Boost PFC converter without rectifier diode and control method thereof

Abstract

The invention discloses a boost PFC converter without a rectifier diode and a control method thereof, and relates to the technical field of PFC converters. The topological structure of the boost PFC converter comprises a switching tube S1, a primary side inductor L1, a boost diode D1, a switching tube S2 and a secondary side inductor L2. One end of an alternating current input side is connected with a synonym terminal of a primary side inductor L1, a dotted terminal of the primary side inductor L1 is connected with a drain electrode of a switch tube S1 and an anode of a boost diode D1, a source electrode of the switch tube S1 is connected with a synonym terminal of a secondary side inductor L2, and a cathode of the boost diode D1 is connected with an anode of an output capacitor Co and one end of a load RL; the other end of the alternating current input side is connected with the drain electrode of the switch tube S2, and the source electrode of the switch tube S2 is connected with the dotted terminal of the secondary side inductor L2, the negative electrode of the output capacitor Co and one end of the load RL. Input diode rectification is completely cancelled, diodes on the output side are further reduced, and boost conversion of the converter is achieved only through five elements.

Description

Technical Field

[0001] This invention belongs to the field of PFC converter technology, and particularly relates to a boost PFC converter without rectifier diodes and its control method. Background Technology

[0002] Traditional single-phase boost power factor correction (PFC) converters are widely used in AC-DC rectifier circuits to reduce total harmonic distortion of input current (THDi) and improve power factor (PF). However, as... Figure 1 As shown in (a), traditional boost PFC converters require a diode rectifier bridge. This diode rectifier bridge requires four diodes to form a full-bridge structure, increasing the diode losses during circuit conduction. To address this issue, some bridgeless AC-DC topologies have been proposed in recent years, such as... Figure 1 (b) shows the bridgeless PFC converter and its derivative structures. Although these bridgeless topologies increase the overall number of devices by using dual conversion units, they reduce the number of conducting devices in the current path, thereby reducing conduction losses and improving efficiency.

[0003] However, this bridgeless topology, such as Figure 1 As shown in (b), two rectifier diodes are still required, which is detrimental to the widespread application of bridgeless boost converters, which already require a large number of components. Therefore, it is necessary to seek further methods to reduce the number of components in bridgeless boost PFC converters.

[0004] Therefore, this invention proposes a boost PFC converter without rectifier diodes and its control method. By introducing a boost unit and a buck-boost unit, the input diode rectification is completely eliminated, and the number of diodes on the output side can be further reduced. The boost conversion of the converter is achieved with only 5 components. Summary of the Invention

[0005] The purpose of this invention is to provide a boost PFC converter without rectifier diodes and its control method, so as to solve the problems mentioned in the background art, such as the large number of devices still existing in traditional bridgeless boost PFC converters with boost output capability, and the presence of diode rectifier bridges on the input side, which are not conducive to improving the overall cost and power density of the converter.

[0006] To achieve the above objectives, the present invention employs the following technical solution: In a first aspect, the present invention proposes a boost PFC converter without rectifier diodes, wherein the topology of the boost PFC converter includes a boost unit and a buck-boost unit. The boost unit includes a switching transistor. S 1. Primary inductor L 1. Boost Diode D 1; The buck-boost unit includes a switching transistor. S 2. Secondary inductor L 2; One end of the AC input side is connected to the primary inductor. L 1. The opposite-named terminal is connected, and the primary inductor is connected. L The same terminal of 1 and the switching transistor S 1's drain and boost diode D 1. Anode connection, switching transistor S 1 source and secondary inductance L Connect the opposite terminals of 2 to the boost diode. D Cathode and output capacitor of 1 C o Positive electrode, load R L One end is connected; The other end of the AC input side is connected to the switching transistor. S 2. Drain connection, switching transistor S 2 source and secondary inductance L 2's corresponding terminal, output capacitor C o negative electrode and load R L One end is connected.

[0007] Preferably, the boost PFC converter operates in boost mode during the positive half of the AC input cycle and in buck-boost mode during the negative half of the AC input cycle.

[0008] Preferably, the boost PFC converter has a primary-side inductance L 1 and secondary inductor L Introduce an ideal transformer between 2 T The operating modes of the boost PFC converter during the positive half-AC input cycle are as follows: Operating mode 1: Switching transistor S 1. Switching transistor S 2 is in the on state, and the input current flows through the switching transistor. S 1. Switching transistor S 2. Towards the primary inductor L 1. Secondary inductor L 2. Charging; Ideal Transformer T Generate primary current i T1 and secondary currenti T2 Output capacitor C o To the load R L powered by; Operating mode 2: Switching transistor S 1. Switching transistor S 2. When the circuit is turned off, the input current flows through the primary inductor. L 1. Boost Diode D 1 and switching transistor S The body diode of 2 is the output capacitor. C o Charge and to load R L Power supply; during this stage, the secondary inductor current... i L2 Flow Manager Thinks Transformer T The secondary side generates the primary side current. i T1 Stored in the secondary inductor L The energy in step 2 is transferred to the output side; Operating mode 3: When the primary inductor current i L1 and secondary inductor current i L2 This mode begins when the capacitance drops to zero; in this mode, the output capacitance... C o For load R L powered by.

[0009] Furthermore, the operating mode of the boost PFC converter during the negative half-AC input cycle is as follows: Operating mode 4: Switching transistor S 1. Switching transistor S 2 is in the on state, and the input current flows through the switching transistor. S 1. Switching transistor S 2. Towards the primary inductor L 1. Secondary inductor L 2. Charging; Ideal Transformer T Generate primary current i T1 and secondary current i T2 Output capacitor C o To the load R L powered by; Operating mode 5: Switching transistor S 1. Switching transistor S 2. When turned off, the secondary inductor current... iL2 Flow through the switching transistor S 1. Body diode and boost diode D 1, for the output capacitor C o Charge and to load R L Power supply; during this stage, the primary inductor current... i L1 Flow Manager Thinks Transformer T The primary side generates a secondary current. i T2 Stored in the primary inductor L The energy in step 1 is transferred to the output side; Operating mode 6: When the primary inductor current i L1 and secondary inductor current i L2 This mode begins when the capacitance drops to zero; in this mode, the output capacitance... C o For load R L powered by.

[0010] In a second aspect, this invention proposes a first control method for a boost PFC converter without a rectifier diode, employing a single voltage loop feedback to generate a switching transistor drive signal. S 1 and switching transistor S 2. Use the exact same drive signal.

[0011] Preferably, the generation process of the same driving signal is as follows: Output voltage V o After sampling, compared with the reference voltage V ref The voltage error is compared and then fed into the PI module to generate an error signal. v e Then the error signal v e With sawtooth waves v saw Compare and generate a drive duty cycle signal v gs .

[0012] In its third aspect, this invention proposes a second control method for a boost PFC converter without a rectifier diode. This method employs a single-voltage loop feedback and input voltage sampling feedback to jointly form the switching transistor drive signal. S 1 and switching transistor S 2. Different drive signals are used to reduce the conduction loss of the boost PFC converter circuit.

[0013] Preferably, the generation process of the different driving signals is as follows: Output voltage respectively V o and input voltage v in Sampling; Input voltage v in The input voltage obtained by the input voltage sampling circuit v in,fb Input voltage v in,fb The voltage is compared with 0V by comparator C2 to generate an input voltage indication signal. v in,p ; At the same time, the output voltage V o The output voltage obtained by the output voltage sampling circuit V o,fb Output voltage V o,fb With reference voltage V ref After comparison by comparator C1, the obtained voltage error is sent to the PI module to generate an error signal. v e Then v e With sawtooth waves v saw Compare and generate a basic duty cycle signal. v gs ; Obtained through NOT gate pairs v in,p Invert the phase to generate v in,n This signal is used to indicate that the input voltage is in the negative half-cycle; finally, v gs and v in,n Input to an OR gate to generate a drive signal v gs1 ;Will v gs and v in,p Input to an OR gate to generate a drive signal v gs2 .

[0014] Compared with the prior art, the beneficial effects of the present invention are: (1) The boost PFC converter without rectifier diodes in this invention completely eliminates the input diode rectification by introducing boost boost unit and buck-boost buck-boost unit, and can further reduce the diodes on the output side. The boost conversion of the converter is achieved with only 5 components.

[0015] (2) In this invention, the boost PFC converter completely eliminates the diode rectifier bridge, which reduces energy loss and simplifies the circuit structure. It uses only 5 devices and can achieve boost output.

[0016] (3) The boost PFC converter circuit in this invention can be closed-loop controlled by a simple single voltage loop feedback, which is simple to control.

[0017] (4) In order to further improve efficiency, the single voltage loop feedback can also be combined with the input voltage sampling feedback to form the switching transistor drive signal, thereby reducing the conduction loss of the converter. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the traditional boost PFC converter topology in the background technology. Figure 1 (a) is a bridge-type boost PFC converter. Figure 1 (b) is a bridgeless dual boost PFC converter. Figure 2 This is a schematic diagram of the boost PFC converter topology without rectifier diodes in this invention; Figure 3 This is a diagram showing the boost operation mode of the boost PFC converter without rectifier diodes in this invention during the positive half-cycle. Figure 3 (a) represents mode 1. Figure 3 (b) represents mode 2. Figure 3 (c) represents mode 3); Figure 4 This is a diagram showing the buck-boost operating modes of the boost PFC converter without rectifier diodes in this invention during the negative half-cycle. Figure 4 (a) represents mode 4. Figure 4 (b) represents mode 5. Figure 4 (c) is mode 6); Figure 5 The waveform diagrams of key components in the boost PFC converter without rectifier diodes in this invention are shown in boost mode and buck-boost mode. Figure 5 (a) is the boost mode. Figure 5 (b) is the boost / buck mode); Figure 6 The circuit control principle of the boost PFC converter without rectifier diodes in this invention. Figure 1 ; Figure 7 The circuit control principle of the boost PFC converter without rectifier diodes in this invention. Figure 2 ; Figure 8The simulation waveforms of key components in the boost PFC converter without rectifier diodes in this invention are shown in the boost operation mode and the AC input and buck-boost operation modes. Figure 8 (a) represents the boost operation mode. Figure 8 (b) is the AC input cycle. Figure 8 (c) is the boost / buck operation mode. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Example 1: A boost PFC converter without rectifier diodes, including boost units and buck-boost units, such as... Figure 2 As shown.

[0021] The circuit topology mainly includes one MOSFET switch. S 1. One MOSFET switch S 2. One primary-side inductor L 1. One secondary inductor L 2. One ideal flyback transformer T 1 boost diode D 1. One step-up / step-down diode D 2. One output capacitor C o and 1 resistive load R L Note the step-up / step-down diode. D 2 can also be omitted; it is retained here for clear illustration of the buck-boost unit's structure. And in the coupling inductor... L 1 and L Between 2, an ideal transformer is introduced. T This is used to explain the coupling relationship and working principle.

[0022] Specifically, one end of the AC input side is connected to the primary inductor. L 1. Connection of the opposite terminal. Primary inductor. L The same terminal of 1 and the switching transistor S 1's drain and boost diode D Anode connection of 1. Switching transistor. S 1 source and secondary inductance L Connect the opposite terminals of diode 2. Boost diode. D Cathode and output capacitor of 1C o Positive electrode, load R L One end is connected.

[0023] The other end of the AC input side is connected to the switching transistor. S 2. Drain connection, switching transistor S 2 source and secondary inductance L 2's corresponding terminal, output capacitor C o negative electrode and load R L One end is connected.

[0024] This embodiment mainly uses Figure 2 The middle circuit section mainly introduces the working principle of a true bridgeless boost converter.

[0025] It should be noted that, for better explanation of the working principle, the coupled inductor... L 1 and L Between 2, an ideal transformer is introduced. T This is to illustrate the coupling relationship and working principle. To avoid reverse recovery losses of the output diode, this converter is mainly designed in discontinuous conduction mode (DCM).

[0026] The operating mode diagram of the positive half-AC input cycle of the circuit of this invention is as follows: Figure 3 As shown. Figure 3 (a) is the equivalent circuit of the AC-DC bridgeless boost PFC converter in the positive half-cycle of the AC input in mode 1. Figure 3 (b) is the equivalent circuit of the AC-DC bridgeless boost PFC converter in the positive half-cycle of the AC input in mode 2. Figure 3 (c) is the equivalent circuit of the AC-DC bridgeless boost PFC converter in the positive half-cycle of the AC input in mode 3.

[0027] The operating mode diagram of the negative half-AC input cycle of the circuit of this invention is as follows: Figure 4 As shown. Figure 4 (a) is the equivalent circuit of the AC-DC bridgeless boost PFC converter in the negative half-cycle of the AC input mode 4. Figure 4 (b) is the equivalent circuit of the AC-DC bridgeless boost PFC converter in the negative half-cycle of the AC input mode 5. Figure 4 (c) is the equivalent circuit of the AC-DC bridgeless boost PFC converter in the negative half-cycle of the AC input mode 6.

[0028] Operating mode 1: In this stage, the switching transistor... S 1. Switching transistorS 2 is in the ON state, and the input current flows through the switching transistor. S 1. Switching transistor S 2. Towards the primary inductor L 1. Secondary inductor L 2. Charging; An ideal transformer generates primary current. i T1 and secondary current i T2 Output capacitor C o To the load R L powered by.

[0029] Operating mode 2: Switching transistor S 1. Switching transistor S 2. When the circuit is turned off, the input current flows through the primary inductor. L 1. Boost Diode D 1 and switching transistor S The body diode of 2 is the output capacitor. C o Charge and to load R L Power supply. During this stage, the secondary inductor current... i L2 Flow Manager's Transformer T The secondary side generates the primary side current. i T1 In this way, the data stored in the secondary inductor... L The energy in step 2 can be transferred to the output side.

[0030] Operating mode 3: When the primary inductor current i L1 and secondary inductor current i L2 This mode begins when the capacitance drops to zero. In this mode, the output capacitance... C o For load R L powered by.

[0031] Operating mode 4: In this stage, the switching transistor... S 1. Switching transistor S 2 is in the on state, and the input current flows through the switching transistor. S 1. Switching transistor S 2. Towards the primary inductor L 1. Secondary inductor L 2. Charging; An ideal transformer generates primary current. i T1 and secondary current i T2 Output capacitor Co To the load R L powered by.

[0032] Operating mode 5: Switching transistor S 1. Switching transistor S 2. When turned off, the secondary inductor current... i L2 Flow through the switching transistor S 1. Body diode and boost diode D 1, for the output capacitor C o Charge and to load R L Power supply. During this stage, the primary inductor current... i L1 Flow Manager's Transformer T The primary side generates a secondary current. i T2 In this way, the energy stored in the primary-side inductance is... L The energy in step 1 can be transferred to the output side.

[0033] Operating mode 6: When the primary inductor current i L1 and secondary inductor current i L2 This mode begins when the capacitance drops to zero. In this mode, the output capacitance... C o For load R L powered by.

[0034] Figure 5 The boost mode of the bridgeless PFC converter of this invention (e.g.) Figure 5 (a) and boost / blow modes (e.g.) Figure 5 (b) shows the theoretical waveforms of the key components. d bon This refers to the duty cycle of the switching transistor in boost mode. d bbon This refers to the duty cycle of the switching transistor in buck-boost mode. d boff and d bboff The duty cycle for freewheeling inductor current shutdown. T s One switching cycle. (By...) Figure 5 It can be seen that the key components of the conversion unit mainly operate within half of the power frequency cycle and do not interfere with each other.

[0035] Depend on Figure 3 and Figure 4As can be seen from the operating modes shown, the converter of this invention can utilize the body diode of the switching transistors to achieve the freewheeling path; therefore, the two switching transistors... S 1 and switching transistor S 2. The exact same drive signal can be used.

[0036] Figure 6 This invention employs a single voltage feedback loop to regulate the output voltage, and utilizes a boost-type PFC converter operating in discontinuous conduction mode (DCM) to achieve high power factor correction and low total power dissipation (PF) and total power dissipation (THDi) through natural power factor correction. It can be seen that... Figure 6 In the middle, the output voltage V o After sampling, the data is directly sent to comparator C1 and compared with the reference voltage. V ref The voltage error is compared and then fed into the PI module to generate an error signal. v e Subsequently, the error signal v e With sawtooth waves v saw Compare and generate a drive duty cycle signal v gs .

[0037] On the other hand, in order to further reduce the conduction loss of the circuit, the present invention provides a second control scheme. Figure 7 This is a block diagram illustrating the second control principle of the bridgeless PFC converter of the present invention. This block diagram addresses the output voltage... V o and input voltage v in Sampling was performed, among which k o and k i These represent the voltage division coefficients in the output voltage sampling circuit and the input voltage sampling circuit, respectively. The sampled input voltage... v in,fb The voltage is compared with 0V by comparator C2 to generate an input voltage indication signal. v in,p At the same time, the sampled output voltage V o,fb With reference voltage V ref After comparison by comparator C1, the obtained voltage error is sent to the PI module to generate an error signal. v e Subsequently, v e With sawtooth waves v sawCompare and generate a basic duty cycle signal. v gs The result obtained through NOT gate pairs v in,p Invert the phase to generate v in,n This signal is used to indicate that the input voltage is in the negative half-cycle. Finally, v gs and v in,n Input to an OR gate to generate a drive signal v gs1 ;Will v gs and v in,p Input to an OR gate to generate a drive signal v gs2 .

[0038] As can be seen, in control scheme one, the present invention mainly generates and drives MOSFET switching transistors through a single voltage loop control. S 1 and MOSFET switching transistor S The driving signal is 2. Furthermore, since the conduction loss of the MOSFET is significantly lower than that of its body diode, in control scheme two, the control circuit actively turns on the MOSFET to improve the overall circuit efficiency.

[0039] System simulation results: To verify the feasibility of the circuit of this invention operating at a 220Vac input, the circuit was simulated using PSIM simulation software. Specific parameters: AC input RMS voltage. V in 110V, input frequency f L The switching frequency of the PFC converter is 50Hz. f s 65kHz, output voltage V o 400V, boost inductor L 1 with step-up / step-down inductors L 2 is 200uH, ideal transformer T The winding ratio is 6:10, and the output capacitor... C o for Input filter inductor L f The input filter capacitor is 1.2mH. L c The output power is 0.1uF. P o The power is 200W. Table 1 shows the simulation parameters of the circuit in this patent.

[0040] Table 1. Converter circuit parameters of the present invention

[0041] Depend on Figure 8 (b) shows that the converter can operate stably from the perspective of AC input cycle. The control block diagram can effectively stabilize the converter output voltage at 400V. Furthermore, from... Figure 8 (a) and Figure 8 As can be observed in (c): Under boost operation mode, the inductor current i L1 and i L2 Both inductor currents are positive; however, in the step-up / step-down operating mode, both inductor currents are negative, a characteristic that is completely consistent with the theoretical waveform and the analysis results of the operating mode. It can also be observed that the primary current of an ideal transformer... i T1 With secondary current i T2 This will cause corresponding changes, providing a reasonable flow path for the inductor current. This avoids voltage spikes, allowing the converter to operate smoothly throughout the entire AC input cycle. Figure 8 (b) shows good performance. The simulated PF value is approximately 0.99.

[0042] Based on the theoretical analysis and simulation results above, it can be seen that the true bridgeless converter proposed in this invention, based on a boost unit and a buck-boost unit, contains only 5 power components, completely eliminating the need for rectifier diodes. Furthermore, the two switching transistors can use identical drive signals, resulting in a simple and reliable circuit control scheme. By introducing control logic related to the input voltage, a closed-loop control block diagram is proposed. Finally, the feasibility of the true bridgeless converter and its control block diagram is verified using a 200W simulation model. The results show that the converter's power factor (PF) can reach approximately 0.99, and the input current waveform exhibits sinusoidal characteristics.

[0043] The above description is only for the purpose of helping to understand the method and core essence of the present invention, but the scope of protection of the present invention is not limited thereto. For those skilled in the art, any equivalent substitutions or modifications made to the technical solution and inventive concept disclosed in the present invention within the scope of the technology disclosed in the present invention should be covered within the scope of protection of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A boost PFC converter without rectifier diodes, characterized in that, The topology of the boost PFC converter includes a boost unit and a buck-boost unit; The boost unit includes a switching transistor. S 1. Primary inductor L 1. Boost Diode D 1; The buck-boost unit includes a switching transistor. S 2. Secondary inductor L 2; One end of the AC input side is connected to the primary inductor. L 1. The opposite-named terminal is connected, and the primary inductor is connected. L The same terminal of 1 and the switching transistor S 1's drain and boost diode D 1. Anode connection, switching transistor S 1 source and secondary inductance L Connect the opposite terminals of 2 to the boost diode. D Cathode and output capacitor of 1 C o Positive electrode, load R L One end is connected; The other end of the AC input side is connected to the switching transistor. S 2. Drain connection, switching transistor S 2 source and secondary inductance L 2's corresponding terminal, output capacitor C o negative electrode and load R L One end is connected.

2. The boost PFC converter without rectifier diodes according to claim 1, characterized in that, The boost PFC converter operates in boost mode during the positive half of the AC input cycle and in buck-boost mode during the negative half of the AC input cycle.

3. The boost PFC converter without rectifier diodes according to claim 1, characterized in that, The boost PFC converter has a primary-side inductor L 1 and secondary inductor L Introduce an ideal transformer between 2 T The operating modes of the boost PFC converter during the positive half-AC input cycle are as follows: Operating mode 1: Switching transistor S 1. Switching transistor S 2 is in the on state, and the input current flows through the switching transistor. S 1. Switching transistor S 2. Towards the primary inductor L 1. Secondary inductor L 2. Charging; Ideal Transformer T Generate primary current i T1 and secondary current i T2 Output capacitor C o To the load R L powered by; Operating mode 2: Switching transistor S 1. Switching transistor S 2. When the circuit is turned off, the input current flows through the primary inductor. L 1. Boost Diode D 1 and switching transistor S The body diode of 2 is the output capacitor. C o Charge and to load R L Power supply; during this stage, the secondary inductor current... i L2 Flow Manager's Transformer T The secondary side generates the primary side current. i T1 Stored in the secondary inductor L The energy in step 2 is transferred to the output side; Operating mode 3: When the primary inductor current i L1 and secondary inductor current i L2 This mode begins when the capacitance drops to zero; in this mode, the output capacitance... C o For load R L powered by.

4. The boost PFC converter without rectifier diodes according to claim 3, characterized in that, The operating mode of the boost PFC converter during the negative half-AC input cycle is as follows: Operating mode 4: Switching transistor S 1. Switching transistor S 2 is in the on state, and the input current flows through the switching transistor. S 1. Switching transistor S 2. Towards the primary inductor L 1. Secondary inductor L 2. Charging; Ideal Transformer T Generate primary current i T1 and secondary current i T2 Output capacitor C o To the load R L powered by; Operating mode 5: Switching transistor S 1. Switching transistor S 2. When turned off, the secondary inductor current... i L2 Flow through the switching transistor S 1. Body diode and boost diode D 1, for the output capacitor C o Charge and to load R L Power supply; during this stage, the primary inductor current... i L1 Flow Manager's Transformer T The primary side generates a secondary current. i T2 Stored in the primary inductor L The energy in step 1 is transferred to the output side; Operating mode 6: When the primary inductor current i L1 and secondary inductor current i L2 This mode begins when the capacitance drops to zero; in this mode, the output capacitance... C o For load R L powered by.

5. The control method for the boost PFC converter without rectifier diodes as described in any one of claims 1-4, characterized in that, A single voltage loop feedback is used to generate the drive signal for the switching transistor. S 1 and switching transistor S 2. Use the exact same drive signal.

6. The control method for the boost PFC converter without rectifier diodes according to claim 5, characterized in that, The process of generating the same driving signal is as follows: Output voltage V o After sampling, compared with the reference voltage V ref The voltage error is compared and then fed into the PI module to generate an error signal. v e Then the error signal v e With sawtooth waves v saw Compare and generate a drive duty cycle signal v gs .

7. The control method for the boost PFC converter without rectifier diodes as described in any one of claims 1-4, characterized in that, The switching transistor drive signal is composed of a single voltage loop feedback and an input voltage sampling feedback. S 1 and switching transistor S 2. Different drive signals are used to reduce the conduction loss of the boost PFC converter circuit.

8. The control method for the boost PFC converter without rectifier diodes according to claim 7, characterized in that, The generation process of the different driving signals is as follows: Output voltage respectively V o and input voltage v in Sampling; Input voltage v in The input voltage obtained by the input voltage sampling circuit v in,fb Input voltage v in,fb The voltage is compared with 0V by comparator C2 to generate an input voltage indication signal. v in,p ; At the same time, the output voltage V o The output voltage obtained by the output voltage sampling circuit V o,fb Output voltage V o,fb With reference voltage V ref After comparison by comparator C1, the obtained voltage error is sent to the PI module to generate an error signal. v e Then v e With sawtooth waves v saw Compare and generate a basic duty cycle signal. v gs ; Obtained through NOT gate pairs v in,p Invert the phase to generate v in,n This signal is used to indicate that the input voltage is in the negative half-cycle; finally, v gs and v in,n Input to an OR gate to generate a drive signal v gs1 ;Will v gs and v in,p Input to an OR gate to generate a drive signal v gs2 .

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