Magnetic isolation transformer driving circuit suitable for double-transistor flyback auxiliary power supply

Abstract

The invention discloses a magnetic isolation transformer driving circuit suitable for a double-transistor flyback auxiliary power supply, and belongs to the technical field of power supplies. According to the scheme, the blocking capacitors are arranged on the primary side and the secondary side of the transformer, the discharging resistor is added to the blocking capacitor on the secondary side of the transformer, the driving switch-on diode and the gate-level switch-off PNP type triode are added to the power MOS tube, rapid and reliable switch-off of the power MOS tube is achieved, and the problem that the power MOS tube is switched on by mistake is solved by providing a discharging loop through the discharging resistor. The scheme of the invention has the advantages of high isolation, good driving consistency, reliable circuit and low cost.

Description

Technical Field

[0001] The present invention relates to the technical field of power supply, and in particular to a magnetic isolation transformer driving circuit suitable for a dual-tube flyback auxiliary power supply. Background Art

[0002] In the topology of a dual-tube flyback power supply, the dual-tube drive signals must maintain a certain degree of isolation and consistency. In applications with higher input voltage levels, such as photovoltaic and APF auxiliary power supplies, the input voltage is as high as 1000V, or even in the design of auxiliary power products above 1500V. The drive solution using a driver chip is no longer applicable. Instead, it is replaced by a power tube drive circuit. The principle of the power tube drive circuit is to connect the external input PWM control signal to the primary winding of the drive transformer, and control the conduction and shutdown of the two power MOS tubes simultaneously through the two secondary windings. Since a drive transformer is used, the drive circuit needs to consider the magnetic isolation of the transformer. There are two commonly used solutions:

[0003] 1. Single capacitor DC isolation magnetic isolation transformer drive circuit: The circuit is as follows Figure 1 As shown, a DC blocking capacitor C2 is added to the primary side of the transformer to solve the magnetic reset problem of the primary side excitation inductance of the transformer. This solution has the problem that the power MOS tube cannot be turned on normally due to insufficient driving voltage of the power MOS tube under a large duty cycle. Figure 2 As shown, in steady state, assuming that the period of the PWM (Pulse Width Modulation) drive signal is T and the duty cycle is D, according to the volt-second balance:

[0004] (V_in-V_C2)*D*T=V_C2*(1-D)*T

[0005] That is, V_C2 = D*V_in. Assuming that the input-output turns ratio of the driving transformer T1 is 1, we have:

[0006] Vgs=V_P=V_in-V_C2=(1-D)*V_in

[0007] From the above analysis, it can be seen that when the PWM drive signal input is high level, the gate drive voltage Vgs of the power MOS tube is (1-D)*V_in; when the PWM drive signal input is low level, the gate drive voltage Vgs of the power MOS tube is -D*V_in. This magnetic isolation transformer drive circuit has a simple circuit, and has the advantages of negative voltage shutdown and strong anti-interference ability. However, since its gate drive voltage Vgs is related to the size of the duty cycle, in the case of a large duty cycle, the high level amplitude of the gate drive voltage Vgs is low, and it may not be possible to ensure the reliable opening of the power MOS tube.

[0008] 2. Dual capacitor DC isolation magnetic isolation transformer drive circuit: Circuit as follows Figure 3 As shown, blocking capacitors (capacitors C2, C3, C4) are added to both the primary and secondary sides of the transformer to adapt to applications with large duty cycle changes. This solution adds blocking capacitors C3, C4 and freewheeling diodes D2, D3 on the secondary side of the driving transformer on the basis of the first solution. Although the presence of blocking capacitors C3 and C4 solves the problem of insufficient gate drive voltage caused by the blocking capacitors on the primary side of the driving transformer, when the PWM driving signal is turned off for too long (i.e., the duty cycle is extremely low), after the secondary winding of the driving transformer completes the freewheeling through the freewheeling diodes D2 and D3, the blocking capacitors C3 and C4 will charge the gate parasitic capacitance of the power MOS tube, causing its gate drive voltage to gradually increase from 0V, which may cause the power MOS tube to be turned on by mistake. For example, the gate drive turn-on threshold voltage of the widely used silicon carbide MOS tube may be as low as 1V, and in this application scenario, it may be turned on by mistake. The charging circuit is as follows Figure 4 As shown by the arrow mark, the relevant voltage waveform is as follows Figure 5 As shown, curve 1 is the PWM drive signal, curve 2 is the gate drive voltage Vgs, Figure 5 It can be seen that during the period when the PWM drive signal input is at a low level, the gate drive voltage Vgs will rise, so there is a problem of the power MOS tube being turned on by mistake. Summary of the invention

[0009] The technical problem to be solved by the present invention is: in view of the above-mentioned defects of the prior art, a magnetic isolation transformer driving circuit suitable for a dual-tube flyback auxiliary power supply is provided.

[0010] To achieve the above-mentioned object, the present invention provides a magnetic isolation transformer driving circuit suitable for a dual-tube flyback auxiliary power supply, comprising a PWM driving signal input terminal, an NPN-type first transistor, a PNP-type second transistor, a second capacitor, a driving transformer, a third capacitor, a fourth capacitor, an eleventh resistor, a twelfth resistor, a second diode, a third diode, a fifth diode, a sixth diode, a PNP-type third transistor, and a PNP-type fourth transistor;

[0011] The PWM driving signal input terminal is connected to the base of the first transistor and the second transistor at the same time, the emitter of the first transistor is connected to the emitter of the second transistor and one end of the second capacitor respectively, the collector of the first transistor is connected to the power supply, and the collector of the second transistor is grounded; the other end of the second capacitor is connected to the upper end of the primary winding of the driving transformer, and the lower end of the primary winding of the driving transformer is grounded;

[0012] The upper end of the first secondary winding of the driving transformer is respectively connected to the eleventh resistor and one end of the third capacitor, and the lower end of the first secondary winding of the driving transformer is respectively connected to the anode of the second diode, the collector of the third transistor, and the source of the first power MOS tube; the other end of the third capacitor is respectively connected to the other end of the eleventh resistor, the cathode of the second diode, the base of the third transistor, and the anode of the fifth diode, and the cathode of the fifth diode is connected to the gate of the first power MOS tube;

[0013] The upper end of the second secondary winding of the driving transformer is respectively connected to the twelfth resistor and one end of the fourth capacitor, and the lower end of the first secondary winding of the driving transformer is respectively connected to the anode of the third diode, the collector of the fourth transistor, and the source of the second power MOS tube; the other end of the fourth capacitor is respectively connected to the other end of the twelfth resistor, the cathode of the third diode, the base of the fourth transistor, and the anode of the sixth diode, and the cathode of the sixth diode is connected to the gate of the second power MOS tube.

[0014] In the magnetic isolation transformer driving circuit applicable to the dual-tube flyback auxiliary power supply of the present invention, the driving circuit further includes a first resistor, a first capacitor, and a second resistor;

[0015] One end of the first resistor is connected to the PWM drive signal input end, and the other end of the first resistor is respectively connected to one end of the first capacitor, one end of the second resistor, the base of the first transistor, and the base of the second transistor; the other end of the first capacitor and the other end of the second resistor are grounded.

[0016] In the magnetic isolation transformer driving circuit suitable for a dual-tube flyback auxiliary power supply of the present invention, the driving circuit also includes a first diode, the anode of the first diode is connected to the upper end of the primary winding of the driving transformer, and the cathode of the first diode is respectively connected to the emitter of the first transistor and the emitter of the second transistor.

[0017] In the magnetic isolation transformer driving circuit applicable to the dual-tube flyback auxiliary power supply of the present invention, the driving circuit further includes a sixth resistor, a seventh resistor, a ninth resistor, and a tenth resistor;

[0018] One end of the sixth resistor is connected to the cathode of the fifth diode, and the other end is respectively connected to one end of the seventh resistor and the emitter of the third transistor; the other end of the seventh resistor is connected to the gate of the first power MOS tube;

[0019] One end of the ninth resistor is connected to the cathode of the sixth diode, and the other end is respectively connected to one end of the tenth resistor and the emitter of the fourth transistor; the other end of the tenth resistor is connected to the gate of the second power MOS tube.

[0020] In the magnetic isolation transformer driving circuit applicable to the dual-tube flyback auxiliary power supply of the present invention, the driving circuit further includes a fifth resistor, a fifth capacitor, an eighth resistor, and a sixth capacitor;

[0021] One end of the fifth resistor is connected to the anode of the fifth diode, and the other end is connected to the base of the third transistor; two ends of the fifth capacitor are respectively connected to two ends of the fifth resistor;

[0022] One end of the eighth resistor is connected to the anode of the sixth diode, and the other end is connected to the base of the fourth transistor; the two ends of the sixth capacitor are respectively connected to the two ends of the sixth resistor.

[0023] In the magnetic isolation transformer driving circuit applicable to the dual-tube flyback auxiliary power supply of the present invention, the driving circuit further includes a third resistor and a fourth resistor;

[0024] One end of the third resistor is connected to the gate of the first power MOS tube, and the other end is connected to the source of the first power MOS tube;

[0025] One end of the fourth resistor is connected to the gate of the second power MOS tube, and the other end is connected to the source of the second power MOS tube.

[0026] The present invention has the following beneficial effects: the scheme of the present invention sets a DC blocking capacitor on both the primary and secondary sides of the transformer, adds a discharge resistor to the DC blocking capacitor on the secondary side of the transformer, and adds a drive turn-on diode and a gate-level turn-off PNP transistor to the power MOS tube, so as to realize fast and reliable turn-off of the power MOS tube, and provide a discharge circuit through the discharge resistor to solve the problem of erroneous turn-on of the power MOS tube. The scheme of the present invention has the advantages of high isolation, good drive consistency, reliable circuit and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0028] Figure 1-2 This is a schematic diagram of a single capacitor DC magnetic isolation transformer drive circuit.

[0029] Figure 3 It is a schematic diagram of the dual-capacitor DC-isolation magnetic isolation transformer driving circuit.

[0030] Figure 4 for Figure 3 The schematic diagram of the gate parasitic capacitance charging loop of the power MOS tube in the dual-capacitor DC-isolating magnetic isolation transformer driving circuit is shown.

[0031] Figure 5 for Figure 3 The PWM drive signal and power MOS tube gate drive voltage waveform of the dual-capacitor DC-isolation magnetic isolation transformer drive circuit are shown.

[0032] Figure 6 A schematic diagram of a driving circuit provided by an embodiment of the present invention.

[0033] Figure 7 for Figure 6 The shown diagram is a current loop diagram of the driving circuit when the power MOS tube is turned on.

[0034] Figure 8 for Figure 6 The shown diagram is a current loop diagram of the driving circuit when the power MOS tube is turned off.

[0035] Fig. 9 for Figure 6 The driving circuit PWM driving signal and the power MOS tube gate driving voltage waveform are shown. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] The embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings of the specification. It should be understood that the embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0038] The driving circuit provided by the embodiment of the present invention is suitable for a dual-transistor flyback auxiliary power supply.

[0039] like Figure 6As shown, an embodiment of the present invention provides a magnetic isolation transformer driving circuit suitable for a dual-tube flyback auxiliary power supply, including a PWM drive signal input terminal, an NPN-type first transistor Q1, a PNP-type second transistor Q2, a second capacitor C2, a drive transformer T1, a third capacitor C3, a fourth capacitor C4, an eleventh resistor R11, a twelfth resistor R12, a second diode D2, a third diode D3, a fifth diode D5, a sixth diode D6, a PNP-type third transistor Q3, and a PNP-type fourth transistor Q4.

[0040] The PWM driving signal input terminal is connected to the base of the first transistor Q1 and the second transistor Q2 at the same time, the emitter of the first transistor Q1 is connected to the emitter of the second transistor Q2 and one end of the second capacitor C2 respectively, the collector of the first transistor Q1 is connected to the power supply Vcc, and the collector of the second transistor Q2 is grounded; the other end of the second capacitor C2 is connected to the upper end of the primary winding of the driving transformer T1, and the lower end of the primary winding of the driving transformer T1 is grounded;

[0041] The upper end of the first secondary winding of the driving transformer T1 is respectively connected to the eleventh resistor R11 and one end of the third capacitor C3, and the lower end of the first secondary winding of the driving transformer T1 is respectively connected to the anode of the second diode D2, the collector of the third transistor Q3, and the source of the first power MOS tube; the other end of the third capacitor C3 is respectively connected to the other end of the eleventh resistor R11, the cathode of the second diode D2, the base of the third transistor Q3, and the anode of the fifth diode D5, and the cathode of the fifth diode D5 is connected to the gate of the first power MOS tube;

[0042] The upper end of the second secondary winding of the driving transformer T1 is respectively connected to the twelfth resistor R12 and one end of the fourth capacitor C4, and the lower end of the first secondary winding of the driving transformer T1 is respectively connected to the anode of the third diode D3, the collector of the fourth transistor Q4, and the source of the second power MOS tube; the other end of the fourth capacitor C4 is respectively connected to the other end of the twelfth resistor R12, the cathode of the third diode D3, the base of the fourth transistor Q4, and the anode of the sixth diode D6, and the cathode of the sixth diode D6 is connected to the gate of the second power MOS tube.

[0043] Among them, the second capacitor C2 is a primary side DC blocking capacitor, the first transistor Q1 and the second transistor Q2 form a push-pull circuit, amplify the input PWM drive signal, and then connect it to the primary winding of the drive transformer T1 through the second capacitor C2, and generate two identical drive signals on the first secondary winding and the second secondary winding of the drive transformer T1, which are used to drive the first power MOS tube and the second power MOS tube respectively. The third capacitor C3 and the fourth capacitor C4 are both secondary side DC blocking capacitors, and the eleventh resistor R11 and the twelfth resistor R12 are both discharge resistors, which are connected in parallel to the third capacitor C3 and the fourth capacitor C4 respectively. The primary side DC blocking capacitor and the secondary side DC blocking capacitor enhance the electrical isolation between the secondary side of the transformer and the main circuit, reduce electromagnetic interference and other potential electrical problems, and ensure the safety and stability of the system. The discharge resistor effectively prevents the secondary side DC blocking capacitor from charging the parasitic capacitance of the gate of the power MOS tube, preventing the gate drive voltage from rising, thereby improving the stability and reliability of the system. The fifth diode D5 and the sixth diode D6 are both driver-on diodes, and the third transistor Q3 and the fourth transistor Q4 are both gate-off PNP transistors. By adding driver-on diodes and gate-off PNP transistors to the power MOS tube, the power MOS tube is quickly and reliably turned off, the switching time is shortened, and the energy loss and thermal stress caused by delayed or incomplete shutdown are reduced, the performance and life of the overall circuit are improved, and the overall reliability of the circuit is improved, and the failure rate and maintenance cost are reduced. By optimizing the design of the driving circuit, the present invention ensures that each power MOS tube can obtain a consistent and stable driving signal, eliminates performance fluctuations caused by unstable driving signals, and improves the working efficiency and driving consistency of the system.

[0044] In some embodiments of the present invention, the driving circuit further includes a first resistor R1, a first capacitor C1, and a second resistor R2;

[0045] One end of the first resistor R1 is connected to the PWM drive signal input end, and the other end of the first resistor R1 is respectively connected to one end of the first capacitor C1, one end of the second resistor R2, the base of the first transistor Q1, and the base of the second transistor Q2; the other end of the first capacitor C1 and the other end of the second resistor R2 are grounded. The first resistor R1 is the base current limiting resistor of the first transistor Q1 and the second transistor Q2, the first capacitor C1 is the base input filter capacitor of the first transistor Q1 and the second transistor Q2, and the second resistor R2 is a base pull-down resistor to ensure reliable shutdown.

[0046] In some embodiments of the present invention, the driving circuit further includes a first diode D1, the anode of the first diode D1 is connected to the upper end of the primary winding of the driving transformer T1, and the cathode of the first diode D1 is connected to the emitter of the first transistor Q1 and the emitter of the second transistor Q2 respectively. The first diode D1 is a freewheeling diode of the second capacitor C2.

[0047] In some embodiments of the present invention, the driving circuit further includes a sixth resistor R6, a seventh resistor R7, a ninth resistor R9, and a tenth resistor R10;

[0048] One end of the sixth resistor R6 is connected to the cathode of the fifth diode D5, and the other end is respectively connected to one end of the seventh resistor R7 and the emitter of the third transistor Q3; the other end of the seventh resistor R7 is connected to the gate of the first power MOS tube;

[0049] One end of the ninth resistor R9 is connected to the cathode of the sixth diode D6, and the other end is respectively connected to one end of the tenth resistor R10 and the emitter of the fourth transistor Q4; the other end of the tenth resistor R10 is connected to the gate of the second power MOS tube. The sixth resistor R6, the seventh resistor R7, the ninth resistor R9, and the tenth resistor R10 are all gate-level driving resistors.

[0050] In some embodiments of the present invention, the driving circuit further includes a fifth resistor R5, a fifth capacitor C5, an eighth resistor R8, and a sixth capacitor C6;

[0051] One end of the fifth resistor R5 is connected to the anode of the fifth diode D5, and the other end is connected to the base of the third transistor Q3; both ends of the fifth capacitor C5 are connected to both ends of the fifth resistor R5 respectively;

[0052] One end of the eighth resistor R8 is connected to the anode of the sixth diode D6 , and the other end is connected to the base of the fourth transistor Q4 ; both ends of the sixth capacitor C6 are respectively connected to both ends of the sixth resistor R6 .

[0053] The fifth resistor R5 and the eighth resistor R8 are base current limiting resistors of the third transistor Q3 and the fourth transistor Q4 respectively, and the fifth capacitor C5 and the sixth capacitor C6 are acceleration capacitors.

[0054] In some embodiments of the present invention, the driving circuit further includes a third resistor R3 and a fourth resistor R4;

[0055] One end of the third resistor R3 is connected to the gate of the first power MOS tube, and the other end is connected to the source of the first power MOS tube;

[0056] One end of the fourth resistor R4 is connected to the gate of the second power MOS tube, and the other end is connected to the source of the second power MOS tube. The third resistor R3 and the fourth resistor R4 are gate-level pull-down resistors of the first power MOS tube and the second power MOS tube, respectively.

[0057] Figure 6 The operating principle of the drive circuit shown is as follows:

[0058] (1) The on state of the power MOS tube:

[0059] When the PWM drive signal input is at a high level, the first transistor Q1 is turned on, the second transistor Q2 is turned off, and the Vcc power supply charges the second capacitor C2 and the primary excitation inductance of the driving transformer T1 through the first transistor Q1. At this time, the winding polarity of the driving transformer T1 is positive at the top and negative at the bottom (both the primary and secondary windings). The secondary winding, together with the third capacitor C3 and the fourth capacitor C4, charges the gate parasitic capacitance of the two power MOS tubes through the fifth diode D5-sixth resistor R6-seventh resistor R7, sixth diode D6-ninth resistor R9-tenth resistor R10, so that the power MOS tube is turned on. At this time, the third transistor Q3 and the fourth quadrupole Q4 are in the cut-off state. The polarity identification and current loop of the main components are as follows: Figure 7 shown.

[0060] (2) The off state of the power MOS tube:

[0061] When the PWM drive signal input is at a low level, the first transistor Q1 is turned off, and the second transistor Q2 is turned on. At this time, the winding polarity of the driving transformer T1 is negative at the top and positive at the bottom (both the primary and secondary windings), and the second capacitor C2 of the primary side of the driving transformer charges the excitation inductance of the primary side of the driving transformer T1 through the second transistor Q2; at the same time, the secondary winding of the driving transformer T1 charges the third capacitor C3 and the fourth capacitor C4 through the second diode D2 and the third diode D3, causing the third transistor Q3 and the fourth transistor Q4 to be turned on, so that the power MOS The gate charge of the tube is quickly discharged through the third transistor Q3 and the fourth transistor Q4 to achieve rapid shutdown; the first diode D1 provides a discharge circuit for the second capacitor C2 in the abnormal shutdown state to prevent the core saturation of the driving transformer T1; the eleventh resistor R11 and the twelfth resistor R12 provide a discharge circuit for the third capacitor C3 and the fourth capacitor C4 to avoid the third capacitor C3 and the fourth capacitor C4 charging the gate parasitic capacitance of the power MOS tube during the shutdown period of the power MOS tube, resulting in the gate drive voltage rising and the wrong opening. The polarity identification and current circuit of the main components are as follows Figure 8 As shown. Fig. 9As shown, curve 1 is the PWM drive signal, and curve 2 is the gate drive voltage Vgs. During the period when the PWM drive signal is input at a low level, the gate drive voltage Vgs is always at a low level, with a voltage value of about 0V, and there is no rise in the Vgs voltage, which ensures the reliable shutdown of the power MOS tube and prevents false start-up.

[0062] Although the embodiments of the present invention add additional components compared to the background art, these components are common and economical electronic components, so the overall cost does not increase significantly. Compared with the prior art, the present invention provides a more economical and efficient solution, which is suitable for large-scale production and application.

[0063] In summary, the present invention has the following beneficial effects: the scheme of the present invention sets a DC blocking capacitor on both the primary and secondary sides of the transformer, adds a discharge resistor to the DC blocking capacitor on the secondary side of the transformer, and adds a drive turn-on diode and a gate-level turn-off PNP transistor to the power MOS tube, so as to realize fast and reliable turn-off of the power MOS tube, and provide a discharge circuit through the discharge resistor to solve the problem of erroneous turn-on of the power MOS tube. The scheme of the present invention has the advantages of high isolation, good drive consistency, reliable circuit and low cost.

[0064] The above are only specific implementations of the present invention, which cannot be used to limit the scope of the present invention. Equivalent changes made by ordinary technicians in this technical field based on this creation, as well as changes known to technicians in this field, should still fall within the scope of the present invention.

Claims

1. A magnetic isolation transformer driving circuit suitable for a dual-tube flyback auxiliary power supply, characterized in that: It includes a PWM drive signal input terminal, an NPN type first transistor (Q1), a PNP type second transistor (Q2), a second capacitor (C2), a drive transformer (T1), a third capacitor (C3), a fourth capacitor (C4), an eleventh resistor (R11), a twelfth resistor (R12), a second diode (D2), a third diode (D3), a fifth diode (D5), a sixth diode (D6), a PNP type third transistor (Q3), and a PNP type fourth transistor (Q4); The PWM drive signal input end is simultaneously connected to the bases of the first transistor (Q1) and the second transistor (Q2); the emitter of the first transistor (Q1) is respectively connected to the emitter of the second transistor (Q2) and one end of the second capacitor (C2); the collector of the first transistor (Q1) is connected to a power supply (Vcc), and the collector of the second transistor (Q2) is grounded; the other end of the second capacitor (C2) is connected to the upper end of the primary winding of the drive transformer (T1), and the lower end of the primary winding of the drive transformer (T1) is grounded; The upper end of the first secondary winding of the driving transformer (T1) is respectively connected to the eleventh resistor (R11) and one end of the third capacitor (C3), and the lower end of the first secondary winding of the driving transformer (T1) is respectively connected to the anode of the second diode (D2), the collector of the third triode (Q3), and the source of the first power MOS tube; the other end of the third capacitor (C3) is respectively connected to the other end of the eleventh resistor (R11), the cathode of the second diode (D2), the base of the third triode (Q3), and the anode of the fifth diode (D5), and the cathode of the fifth diode (D5) is connected to the gate of the first power MOS tube; The upper end of the second secondary winding of the driving transformer (T1) is respectively connected to the twelfth resistor (R12) and one end of the fourth capacitor (C4); the lower end of the first secondary winding of the driving transformer (T1) is respectively connected to the anode of the third diode (D3), the collector of the fourth triode (Q4), and the source of the second power MOS tube; the other end of the fourth capacitor (C4) is respectively connected to the other end of the twelfth resistor (R12), the cathode of the third diode (D3), the base of the fourth triode (Q4), and the anode of the sixth diode (D6); the cathode of the sixth diode (D6) is connected to the gate of the second power MOS tube.

2. The magnetic isolation transformer driving circuit suitable for a dual-switch flyback auxiliary power supply according to claim 1, characterized in that: The driving circuit also includes a first resistor (R1), a first capacitor (C1), and a second resistor (R2); One end of the first resistor (R1) is connected to the PWM drive signal input end, and the other end of the first resistor (R1) is respectively connected to one end of the first capacitor (C1), one end of the second resistor (R2), the base of the first transistor (Q1), and the base of the second transistor (Q2); the other end of the first capacitor (C1) and the other end of the second resistor (R2) are grounded.

3. The magnetic isolation transformer driving circuit suitable for a dual-transistor flyback auxiliary power supply according to claim 1, characterized in that: The drive circuit also includes a first diode (D1), an anode of the first diode (D1) is connected to the upper end of the primary winding of the drive transformer (T1), and a cathode of the first diode (D1) is respectively connected to the emitter of the first transistor (Q1) and the emitter of the second transistor (Q2).

4. The magnetic isolation transformer driving circuit suitable for a dual-transistor flyback auxiliary power supply according to claim 1, characterized in that: The driving circuit further includes a sixth resistor (R6), a seventh resistor (R7), a ninth resistor (R9), and a tenth resistor (R10); One end of the sixth resistor (R6) is connected to the cathode of the fifth diode (D5), and the other end is respectively connected to one end of the seventh resistor (R7) and the emitter of the third transistor (Q3); the other end of the seventh resistor (R7) is connected to the gate of the first power MOS tube; One end of the ninth resistor (R9) is connected to the cathode of the sixth diode (D6), and the other end is respectively connected to one end of the tenth resistor (R10) and the emitter of the fourth transistor (Q4); the other end of the tenth resistor (R10) is connected to the gate of the second power MOS tube.

5. The magnetic isolation transformer driving circuit suitable for a dual-transistor flyback auxiliary power supply according to claim 1, characterized in that: The driving circuit also includes a fifth resistor (R5), a fifth capacitor (C5), an eighth resistor (R8), and a sixth capacitor (C6); One end of the fifth resistor (R5) is connected to the anode of the fifth diode (D5), and the other end is connected to the base of the third transistor (Q3); two ends of the fifth capacitor (C5) are respectively connected to two ends of the fifth resistor (R5); One end of the eighth resistor (R8) is connected to the anode of the sixth diode (D6), and the other end is connected to the base of the fourth transistor (Q4); the two ends of the sixth capacitor (C6) are respectively connected to the two ends of the sixth resistor (R6).

6. The magnetic isolation transformer driving circuit suitable for a dual-transistor flyback auxiliary power supply according to claim 1, characterized in that: The driving circuit also includes a third resistor (R3) and a fourth resistor (R4); One end of the third resistor (R3) is connected to the gate of the first power MOS tube, and the other end is connected to the source of the first power MOS tube; One end of the fourth resistor (R4) is connected to the gate of the second power MOS tube, and the other end is connected to the source of the second power MOS tube.

Images