode D7, and the eighth diode D8, and the boosted ac voltage is full-wave rectified to generate the dc high voltage.

Referring to fig. 1, as an embodiment of the output circuit 103, the output circuit 103 includes a storage capacitor EC1 and a fourth non-polar capacitor C4, a positive electrode of the storage capacitor EC1 is connected to one end of the fourth non-polar capacitor C4 and the voltage output terminal Hv of the output circuit 103, respectively, and a negative electrode of the storage capacitor EC1 is connected to the reference terminal and the other end of the fourth non-polar capacitor C4, respectively.

In the above embodiment, since the output voltage contains high-frequency components, the fourth nonpolar capacitor C4 is used as a high-frequency capacitor to filter the high-frequency interference in the circuit, and the dc voltage output from the rectifying circuit 102 is stored by the storage capacitor EC1, so that the load can be easily supplied through the voltage output terminal Hv of the output circuit 103.

It should be noted that the number of the energy storage capacitors can be adjusted according to actual situations, for example, a plurality of energy storage capacitors can be connected in parallel to store more electric energy.

As a further embodiment of the push-pull series resonant soft switching circuit, referring to fig. 1, further comprising a bleeder circuit 106, the bleeder circuit 106 comprising a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, and a tenth resistor R10;

one end of the seventh resistor R7 is connected to the voltage output terminal Hv of the output circuit 103 and one end of the eighth resistor R8, and the other end is connected to one end of the ninth resistor R9, the other end of the ninth resistor R9 is connected to the reference terminal, the other end of the eighth resistor R8 is connected to one end of the tenth resistor R10, and the other end of the tenth resistor R10 is connected to the reference terminal.

In the above embodiment, the bleed-off circuit 106 composed of the seventh resistor R7, the eighth resistor R8, the ninth resistor R9 and the tenth resistor R10 is used to quickly bleed off the residual charge on the energy storage capacitor EC1 after power failure, so as to improve safety.

It should be noted that the number of the bleeder resistors in the bleeder circuit 106 may be adjusted according to actual conditions, that is, the residual charge on the energy storage capacitor EC1 may be quickly drained after power failure.

Based on the control circuit 104 side, the embodiment of the invention also discloses a switching method of the push-pull series resonance soft switch switching circuit.

Referring to fig. 2, a switching method of a push-pull series resonant soft switching circuit, which can be applied to the above-mentioned push-pull series resonant soft switching circuit, includes,

and S11, detecting a voltage value represented by the direct-current voltage input by the direct-current power supply DC, determining a corresponding preset control strategy according to the voltage value of the direct-current voltage based on a preset mapping table, and generating a corresponding control signal according to the preset control strategy.

The preset mapping table comprises a corresponding relation between a plurality of groups of voltage intervals and a preset control strategy.

And S12, sending the control signal to the switch switching circuit 105, and controlling the switch switching circuit 105 to switch the corresponding tap access circuit of the secondary winding of the transformer T1 so as to adjust to the corresponding gear.

The corresponding tap of the secondary winding of the transformer T1 is switched into the circuit, so that the turn ratio of the secondary winding of the transformer T1 can be changed, and the adjustment of a voltage output gear is realized.

It should be noted that the switching method provided in this embodiment may be regarded as a method executed by the control circuit 104 in the push-pull series resonant soft-switch switching circuit provided in the above embodiment, and therefore, for specific execution steps of the switching method provided in this embodiment, reference may be made to the description of the push-pull series resonant soft-switch switching circuit in the above embodiment, and details are not repeated here. It should also be understood that, for a detailed implementation method of the switching method in this embodiment, reference may be made to implementation logic of the control circuit 104 in the push-pull series resonant soft switching circuit in the foregoing embodiment, and the implementation logic of the two is the same, and is not described herein again.

The above switching method is explained in detail by the following embodiments: the switching method comprises the steps that a control circuit detects a voltage value represented by direct-current voltage input by a direct-current power supply DC, determines a corresponding preset control strategy according to the voltage value of the direct-current voltage based on a preset mapping table, and generates a corresponding control signal according to the preset control strategy; the switch switching circuit 105 switches the corresponding tap access circuit of the secondary winding of the transformer T1 in response to the control signal to adjust to the corresponding gear.

In the above embodiment, the control circuit 104 detects the DC voltage of the DC power supply DC input, determines a corresponding preset control strategy according to the voltage value of the DC voltage based on a preset mapping table, generates a control signal and sends the control signal to the switch switching circuit 105, the switch switching circuit 105 switches the corresponding tap access circuit of the secondary winding of the transformer T1 in response to the control signal, further changes the turn ratio of the secondary winding of the transformer T1, and adjusts different voltage output gears according to different input voltages, that is, the output voltage can be maintained in a stable range when a wide voltage range is input, thereby achieving adjustment of the output voltage without changing a resonance point, and reducing circuit loss.

The embodiment of the invention also discloses a chip.

A chip comprises the push-pull series resonance soft switching circuit.

The foregoing is a preferred embodiment of the present invention and is not intended to limit the scope of the invention in any way, and any feature disclosed in this specification (including the abstract and drawings) may be replaced by alternative features serving equivalent or similar purposes, unless expressly stated otherwise. That is, unless expressly stated otherwise, each feature is only an example of a generic series of equivalent or similar features.