End-to-end high-efficiency single-stage direct current chopper circuit and control method thereof

Abstract

The invention relates to an end-to-end single-stage direct current chopper circuit and a control method thereof. The circuit comprises an input filter circuit, a symmetrical half-bridge circuit, a high-frequency transformer, a current-doubling synchronous rectification circuit, a current sampling transformer, a PWM control chip and an isolation driving chip. Compared with a traditional distributed secondary power supply and tertiary power supply two-stage circuit, the end-to-end efficient single-stage direct current chopper circuit has the advantages of being simple in circuit structure, high in conversion efficiency and small in size. Meanwhile, a third-generation power semiconductor bare chip and a magnetic integrated element are subjected to high-frequency hybrid integrated design, the size can be reduced by 40% compared with that of a traditional circuit architecture, a circuit control method is optimized, the power density of the circuit can be greatly improved, and the power conversion efficiency is improved to 90% from 74.6% compared with that of a traditional two-stage power supply architecture.

Description

Technical Field

[0001] The present invention relates to the technical field of DC / DC regulated power supply, and in particular to an end-to-end high-efficiency single-stage DC chopper circuit and a control method thereof. Background Art

[0002] With the development of modern technology, the system is evolving towards the direction of increasing informatization, integration and intelligence. Under this development trend, the whole machine power supply system has put forward more stringent requirements for the DC / DC regulated power supply with low voltage and high current output. From the principle level, lowering the operating voltage can reduce the internal power loss of the integrated chip, which is of great significance for the stable operation and performance improvement of the chip. At the same time, chip technology continues to advance, chip functions are becoming increasingly rich and the integration continues to rise, which requires the power supply to provide more and more current to the chip to ensure the normal operation of the chip.

[0003] In the traditional power supply architecture, for low voltage and high current power supply requirements of controllers such as FPGA and DSP, the following are commonly used: Figure 1 The combined power supply architecture of secondary power supply + tertiary power supply is shown. This two-stage architecture has obvious defects. Since it requires two power converters, the efficiency of the power supply system will decrease after each power conversion. Moreover, this architecture will increase the size of the power supply system and increase the cost. Specifically, the conversion efficiency of the medium and low power secondary power supplies widely used in the current system is only about 82%, the conversion efficiency of the high current load point power supply is about 91%, and the comprehensive efficiency of the two-stage conversion is only 74.6%.

[0004] In response to the demand for low-voltage and high-current power supply, how can the power supply architecture be transformed from a distributed "secondary power supply + tertiary power supply" two-level structure to a Figure 2 The transformation of the single-stage (secondary power bus end-load end) power supply architecture shown in the figure is imperative. How to achieve this end-to-end efficient single-stage solution to replace the traditional two-stage solution is of vital importance to effectively simplify the power supply system architecture and improve power conversion efficiency.

[0005] Therefore, developing an end-to-end efficient single-stage DC chopper circuit suitable for low-voltage and high-current DC / DC regulated power supply architecture has become an urgent need in current technological development. Summary of the invention

[0006] In order to address the deficiencies in the prior art, the object of the present invention is to provide an end-to-end high-efficiency single-stage DC chopper circuit and a control method thereof, which can effectively simplify the power supply system architecture, realize an end-to-end high-efficiency single-stage power supply architecture, reduce the size of the circuit, and improve the power density and power conversion efficiency of the circuit.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] An end-to-end single-stage DC chopper circuit comprises an input filter circuit, a symmetrical half-bridge circuit, a high-frequency transformer, a current-doubling synchronous rectification circuit, a current sampling transformer, a PWM control chip and an isolation drive chip.

[0009] The input filter circuit is used to filter out high-frequency noise and ripples in the input power supply.

[0010] The symmetrical half-bridge circuit is used to convert the input DC voltage into a high-frequency square wave voltage to drive the primary winding of the high-frequency transformer.

[0011] The high-frequency transformer is used to transfer the high-frequency square wave voltage generated by the symmetrical half-bridge circuit from the primary winding to the secondary winding to achieve voltage stepping.

[0012] The current-doubling synchronous rectification circuit is used to rectify the voltage signal of the secondary winding of the high-frequency transformer into a direct current voltage.

[0013] The current sampling transformer is used to collect current at the connection node between the symmetrical half-bridge circuit and the high-frequency transformer, and send the collected current signal to the PWM control chip.

[0014] The PWM control chip is used to generate a control signal according to the current signal collected by the current sampling transformer, control the power switch tube in the symmetrical half-bridge circuit and the synchronous rectifier tube in the current-doubling synchronous rectification circuit, and adjust the output voltage by adjusting the duty cycle of the control signal.

[0015] The isolation driving chip is used to transmit the control signal of the PWM control chip to the synchronous rectifier tube in the current-doubling synchronous rectification circuit.

[0016] Preferably according to the present invention, the symmetrical half-bridge circuit includes a power tube Q1, a power tube Q2, an energy storage voltage-dividing capacitor C1, an energy storage voltage-dividing capacitor C2 and an energy storage voltage-dividing capacitor C3.

[0017] The first end of the energy storage voltage-dividing capacitor C2 is connected to the positive end of the input power supply, and the second end of the energy storage voltage-dividing capacitor C2 is connected to the negative end of the input power supply; the drain of the power tube Q1 is respectively connected to the first end of the capacitor C2 and the first end of the energy storage voltage-dividing capacitor C1; the source of the power tube Q1 is connected to the drain of the power tube Q2; the source of the power tube Q2 is respectively connected to the second end of the capacitor C2 and the second end of the energy storage voltage-dividing capacitor C3; the second end of the energy storage voltage-dividing capacitor C1 is connected to the first end of the energy storage voltage-dividing capacitor C3; the same-name ends of the primary winding of the high-frequency transformer T1 are respectively connected to the source of the power tube Q1 and the drain of the power tube Q2; the opposite-name ends of the primary winding of the transformer T1 are respectively connected to the second end of the energy storage voltage-dividing capacitor C1 and the first end of the energy storage voltage-dividing capacitor C3.

[0018] Preferably according to the present invention, the current doubling synchronous filtering circuit includes a synchronous rectifier tube Q3, a synchronous rectifier tube Q4, an output filter inductor L1, an output filter inductor L2, an output filter capacitor C4 and an output filter capacitor C5.

[0019] The drain of the synchronous rectifier Q3 is respectively connected to the same-name end of the secondary winding of the high-frequency transformer T1 and the first end of the output filter inductor L1; the source of the synchronous rectifier Q3 is connected to the source of the synchronous rectifier Q4; the drain of the synchronous rectifier Q4 is respectively connected to the opposite-name end of the secondary winding of the high-frequency transformer T1 and the first end of the output filter inductor L2; one end of the output filter capacitor C4 and the output filter capacitor C5 connected in parallel is connected to the connection node of the second end of the output filter inductor L1 and the second end of the output filter inductor L2, and the other end is connected to the connection node of the source of the synchronous rectifier Q3 and the source of the synchronous rectifier Q4; the load is connected in parallel to both ends of the output filter capacitor C4 and the output filter capacitor C5.

[0020] Preferably according to the present invention, the output pin OUTA of the PWM control chip is connected to the gate of the power tube Q1; the output pin OUTA of the PWM control chip is connected to the gate of the power tube Q2; the output pin SRA of the PWM control chip is connected to the gate of the synchronous rectifier Q3; the output pin SRB of the PWM control chip is connected to the gate of the synchronous rectifier Q4.

[0021] Preferably according to the present invention, the isolation driving chip includes a half-bridge isolation driving circuit and a rectifier isolation driving circuit.

[0022] Preferably according to the present invention, the half-bridge isolation drive circuit includes a half-bridge driver, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a resistor R9, a capacitor C6, a capacitor C7, a capacitor C8, a capacitor C9, a diode D1, a diode D2, a diode D3, a diode D4, a diode D5, a diode D6, a diode D7, a Zener diode Dz1 and a Zener diode Dz2.

[0023] The BST pin of the half-bridge driver is respectively connected to the cathode of the diode D3 and the first end of the capacitor C8, the anode of the diode D3 is connected to the power supply via the resistor R9, and the second end of the capacitor C8 is grounded; the HG pin of the half-bridge driver is connected to the cathode of the diode D1, the anode of the diode D1 is connected to the first end of the resistor R2, the second end of the resistor R2 is connected to the first end of the capacitor C6, and the second end of the capacitor C6 is connected to the cathode of the voltage-stabilizing diode Dz1; the first end of the resistor R1 is connected to the cathode of the diode D1, and the second end is respectively connected to the node between the resistor R2 and the capacitor C6 and the first end of the resistor R3; the second end of the resistor R3 is respectively connected to the second end of the capacitor C6, the cathode of the voltage-stabilizing diode Dz1, and the gate of the power tube Q1; the anode of the voltage-stabilizing diode Dz1 is respectively connected to the cathode of the diode D2 and the anode of the diode D3, and the anode of the diode D2 is connected to the cathode of the diode D3 and then connected to the HS pin of the half-bridge driver, the second end of the resistor R4, and the gate of the power tube Q1. The LG pin of the half-bridge driver is respectively connected to the cathode of the diode D4 and the first end of the resistor R5; the anode of the diode D4 is connected to the first end of the resistor R6, the second end of the resistor R6 is connected to the first end of the capacitor C7, and the second end of the capacitor C7 is respectively connected to the second end of the resistor R7, the cathode of the voltage zener diode Dz2, and the gate of the power tube Q2; the first end of the resistor R5 is connected to the cathode of the diode D4, and the second end of the resistor R5 is respectively connected to the node between the resistor R6 and the capacitor C7 and the first end of the resistor R7; the anode of the voltage zener diode Dz2 is respectively connected to the cathode of the diode D5 and the anode of the diode D6; the anode of the diode D5 and the cathode of the diode D6 are connected and then connected to the LS pin of the half-bridge driver, the second end of the resistor R8, and the source of the power tube Q2; the first end of the resistor R8 is connected to the gate of the power tube Q2; the VCC pin of the half-bridge driver is grounded via the capacitor C9.

[0024] Preferably according to the present invention, the rectifier isolation drive circuit includes an isolation driver N1, a resistor Roff, a resistor Ron, a resistor Ra, a resistor Rb, a resistor R10, a resistor R11, a resistor R12, a resistor R13, a capacitor C10, a capacitor C11, a capacitor Cc, a capacitor C13, a diode D8, a diode D8, a diode D9, a diode Dz3 and a diode Dz4.

[0025] The INA pin of the isolation driver N1 is connected to the SRA signal output by the PWM control chip, and the INB pin of the isolation driver N1 is connected to the SRB signal output by the PWM control chip; the power pin of the isolation driver N1 is connected to the power supply, and the power pin is also grounded through the capacitor C10; the ground pin of the isolation driver N1 is grounded; the pin OUA of the isolation driver N1 is connected to the cathode of the diode D8, the anode of the diode D8 is connected to the first end of the resistor Roff, the second end of the resistor Roff is connected to the first end of the capacitor Cc, and the second end of the capacitor Cc is respectively connected to the second end of the resistor Ra, the cathode of the voltage stabilizing diode Dz3, the first end of the resistor Rb, and the gate of the synchronous rectifier Q3; the first end of the resistor Ron is connected to the cathode of the diode D8, and the second end is respectively connected to the node between the resistor Roff and the capacitor Cc, and the first end of the resistor Ra; the anode of the voltage stabilizing diode Dz3, the first end of the resistor Rb, and the source of the synchronous rectifier Q3 are all grounded; the drain of the synchronous rectifier Q3 is connected to the power supply.

[0026] The OUB pin of the isolation driver N1 is connected to the cathode of the diode D9, the anode of the diode D9 is connected to the first end of the resistor R10, the second end of the resistor R10 is connected to the first end of the capacitor C13, and the second end of the capacitor C13 is respectively connected to the second end of the resistor R12, the cathode of the voltage-stabilizing diode Dz4, the first end of the resistor R13, and the gate of the synchronous rectifier Q4; the first end of the resistor R11 is connected to the cathode of the diode D9, and the second end is respectively connected to the node between the resistor R10 and the capacitor C13, and the first end of the resistor R12; the anode of the voltage-stabilizing diode Dz4, the first end of the resistor R13, and the source of the synchronous rectifier Q4 are all grounded; the drain of the synchronous rectifier Q4 is connected to the power supply.

[0027] Preferably according to the present invention, the power tube Q1, the power tube Q2, the synchronous rectifier tube Q3 and the synchronous rectifier tube Q4 are all gallium nitride field effect transistors GaN FET.

[0028] Preferably, according to the present invention, the synchronous rectifier Q3, the synchronous rectifier Q4 and the isolation driver N1 are assembled by bare chips using a hybrid integration process; the synchronous rectifier Q3, the synchronous rectifier Q4 and the isolation driver N1 are integrated on a substrate, and wiring is provided on the substrate; the wiring is a gold conductor; the electrical interconnection between the synchronous rectifier Q3, the synchronous rectifier Q4 and the bare chips of the isolation driver N1 is achieved by gold wire or aluminum wire bonding.

[0029] The present invention also includes a control method for the end-to-end single-stage DC chopper circuit, the method comprising the following steps:

[0030] S1, input filter circuit filters out high-frequency noise and ripple in the input power supply;

[0031] S2, the symmetrical half-bridge circuit converts the input DC voltage into a high-frequency square wave voltage to drive the primary winding of the high-frequency transformer T1;

[0032] S3, high-frequency transformer T1 transfers the high-frequency square wave voltage generated by the symmetrical half-bridge circuit from the primary winding to the secondary winding to achieve voltage rise and fall;

[0033] S4, a current-doubling synchronous rectification circuit rectifies the voltage signal of the secondary winding of the high-frequency transformer into a DC voltage;

[0034] S5, the current sampling transformer collects current at the connection node between the symmetrical half-bridge circuit and the high-frequency transformer, and sends the collected current signal to the PWM control chip;

[0035] S6. The PWM control chip generates a control signal according to the current signal collected by the current sampling transformer, and based on the control signal, controls the power switch tube in the symmetrical half-bridge circuit and the synchronous rectifier tube switch in the current doubling synchronous rectification circuit, and adjusts the output voltage by adjusting the duty cycle of the control signal.

[0036] Compared with the prior art, the advantages of the present invention are:

[0037] Compared with the traditional distributed "secondary power supply + tertiary power supply" two-stage circuit, the end-to-end high-efficiency single-stage DC chopper circuit proposed in the present invention has the advantages of simple circuit structure, high conversion efficiency and small size. The high-frequency transformer used in the present invention works in the first and third quadrants, and the transformer has high working efficiency; the current doubler synchronous rectification circuit can reduce the effective value of the output inductor current and the secondary current of the transformer T1, so that the conduction loss of the output inductor and the secondary winding of the transformer T1 is greatly reduced; the current doubler synchronous rectification circuit reduces the output current ripple through the mutual offset of the current ripple of the two output filter inductors, thereby reducing the size of the output filter, thereby improving the transient response speed and power density. The power tube and synchronous rectifier in the present invention are made of the third-generation semiconductor material GaN. Compared with the traditional Si semiconductor material, the third-generation semiconductor material GaN has a higher electron saturation drift velocity and electron mobility, so that the transistor based on GaN material has lower conduction loss and higher switching speed; in addition, GaN HEMT has a smaller gate charge and junction capacitance, which means that less energy is stored in the off stage, which is conducive to improving the switching frequency and switching efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a schematic diagram of the combined power supply architecture of secondary power supply + tertiary power supply;

[0039] Figure 2It is a schematic diagram of a single-stage (secondary power bus end-load end) power supply architecture;

[0040] Figure 3 It is a schematic diagram of an end-to-end single-stage DC chopper circuit in the present invention;

[0041] Figure 4 is a circuit diagram of an end-to-end single-stage DC chopper circuit in the present invention;

[0042] Figure 5 It is a driving waveform diagram of each mode switch device in an end-to-end single-stage DC chopper circuit and a current waveform diagram on the output filter inductor, wherein the abscissa represents time, the ordinate of the upper waveform diagram represents the driving voltage during each switch period, and the lower waveform diagram represents the current on each output filter inductor;

[0043] Figure 6 It is a circuit schematic diagram of a half-bridge isolation drive circuit in the present invention;

[0044] Figure 7 It is the schematic diagram of the opening circuit of the half-bridge isolation drive circuit;

[0045] Figure 8 It is the shutdown circuit schematic diagram of the half-bridge isolation drive circuit;

[0046] Fig. 9 It is the circuit schematic diagram of the rectifier isolation drive circuit;

[0047] Fig.10 It is a schematic diagram of the interconnection between the isolation driver and the synchronous rectifier;

[0048] Fig.11 It is the output voltage startup waveform;

[0049] Fig.12 It is the driving waveform of the main power MOS tube and SR MOS;

[0050] Fig.13 It is the waveform of input current and CS Pin voltage;

[0051] Fig.14 It is the voltage stress waveform of the main power MOS tube and SR MOS;

[0052] Fig.15 It is the waveform diagram of inductor current and output current;

[0053] Fig.16 Output voltage changes with input voltage curve;

[0054] Fig.171 is a waveform diagram of output voltage regulation, wherein (a) is a waveform diagram of output voltage regulation between 0.8V and 1.0V, and (b) is a waveform diagram of output voltage regulation between 1.2V and 1.0V. DETAILED DESCRIPTION

[0055] The present invention will be further described below in conjunction with the accompanying drawings:

[0056] The end-to-end single-stage DC chopper circuit has the characteristics of high input-output voltage conversion ratio, large output current, high conversion efficiency, etc. In order to achieve a high voltage conversion ratio, the system conversion efficiency, stability and dynamic characteristics must be taken into account at the same time. After comprehensive analysis through creative labor, the present invention selects half-bridge + current doubler rectification as the main circuit topology of the end-to-end single-stage DC chopper circuit described in the present invention.

[0057] like Figure 3 The end-to-end single-stage DC chopper circuit shown in the figure includes an input filter circuit, a symmetrical half-bridge circuit, a high-frequency transformer T1, a current-doubler synchronous rectification circuit, a current sampling transformer, a PWM control chip and an isolation driver chip. Figure 3 In the invention, SRMOS (Synchronous Rectification MOSFET) is a synchronous rectifier, which is a device that uses MOSFET (metal-oxide-semiconductor field-effect transistor) to realize synchronous rectification function.

[0058] Specifically, the output end of the input filter circuit is connected to the input end of the symmetrical half-bridge circuit, and the output end of the symmetrical half-bridge circuit is connected to the primary winding of the high-frequency transformer T1. The secondary winding of the high-frequency transformer T1 is connected to the input end of the current-doubling synchronous rectification circuit. The current sampling transformer is used to collect current at the connection node between the symmetrical half-bridge circuit and the high-frequency transformer T1, and send the collected current signal to the PWM control chip; the output end of the PWM control chip is respectively connected to the control end of the symmetrical half-bridge circuit and the control end of the current-doubling synchronous rectification circuit. The PWM control chip sends control signals to the symmetrical half-bridge circuit and the current-doubling synchronous rectification circuit. The output end of the current-doubling synchronous rectification circuit is connected to a load.

[0059] Furthermore, the input filter circuit is used to filter out high-frequency noise and ripple in the input power supply to ensure the stability of the input voltage. The input filter circuit can also suppress electromagnetic interference (EMI) to prevent external noise from entering the circuit. The input filter circuit can improve the quality of the input power supply, reduce interference to subsequent circuits, and improve the stability and reliability of the system.

[0060] The symmetrical half-bridge circuit is used to convert the input DC voltage into a high-frequency square wave voltage to drive the primary winding of the high-frequency transformer T1. The symmetrical half-bridge circuit converts the input DC voltage into a high-frequency square wave voltage through two complementary conduction switching tubes and two energy storage voltage-dividing capacitors to drive the primary winding of the high-frequency transformer. The symmetrical half-bridge circuit can reduce the voltage stress of the switching tube through complementary conduction, improve efficiency and reliability, and the symmetrical structure can also reduce electromagnetic interference.

[0061] The high-frequency transformer T1 is used to transfer the high-frequency square wave voltage generated by the symmetrical half-bridge circuit from the primary winding to the secondary winding to achieve voltage rise and fall. The primary winding and the secondary winding of the high-frequency transformer T1 usually use ferrite or other high magnetic permeability materials as the magnetic core. The high-frequency transformer T1 can achieve efficient voltage conversion and electrical isolation, reduce the size and weight of the transformer, and improve the power density.

[0062] The current-doubling synchronous rectification circuit is used to rectify the voltage signal of the secondary winding of the high-frequency transformer T1 into a DC voltage. The current-doubling synchronous rectification circuit rectifies the voltage signal of the secondary winding of the high-frequency transformer T1 into a DC voltage through two synchronous rectifiers and output filter inductors and capacitors, which can significantly improve the rectification efficiency and reduce the output current ripple.

[0063] The current sampling transformer is used to collect current at the connection node between the symmetrical half-bridge circuit and the high-frequency transformer T1, and send the collected current signal to the PWM control chip for feedback control and protection. The current sampling transformer can adopt a small transformer, whose primary winding is connected in series in the circuit, and the secondary winding is used for sampling current. The current sampling transformer can provide real-time current feedback for closed-loop control and protection to ensure the stability and safety of the system.

[0064] The PWM control chip is used to generate a control signal to control the power switch tube in the symmetrical half-bridge circuit and the synchronous rectifier tube in the current-doubling synchronous rectifier circuit, and adjust the output voltage by adjusting the duty cycle of the control signal. The PWM control chip can achieve high-precision voltage regulation and fast dynamic response, and provide multiple protection functions (such as overcurrent protection, overvoltage protection, etc.).

[0065] The isolation driver chip is used to transmit the control signal of the PWM control chip to the synchronous rectifier tube in the current-doubling synchronous rectifier circuit. The isolation driver chip provides electrical isolation to ensure that there is no direct electrical connection between the control signal on the low-voltage side and the power switch tube on the high-voltage side, protect the control circuit on the low-voltage side, reduce noise and interference, and improve the safety and reliability of the system.

[0066] The end-to-end single-stage DC chopper circuit of the present invention is described in detail below in conjunction with the circuit diagram.

[0067] The circuit of end-to-end single-stage DC chopper circuit is as follows Figure 4 As shown, the primary side of the high-frequency transformer T1 is a symmetrical half-bridge circuit composed of two complementary conducting power tubes Q1 and Q2 and energy storage voltage divider capacitors C1 and C3; the secondary side of the high-frequency transformer T1 is a current doubling synchronous rectification circuit composed of synchronous rectifier tubes Q3 and Q4, output filter inductors L1 and L2, and output filter capacitors C4 and C5.

[0068] like Figure 4 As shown, the symmetrical half-bridge circuit includes a power tube Q1, a power tube Q2, an energy storage voltage-dividing capacitor C1, an energy storage voltage-dividing capacitor C2 and an energy storage voltage-dividing capacitor C3; the first end of the energy storage voltage-dividing capacitor C2 is connected to the positive end of the input power supply, and the second end of the energy storage voltage-dividing capacitor C2 is connected to the negative end of the input power supply; the drain of the power tube Q1 is respectively connected to the first end of the capacitor C2 and the first end of the energy storage voltage-dividing capacitor C1; the source of the power tube Q1 is connected to the drain of the power tube Q2; the source of the power tube Q2 is respectively connected to the second end of the capacitor C2 and the second end of the energy storage voltage-dividing capacitor C3; the second end of the energy storage voltage-dividing capacitor C1 is connected to the first end of the energy storage voltage-dividing capacitor C3. The same-name ends of the primary winding of the high-frequency transformer T1 are respectively connected to the source of the power tube Q1 and the drain of the power tube Q2. The opposite-name ends of the primary winding of the transformer T1 are respectively connected to the second end of the energy storage voltage-dividing capacitor C1 and the first end of the energy storage voltage-dividing capacitor C3.

[0069] The current-doubling synchronous filter circuit includes a synchronous rectifier Q3, a synchronous rectifier Q4, an output filter inductor L1, an output filter inductor L2, an output filter capacitor C4 and an output filter capacitor C5. The drain of the synchronous rectifier Q3 is respectively connected to the same-name end of the secondary winding of the high-frequency transformer T1 and the first end of the output filter inductor L1; the source of the synchronous rectifier Q3 is connected to the source of the synchronous rectifier Q4; the drain of the synchronous rectifier Q4 is respectively connected to the opposite-name end of the secondary winding of the high-frequency transformer T1 and the first end of the output filter inductor L2; one end of the output filter capacitor C4 connected in parallel with the output filter capacitor C5 is connected to the connection node of the second end of the output filter inductor L1 and the second end of the output filter inductor L2, and the other end is connected to the connection node of the source of the synchronous rectifier Q3 and the source of the synchronous rectifier Q4. The load is connected in parallel to both ends of the output filter capacitor C4 and the output filter capacitor C5.

[0070] The output pin OUTA of the PWM control chip is connected to the gate of the power tube Q1; the output pin OUTA of the PWM control chip is connected to the gate of the power tube Q2. The output pin SRA of the PWM control chip is connected to the gate of the synchronous rectifier Q3; the output pin SRB of the PWM control chip is connected to the gate of the synchronous rectifier Q4.

[0071] Figure 4 The operation of the end-to-end single-stage DC chopper circuit shown in the figure is divided into four modes. The driving waveform of the switching device in each mode and the current waveform on the inductor are as follows: Figure 5 shown.

[0072] ①T0~T1-----D1 period:

[0073] The power tube Q1 in the main switch tube is turned on, and the power tube Q2 is turned off; the synchronous rectifier tube Q3 is turned off, and the synchronous rectifier tube Q4 is turned on. When the power tube Q1 is turned on and the power tube Q2 is turned off, the voltage on the energy storage voltage divider capacitor C3 is added to the primary winding of the high-frequency transformer T1 through the turned-on power tube Q1. The voltage on the primary winding is positive at the top and negative at the bottom, and the secondary winding accordingly induces a voltage in the same direction; at this time, the synchronous rectifier tube Q3 is turned off, and the synchronous rectifier tube Q4 is turned on, and the current on the output filter inductor L1 increases and flows through the load, forming a loop through the turned-on synchronous rectifier tube Q4 and the secondary winding of the high-frequency transformer T1; at the same time, the current on the output filter inductor L2 decreases, and the current flows through the load, and also forms a loop with itself through the turned-on synchronous rectifier tube Q4.

[0074] ②T1~T2-----Dead zone δ1 period:

[0075] The power tubes Q1 and Q2 as the main switch tubes are turned off, and the synchronous rectifier tubes Q3 and Q4 are turned on. Since the two main switch power tubes Q1 and Q2 are turned off, the energy storage voltage divider capacitors C1 and C2 are ideal energy storage capacitors, and the voltage on them is Vin / 2, so the voltage on the primary winding of the high-frequency transformer T1 is zero, and the voltage on the secondary winding is also zero; at this time, the synchronous rectifier tubes Q3 and Q4 are both turned on, which on the one hand ensures that the voltage on the secondary winding of the high-frequency transformer T1 is zero, and on the other hand provides a freewheeling channel for the output filter inductor L1 and the output filter inductor L2; the energy stored in the output filter inductor L1 and the output filter inductor L2 flows through the load in the form of current, and the current I L1 ,I L2 Both are reduced, and the turned-on synchronous rectifier Q3 and synchronous rectifier Q4 jointly provide current for the load.

[0076] ③T2~T3-----D2 period:

[0077] The power tube Q1 in the main switch tube is turned off, and the power tube Q2 is turned on; the synchronous rectifier tube Q3 is turned on, and Q4 is turned off. When the power tube Q1 is turned off and the power tube Q2 is turned on, the voltage on the energy storage capacitor C2 is added to the primary winding of the high-frequency transformer T1 through the turned-on power tube Q2. The voltage of the primary winding of the high-frequency transformer T1 is negative at the top and positive at the bottom, and the secondary winding accordingly induces a voltage in the same direction; at this time, the synchronous rectifier tube Q3 is turned on, the synchronous rectifier tube Q4 is turned off, and the current I on the output filter inductor L2 is L2 The current increases and flows through the load, forming a loop through the turned-on synchronous rectifier Q3 and the secondary winding of the high-frequency transformer T1; at the same time, the current on the output filter inductor L1 decreases, and the current flows through the load, and also forms a loop with itself through the turned-on synchronous rectifier Q3.

[0078] ④T3~T4-----Dead zone δ2 period:

[0079] The power tubes Q1 and Q2 in the main switch tube are turned off, and the synchronous rectifier tubes Q3 and Q4 are turned on. The working state of each device in this process is similar to ②, and will not be repeated.

[0080] Preferably according to the present invention, the isolation driving chip includes a half-bridge isolation driving circuit and a rectifier isolation driving circuit.

[0081] like Figure 6 to Figure 8As shown, the half-bridge isolation drive circuit includes a half-bridge driver, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a resistor R9, a capacitor C6, a capacitor C7, a capacitor C8, a capacitor C9, a diode D1, a diode D2, a diode D3, a diode D4, a diode D5, a diode D6, a diode D7, a Zener diode Dz1 and a Zener diode Dz2. The BST pin of the half-bridge driver is respectively connected to the cathode of the diode D3 and the first end of the capacitor C8, the anode of the diode D3 is connected to the power supply via the resistor R9, and the second end of the capacitor C8 is grounded; the HG pin of the half-bridge driver is connected to the cathode of the diode D1, the anode of the diode D1 is connected to the first end of the resistor R2, the second end of the resistor R2 is connected to the first end of the capacitor C6, and the second end of the capacitor C6 is connected to the cathode of the voltage-stabilizing diode Dz1; the first end of the resistor R1 is connected to the cathode of the diode D1, and the second end is respectively connected to the node between the resistor R2 and the capacitor C6 and the first end of the resistor R3; the second end of the resistor R3 is respectively connected to the second end of the capacitor C6, the cathode of the voltage-stabilizing diode Dz1, and the gate of the power tube Q1; the anode of the voltage-stabilizing diode Dz1 is respectively connected to the cathode of the diode D2 and the anode of the diode D3, and the anode of the diode D2 is connected to the cathode of the diode D3 and then connected to the HS pin of the half-bridge driver, the second end of the resistor R4, The source of the power tube Q1 is connected; the LG pin of the half-bridge driver is respectively connected to the cathode of the diode D4 and the first end of the resistor R5; the anode of the diode D4 is connected to the first end of the resistor R6, the second end of the resistor R6 is connected to the first end of the capacitor C7, and the second end of the capacitor C7 is respectively connected to the second end of the resistor R7, the cathode of the voltage-stabilizing diode Dz2, and the gate of the power tube Q2; the first end of the resistor R5 is connected to the cathode of the diode D4, and the second end of the resistor R5 is respectively connected to the node between the resistor R6 and the capacitor C7 and the first end of the resistor R7; the anode of the voltage-stabilizing diode Dz2 is respectively connected to the cathode of the diode D5 and the anode of the diode D6; the anode of the diode D5 and the cathode of the diode D6 are connected and then connected to the LS pin of the half-bridge driver, the second end of the resistor R8, and the source of the power tube Q2; the first end of the resistor R8 is connected to the gate of the power tube Q2; the VCC pin of the half-bridge driver is grounded via the capacitor C9. Preferably, the power tube Q1 and the power tube Q2 are gallium nitride field effect transistors GaN FET.

[0082] The pin meanings of the half-bridge driver are as follows:

[0083] (1) HS pin

[0084] The HS (High-Side) pin is used to connect the source of the high-end power switch (usually MOSFET or IGBT) in the half-bridge driver. In the half-bridge circuit, the high-end power switch is a switching device connected between the positive voltage of the power supply and the load. This pin is mainly used to realize the control signal transmission and status monitoring of the high-end power switch in the half-bridge circuit. It provides a feedback signal path for the high-end power switch, so that the half-bridge driver can understand the working status of the high-end power switch, such as whether it is normally turned on or off, and whether there are abnormal conditions such as overcurrent and overvoltage. At the same time, it also participates in the driving process of the high-end power switch, and transmits the appropriate drive signal to the high-end power switch by cooperating with other pins to realize the normal operation of the half-bridge circuit.

[0085] (2)HG pin

[0086] The HG (High-Side Gate) pin is used to drive the gate of the high-side power switch in the half-bridge driver. The gate is the key electrode that controls the on and off of the power switch. This pin outputs a drive signal to control the on and off of the high-side power switch. When the HG pin outputs a suitable high-level signal, a sufficient voltage difference will be formed between the gate and source of the high-side power switch to turn on the high-side power switch, allowing current to flow from the positive end of the power supply to the load through the high-side power switch. When the HG pin outputs a low-level signal, the high-side power switch is turned off, and the current cannot flow from the positive end of the power supply to the load through the high-side power switch. Parameters such as the timing and voltage amplitude of the drive signal are very important for the normal operation of the half-bridge circuit and the performance and life of the power switch.

[0087] (3) LS pin

[0088] The LS (Low-Side) pin is used to connect the source of the low-end power switch in the half-bridge circuit. The low-end power switch is a switching device connected between the load and the ground (or the negative end of the power supply). The LS pin is mainly used to transmit the feedback signal of the low-end power switch so that the half-bridge driver can monitor the working status of the low-end power switch. At the same time, it also plays a role in the process of driving the low-end power switch. It is an important connection point between the half-bridge driver and the low-end power switch. By cooperating with other pins, it ensures that the low-end power switch is turned on and off in the correct timing, so as to work together with the high-end power switch to realize the function of the half-bridge circuit.

[0089] (4)LG pin

[0090] The LG (Low-Side Gate) pin is used to drive the gate of the low-side power switch in the half-bridge circuit. The signal output by the LG pin is used to control the on and off of the low-side power switch. When the LG pin outputs a high-level signal, the low-side power switch is turned on, so that the load can be connected to the ground (or the negative end of the power supply) through the low-side power switch; when the LG pin outputs a low-level signal, the low-side power switch is turned off. By precisely controlling the timing and level of the output signal of the LG pin, it is possible to ensure that the low-side power switch and the high-side power switch are alternately turned on and off, avoiding the situation where the two power switches are turned on at the same time, thereby ensuring the safe and efficient operation of the half-bridge circuit.

[0091] (5) BST pin

[0092] The BST (Bootstrap) pin is the bootstrap pin in the half-bridge driver. In the half-bridge circuit, since the source voltage of the high-end power switch changes with the working state of the circuit, a driving voltage higher than its source voltage is required to normally drive the gate of the high-end power switch. The BST pin is the connection point for providing this bootstrap voltage. During the circuit initialization stage or the operation of the half-bridge circuit, a driving voltage higher than its source voltage is provided to the gate of the high-end power switch through the external circuit and the bootstrap capacitor C8 to ensure that the high-end power switch can be turned on and off normally.

[0093] (6) VCC pin

[0094] The VCC pin is the power input pin of the half-bridge driver, which is used to provide working power for the logic circuit, drive circuit, etc. inside the half-bridge driver. The power supply voltage connected to the VCC pin provides the necessary power for the normal operation of the half-bridge driver.

[0095] like Figure 7 In the power tube turn-on process shown in FIG. 1 , the drive current loop is composed of resistor R1, resistor R3, capacitor C6, resistor R4, power tube Q1 (GaN FET), and capacitor C8. The drive voltage output by the HG pin of the half-bridge driver quickly charges the junction capacitance of the power tube Q1 through resistor R1 and capacitor C6, so that the gate-source voltage of the power tube Q1 rises quickly to turn on the power tube Q1.

[0096] like Figure 8In the power tube shutdown process shown in the figure, the driving current loop is composed of a diode D1, a resistor R2, a resistor R3, a capacitor C6, a voltage-stabilizing diode Dz1, a diode D2, a diode D3, a resistor R4, and a GaN FET. The gate charge of the power tube Q1 (GaN FET) is mainly discharged quickly through the capacitor C6, the diode D1, and the resistor R2, and the gate-source voltage of the power tube Q1 is quickly pulled down to turn off the power tube Q1. After the gate charge of the power tube Q1 is discharged, because the capacitor C1 needs to continue to discharge, the voltage-stabilizing diode Dz1 flows through current to generate a negative gate voltage.

[0097] like Fig. 9 As shown, the rectifier isolation drive circuit includes an isolation driver N1, a resistor Roff, a resistor Ron, a resistor Ra, a resistor Rb, a resistor R10, a resistor R11, a resistor R12, a resistor R13, a capacitor C10, a capacitor C11, a capacitor Cc, a capacitor C13, a diode D8, a diode D8, a diode D9, a diode Dz3 and a diode Dz4.

[0098] Specifically, the INA pin of the isolation driver N1 is connected to the SRA signal output by the PWM control chip, and the INB pin of the isolation driver N1 is connected to the SRB signal output by the PWM control chip. The power pin of the isolation driver N1 is connected to the power supply, and the power pin is also grounded through the capacitor C10. The ground pin of the isolation driver N1 is grounded. The pin OUA of the isolation driver N1 is connected to the cathode of the diode D8, the anode of the diode D8 is connected to the first end of the resistor Roff, the second end of the resistor Roff is connected to the first end of the capacitor Cc, and the second end of the capacitor Cc is respectively connected to the second end of the resistor Ra, the cathode of the voltage stabilizing diode Dz3, the first end of the resistor Rb, and the gate of the synchronous rectifier Q3. The first end of the resistor Ron is connected to the cathode of the diode D8, and the second end is respectively connected to the node between the resistor Roff and the capacitor Cc, and the first end of the resistor Ra. The anode of the voltage stabilizing diode Dz3, the first end of the resistor Rb, and the source of the synchronous rectifier Q3 are all grounded. The drain of the synchronous rectifier Q3 is connected to the power supply.

[0099] The OUB pin of the isolation driver N1 is connected to the cathode of the diode D9, the anode of the diode D9 is connected to the first end of the resistor R10, the second end of the resistor R10 is connected to the first end of the capacitor C13, and the second end of the capacitor C13 is respectively connected to the second end of the resistor R12, the cathode of the voltage stabilizing diode Dz4, the first end of the resistor R13, and the gate of the synchronous rectifier Q4. The first end of the resistor R11 is connected to the cathode of the diode D9, and the second end is respectively connected to the node between the resistor R10 and the capacitor C13 and the first end of the resistor R12. The anode of the voltage stabilizing diode Dz4, the first end of the resistor R13, and the source of the synchronous rectifier Q4 are all grounded. The drain of the synchronous rectifier Q4 is connected to the power supply.

[0100] The following takes the synchronous rectifier tube Q3 as an example to introduce the working principle of the rectifier isolation drive circuit.

[0101] like Fig. 9 As shown, the synchronous drive signals SRA and SRB generated by the PWM control chip are connected to the input terminals INA and INB of the isolation driver N1. The isolation driver N1 realizes the isolated transmission of the signal inside, isolates the synchronous drive signal from the primary side, amplifies it, and outputs it from the OUA pin and OUB pin of the isolation driver. Taking OUTA as an example, when turned on, the synchronous signal drive current loop is composed of resistor Ron, resistor Ra, capacitor Cc, resistor Rb, and synchronous rectifier Q3 (using GaN FET). The drive signal quickly charges the junction capacitor of the synchronous rectifier Q3 through resistor Ron and capacitor Cc, and the gate voltage of the synchronous rectifier Q3 rises quickly to turn on the synchronous rectifier Q3. When turned off, the drive current loop is composed of resistor Ron, resistor Roff, diode D1, resistor Ra, capacitor Cc, resistor Rb, voltage regulator diode Dz3, and synchronous rectifier Q3 (using GaN FET). The gate charge of the synchronous rectifier Q3 is quickly released through D8, resistor Roff, and capacitor Cc, and the gate voltage is quickly pulled down to turn off the power tube.

[0102] According to a preferred embodiment of the present invention, the synchronous rectifier Q3, the synchronous rectifier Q4 and the isolation driver N1 are assembled by bare chips using a hybrid integration process. Fig.10 As shown, the synchronous rectifier Q3, the synchronous rectifier Q4 and the isolation driver N1 are all integrated on a substrate, the wiring on the substrate is a gold conductor, and the electrical interconnection between the synchronous rectifier Q3, the synchronous rectifier Q4 and the bare chip of the isolation driver N1 is bonded by gold wire or aluminum wire.

[0103] The present invention also includes a control method for the end-to-end single-stage DC chopper circuit, the method comprising the following steps:

[0104] S1, input filter circuit filters out high-frequency noise and ripple in the input power supply;

[0105] S2, the symmetrical half-bridge circuit converts the input DC voltage into a high-frequency square wave voltage to drive the primary winding of the high-frequency transformer T1;

[0106] S3, high-frequency transformer T1 transfers the high-frequency square wave voltage generated by the symmetrical half-bridge circuit from the primary winding to the secondary winding to achieve voltage rise and fall;

[0107] S4, a current-doubling synchronous rectification circuit rectifies the voltage signal of the secondary winding of the high-frequency transformer into a DC voltage;

[0108] S5, the current sampling transformer collects current at the connection node between the symmetrical half-bridge circuit and the high-frequency transformer, and sends the collected current signal to the PWM control chip;

[0109] S6. The PWM control chip generates a control signal according to the current signal collected by the current sampling transformer, and based on the control signal, controls the power switch tube in the symmetrical half-bridge circuit and the synchronous rectifier tube switch in the current doubling synchronous rectification circuit, and adjusts the output voltage by adjusting the duty cycle of the control signal.

[0110] Circuit simulation was performed for the main power topology of half-bridge + current-doubling synchronous rectification in the end-to-end single-stage DC chopper circuit described in the present invention. The simulation software used was Simplis, and the circuit simulation was performed using time domain analysis and frequency domain. After the schematic diagram was drawn, the Simplis software was first used to perform transient analysis. Fig.11 The waveform shown is the output voltage establishment waveform at full load with 28V input. The output voltage oscillates slightly at startup and then stabilizes at 1V output. Fig.12 The figure shows the driving waveforms of the primary-side main power MOS and the secondary-side SR MOS of the half-bridge current doubler rectifier topology. It can be seen from the figure that there are dead zones on both sides of the waveform, about 50ns. Fig.13 The waveforms of the input current and the pulse width modulator current sampling CS pin are shown. The input current is about 1.94A, and the maximum amplitude of the CS pin is 265mV, which does not exceed the maximum threshold of 0.5V. Fig.14 The voltage stress waveforms of the main power MOS and the SR MOS are shown. The maximum voltage stress of the main MOS is about Vdc≈27.96V, and the voltage stress of the SR MOS is Vdc / (2×n)≈6.68V, where n is the transformer turns ratio. Fig.15 The output inductor waveform and output current waveform are shown. The DC component of the output current is about 49.7A, and the ripple current ΔI is about 3A. The currents on the output inductor are 24.34A and 25.35A respectively, and the inductor ripple current is about 3.7A. Fig.16 The output voltage changes with the input voltage. The input voltage jumps from 20V→28V→38V. The output voltage fluctuates briefly with the input voltage and finally stabilizes at around 1.0V. Fig.17 The waveform shown is the output voltage adjusted from 0.8V, 1V, and 1.2V. By changing the output sampling resistor, the output voltage can be adjusted between 0.8V and 1.2V.

[0111] The above-described embodiments are merely descriptions of preferred implementations of the present invention and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the scope of protection determined by the claims of the present invention.

Claims

1. An end-to-end single-stage DC chopper circuit, characterized in that: The circuit includes an input filter circuit, a symmetrical half-bridge circuit, a high-frequency transformer, a current-doubling synchronous rectification circuit, a current sampling transformer, a PWM control chip and an isolation drive chip; The input filter circuit is used to filter out high-frequency noise and ripples in the input power supply; The symmetrical half-bridge circuit is used to convert the input DC voltage into a high-frequency square wave voltage to drive the primary winding of the high-frequency transformer; The high-frequency transformer is used to transfer the high-frequency square wave voltage generated by the symmetrical half-bridge circuit from the primary winding to the secondary winding to achieve voltage rise and fall; The current-doubling synchronous rectification circuit is used to rectify the voltage signal of the secondary winding of the high-frequency transformer into a DC voltage; The current sampling transformer is used to collect current at the connection node between the symmetrical half-bridge circuit and the high-frequency transformer, and send the collected current signal to the PWM control chip; The PWM control chip is used to generate a control signal according to the current signal collected by the current sampling transformer, control the power switch tube in the symmetrical half-bridge circuit and the synchronous rectifier tube in the current-doubling synchronous rectification circuit, and adjust the output voltage by adjusting the duty cycle of the control signal; The isolation driving chip is used to transmit the control signal of the PWM control chip to the synchronous rectifier tube in the current-doubling synchronous rectification circuit.

2. The end-to-end single-stage DC chopper circuit according to claim 1, characterized in that: The symmetrical half-bridge circuit includes a power tube Q1, a power tube Q2, an energy storage voltage-dividing capacitor C1, an energy storage voltage-dividing capacitor C2 and an energy storage voltage-dividing capacitor C3; The first end of the energy storage voltage-dividing capacitor C2 is connected to the positive end of the input power supply, and the second end of the energy storage voltage-dividing capacitor C2 is connected to the negative end of the input power supply; the drain of the power tube Q1 is respectively connected to the first end of the capacitor C2 and the first end of the energy storage voltage-dividing capacitor C1; the source of the power tube Q1 is connected to the drain of the power tube Q2; the source of the power tube Q2 is respectively connected to the second end of the capacitor C2 and the second end of the energy storage voltage-dividing capacitor C3; the second end of the energy storage voltage-dividing capacitor C1 is connected to the first end of the energy storage voltage-dividing capacitor C3; the same-name ends of the primary winding of the high-frequency transformer T1 are respectively connected to the source of the power tube Q1 and the drain of the power tube Q2; the opposite-name ends of the primary winding of the transformer T1 are respectively connected to the second end of the energy storage voltage-dividing capacitor C1 and the first end of the energy storage voltage-dividing capacitor C3.

3. The end-to-end single-stage DC chopper circuit according to claim 2, characterized in that: The current-doubling synchronous filtering circuit includes a synchronous rectifier tube Q3, a synchronous rectifier tube Q4, an output filter inductor L1, an output filter inductor L2, an output filter capacitor C4 and an output filter capacitor C5; The drain of the synchronous rectifier Q3 is respectively connected to the same-name end of the secondary winding of the high-frequency transformer T1 and the first end of the output filter inductor L1; the source of the synchronous rectifier Q3 is connected to the source of the synchronous rectifier Q4; the drain of the synchronous rectifier Q4 is respectively connected to the opposite-name end of the secondary winding of the high-frequency transformer T1 and the first end of the output filter inductor L2; one end of the output filter capacitor C4 and the output filter capacitor C5 connected in parallel is connected to the connection node of the second end of the output filter inductor L1 and the second end of the output filter inductor L2, and the other end is connected to the connection node of the source of the synchronous rectifier Q3 and the source of the synchronous rectifier Q4; the load is connected in parallel to both ends of the output filter capacitor C4 and the output filter capacitor C5.

4. The end-to-end single-stage DC chopper circuit according to claim 3, characterized in that: The output pin OUTA of the PWM control chip is connected to the gate of the power tube Q1; the output pin OUTA of the PWM control chip is connected to the gate of the power tube Q2; The output pin SRA of the PWM control chip is connected to the gate of the synchronous rectifier Q3; the output pin SRB of the PWM control chip is connected to the gate of the synchronous rectifier Q4.

5. The end-to-end single-stage DC chopper circuit according to claim 4, characterized in that: The isolation driving chip includes a half-bridge isolation driving circuit and a rectifier isolation driving circuit.

6. The end-to-end single-stage DC chopper circuit according to claim 5, characterized in that: The half-bridge isolation drive circuit includes a half-bridge driver, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a resistor R9, a capacitor C6, a capacitor C7, a capacitor C8, a capacitor C9, a diode D1, a diode D2, a diode D3, a diode D4, a diode D5, a diode D6, a diode D7, a zener diode Dz1 and a zener diode Dz2; The BST pin of the half-bridge driver is respectively connected to the cathode of the diode D3 and the first end of the capacitor C8, the anode of the diode D3 is connected to the power supply via the resistor R9, and the second end of the capacitor C8 is grounded; the HG pin of the half-bridge driver is connected to the cathode of the diode D1, the anode of the diode D1 is connected to the first end of the resistor R2, the second end of the resistor R2 is connected to the first end of the capacitor C6, and the second end of the capacitor C6 is connected to the cathode of the voltage-stabilizing diode Dz1; the first end of the resistor R1 is connected to the cathode of the diode D1, and the second end is respectively connected to the node between the resistor R2 and the capacitor C6 and the first end of the resistor R3; the second end of the resistor R3 is respectively connected to the second end of the capacitor C6, the cathode of the voltage-stabilizing diode Dz1, and the gate of the power tube Q1; the anode of the voltage-stabilizing diode Dz1 is respectively connected to the cathode of the diode D2 and the anode of the diode D3, and the anode of the diode D2 is connected to the cathode of the diode D3 and then connected to the HS pin of the half-bridge driver, the second end of the resistor R4, and the gate of the power tube Q1. The LG pin of the half-bridge driver is respectively connected to the cathode of the diode D4 and the first end of the resistor R5; the anode of the diode D4 is connected to the first end of the resistor R6, the second end of the resistor R6 is connected to the first end of the capacitor C7, and the second end of the capacitor C7 is respectively connected to the second end of the resistor R7, the cathode of the voltage zener diode Dz2, and the gate of the power tube Q2; the first end of the resistor R5 is connected to the cathode of the diode D4, and the second end of the resistor R5 is respectively connected to the node between the resistor R6 and the capacitor C7 and the first end of the resistor R7; the anode of the voltage zener diode Dz2 is respectively connected to the cathode of the diode D5 and the anode of the diode D6; the anode of the diode D5 and the cathode of the diode D6 are connected and then connected to the LS pin of the half-bridge driver, the second end of the resistor R8, and the source of the power tube Q2; the first end of the resistor R8 is connected to the gate of the power tube Q2; the VCC pin of the half-bridge driver is grounded via the capacitor C9.

7. The end-to-end single-stage DC chopper circuit according to claim 6, characterized in that: The rectifier isolation drive circuit includes an isolation driver N1, a resistor Roff, a resistor Ron, a resistor Ra, a resistor Rb, a resistor R10, a resistor R11, a resistor R12, a resistor R13, a capacitor C10, a capacitor C11, a capacitor Cc, a capacitor C13, a diode D8, a diode D8, a diode D9, a diode Dz3 and a diode Dz4; The INA pin of the isolation driver N1 is connected to the SRA signal output by the PWM control chip, and the INB pin of the isolation driver N1 is connected to the SRB signal output by the PWM control chip; the power pin of the isolation driver N1 is connected to the power supply, and the power pin is also grounded through the capacitor C10; the ground pin of the isolation driver N1 is grounded; the pin OUA of the isolation driver N1 is connected to the cathode of the diode D8, the anode of the diode D8 is connected to the first end of the resistor Roff, the second end of the resistor Roff is connected to the first end of the capacitor Cc, and the second end of the capacitor Cc is respectively connected to the second end of the resistor Ra, the cathode of the voltage stabilizing diode Dz3, the first end of the resistor Rb, and the gate of the synchronous rectifier Q3; the first end of the resistor Ron is connected to the cathode of the diode D8, and the second end is respectively connected to the node between the resistor Roff and the capacitor Cc, and the first end of the resistor Ra; the anode of the voltage stabilizing diode Dz3, the first end of the resistor Rb and the source of the synchronous rectifier Q3 are all grounded; the drain of the synchronous rectifier Q3 is connected to the power supply; The OUB pin of the isolation driver N1 is connected to the cathode of the diode D9, the anode of the diode D9 is connected to the first end of the resistor R10, the second end of the resistor R10 is connected to the first end of the capacitor C13, and the second end of the capacitor C13 is respectively connected to the second end of the resistor R12, the cathode of the voltage-stabilizing diode Dz4, the first end of the resistor R13, and the gate of the synchronous rectifier Q4; the first end of the resistor R11 is connected to the cathode of the diode D9, and the second end is respectively connected to the node between the resistor R10 and the capacitor C13, and the first end of the resistor R12; the anode of the voltage-stabilizing diode Dz4, the first end of the resistor R13, and the source of the synchronous rectifier Q4 are all grounded; the drain of the synchronous rectifier Q4 is connected to the power supply.

8. The end-to-end single-stage DC chopper circuit according to claim 7, characterized in that: The power tube Q1, the power tube Q2, the synchronous rectifier tube Q3 and the synchronous rectifier tube Q4 are all gallium nitride field effect transistors GaN FET.

9. The end-to-end single-stage DC chopper circuit according to claim 8, characterized in that: The synchronous rectifier Q3, the synchronous rectifier Q4 and the isolation driver N1 are assembled with bare chips using a hybrid integration process; the synchronous rectifier Q3, the synchronous rectifier Q4 and the isolation driver N1 are integrated on a substrate, and wiring is provided on the substrate; the wiring is a gold conductor; the electrical interconnection between the synchronous rectifier Q3, the synchronous rectifier Q4 and the bare chips of the isolation driver N1 is achieved by gold wire or aluminum wire bonding.

10. The control method of the end-to-end single-stage DC chopper circuit according to claim 9, characterized in that: The method comprises the following steps: S1, input filter circuit filters out high-frequency noise and ripple in the input power supply; S2, the symmetrical half-bridge circuit converts the input DC voltage into a high-frequency square wave voltage to drive the primary winding of the high-frequency transformer T1; S3, high-frequency transformer T1 transfers the high-frequency square wave voltage generated by the symmetrical half-bridge circuit from the primary winding to the secondary winding to achieve voltage rise and fall; S4, the current doubling synchronous rectification circuit rectifies the voltage signal of the secondary winding of the high-frequency transformer into a DC voltage; S5, the current sampling transformer collects current at the connection node between the symmetrical half-bridge circuit and the high-frequency transformer, and sends the collected current signal to the PWM control chip; S6. The PWM control chip generates a control signal according to the current signal collected by the current sampling transformer, and based on the control signal, controls the power switch tube in the symmetrical half-bridge circuit and the synchronous rectifier tube switch in the current doubling synchronous rectification circuit, and adjusts the output voltage by adjusting the duty cycle of the control signal.

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