Forward converter and forward power factor corrector

Abstract

A forward converter comprises a voltage conversion device, a switch and an auxiliary device. The voltage conversion device comprises a primary side winding and a secondary side winding, and is used for converting an input voltage into an output voltage. The switch is connected to the voltage conversion device and switches to enable the voltage conversion device to receive or not receive the input voltage. The auxiliary device is connected to the voltage conversion device, stores the electric energy released by the voltage conversion device and generates a compensation voltage when the switch is turned off, and provides the compensation voltage when the switch is turned on, and the compensation voltage and the input voltage have the same polarity. The invention further provides a forward power factor corrector comprising the forward converter and the rectifying device.

Description

Technical Field

[0001] The invention relates to a forward converter and a forward power factor corrector. Background Art

[0002] Currently, many electrical appliances use low-voltage direct current. However, since the mains power is alternating current, AC-DC conversion is required. In order to reduce the virtual power of the power system and reduce the system interference caused by current harmonics, many electrical appliances are required to have high power factors and low current harmonics. Therefore, power factor correctors are widely used.

[0003] For safety and performance reasons, power factor correctors are required to have high power factor, high conversion efficiency, and electrical isolation. Conventional circuit architectures such as flyback have poor conversion efficiency. For traditional forward circuits, when the input AC power is in a low voltage state, if the induced voltage on the secondary side is less than the output voltage at the output end of the power factor corrector, the input current cannot be introduced, resulting in a current dead zone. Therefore, the power factor correction effect is not good, and the transformer demagnetization needs to be processed additionally. Other conventional technologies and circuit architectures also face different technical bottlenecks and cannot meet increasingly stringent regulatory requirements. Summary of the invention

[0004] In view of the above, the present invention provides a forward converter and a forward power factor corrector.

[0005] According to an embodiment of the present invention, a forward converter includes a voltage conversion device, a switch and an auxiliary device. The voltage conversion device includes a primary winding and a secondary winding, and is used to convert an input voltage into an output voltage. The switch is connected to the voltage conversion device, and is switched so that the voltage conversion device receives or does not receive the input voltage. The auxiliary device is connected to the voltage conversion device, and when the switch is turned off, the auxiliary device stores the electric energy released by the voltage conversion device and generates a compensation voltage, and when the switch is turned on, the auxiliary device provides the compensation voltage, wherein the compensation voltage has the same polarity as the input voltage.

[0006] In an embodiment of the forward converter of the present invention, the auxiliary device includes an auxiliary capacitor.

[0007] In one embodiment of the forward converter of the present invention, the auxiliary device further comprises:

[0008] an auxiliary diode, an anode terminal of the auxiliary diode is connected to the first terminal of the auxiliary capacitor; and

[0009] An auxiliary winding is coupled to the primary winding and the secondary winding, wherein one end of the auxiliary winding is connected to the cathode end of the auxiliary diode, and the other end of the auxiliary winding is connected to the second end of the auxiliary capacitor.

[0010] In one embodiment of the forward converter of the present invention, the voltage conversion device further includes an energy storage inductor for outputting the output voltage, the auxiliary diode is a first auxiliary diode, the auxiliary winding is a first auxiliary winding, and the auxiliary device further includes:

[0011] a second auxiliary diode, an anode terminal of the second auxiliary diode being connected to the first terminal of the auxiliary capacitor; and

[0012] A second auxiliary winding is coupled to the energy storage inductor, wherein one end of the second auxiliary winding is connected to the cathode end of the second auxiliary diode, and the other end of the second auxiliary winding is connected to the second end of the auxiliary capacitor.

[0013] In one embodiment of the forward converter of the present invention, the voltage conversion device further comprises an energy storage inductor for outputting the output voltage, and the auxiliary device further comprises:

[0014] an auxiliary diode, an anode terminal of the auxiliary diode is connected to the first terminal of the auxiliary capacitor; and

[0015] An auxiliary winding is coupled to the energy storage inductor, wherein one end of the auxiliary winding is connected to the cathode end of the auxiliary diode, and the other end of the auxiliary winding is connected to the second end of the auxiliary capacitor.

[0016] In one embodiment of the forward converter described above, the voltage conversion device further includes an energy storage inductor, a first end of the energy storage inductor is used to output the output voltage, one end of the auxiliary device is connected to the secondary winding, and the other end of the auxiliary device is connected to the second end of the energy storage inductor.

[0017] In one embodiment of the forward converter of the present invention, the auxiliary device comprises:

[0018] An auxiliary capacitor, wherein a first end of the auxiliary capacitor is connected to the secondary winding, and a second end of the auxiliary capacitor is connected to the second end of the energy storage inductor.

[0019] In one embodiment of the forward converter of the present invention, the auxiliary device further comprises:

[0020] an auxiliary diode, an anode terminal of the auxiliary diode is connected to the first terminal of the auxiliary capacitor; and

[0021] An auxiliary winding is coupled to the energy storage inductor, wherein one end of the auxiliary winding is connected to the cathode end of the auxiliary diode, and the other end of the auxiliary winding is connected to the second end of the auxiliary capacitor.

[0022] In one embodiment of the forward converter of the present invention, the auxiliary device further comprises:

[0023] an auxiliary diode, an anode terminal of the auxiliary diode is connected to the first terminal of the auxiliary capacitor; and

[0024] An auxiliary winding is coupled to the primary winding and the secondary winding, wherein one end of the auxiliary winding is connected to the cathode end of the auxiliary diode, and the other end of the auxiliary winding is connected to the second end of the auxiliary capacitor.

[0025] In one embodiment of the forward converter of the present invention, the auxiliary diode is a first auxiliary diode, the auxiliary winding is a first auxiliary winding, and the auxiliary device further comprises:

[0026] a second auxiliary diode, an anode terminal of the second auxiliary diode being connected to the first terminal of the auxiliary capacitor; and

[0027] A second auxiliary winding is coupled to the energy storage inductor, wherein one end of the second auxiliary winding is connected to the cathode end of the second auxiliary diode, and the other end of the second auxiliary winding is connected to the second end of the auxiliary capacitor.

[0028] In an embodiment of the forward converter of the present invention, one end of the auxiliary device is used to receive the input voltage, and the other end of the auxiliary device is connected to the primary winding.

[0029] In one embodiment of the forward converter of the present invention, the auxiliary device comprises:

[0030] an auxiliary capacitor, wherein a first end of the auxiliary capacitor is used to receive the input voltage, and a second end of the auxiliary capacitor is connected to the primary winding;

[0031] an auxiliary diode, an anode terminal of the auxiliary diode is connected to the first terminal of the auxiliary capacitor; and

[0032] An auxiliary winding is coupled to the primary winding and the secondary winding, wherein one end of the auxiliary winding is connected to the cathode end of the auxiliary diode, and the other end of the auxiliary winding is connected to the second end of the auxiliary capacitor.

[0033] In one embodiment of the forward converter of the present invention, the voltage conversion device further includes an energy storage inductor for outputting the output voltage, the auxiliary diode is a first auxiliary diode, the auxiliary winding is a first auxiliary winding, and the auxiliary device further includes:

[0034] a second auxiliary diode, an anode terminal of the second auxiliary diode being connected to the first terminal of the auxiliary capacitor; and

[0035] A second auxiliary winding is coupled to the energy storage inductor, wherein one end of the second auxiliary winding is connected to the cathode end of the second auxiliary diode, and the other end of the second auxiliary winding is connected to the second end of the auxiliary capacitor.

[0036] According to an embodiment of the present invention, a forward power factor corrector comprises the forward converter and a rectifying device as described above. The rectifying device is connected to the forward converter and is used to receive and rectify power to generate an input voltage.

[0037] By means of the above structure, the forward converter disclosed in this case can have the advantages of high conversion efficiency, meeting the transformer winding demagnetization requirements, providing compensation voltage, small size and light weight through the setting of auxiliary devices, and can avoid adding complex and high-cost mechanisms. In addition to the above advantages, the forward power factor corrector including the above forward converter disclosed in this case can reduce the current blind area through the compensation voltage of the auxiliary device, and can achieve the effect of high power factor and low harmonic rate.

[0038] The above description of the disclosed content and the following description of the embodiments are used to demonstrate and explain the spirit and principle of the present invention, and to provide a further explanation of the scope of the patent application of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 FIG. 4 is a block diagram of a forward converter according to an embodiment of the present invention.

[0040] Figure 2 FIG. 4 is a block diagram of a forward power factor corrector according to an embodiment of the present invention.

[0041] Figure 3 FIG. 4 is a block diagram of a forward power factor corrector according to another embodiment of the present invention.

[0042] Figure 4 Exemplarily depicted Figure 3 A circuit diagram of a rectifier and a filter device included in a forward power factor corrector.

[0043] Figure 5 FIG. 4 is a circuit diagram of a forward converter according to a first embodiment of the present invention.

[0044] FIG. 6A to FIG. 6C Draw separately Figure 5 The forward converter has a first operation mode, a second operation mode and a third operation mode.

[0045] Figure 7 FIG. 4 is a circuit diagram of a forward converter according to a second embodiment of the present invention.

[0046] FIG. 8A to FIG. 8D Draw separately Figure 7 The forward converter has a first operation mode, a second operation mode, a third operation mode and a fourth operation mode.

[0047] Fig. 9 FIG. 4 is a circuit diagram of a forward converter according to a third embodiment of the present invention.

[0048] FIG. 10A to FIG. 10C Draw separately Fig. 9 The forward converter has a first operation mode, a second operation mode and a third operation mode.

[0049] Fig.11 FIG. 4 is a circuit diagram of a forward converter according to a fourth embodiment of the present invention.

[0050] FIG. 12A to FIG. 12D Draw separately Fig.11 The forward converter has a first operation mode, a second operation mode, a third operation mode and a fourth operation mode.

[0051] Fig.13 FIG. 5 is a circuit diagram of a forward converter according to a fifth embodiment of the present invention.

[0052] FIG. 14A to FIG. 14C Draw separately Fig.13 The forward converter has a first operation mode, a second operation mode and a third operation mode.

[0053] Fig.15 FIG. 4 is a circuit diagram of a forward converter according to a sixth embodiment of the present invention.

[0054] FIG. 16A to FIG. 16D Draw separately Fig.15 The forward converter has a first operation mode, a second operation mode, a third operation mode and a fourth operation mode.

[0055] Fig.17 The waveform diagrams of the gate-source voltage, the current flowing through, and the drain-source voltage of the switch of the forward converter according to an embodiment of the present invention are exemplarily presented.

[0056] Fig.18 The relationship between the output voltage and the switching duty cycle of a forward power factor corrector according to an embodiment of the present invention is exemplarily presented.

[0057] Wherein, the reference numerals are:

[0058] 1,1_1,1_2,1_3,1_4,1_5,1_6: Forward converter

[0059] 2: Rectification device

[0060] 3: Filter device

[0061] 10,10_1,10_2,10_3,10_4,10_5,10_6: switch

[0062] 20,20_1,20_2,20_3,20_4,20_5,20_6: Voltage conversion device

[0063] 30,30_1,30_2,30_3,30_4,30_5,30_6: Auxiliary devices

[0064] 100,100': Forward Power Factor Corrector

[0065] V s :power supply

[0066] V i :Input voltage

[0067] V o :Output voltage

[0068] V ca :Compensation voltage

[0069] D 21 ,D 22 ,D 23 ,D 24 :diode

[0070] Q1: Active power switch components

[0071] 201,N1: primary winding

[0072] 202, N2: Secondary winding

[0073] La1, La2, La3, La4, La5: Auxiliary winding

[0074] Da1, Da2, Da3, Da4, Da5: Auxiliary diodes

[0075] D1,D2: Flywheel diode

[0076] L1: Energy storage inductor

[0077] L f :inductance

[0078] C1: Output capacitor

[0079] Ca: auxiliary capacitor

[0080] D f :capacitance

[0081] Vgs, Vds: voltage

[0082] Ids,Is,I2: Current

[0083] d1: Remove sector interval DETAILED DESCRIPTION

[0084] The detailed features and advantages of the present invention are described in detail in the following embodiments, and the contents are sufficient to enable any person skilled in the relevant art to understand the technical content of the present invention and implement it accordingly, and according to the contents disclosed in this specification, the scope of the patent application and the drawings, any person skilled in the relevant art can easily understand the relevant purposes and advantages of the present invention. The following examples further illustrate the viewpoints of the present invention in detail, but do not limit the scope of the present invention in any viewpoint.

[0085] Please refer to Figure 1 , Figure 1 FIG. 1 is a block diagram of a forward converter according to an embodiment of the present invention. Figure 1 As shown, the forward converter 1 comprises a switch 10, a voltage conversion device 20 and an auxiliary device 30. The switch 10 is connected to the voltage conversion device 20, and the voltage conversion device 20 is connected to the auxiliary device 30.

[0086] The switch 10 is used for switching so that the voltage conversion device 20 receives or does not receive the input voltage. For example, the switch 10 may be an active power switch component, which is used for being triggered to be turned off or turned on so that the voltage conversion device 20 receives or does not receive the input voltage.

[0087] The voltage conversion device 20 includes a primary winding 201 and a secondary winding 202, and is used to convert an input voltage into an output voltage. The primary winding 201 and the secondary winding 202 each include one or more coils. In one embodiment, the voltage conversion device 20 may further include a flywheel diode, an energy storage inductor, and an output capacitor. The first end of the energy storage inductor is used to output the output voltage. The cathode end of the flywheel diode and the second end of the energy storage inductor can be connected to a first node together, and the first node can be connected to the auxiliary device 30. One end of the output capacitor can be connected to the other end of the energy storage inductor, and the other end of the output capacitor can be connected to the anode end of the flywheel diode.

[0088] The auxiliary device 30 may include one or more passive components. One end of the auxiliary device 30 is connected to the secondary winding 202, and the other end of the auxiliary device 30 is connected to the second end of the energy storage inductor of the voltage conversion device 20. Alternatively, one end of the auxiliary device 30 is used to receive the input voltage, and the other end of the auxiliary device 30 is connected to the primary winding N1. When the switch 10 is turned off, the auxiliary device 30 stores the electric energy released by the voltage conversion device 20 and generates a compensation voltage; when the switch 10 is turned on, the auxiliary device 30 provides a compensation voltage, wherein the compensation voltage has the same polarity as the input voltage.

[0089] By storing the electric energy released by the voltage conversion device when the switch is turned off and generating a compensation voltage, the forward converter can have a demagnetization function and can provide a compensation voltage when the switch is turned on. In particular, in AC input applications, the compensation voltage can reduce the current dead zone condition.

[0090] Please refer to Figure 2 , Figure 2 FIG. 1 is a block diagram of a forward power factor corrector according to an embodiment of the present invention. Figure 2 As shown, the forward power factor corrector 100 includes a forward converter 1 and a rectifying device 2. The forward converter 1 can be as follows: Figure 1 The forward converter 1 shown. The rectifier device 2 is connected to the power supply V s and a forward converter 1, a rectifier 2 for receiving and rectifying a power source V s To generate the aforementioned input voltage. Specifically, the power supply V s The AC power can be provided, converted into DC power by the rectifier 2 and provided to the forward converter 1. The forward converter 1 converts the input voltage into the output voltage V o , where the output voltage V o The output voltage can be output to a load connected to the forward converter 1 .

[0091] Please refer to Figure 3 , Figure 3 FIG. 1 is a block diagram of a forward power factor corrector according to another embodiment of the present invention. Figure 3 As shown, the forward power factor corrector 100' comprises a forward converter 1, a rectifying device 2 and a filtering device 3. The rectifying device 2 is connected to the forward converter 1 and the filtering device 3, wherein the connection relationship and operation between the forward converter 1 and the rectifying device 2 are the same as those in the above embodiment, and are not described in detail here. In this embodiment, the filtering device 3 is connected between the rectifying device 2 and the power source V s The AC power is first filtered and then transmitted to the rectifying device 2 for AC-DC conversion.

[0092] To further explain the circuit of the filter device 3 and the rectifier device 2, please refer to Figure 4 , Figure 4 Exemplarily depicted Figure 3 The circuit diagram of the rectifier 2 and the filter 3 included in the forward power factor corrector 100' is shown in FIG. Figure 4 As shown, the rectifying device 2 may include a first diode D 21 , the second diode D 22 , the third diode D 23 and the fourth diode D 24 The first diode D 21The anode terminal is connected to the third diode D 23 The cathode terminal of the first diode D 21 The cathode terminal is connected to the second diode D 22 The cathode terminal of the second diode D 22 The anode terminal is connected to the fourth diode D 24 The cathode terminal of the third diode D 23 The anode terminal is connected to the fourth diode D 24 The filter device 3 may include a capacitor D f And inductance L f . Capacitor D f The first end is connected to the inductor L f The first end of the first diode D 21 The anode of the third diode D 23 The cathode terminal of capacitor D f The second end is connected to the power supply V s , the second diode D 22 The anode terminal and the fourth diode D 24 The cathode terminal of the inductor L f The second end is connected to the power supply V s .

[0093] The filter device 3 is used to receive and filter the power supply V s , to generate a filtered power supply V s , the rectifier 2 is used to receive and rectify the filtered power supply V s In the second diode D 22 The cathode terminal of the fourth diode D 24 The aforementioned input voltage V is generated between the anode terminals of i The forward converter 1 converts the input voltage V i Converted to output voltage V o , where the output voltage V o can be output to the load connected to the forward converter 1. It should be particularly noted that, Figure 4 The following is a basic circuit diagram for realizing the rectifier 2 and the filter 3, but it is not intended to limit the rectifier 2 and the filter 3 to only Figure 4 The circuit architecture shown is implemented. In addition, Figure 4 The filter device 3 shown is a selectively arranged circuit.

[0094] The following further describes several embodiments of implementing the forward converter 1. Figure 5 , Figure 5 FIG. 1 is a circuit diagram of a forward converter according to the first embodiment of the present invention. Figure 5As shown, the forward converter 1_1 includes a switch 10_1 , a voltage conversion device 20_1 , and an auxiliary device 30_1 .

[0095] The switch 10_1 includes an active power switch component Q1. The voltage conversion device 20_1 includes a primary winding N1 and a secondary winding N2, as well as the aforementioned flywheel diode D1, energy storage inductor L1 and output capacitor C1. The auxiliary device 30_1 includes an auxiliary capacitor Ca.

[0096] Specifically, the first end of the energy storage inductor L1 is used to output the output voltage V o The second end of the energy storage inductor L1 is connected to the cathode end of the flywheel diode D1, one end of the auxiliary capacitor Ca of the auxiliary device 30_1 is connected to the secondary winding N2, and the other end of the auxiliary capacitor Ca is connected to the second end of the energy storage inductor L1 and the cathode end of the flywheel diode D1.

[0097] Please refer to Figure 5 and FIG. 6A to FIG. 6C ,in FIG. 6A to FIG. 6C Draw separately Figure 5 The forward converter has a first operation mode, a second operation mode and a third operation mode.

[0098] Please refer to Fig. 6A In the first operation mode, the active power switch component Q1 is turned on and the flywheel diode D1 is turned off. When the active power switch component Q1 is turned on, the input voltage V i The primary winding N1 of the voltage conversion device 20_1 is powered, the induced voltage of the secondary winding N2 of the voltage conversion device 20_1 and the compensation voltage V of the auxiliary capacitor Ca are ca The output capacitor C1 is charged together. At this time, the energy storage inductor L1 stores energy, and the auxiliary capacitor Ca is in a discharge state. This operation mode continues until the active power switch component Q1 is turned off and enters the second operation mode.

[0099] Please refer to Figure 6B In the second operation mode, the active power switch component Q1 is turned off and the flywheel diode D1 is turned on. The magnetized secondary winding N2 can be demagnetized through the path formed by the flywheel diode D1 to the auxiliary capacitor Ca, and the auxiliary capacitor Ca can be charged to establish the compensation voltage V ca The energy storage inductor L1 can release energy through the path formed by the output capacitor C1 and the flywheel diode D1. This operation mode continues until the secondary winding N2 and the energy storage inductor L1 have released all their energy, and then enters the third operation mode.

[0100] Please refer to Figure 6CIn the third operation mode, the active power switch component Q1 and the flywheel diode D1 are turned off, and the forward converter is in a non-conversion state. The energy stored in the output capacitor C1 can continue to provide current to the load. Then, when the active power switch component Q1 is turned on again, the energy stored in the auxiliary capacitor Ca is used to charge the output capacitor C1, that is, the forward converter 1_1 returns to the state of non-conversion. Fig. 6A Specifically, in the case of the forward converter of this embodiment, when the circuit design operates in the continuous current mode, the third operation mode may not exist, that is, the first operation mode may be directly returned to after the second operation mode.

[0101] Please refer to Figure 7 , Figure 7 FIG. 2 is a circuit diagram of a forward converter according to a second embodiment of the present invention. Figure 7 As shown, the forward converter 1_2 includes a switch 10_2, a voltage conversion device 20_2 and an auxiliary device 30_2, wherein the implementation circuits / devices, functions and connection relationships of the switch 10_2 and the voltage conversion device 20_2 are the same as Figure 5 The forward converter 1_1 includes a switch 10_1 and a voltage conversion device 20_1.

[0102] The auxiliary device 30_2 includes an auxiliary capacitor Ca, an auxiliary diode Da1, and an auxiliary winding La1. The anode terminal of the auxiliary diode Da1 is connected to the first terminal of the auxiliary capacitor Ca. The auxiliary winding La1 is coupled to the energy storage inductor L1 of the voltage conversion device 20_2, one end of the auxiliary winding La1 is connected to the cathode terminal of the auxiliary diode Da1, and the other end of the auxiliary winding La1 is connected to the second terminal of the auxiliary capacitor Ca.

[0103] Please refer to Figure 7 and FIG. 8A to FIG. 8D ,in FIG. 8A to FIG. 8D Draw separately Figure 7 The forward converter has a first operation mode, a second operation mode, a third operation mode and a fourth operation mode.

[0104] Please refer to Fig. 8A In the first operation mode, the active power switch component Q1 is turned on, the auxiliary diode Da1 is turned off, and the flywheel diode D1 is turned off. When the active power switch component Q1 is turned on, the input voltage V i The primary winding N1 of the voltage conversion device 20_2 is powered, and the induced voltage of the secondary winding N2 of the voltage conversion device 20_2 and the compensation voltage V of the auxiliary capacitor Ca are ca At this time, the energy storage inductor L1 stores energy, the auxiliary capacitor Ca is in a discharge state, and V caThis operation mode continues until the active power switch component Q1 is turned off and enters the second operation mode.

[0105] Please refer to Figure 8B In the second operation mode, the active power switch component Q1 is turned off, the auxiliary diode Da1 is turned on, and the flywheel diode D1 is turned off. The magnetized secondary winding N2 can be demagnetized through the path formed by the auxiliary diode Da1 to the auxiliary capacitor Ca, and the auxiliary capacitor Ca can be charged to establish the compensation voltage V ca , V ca The energy storage inductor L1 can release the stored energy to the auxiliary capacitor Ca through the auxiliary winding La1. This operation mode continues until the compensation voltage V ca The output voltage V o The equivalent voltage on the auxiliary winding La1 side is mapped according to the turns ratio of the energy storage inductor L1 and the auxiliary winding La1.

[0106] Please refer to Figure 8C In the third operation mode, the active power switch component Q1 is turned off, the auxiliary diode Da1 is turned off, and the flywheel diode D1 is turned on. The magnetized secondary winding N2 continues to be demagnetized through the path formed by the flywheel diode D1 to the auxiliary capacitor Ca, and the auxiliary capacitor Ca can be charged to establish the compensation voltage V ca The inductor L1 releases the stored energy through the path formed by D1 and the output capacitor C1. This operation mode continues until the energy of the energy storage inductor L1 and the magnetized secondary winding N2 is completely released, and enters the fourth operation mode.

[0107] Please refer to Fig.8D In the fourth operation mode, the active power switch component Q1, the flywheel diode D1 and the auxiliary diode Da1 are all turned off, and the forward converter is in a non-conversion state. The energy stored in the output capacitor C1 can continue to provide current to the load. Then, when the active power switch Q1 is turned on again, the energy stored in the auxiliary capacitor Ca is used to charge the output capacitor C1, that is, the forward converter 1_2 returns to the state of non-conversion. Fig. 8A Specifically, in the case of the forward converter of this embodiment, when the circuit design operates in the continuous current mode, the fourth operation mode may not exist, that is, the first operation mode may be directly returned to after the third operation mode.

[0108] Please refer to Fig. 9 , Fig. 9 FIG. 1 is a circuit diagram of a forward converter according to a third embodiment of the present invention. Fig. 9As shown, the forward converter 1_3 includes a switch 10_3, a voltage conversion device 20_3 and an auxiliary device 30_3, wherein the implementation circuits / devices, functions and connection relationships of the switch 10_3 and the voltage conversion device 20_3 are the same as those of Figure 5 The switch 10_1 and the voltage conversion device 20_1 included in the forward converter 1_1 are not described in detail here.

[0109] The auxiliary device 30_3 includes an auxiliary capacitor Ca, an auxiliary diode Da2, and an auxiliary winding La2. The anode terminal of the auxiliary diode Da2 is connected to the first terminal of the auxiliary capacitor Ca. The auxiliary winding La2 is coupled to the primary winding N1 and the secondary winding N2. One end of the auxiliary winding La2 is connected to the cathode terminal of the auxiliary diode Da2, and the other end of the auxiliary winding La2 is connected to the second terminal of the auxiliary capacitor Ca.

[0110] Please refer to Fig. 9 and FIG. 10A to FIG. 10C ,in FIG. 10A to FIG. 10C Draw separately Fig. 9 The forward converter has a first operation mode, a second operation mode and a third operation mode.

[0111] Please refer to Fig. 10A In the first operation mode, the active power switch component Q1 is turned on, the auxiliary diode Da2 is turned off, and the flywheel diode D1 is turned off. When the active power switch component Q1 is turned on, the input voltage V i The primary winding N1 of the voltage conversion device 20_3 is powered, the induced voltage of the secondary winding N2 of the voltage conversion device 20_3 and the compensation voltage V of the auxiliary capacitor Ca are ca The output capacitor C1 is charged together. At this time, the energy storage inductor L1 stores energy, and the auxiliary capacitor Ca is in a discharge state. This operation mode continues until the active power switch component Q1 is turned off and enters the second operation mode.

[0112] Please refer to Fig. 10B In the second operation mode, the active power switch component Q1 is turned off, the auxiliary diode Da2 is turned on, and the flywheel diode D1 is turned off. Since the auxiliary winding La2 is coupled with the primary winding N1 and the secondary winding N2, the energy stored in the primary winding N1 and the secondary winding N2 can be released from the auxiliary winding La2 for demagnetization, and the auxiliary capacitor Ca can be charged to establish the compensation voltage V ca. The energy storage inductor L1 can release energy through the path formed by the output capacitor C1 and the flywheel diode D1. This operation mode continues until the demagnetization is completed and the energy storage inductor L1 completes energy release. In particular, in some embodiments, the demagnetization of the auxiliary winding La2 through the auxiliary diode Da2 and the auxiliary capacitor Ca and the energy release of the energy storage inductor L1 through the output capacitor C1 and the flywheel diode D1 can be completed at different times. When the demagnetization of the auxiliary winding La2 and the energy release of the energy storage inductor L1 are completed, the auxiliary device 30_2 enters the third operation mode.

[0113] Please refer to Fig. 10C In the third operation mode, since the energy stored in the energy storage inductor L1 has been completely released, the current on the energy storage inductor L1 drops to zero, and after the magnetized secondary winding N2 has completely released energy in the second operation mode, the current on the auxiliary capacitor Ca drops to zero, the flywheel diode D1 and the auxiliary diode Da2 both enter the cut-off state, and the active power switch component Q1 remains in the cut-off state. The energy stored in the output capacitor C1 can continue to provide current to the load. When the active power switch component Q1 is triggered to turn on again, the energy stored in the auxiliary capacitor Ca is used to charge the output capacitor C1, that is, the forward converter 1_3 returns to the first operation mode again. In particular, in the application where the circuit design of the forward converter of this embodiment operates in the continuous current mode, the third operation mode may not exist, that is, it can directly return to the first operation mode after the second operation mode.

[0114] Please refer to Fig.11 , Fig.11 FIG. 4 is a circuit diagram of a forward converter according to a fourth embodiment of the present invention. Fig.11 As shown, the forward converter 1_4 includes a switch 10_4, a voltage conversion device 20_4 and an auxiliary device 30_4, wherein the implementation circuit / device, function and connection relationship of the switch 10_4 can be the same as Figure 5 The switch 10_1 and the voltage conversion device 20_4 included in the forward converter 1_1 may have the same implementation circuit / device, function and connection relationship as those in Figure 7 The voltage conversion device 20_2 included in the forward converter 1_2 is not described in detail here.

[0115] The auxiliary device 30_4 includes an auxiliary capacitor Ca, a first auxiliary diode Da2, a first auxiliary winding La2, a second auxiliary diode Da3 and a second auxiliary winding La3. The anode terminal of the first auxiliary diode Da2 is connected to the first end of the auxiliary capacitor Ca. The first auxiliary winding La2 is coupled to the primary winding N1 and the secondary winding N2, wherein one end of the first auxiliary winding La2 is connected to the cathode terminal of the first auxiliary diode Da2, and the other end of the first auxiliary winding La2 is connected to the second end of the auxiliary capacitor Ca. The anode terminal of the second auxiliary diode Da3 is connected to the first end of the auxiliary capacitor Ca. One end of the second auxiliary winding La3 is connected to the cathode terminal of the second auxiliary diode Da3, and the other end of the second auxiliary winding La3 is connected to the second end of the auxiliary capacitor Ca. The second auxiliary winding La3 is coupled to the energy storage inductor L1.

[0116] Please refer to Fig.11 and FIG. 12A to FIG. 12D ,in FIG. 12A to FIG. 12D Draw separately Fig.11 The forward converter has a first operation mode, a second operation mode, a third operation mode and a fourth operation mode.

[0117] Please refer to Fig. 12A In the first operation mode, the active power switch component Q1 is turned on, the first auxiliary diode Da2 is turned off, the second auxiliary diode Da3 is turned off, and the flywheel diode D1 is turned off. When the active power switch component Q1 is turned on, the input voltage V i The primary winding N1 of the voltage conversion device 20_4 is powered, the induced voltage of the secondary winding N2 of the voltage conversion device 20_4 and the compensation voltage V of the auxiliary capacitor Ca are ca The output capacitor C1 is charged together. At this time, the energy storage inductor L1 stores energy and the auxiliary capacitor Ca is in a discharge state. This operation mode continues until the active power switch component Q1 is turned off and enters the second operation mode.

[0118] Please refer to Fig. 12B In the second operation mode, the active power switch component Q1 is turned off, the first auxiliary diode Da2 is turned on, the second auxiliary diode Da3 is turned on, and the flywheel diode D1 is turned off. Since the first auxiliary winding La2 is coupled with the primary winding N1 and the secondary winding N2, the magnetized secondary winding N2 can release energy through the path formed by the first auxiliary diode Da2 to the auxiliary capacitor Ca through the coupling inductance with the first auxiliary winding La2 to demagnetize, and can charge the auxiliary capacitor Ca to establish the compensation voltage V ca Since the second auxiliary winding La3 and the energy storage inductor L1 are coupled to each other, the energy stored in the energy storage inductor L1 can be released from the second auxiliary winding La3 to charge the auxiliary capacitor Ca. Therefore, the compensation voltage Vca This operation mode continues until the compensation voltage V ca The output voltage V o The equivalent voltage on the second auxiliary winding La3 is mapped according to the turns ratio between the energy storage inductor L1 and the second auxiliary winding La3 .

[0119] Please refer to Fig. 12C In the third operation mode, the active power switch component Q1 is turned off, the first auxiliary diode Da2 is turned on, the second auxiliary diode Da3 is turned off, and the flywheel diode D1 is turned on. The magnetized secondary winding N2 continues to be demagnetized through the path formed by the first auxiliary diode Da2 to the auxiliary capacitor Ca, and continues to charge the auxiliary capacitor Ca to establish the compensation voltage V ca The energy storage inductor L1 continues to release energy to charge the output capacitor C1. This operation mode continues until the energy of the magnetized secondary winding N2 and the energy storage inductor L1 is completely released, and the fourth operation mode is entered.

[0120] Please refer to Fig.12D , when the magnetized secondary winding N2 and the energy storage inductor L1 are completely released in the third operation mode, the current on the auxiliary capacitor Ca and the energy storage inductor L1 drops to zero, and the first auxiliary diode Da2, the second auxiliary diode Da3 and the flywheel diode D1 are all in the cut-off state. The energy stored in the output capacitor C1 can continue to provide current to the load. When the active power switch component Q1 is triggered to turn on again, the energy stored in the auxiliary capacitor Ca is used to charge the output capacitor C1, that is, the forward converter 1_4 returns to the first operation mode again. In particular, in the application where the circuit design of the forward converter of this embodiment operates in the continuous current mode, the fourth operation mode may not exist, that is, it can directly return to the first operation mode after the third operation mode.

[0121] Please refer to Fig.13 , Fig.13 FIG. 4 is a circuit diagram of a forward converter according to a fifth embodiment of the present invention. Fig.13 As shown, the forward converter 1_5 includes a switch 10_5, a voltage conversion device 20_5 and an auxiliary device 30_5, wherein the implementation circuit / device and function of the switch 10_5 can be the same as Figure 5 The switch 10_1 included in the forward converter 1_1 is not described in detail here.

[0122] Apart from Figure 5In addition to the components of the voltage conversion device 20_1 shown, the voltage conversion device 20_5 of the forward converter 1_5 further includes another flywheel diode D2, the anode terminal of the flywheel diode D2 is connected to the secondary winding N2, and the cathode terminal of the flywheel diode D2 is connected to the second end of the energy storage inductor L1.

[0123] The auxiliary device 30_5 is disposed on the primary side of the forward converter 1_5. Specifically, one end of the auxiliary device 30_5 is used to receive the input voltage V i The other end of the auxiliary device 30_5 is connected to the primary winding N1. The auxiliary device 30_5 includes an auxiliary capacitor Ca, an auxiliary diode Da4, and an auxiliary winding La4. The first end of the auxiliary capacitor Ca is used to receive the input voltage V i , and the second end of the auxiliary capacitor Ca is connected to the primary winding N1. The anode end of the auxiliary diode Da4 is connected to the first end of the auxiliary capacitor Ca. The auxiliary winding La4 is coupled to the primary winding N1 and the secondary winding N2, wherein one end of the auxiliary winding La4 is connected to the cathode end of the auxiliary diode Da4, and the other end of the auxiliary winding La4 is connected to the second end of the auxiliary capacitor Ca.

[0124] Please refer to Fig.13 and FIG. 14A to FIG. 14C ,in FIG. 14A to FIG. 14C Draw separately Fig.13 The forward converter has a first operation mode, a second operation mode and a third operation mode.

[0125] Please refer to Fig.14A In the first operation mode, the active power switch component Q1 is turned on, the auxiliary diode Da4 is turned off, the flywheel diode D1 is turned off, and the flywheel diode D2 is turned on. When the active power switch component Q1 is turned on, the input voltage V i The auxiliary capacitor Ca supplies power to the primary winding N1 of the voltage conversion device 20_5, and the induced voltage of the secondary winding N2 of the voltage conversion device 20_5 charges the output capacitor C1 via the flywheel diode D2. At this time, the energy storage inductor L1 stores energy, and the auxiliary capacitor Ca is in a discharge state. This operation mode continues until the active power switch component Q1 is turned off and enters the second operation mode.

[0126] Please refer to Fig. 14B In the second operation mode, the active power switch component Q1 is turned off, the auxiliary diode Da4 is turned on, the flywheel diode D1 is turned on, and the flywheel diode D2 is turned off. Since the auxiliary winding La4 is coupled with the primary winding N1 and the secondary winding N2, the energy stored in the primary winding N1 and the secondary winding N2 can be released from the auxiliary winding La4 for demagnetization, and the auxiliary capacitor Ca can be charged to establish the compensation voltage V ca. The energy storage inductor L1 can release energy through the path formed by the output capacitor C1 and the flywheel diode D1. This operation mode continues until the demagnetization is completed and the energy storage inductor L1 completes energy release. In particular, in some embodiments, the demagnetization performed by the auxiliary winding La4 through the auxiliary diode Da4 and the auxiliary capacitor Ca and the energy release performed by the energy storage inductor L1 through the output capacitor C1 and the flywheel diode D1 can be completed at different times. When the demagnetization of the auxiliary winding La4 and the energy release of the energy storage inductor L1 are both completed, the auxiliary device 30_5 enters the third operation mode.

[0127] Please refer to Fig. 14C In the third operation mode, the energy stored in the primary winding N1 and the secondary winding N2 has been completely released, and after the energy storage inductor L1 has completely released its energy in the second operation mode, the current on the energy storage inductor L1 drops to zero, and the active power switch component Q1, the flywheel diodes D1 and D2, and the auxiliary diode Da4 all enter the cut-off state. When the active power switch component Q1 is triggered to turn on again, the energy stored in the auxiliary capacitor Ca is used to charge the output capacitor C1, that is, the forward converter 1_5 returns to the first operation mode again. The energy stored in the output capacitor C1 can continue to provide current to the load. In particular, in the application where the forward converter of this embodiment is designed to operate in the continuous current mode, the third operation mode may not exist, that is, it can directly return to the first operation mode after the second operation mode.

[0128] Please refer to Fig.15 , Fig.15 FIG. 4 is a circuit diagram of a forward converter according to a sixth embodiment of the present invention. Fig.15 As shown, the forward converter 1_6 includes a switch 10_6, a voltage conversion device 20_6 and an auxiliary device 30_6, wherein the implementation circuits / devices and functions of the switch 10_6 and the voltage conversion device 20_6 may be the same as Fig.13 The switch 10_5 and the voltage conversion device 20_5 included in the forward converter 1_5 are not described in detail here.

[0129] The auxiliary device 30_6 is disposed on the primary side of the forward converter 1_6. The auxiliary device 30_6 includes an auxiliary capacitor Ca, a first auxiliary diode Da4, a second auxiliary diode Da5, a first auxiliary winding La4, and a second auxiliary winding La5. The first end of the auxiliary capacitor Ca is used to receive the input voltage V i, and the second end of the auxiliary capacitor Ca is connected to the primary winding N1. The anode end of the first auxiliary diode Da4 is connected to the first end of the auxiliary capacitor Ca. The first auxiliary winding La4 is coupled to the primary winding N1 and the secondary winding N2. One end of the first auxiliary winding La4 is connected to the cathode end of the first auxiliary diode Da4, and the other end of the first auxiliary winding La4 is connected to the second end of the auxiliary capacitor Ca. The anode end of the second auxiliary diode Da5 is connected to the first end of the auxiliary capacitor Ca. The second auxiliary winding La5 is coupled to the energy storage inductor L1. One end of the second auxiliary winding La5 is connected to the cathode end of the second auxiliary diode Da5, and the other end of the second auxiliary winding La5 is connected to the second end of the auxiliary capacitor Ca.

[0130] Please refer to Fig.15 and FIG. 16A to FIG. 16D ,in FIG. 16A to FIG. 16D Draw separately Fig.15 The forward converter has a first operation mode, a second operation mode, a third operation mode and a fourth operation mode.

[0131] Please refer to Fig.16A In the first operation mode, the active power switch component Q1 is turned on, the first auxiliary diode Da4 is turned off, the second auxiliary diode Da5 is turned off, the flywheel diode D1 is turned off, and the flywheel diode D2 is turned on. When the active power switch component Q1 is turned on, the input voltage V i The auxiliary capacitor Ca supplies power to the primary winding N1 of the voltage conversion device 20_6, and the induced voltage of the secondary winding N2 of the voltage conversion device 20_6 charges the output capacitor C1. At this time, the energy storage inductor L1 stores energy, and the auxiliary capacitor Ca is in a discharge state. This operation mode continues until the active power switch component Q1 is turned off and enters the second operation mode.

[0132] Please refer to Fig. 16B In the second operation mode, the active power switch component Q1 is turned off, the first auxiliary diode Da4 is turned on, the second auxiliary diode Da5 is turned on, and the flywheel diodes D1 and D2 are turned off. After the active power switch component Q1 is turned off, since the first auxiliary winding La4 is coupled with the primary winding N1 and the secondary winding N2, the energy stored in the primary winding N1 and the secondary winding N2 can be demagnetized through the path formed by the first auxiliary diode Da4 to the auxiliary capacitor Ca, and the auxiliary capacitor Ca can be charged to establish the compensation voltage V ca Since the second auxiliary winding La5 and the energy storage inductor L1 are coupled to each other, the energy stored in the energy storage inductor L1 can charge the auxiliary capacitor Ca through the path formed by the second auxiliary winding La5 through the second auxiliary diode Da5 to the auxiliary capacitor Ca to establish the compensation voltage V ca Therefore, the compensation voltage Vca This operation mode continues until the compensation voltage V ca The third operating mode is entered until the output voltage V o The equivalent voltage on the second auxiliary winding La5 side is mapped according to the turns ratio between the energy storage inductor L1 and the second auxiliary winding La5.

[0133] Please refer to Fig. 16C In the third operation mode, the active power switch component Q1 is turned off, the first auxiliary diode Da4 is turned on, the second auxiliary diode Da5 is turned off, the flywheel diode D1 is turned on, and the flywheel diode D2 is turned off. The first auxiliary winding La4 continues to be demagnetized through the path formed by the first auxiliary diode Da4 to the auxiliary capacitor Ca, and continues to charge the auxiliary capacitor Ca to establish the compensation voltage V ca The energy stored in the energy storage inductor L1 is released through the flywheel diode D1 to charge the output capacitor C1. This operation mode continues until the energy of the first auxiliary winding La4 and the energy storage inductor L1 is completely released, and enters the fourth operation mode.

[0134] Please refer to Fig.16D , when the first auxiliary winding La4 and the energy storage inductor L1 are completely released in the third operation mode, the current of the auxiliary capacitor Ca and the energy storage inductor L1 drops to zero, the first auxiliary diode Da4, the second auxiliary diode Da5 and the flywheel diodes D1 and D2 all enter the cut-off state, and the active power switch component Q1 remains in the cut-off state. The energy stored in the output capacitor C1 can continue to provide current to the load. When the active power switch component Q1 is triggered to turn on again, the energy stored in the auxiliary capacitor Ca is used to charge the output capacitor C1, that is, the forward converter 1_6 returns to the first operation mode again. In particular, in the application where the circuit design of the forward converter of this embodiment operates in the continuous current mode, the fourth operation mode may not exist, that is, it can directly return to the first operation mode after the third operation mode.

[0135] From the description of the above-mentioned multiple embodiments, it can be seen that the auxiliary device of the forward converter of the present case can be summarized into the following multiple embodiments. In the first embodiment, the auxiliary device of the forward converter includes an auxiliary capacitor. In the second embodiment, the auxiliary device includes an auxiliary capacitor, an auxiliary diode and an auxiliary winding, wherein the anode terminal of the auxiliary diode is connected to the first end of the auxiliary capacitor, the auxiliary winding is coupled to the primary winding and the secondary winding, and one end of the auxiliary winding is connected to the cathode terminal of the auxiliary diode, and the other end of the auxiliary winding is connected to the second end of the auxiliary capacitor. In the third embodiment, the voltage conversion device further includes an energy storage inductor for outputting the output voltage, and the auxiliary device includes an auxiliary capacitor, an auxiliary diode and an auxiliary winding, wherein the anode terminal of the auxiliary diode is connected to the first end of the auxiliary capacitor, the auxiliary winding is coupled to the energy storage inductor, and one end of the auxiliary winding is connected to the cathode terminal of the auxiliary diode, and the other end of the auxiliary winding is connected to the second end of the auxiliary capacitor. In a fourth embodiment, the voltage conversion device further includes an energy storage inductor for outputting the output voltage, and the auxiliary device includes an auxiliary capacitor, a first auxiliary diode, a second auxiliary diode, a first auxiliary winding and a second auxiliary winding, the anode terminal of the first auxiliary diode is connected to the first end of the auxiliary capacitor, the first auxiliary winding is coupled to the primary side winding and the secondary side winding, one end of the first auxiliary winding is connected to the cathode terminal of the first auxiliary diode, and the other end of the first auxiliary winding is connected to the second end of the auxiliary capacitor, the anode terminal of the second auxiliary diode is connected to the first end of the auxiliary capacitor, the second auxiliary winding is coupled to the energy storage inductor, one end of the second auxiliary winding is connected to the cathode terminal of the second auxiliary diode, and the other end of the second auxiliary winding is connected to the second end of the auxiliary capacitor.

[0136] The auxiliary device of the above embodiment can be connected to the primary winding or the secondary winding, wherein the primary winding is particularly suitable for the second to fourth embodiments. It should be particularly noted that, by configuring the auxiliary device to be connected to the secondary winding, a diode may not be provided between the secondary winding of the voltage conversion device of the forward converter and the energy storage inductor, and a simpler circuit structure may be provided compared to the configuration in which the auxiliary device is connected to the primary winding.

[0137] Please refer to Fig.17 , Fig.17 The waveform diagram of the voltage at the AC input end, the current at the AC input end, and the secondary side current of the forward power factor corrector of the forward converter according to one embodiment of the present invention is presented as an example. Fig.17 As shown, the voltage V at the AC input terminal s It matches the waveform of the current Is at the AC input end and has a low harmonic rate. In addition, according to the de-sectorization interval d1 of the secondary side current I2, it can be known that the forward power factor corrector can effectively demagnetize.

[0138] Please refer to Fig.18 , Fig.18 The relationship between the output voltage and the switch duty cycle of the forward power factor corrector according to an embodiment of the present invention is presented as an example. The relationship between the output voltage and the switch duty cycle can be presented by the following formula 1:

[0139]

[0140] Where V o is the output voltage, V s is the AC input voltage, such as Figure 2 As shown, D is the switching duty cycle.

[0141] In summary, the forward converter according to one or more embodiments of the present invention can have the advantages of high conversion efficiency, meeting the transformer winding demagnetization requirements, providing compensation voltage, small size and light weight through the provision of auxiliary devices, and can avoid adding complex and high-cost mechanisms. In addition to the above advantages, the forward power factor corrector including the forward converter disclosed in this case can reduce the current blind area through the compensation voltage of the auxiliary device, and can achieve the effect of high power factor and low harmonic rate.

Claims

1. A forward converter, characterized in that: Include: A voltage conversion device, comprising a primary winding and a secondary winding, and used for converting an input voltage into an output voltage; a switch connected to the voltage conversion device and switched to enable the voltage conversion device to receive or not receive the input voltage; and An auxiliary device is connected to the voltage conversion device. When the switch is turned off, the auxiliary device stores the electric energy released by the voltage conversion device and generates a compensation voltage. When the switch is turned on, the auxiliary device provides the compensation voltage. The compensation voltage has the same polarity as the input voltage.

2. The forward converter according to claim 1, wherein: The auxiliary device includes an auxiliary capacitor.

3. The forward converter according to claim 2, wherein: The auxiliary device also includes: an auxiliary diode, an anode terminal of the auxiliary diode is connected to the first terminal of the auxiliary capacitor; and An auxiliary winding is coupled to the primary winding and the secondary winding, wherein one end of the auxiliary winding is connected to the cathode end of the auxiliary diode, and the other end of the auxiliary winding is connected to the second end of the auxiliary capacitor.

4. The forward converter according to claim 3, wherein: The voltage conversion device further includes an energy storage inductor for outputting the output voltage, the auxiliary diode is a first auxiliary diode, the auxiliary winding is a first auxiliary winding, and the auxiliary device further includes: a second auxiliary diode, an anode terminal of the second auxiliary diode being connected to the first terminal of the auxiliary capacitor; and A second auxiliary winding is coupled to the energy storage inductor, wherein one end of the second auxiliary winding is connected to the cathode end of the second auxiliary diode, and the other end of the second auxiliary winding is connected to the second end of the auxiliary capacitor.

5. The forward converter according to claim 2, wherein: The voltage conversion device further comprises an energy storage inductor for outputting the output voltage, and the auxiliary device further comprises: an auxiliary diode, an anode terminal of the auxiliary diode is connected to the first terminal of the auxiliary capacitor; and An auxiliary winding is coupled to the energy storage inductor, wherein one end of the auxiliary winding is connected to the cathode end of the auxiliary diode, and the other end of the auxiliary winding is connected to the second end of the auxiliary capacitor.

6. The forward converter according to claim 1, wherein: The voltage conversion device also includes an energy storage inductor, a first end of the energy storage inductor is used to output the output voltage, one end of the auxiliary device is connected to the secondary winding, and the other end of the auxiliary device is connected to the second end of the energy storage inductor.

7. The forward converter according to claim 6, wherein: The auxiliary device includes: An auxiliary capacitor, wherein a first end of the auxiliary capacitor is connected to the secondary winding, and a second end of the auxiliary capacitor is connected to the second end of the energy storage inductor.

8. The forward converter according to claim 7, wherein: The auxiliary device also includes: an auxiliary diode, an anode terminal of the auxiliary diode is connected to the first terminal of the auxiliary capacitor; and An auxiliary winding is coupled to the energy storage inductor, wherein one end of the auxiliary winding is connected to the cathode end of the auxiliary diode, and the other end of the auxiliary winding is connected to the second end of the auxiliary capacitor.

9. The forward converter according to claim 7, wherein: The auxiliary device also includes: an auxiliary diode, an anode terminal of the auxiliary diode is connected to the first terminal of the auxiliary capacitor; and An auxiliary winding is coupled to the primary winding and the secondary winding, wherein one end of the auxiliary winding is connected to the cathode end of the auxiliary diode, and the other end of the auxiliary winding is connected to the second end of the auxiliary capacitor.

10. The forward converter according to claim 9, wherein: The auxiliary diode is a first auxiliary diode, the auxiliary winding is a first auxiliary winding, and the auxiliary device further comprises: a second auxiliary diode, an anode terminal of the second auxiliary diode being connected to the first terminal of the auxiliary capacitor; and A second auxiliary winding is coupled to the energy storage inductor, wherein one end of the second auxiliary winding is connected to the cathode end of the second auxiliary diode, and the other end of the second auxiliary winding is connected to the second end of the auxiliary capacitor.

11. The forward converter according to claim 1, wherein: One end of the auxiliary device is used for receiving the input voltage, and the other end of the auxiliary device is connected to the primary winding.

12. The forward converter according to claim 11, wherein: The auxiliary device includes: an auxiliary capacitor, wherein a first end of the auxiliary capacitor is used to receive the input voltage, and a second end of the auxiliary capacitor is connected to the primary winding; an auxiliary diode, an anode terminal of the auxiliary diode is connected to the first terminal of the auxiliary capacitor; and An auxiliary winding is coupled to the primary winding and the secondary winding, wherein one end of the auxiliary winding is connected to the cathode end of the auxiliary diode, and the other end of the auxiliary winding is connected to the second end of the auxiliary capacitor.

13. The forward converter according to claim 12, wherein: The voltage conversion device further includes an energy storage inductor for outputting the output voltage, the auxiliary diode is a first auxiliary diode, the auxiliary winding is a first auxiliary winding, and the auxiliary device further includes: a second auxiliary diode, an anode terminal of the second auxiliary diode being connected to the first terminal of the auxiliary capacitor; and A second auxiliary winding is coupled to the energy storage inductor, wherein one end of the second auxiliary winding is connected to the cathode end of the second auxiliary diode, and the other end of the second auxiliary winding is connected to the second end of the auxiliary capacitor.

14. A forward power factor corrector, characterized in that: Include: A forward converter as claimed in any one of claims 1 to 13; and A rectifying device is connected to the forward converter and is used for receiving and rectifying a power source to generate the input voltage.

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