Forward converter and forward power factor compensator

Abstract

To improve a power factor of a forward converter.SOLUTION: A forward converter 1 contains a voltage conversion device 20, a switch 10, and an auxiliary apparatus 30. The voltage conversion device 20 comprises a primary winding 201 and a secondary winding 202, and is constructed so as to convert an input voltage into an output voltage. The switch 10 is connected to the voltage conversion device 20, and switches whether to supply the input voltage to the voltage conversion device 20. The auxiliary apparatus 30 is connected to the voltage conversion device 20. When the switch 10 is disconnected, the auxiliary apparatus 30 accumulates an electric energy discharged by the voltage conversion device 20, and generates an auxiliary voltage, and when the switch 10 is turned on, the auxiliary apparatus 30 supplies the auxiliary voltage. The auxiliary voltage and the input voltage are the same polarity. In addition, the present invention provides a forward power factor improvement device containing the forward converter 1 and a rectification device.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] One embodiment of the present invention relates to a forward converter, or forward power factor corrector. [Background technology]

[0002] At present, many electrical devices use low voltage direct current. However, the power supplied from the main power source is alternating current (AC), so AC-DC conversion is necessary. In order to reduce the reactive power of the power system and reduce the system interference caused by current harmonics, many electrical devices are required to have high power factor and low current harmonics, so power factor correctors are widely used. Summary of the Invention [Problem to be solved by the invention]

[0003] Based on safety and performance considerations, power factor correctors are required to have high power factor, high conversion efficiency, and electrical isolation. Conventional circuit structures such as flyback structures have poor conversion efficiency, and for conventional forward circuits, when the input AC power supply is in a low voltage state, if the induced voltage on the secondary side is lower than the output voltage of the power factor corrector, the input current cannot be introduced, and a current dead zone occurs. Therefore, the power factor correction effect is impaired, and an additional transformer is required to deal with the demagnetization requirements. Other conventional technologies and circuit structures also face various technical bottlenecks and have difficulty in meeting increasingly stringent regulatory requirements. [Means for solving the problem]

[0004] According to one or more embodiments of the present invention, a forward converter includes a voltage converter, a switch, and an auxiliary device. The voltage converter includes a primary winding and a secondary winding and is configured to convert an input voltage into an output voltage. The switch is connected to the voltage converter and configured to switch whether to input the input voltage to the voltage converter. The auxiliary device is connected to the voltage converter, stores electrical energy discharged by the voltage converter, generates a compensation voltage when the switch is turned off, and provides the compensation voltage when the switch is turned on, where the compensation voltage and the input voltage have the same polarity.

[0005] In accordance with one or more embodiments of the present invention, a forward power factor corrector includes the forward converter described above and a rectifier device coupled to the forward converter and configured to rectify an input power source to generate an input voltage. [Brief description of the drawings]

[0006] The present invention will become more fully understood from the following detailed description and the accompanying drawings, which are for purposes of illustration only and are therefore not limiting of the invention. [Figure 1] FIG. 1 is a block diagram showing a forward converter according to an embodiment of the present invention. [Diagram 2] FIG. 1 is a block diagram illustrating a forward power factor corrector according to one embodiment of the present invention. [Diagram 3] FIG. 4 is a block diagram illustrating a forward power factor corrector in accordance with another embodiment of the present invention. [Figure 4] 4 is an exemplary circuit diagram of a rectifier device and a filter device included in the forward power factor corrector of FIG. 3. [Diagram 5] 1 is a circuit diagram showing a forward converter according to a first embodiment of the present invention. [Figure 6A] 6 illustrates a first operation mode, a second operation mode, and a third operation mode of the forward converter of FIG. 5. [Figure 6B]6 illustrates a first operation mode, a second operation mode, and a third operation mode of the forward converter of FIG. 5. [Figure 6C] 6 illustrates a first operation mode, a second operation mode, and a third operation mode of the forward converter of FIG. 5. [Figure 7] FIG. 4 is a circuit diagram showing a forward converter according to a second embodiment of the present invention. [Figure 8A] 8 illustrates a first operation mode, a second operation mode, a third operation mode, and a fourth operation mode of the forward converter of FIG. 7. [Figure 8B] 8 illustrates a first operation mode, a second operation mode, a third operation mode, and a fourth operation mode of the forward converter of FIG. 7. [Figure 8C] 8 illustrates a first operation mode, a second operation mode, a third operation mode, and a fourth operation mode of the forward converter of FIG. 7. [Figure 8D] 8 illustrates a first operation mode, a second operation mode, a third operation mode, and a fourth operation mode of the forward converter of FIG. 7. [Figure 9] FIG. 11 is a circuit diagram showing a forward converter according to a third embodiment of the present invention. [Figure 10A] 10 illustrates a first operation mode, a second operation mode, and a third operation mode of the forward converter of FIG. [Figure 10B] 10 illustrates a first operation mode, a second operation mode, and a third operation mode of the forward converter of FIG. [Figure 10C] 10 illustrates a first operation mode, a second operation mode, and a third operation mode of the forward converter of FIG. [Figure 11] FIG. 11 is a circuit diagram showing a forward converter according to a fourth embodiment of the present invention. [Figure 12A] 12 illustrates a first operation mode, a second operation mode, a third operation mode, and a fourth operation mode of the forward converter of FIG. [Figure 12B] 12 illustrates a first operation mode, a second operation mode, a third operation mode, and a fourth operation mode of the forward converter of FIG. [Figure 12C]12 illustrates a first operation mode, a second operation mode, a third operation mode, and a fourth operation mode of the forward converter of FIG. [Figure 12D] 12 illustrates a first operation mode, a second operation mode, a third operation mode, and a fourth operation mode of the forward converter of FIG. [Figure 13] FIG. 11 is a circuit diagram showing a forward converter according to a fifth embodiment of the present invention. [Figure 14A] 14 illustrates a first operation mode, a second operation mode, and a third operation mode of the forward converter of FIG. [Figure 14B] 14 illustrates a first operation mode, a second operation mode, and a third operation mode of the forward converter of FIG. [Figure 14C] 14 illustrates a first operation mode, a second operation mode, and a third operation mode of the forward converter of FIG. [Figure 15] FIG. 13 is a circuit diagram showing a forward converter according to a sixth embodiment of the present invention. [Figure 16A] 16 illustrates a first operation mode, a second operation mode, a third operation mode, and a fourth operation mode of the forward converter of FIG. [Figure 16B] 16 illustrates a first operation mode, a second operation mode, a third operation mode, and a fourth operation mode of the forward converter of FIG. [Figure 16C] 16 illustrates a first operation mode, a second operation mode, a third operation mode, and a fourth operation mode of the forward converter of FIG. [Figure 16D] 16 illustrates a first operation mode, a second operation mode, a third operation mode, and a fourth operation mode of the forward converter of FIG. [Figure 17] 4 is an exemplary waveform diagram of the gate-source voltage, the current flowing, and the drain-source voltage of a switch of a forward converter according to one embodiment of the present invention. FIG. [Figure 18] FIG. 2 illustrates an example relationship between the output voltage and the switching duty cycle of a forward power factor corrector in accordance with one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] In the following detailed description, for the purpose of explanation, many specific details are described to facilitate understanding of the disclosed embodiments. According to the description, claims and drawings disclosed herein, those skilled in the art can easily understand the concept and features of the present invention. The following embodiments further describe various aspects of the present invention, but are not intended to limit the scope of the present invention.

[0008] Referring to Fig. 1, Fig. 1 is a block diagram showing a forward converter according to one embodiment of the present invention. As shown in Fig. 1, the forward converter 1 includes 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.

[0009] The switch 10 is configured to switch whether or not an input voltage is supplied to the voltage conversion device 20. For example, the switch 10 may be an active power switch element, and is configured to be triggered to be turned off (shut off) or on so that the voltage conversion device 20 receives or does not receive the input voltage.

[0010] The voltage converter 20 includes a primary winding 201 and a secondary winding 202, and is configured 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 an embodiment, the voltage converter 20 may further include a flywheel diode, an energy storage inductor, and an output capacitor. A first terminal of the energy storage inductor may be configured to output an output voltage. A cathode of the flywheel diode and a second terminal of the energy storage inductor may be commonly connected to a first node, and the first node may be connected to the auxiliary device 30. A terminal of the output capacitor may be connected to another terminal of the energy storage inductor, and the other terminal of the energy storage inductor may be connected to an anode of the flywheel diode.

[0011] The auxiliary device 30 may include one or more passive elements. A terminal of the auxiliary device 30 is connected to the secondary winding 202, and another terminal of the auxiliary device 30 is connected to the second terminal of the energy storage inductor of the voltage conversion device 20. Alternatively, a terminal of the auxiliary device 30 may be configured to receive an input voltage, and another terminal of the auxiliary device 30 is connected to the primary winding 201. When the switch 10 is cut off, the auxiliary device 30 stores the energy released by the voltage conversion device 20 and generates a compensation voltage, and when the switch 10 is turned on, the auxiliary device 30 supplies the compensation voltage. Here, the compensation voltage and the input voltage have the same polarity.

[0012] By storing the energy released by the voltage conversion device when the switch is turned off and generating a compensation voltage, the forward converter may have a demagnetizing function and may provide a compensation voltage when the switch is turned on. In particular, in AC input applications, the compensation voltage may alleviate current dead band situations.

[0013] Referring to FIG. 2, FIG. 2 is a block diagram showing a forward power factor corrector according to one embodiment of the present invention. As shown in FIG. 2, the forward power factor corrector 100 includes a forward converter 1 and a rectifier 2. The forward converter 1 may be the forward converter 1 shown in FIG. 1. The rectifier 2 is connected to a power supply V s and the forward converter 1. The rectifier 2 is connected to the power supply V s The power supply V s The AC can be supplied to the forward converter 1, which converts the AC to DC by the rectifier 2 and supplies the DC to the forward converter 1. The forward converter 1 converts the input voltage to an output voltage V o Here, the output voltage V o may be output to a load connected to the forward converter 1.

[0014] Referring to FIG. 3, FIG. 3 is a block diagram showing a forward power factor corrector according to another embodiment of the present invention. As shown in FIG. 3, the forward power factor corrector 100' includes a forward converter 1, a rectifier 2 and a filtering device 3. The rectifier 2 is connected to the forward converter 1 and the filtering device 3, and the connection and operation of the forward converter 1 and the rectifier 2 are the same as those of the above-mentioned embodiment, so the detailed description here may be omitted. In this embodiment, the filtering device 3 is connected to the rectifier 2 and the power supply V s and first filters the AC current, and then transmits the filtered AC current to the rectifier 2 for AC-DC conversion.

[0015] To further explain the circuits of the filtering device 3 and the rectifying device 2, reference is made to FIG. 4, which illustrates a circuit diagram of the rectifying device 2 and the filtering device 3 included in the forward power factor corrector 100′ of FIG. 3. As shown in FIG. 4, the rectifying device 2 includes 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 21 The anode of the third diode D 23 The cathode of the first diode D 21 The cathode of the second diode D 22 The cathode of the second diode D 22 The anode of the fourth diode D 24 The third diode D 23 The anode of the fourth diode D 24 The filtering device 3 is connected to the anode of the capacitor D f and inductor L f The capacitor D f The first terminal of the inductor L f The first terminal of the first diode D 21 anode of the third diode D 23 Connected to the cathode of capacitor Df The second terminal of the power supply V s , the second diode D 22 anode of the fourth diode D 24 The inductor L f The second terminal of the power supply V s is connected to.

[0016] The filtering device 3 is connected to a power supply V s The input is filtered and the filtered power supply V s The rectifier 2 is configured to generate a filtered power supply V s is input and rectified, and the second diode D 22 Cathode of and fourth diode D 24 The input voltage V i The forward converter 1 is configured to generate an input voltage V i The output voltage V o and output voltage V o may be output to a load connected to the forward converter 1. Fig. 4 shows a basic circuit for implementing the rectifier device 2 and the filtering device 3. Fig. 4 does not limit that the rectifier device 2 and the filtering device 3 can be realized only by the circuit structure. Also, the filtering device 3 shown in Fig. 4 is provided selectively.

[0017] The following further describes an embodiment for realizing the above-mentioned forward converter 1. Referring to Fig. 5, Fig. 5 is a circuit diagram of a forward converter according to a first embodiment of the present invention. As shown in Fig. 5, the forward converter 1_1 includes a switch 10_1, a voltage conversion device 20_1, and an auxiliary device 30_1.

[0018] The switch 10_1 includes an active power switch element Q1. The voltage conversion device 20_1 includes a primary winding N1 and a secondary winding N2, the above-mentioned flywheel diode D1, an energy storage inductor L1, and an output capacitor C1. The auxiliary device 30_1 includes an auxiliary capacitor Ca.

[0019] Specifically, the first terminal of the energy storage inductor L1 is connected to the output voltage V o and a second terminal of the energy storage inductor L1 is connected to the cathode of the flywheel diode D1. One end of an 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 terminal of the energy storage inductor L1 and the cathode of the flywheel diode D1.

[0020] Referring to FIG. 5 in conjunction with FIGS. 6A-6B, FIGS. 6A-6C illustrate a first operation mode, a second operation mode, and a third operation mode of the forward converter of FIG.

[0021] 6A, in the first operation mode, the active power switch element Q1 is turned on and the flywheel diode D1 is cut off. When the active power switch element Q1 is turned on, the input voltage V i is supplied to the primary winding N1 of the voltage conversion device 20_1, and an induced voltage of the secondary winding N2 and a compensation voltage V of the auxiliary capacitor Ca of the voltage conversion device 20_1 are ca Both of them charge the output capacitor C1. At the same time, the energy storage inductor L1 stores energy and the auxiliary capacitor Ca is in a discharged state. This mode of operation continues until the active power switch element Q1 is cut off and the second mode of operation is entered.

[0022] 6B, in the second operation mode, the active power switch device Q1 is cut off and the flywheel diode D1 is turned on. The magnetized secondary winding N2 is demagnetized through a path formed from the flywheel diode D1 to the auxiliary capacitor Ca, and the auxiliary capacitor Ca is supplied with a compensation voltage V caThe energy storage inductor L1 can release the energy through the path formed by the output capacitor C1 and the flywheel diode D1. This mode of operation continues until the secondary winding N2 and the energy storage inductor L1 have discharged all the energy and entered the third mode of operation.

[0023] Referring to FIG. 6C, in the third operation mode, the active power switch element Q1 and the flywheel diode D1 are cut off, and the forward converter does not perform conversion. The energy stored in the output capacitor C1 can continue to supply current to the load. When the active power switch element Q1 is turned on again, the output capacitor C1 is charged using the energy stored in the auxiliary capacitor Ca. That is, the forward converter 1_1 returns to the first operation mode of FIG. 6A. In particular, in applications where the forward converter of this embodiment is designed to operate in a continuous current mode, the third operation mode may not exist. That is, after the second operation mode, it may directly return to the first operation mode.

[0024] Referring to Fig. 7, Fig. 7 is a circuit diagram showing a forward converter according to a second embodiment of the present invention. As shown in Fig. 7, the forward converter 1_2 includes a switch 10_2, a voltage conversion device 20_2, and an auxiliary device 30_2. The circuit / device implementation, function and connection of the switch 10_2 and the voltage conversion device 20_2 may be similar to the switch 10_1 and the voltage conversion device 20_1 included in the forward converter 1_1 of Fig. 5.

[0025] The auxiliary device 30_2 includes an auxiliary capacitor Ca, an auxiliary diode Da1, and an auxiliary winding La1. An anode of the auxiliary diode Da1 is connected to a first terminal of the auxiliary capacitor Ca. The auxiliary winding La1 is inductively coupled to an energy storage inductor L1 of the voltage conversion device 20_2. One end of the auxiliary winding La1 is connected to a cathode of the auxiliary diode Da1, and the other end of the auxiliary winding La1 is connected to a second terminal of the auxiliary capacitor Ca.

[0026] 7 and 8A-8D, FIGS. 8A-8D show a first operation mode, a second operation mode, a third operation mode, and a fourth operation mode of the forward converter of FIG.

[0027] 8A, in the first operation mode, the active power switch element Q1 is turned on, the auxiliary diode Da1 is cut off, and the flywheel diode D1 is cut off. When the active power switch element Q1 is turned on, the input voltage V i is supplied to the primary winding N1 of the voltage conversion device 20_2. The induced voltage of the secondary winding N2 and the compensation voltage V of the auxiliary capacitor Ca of the voltage conversion device 20_2 ca At the same time, the energy storage inductor L1 stores energy, the auxiliary capacitor Ca is discharged, and the compensation voltage V ca This mode of operation continues until the active power switch device Q1 is shut off and the second mode of operation is entered.

[0028] 8B, in the second operation mode, the active power switch element Q1 is cut off, the auxiliary diode Da1 is turned on, and the flywheel diode D1 is cut off. The excited secondary winding N2 is demagnetized in the path from the auxiliary diode Da1 to the auxiliary capacitor Ca, and the auxiliary capacitor Ca is charged to generate the compensation voltage V ca is generated, and the compensation voltage 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 Vca becomes equal to the first mapped voltage and the third operation mode is entered. The first mapped voltage is the output voltage V mapped to the auxiliary winding La1 side according to the turns ratio between the energy storage inductor L1 and the auxiliary winding La1. o is the equivalent voltage.

[0029] 8C, in the third operation mode, the active power switch device Q1 is cut off, the auxiliary diode Da1 is cut off, and the flywheel diode D1 is turned on. The magnetized secondary winding N2 is continuously demagnetized through the path formed from the flywheel diode D1 to the auxiliary capacitor Ca, which may be charged to generate the compensation voltage Vca. The inductor L1 releases the stored energy through the path formed by the flywheel diode D1 and the output capacitor C1. This operation mode continues until all the energy stored in the energy storage inductor L1 and the magnetized secondary winding N2 is released, and the fourth operation mode is entered.

[0030] Referring to FIG. 8D, in the fourth operation mode, the active power switch element Q1, the flywheel diode D1, and the auxiliary diode Da1 are cut off, and the forward converter does not perform conversion. The energy stored in the output capacitor C1 can continue to supply current to the load. When the active power switch element Q1 is turned on again, the output capacitor C1 is charged using the energy stored in the auxiliary capacitor Ca. That is, the forward converter 1_2 returns to the first operation mode of FIG. 8A. In particular, in applications where the forward converter of this embodiment is designed to operate in a continuous current mode, the fourth operation mode may not exist. That is, after the third operation mode, it may directly return to the first operation mode.

[0031] Referring to Fig. 9, Fig. 9 is a circuit diagram showing a forward converter according to a third embodiment of the present invention. As shown in Fig. 9, the forward converter 1_3 includes a switch 10_3, a voltage conversion device 20_3, and an auxiliary device 30_3. The circuit / device implementation, function and connection of the switch 10_3 and the voltage conversion device 20_3 may be similar to the switch 10_1 and the voltage conversion device 20_1 included in the forward converter 1_1 of Fig. 1. Detailed description thereof may be omitted here.

[0032] The auxiliary device 30_2 includes an auxiliary capacitor Ca, an auxiliary diode Da2, and an auxiliary winding La2. The anode of the auxiliary diode Da2 is connected to a first terminal of the auxiliary capacitor Ca. The auxiliary winding La2 is inductively coupled to the primary winding N1 and the secondary winding N2. One end of the auxiliary winding La2 is connected to the cathode of the auxiliary diode Da2, and the other end of the auxiliary winding La2 is connected to a second terminal of the auxiliary capacitor Ca.

[0033] 9 and 10A to 10C, FIGS. 10A to 10C show a first operation mode, a second operation mode, and a third operation mode of the forward converter of FIG.

[0034] 10A, in the first operation mode, the active power switch device Q1 is turned on, the auxiliary diode Da2 is cut off, and the flywheel diode D1 is cut off. When the active power switch device Q1 is turned on, the input voltage V i is supplied to the primary winding N1 of the voltage conversion device 20_3. The induced voltage of the secondary winding N2 and the compensation voltage V of the auxiliary capacitor Ca of the voltage conversion device 20_3 ca The output capacitor C1 is charged by the output inductor L1. At the same time, the energy storage inductor L1 stores energy and the auxiliary capacitor Ca is in a discharged state. This operation mode continues until the active power switch element Q1 is cut off and the second operation mode is entered.

[0035] 10B, in the second operation mode, the active power switch element Q1 is cut off, the auxiliary diode Da2 is turned on, and the flywheel diode D1 is cut off. Since the auxiliary winding La2 is inductively coupled with the primary winding N1 and the secondary winding N2, the energy stored in the primary winding N1 and the secondary winding N2 is released through the auxiliary winding La2 and demagnetized, and the auxiliary capacitor Ca is charged to the compensation voltage V caThe energy storage inductor L1 may be charged to generate a current I2C. The energy storage inductor L1 may release energy through a path formed by the output capacitor C1 and the flywheel diode D1. This operation mode continues until demagnetization is completed and the energy storage inductor L1 releases all of its energy. In particular, in some implementations, the demagnetization performed by the auxiliary winding La2 through the auxiliary diode Da2 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 may be completed at different times. When the demagnetization of the auxiliary winding La2 and the energy release of the energy storage inductor L1 are both completed, the auxiliary device 30_2 enters the third operation mode.

[0036] Referring to FIG. 10C, in the third operation mode, the energy stored in the energy storage inductor L1 is completely discharged, so the current of the energy storage inductor L1 decreases to zero, and after the energy is completely discharged from the magnetized secondary winding N2 in the second operation mode, the current of the auxiliary capacitor Ca decreases to zero, the flywheel diode D1 and the auxiliary diode Da2 are both in a cut-off state, and the active power switch element Q1 is still in a cut-off state. The energy stored in the output capacitor C1 can continue to supply current to the load. When the active power switch element Q1 is triggered to turn on again, the energy stored by 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. Particularly, in an application in which the forward converter of this embodiment is designed to operate in a continuous current mode, the third operation mode may not exist. That is, after the second operation mode, it may directly return to the first operation mode.

[0037] Referring to FIG. 11, FIG. 11 is a circuit diagram showing a forward converter according to a fourth embodiment of the present invention. As shown in FIG. 11, the forward converter 1_4 includes a switch 10_4, a voltage conversion device 20_4, and an auxiliary device 30_4. The circuit / device implementation, function and connection of the switch 10_4 may be similar to the circuit / device implementation, function and connection of the switch 10_1 included in the forward converter 1_1 of FIG. 5, and the circuit / device implementation, function and connection of the voltage conversion device 20_4 may be similar to the voltage conversion device 20_2 included in the forward converter 1_2 of FIG. 7. Detailed description of these may be omitted here.

[0038] 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 of the first auxiliary diode Da2 is connected to the first terminal of the auxiliary capacitor Ca. The first auxiliary winding La2 is inductively coupled to the primary winding N1 and the secondary winding N2, one end of the first auxiliary winding La2 is connected to the cathode of the first auxiliary diode Da2, and the other end of the first auxiliary winding La2 is connected to the second terminal of the auxiliary capacitor Ca. The anode of the second auxiliary diode Da3 is connected to the first terminal of the auxiliary capacitor Ca. One end of the second auxiliary winding La3 is connected to the cathode of the second auxiliary diode Da3, and the other end of the second auxiliary winding La3 is connected to the second terminal of the auxiliary capacitor Ca. The second auxiliary winding La3 is inductively coupled to the energy storage inductor L1.

[0039] 11 and 12A to 12D, FIGS. 12A to 12D show a first operation mode, a second operation mode, a third operation mode, and a fourth operation mode of the forward converter of FIG.

[0040] 12A, in the first operation mode, the active power switch element Q1 is turned on, the first auxiliary diode Da2 is cut off, the second auxiliary diode Da3 is cut off, and the flywheel diode D1 is cut off. When the active power switch element Q1 is turned on, the input voltage V iis supplied to the primary winding N1 of the voltage conversion device 20_4. The induced voltage of the secondary winding N2 and the compensation voltage V of the auxiliary capacitor Ca of the voltage conversion device 20_4 ca The output capacitor C1 is charged by the output inductor L1. At the same time, the energy storage inductor L1 stores energy and the auxiliary capacitor Ca is in a discharged state. This operation mode continues until the active power switch element Q1 is cut off and the second operation mode is entered.

[0041] 12B, in the second operation mode, the active power switch element Q1 is cut off, the first auxiliary diode Da2 is turned on, the second auxiliary diode Da3 is turned on, and the flywheel diode D1 is cut off. Since the first auxiliary winding La2 is inductively coupled to the primary winding N1 and the secondary winding N2, the secondary winding N2, which is magnetized by the inductor inductively coupled to the first auxiliary winding La2, discharges energy through a path formed from the first auxiliary diode Da2 to the auxiliary capacitor Ca to perform demagnetization, and the auxiliary capacitor Ca generates a compensation voltage V ca Since the second auxiliary winding La3 is inductively coupled to the energy storage inductor L1, the energy stored in the energy storage inductor L1 can be discharged from the second auxiliary winding La3 to charge the auxiliary capacitor Ca. Therefore, the compensation voltage V ca This mode of operation is achieved by increasing the compensation voltage V ca The second map voltage is determined by the turn ratio of the energy storage inductor L1 and the second auxiliary winding La3, and the output voltage V o is the equivalent voltage mapped to the second auxiliary winding La3 side.

[0042] 12C, in the third operation mode, the active power switch element Q1 is cut off, the first auxiliary diode Da2 is turned on, the second auxiliary diode Da3 is cut off, and the flywheel diode D1 is turned on. The magnetized secondary winding N2 continues to demagnetize through the path from the first auxiliary diode Da2 to the auxiliary capacitor Ca, and continues to charge the auxiliary capacitor Ca to generate the compensation voltage V caThe energy storage inductor L1 continues to release energy to charge the output capacitor C1. This mode of operation continues until the energy stored by the magnetized secondary winding N2 and the energy storage inductor L1 is completely released, entering the fourth mode of operation.

[0043] Referring to FIG. 12D, after the magnetized secondary winding N2 and the energy storage inductor L1 completely release the stored energy in the third operation mode, the current in the auxiliary capacitor Ca and the energy storage inductor L1 decreases to zero, and the first auxiliary diode Da2, the second auxiliary diode Da3 and the flywheel diode D1 are all in a cut-off state. The energy stored in the output capacitor C1 can continue to supply current to the load. When the active power switch element Q1 is triggered to turn on again, the energy stored by 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. Particularly, in applications where the forward converter of this embodiment is designed to operate in a continuous current mode, the fourth operation mode may not exist. That is, after the third operation mode, it may directly return to the first operation mode.

[0044] Referring to Fig. 13, Fig. 13 is a circuit diagram of a forward converter according to a fifth embodiment of the present invention. As shown in Fig. 13, the forward converter 1_5 includes a switch 10_5, a voltage conversion device 20_5, and an auxiliary device 30_5. The circuit / device implementation and function of the switch 10_5 may be similar to the circuit / device implementation and function of the switch 10_1 included in the forward converter 1_1. Detailed description thereof may be omitted here.

[0045] The voltage conversion device 20_5 of the forward converter 1_5 further includes another flywheel diode D2 in addition to the components of the voltage conversion device 20_1 shown in Fig. 5. The anode of the flywheel diode D2 is connected to the secondary winding N2, and the cathode of the flywheel diode D2 is connected to the second terminal of the energy storage inductor L1.

[0046] The auxiliary device 30_5 is disposed on the primary side of the forward converter 1_5. Further, one end of the auxiliary device 30_5 is connected to the input voltage V i The auxiliary device 30_5 is configured to receive the input voltage V at its first terminal and the other terminal 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. A first terminal of the auxiliary capacitor Ca is connected to the input voltage V i The auxiliary winding La4 is configured to receive an input of a first terminal of the auxiliary capacitor Ca and a second terminal of the auxiliary capacitor Ca is connected to the primary winding N1. The anode of the auxiliary diode Da4 is connected to the first terminal of the auxiliary capacitor Ca. The auxiliary winding La4 is inductively coupled to the primary winding N1 and the secondary winding N2, with one end of the auxiliary winding La4 connected to the cathode of the auxiliary diode Da4 and the other end of the auxiliary winding La4 connected to the second terminal of the auxiliary capacitor Ca.

[0047] 13 and 14A to 14C, FIGS. 14A to 14C show a first operation mode, a second operation mode, and a third operation mode of the forward converter of FIG.

[0048] 14A, in the first operation mode, the active power switch device Q1 is turned on, the auxiliary diode Da4 is cut off, the flywheel diode D1 is cut off, and the flywheel diode D2 is turned on. When the active power switch device Q1 is turned on, the input voltage V iand the auxiliary capacitor Ca charges the primary winding N1 of the voltage conversion device 20_5. 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 the same time, the energy storage inductor L1 stores energy and the auxiliary capacitor Ca is in a discharged state. This operation mode continues until the active power switch device Q1 is cut off and the second operation mode is entered.

[0049] 14B, in the second operation mode, the active power switch element Q1 is cut off, the auxiliary diode Da4 is turned on, the flywheel diode D1 is turned on, and the flywheel diode D2 is cut off. Since the auxiliary winding La4 is inductively coupled to the primary winding N1 and the secondary winding N2, the energy stored in the primary winding N1 and the secondary winding N2 is released from the auxiliary winding La4 to perform demagnetization, and the auxiliary capacitor Ca is charged to the compensation voltage V ca The energy storage inductor L1 can release energy through a 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 releases all of its energy. In particular, in some implementations, 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 may 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.

[0050] Referring to FIG. 14C, in the third operation mode, the energy stored in the primary winding N1 and the secondary winding N2 is completely discharged, and in the second operation mode, the energy stored in the energy storage inductor L1 is completely discharged, and when the current of the energy storage inductor L1 decreases to zero, the active power switch element Q1, the flywheel diodes D1, D2, and the auxiliary diode Da4 are all in a cut-off state. When the active power switch element Q1 is triggered to turn on again, the energy stored by 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. The energy stored in the output capacitor C1 can continue to supply current to the load. Particularly, in applications where the forward converter of this embodiment is designed to operate in a continuous current mode, the third operation mode may not exist. That is, after the second operation mode, it may directly return to the first operation mode.

[0051] Referring to Fig. 15, Fig. 15 is a circuit diagram of a forward converter according to a sixth embodiment of the present invention. As shown in Fig. 15, the forward converter 1_6 includes a switch 10_6, a voltage conversion device 20_6, and an auxiliary device 30_6. The circuit / device implementation and functions of the switch 10_6 and the voltage conversion device 20_6 may be similar to the switch 10_5 and the voltage conversion device 20_5 included in the forward converter 1_5 of Fig. 13, and detailed descriptions thereof may be omitted here.

[0052] The auxiliary device 30_6 is provided 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. A first terminal of the auxiliary capacitor Ca is connected to the input voltage V iand a second terminal of the auxiliary capacitor Ca is connected to the primary winding N1. The anode of the first auxiliary diode Da4 is connected to the first terminal of the auxiliary capacitor Ca. The first auxiliary winding La4 is inductively coupled to the primary winding N1 and the secondary winding N2. One end of the first auxiliary winding La4 is connected to the cathode of the first auxiliary diode Da4, and the other end of the first auxiliary winding La4 is connected to the second terminal of the auxiliary capacitor Ca. The anode of the second auxiliary diode Da5 is connected to the first terminal of the auxiliary capacitor Ca. The second auxiliary winding La5 is inductively coupled to the energy storage inductor L1. One end of the second auxiliary winding La5 is connected to the cathode of the second auxiliary diode Da5, and the other end of the second auxiliary winding La5 is connected to the second terminal of the auxiliary capacitor Ca.

[0053] 15 and 16A to 16D, FIGS. 16A to 16D show a first operation mode, a second operation mode, a third operation mode, and a fourth operation mode of the forward converter of FIG.

[0054] 16A, in the first operation mode, the active power switch element Q1 is turned on, the first auxiliary diode Da4 is cut off, the second auxiliary diode Da5 is cut off, the flywheel diode D1 is cut off, and the flywheel diode D2 is turned on. When the active power switch element Q1 is turned on, the input voltage V i and the auxiliary capacitor Ca charges the primary winding N1 of the voltage conversion device 20_6. The induced voltage of the secondary winding N2 of the voltage conversion device 20_6 charges the output capacitor C1. At the same time, the energy storage inductor L1 stores energy and the auxiliary capacitor Ca is in a discharged state. This operation mode continues until the active power switch device Q1 is cut off and the second operation mode is entered.

[0055] 16B, in the second operation mode, the active power switch element Q1 is cut 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 cut off. After the active power switch element Q1 is cut off, the first auxiliary winding La4 is inductively coupled to the primary winding N1 and the secondary winding N2, so that the energy stored in the primary winding N1 and the secondary winding N2 may be used to perform demagnetization through a path formed from the first auxiliary diode Da4 to the auxiliary capacitor Ca, and the auxiliary capacitor Ca is charged to generate the compensation voltage V ca Since the second auxiliary winding La5 is inductively coupled to the energy storage inductor L1, the energy stored by the energy storage inductor L1 charges the auxiliary capacitor Ca through the second auxiliary winding La5 by a path formed from the second auxiliary diode Da5 to the auxiliary capacitor, generating a compensation voltage V ca Therefore, the compensation voltage V ca This mode of operation is achieved by increasing the compensation voltage V ca The third map voltage is determined by the output voltage V depending on the turn ratio of the energy storage inductor L1 and the second auxiliary winding La5. o 4 is the equivalent voltage mapped to the second auxiliary winding La5 side.

[0056] 16C, in the third operation mode, the active power switch element Q1 is cut off, the first auxiliary diode Da4 is turned on, the second auxiliary diode Da5 is cut off, the flywheeling diode D1 is turned on, and the flywheeling diode D2 is cut off. The first auxiliary winding La4 continues to demagnetize in the path from the first auxiliary diode Da4 to the auxiliary capacitor Ca, and continues to charge the auxiliary capacitor Ca to generate the compensation voltage V ca The energy stored by the energy storage inductor L1 is discharged through the flywheel diode D1 to charge the output capacitor C1. This operating mode continues until the energy stored in the first auxiliary winding La4 and the energy storage inductor L1 is completely discharged and the fourth operating mode is entered.

[0057] Referring to FIG. 16D, after the energy stored in the first auxiliary winding La4 and the energy storage inductor L1 in the third operation mode is completely discharged, the current in the auxiliary capacitor Ca and the energy storage inductor L1 decreases to zero, the first auxiliary diode Da4, the second auxiliary diode Da5, the flywheel diodes D1 and D2 are all in a cut-off state, and the active power switch element Q1 is still in a cut-off state. The energy stored in the output capacitor C1 can continue to supply current to the load. When the active power switch element Q1 is triggered to turn on again, the energy stored by 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. Particularly, in applications where the forward converter of this embodiment is designed to operate in a continuous current mode, the fourth operation mode may not exist. That is, after the third operation mode, it may directly return to the first operation mode.

[0058] From the above embodiments, the forward converter and auxiliary device of the present invention can be summarized into various implementations as follows. In a first implementation, the forward converter and the auxiliary device include an auxiliary capacitor. In a second implementation, the auxiliary device includes an auxiliary capacitor, an auxiliary diode, and an auxiliary winding, the anode of the auxiliary diode is connected to a first terminal of the auxiliary capacitor, the auxiliary winding is inductively coupled to the primary winding, one end of the auxiliary winding is connected to a cathode of the auxiliary diode, and the other end of the auxiliary winding is connected to a second terminal of the auxiliary capacitor. In a third implementation, the voltage conversion device further includes an energy storage inductor configured to output an output voltage, the auxiliary device includes an auxiliary capacitor, an auxiliary diode, and an auxiliary winding, the anode of the auxiliary diode is connected to a first terminal of the auxiliary capacitor, the auxiliary winding is inductively coupled to the energy storage inductor, one end of the auxiliary winding is connected to the cathode of the auxiliary diode, and another terminal of the auxiliary winding is connected to the second terminal of the auxiliary capacitor. In a fourth implementation, the voltage conversion device further includes an energy storage inductor configured to output an 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, an anode of the first auxiliary diode is connected to a first terminal of the auxiliary capacitor, the first auxiliary winding is inductively coupled to the primary winding and the secondary winding, a terminal of the first auxiliary winding is connected to a cathode of the first auxiliary diode, another terminal of the first auxiliary winding is connected to a second terminal of the auxiliary capacitor, an anode of the second auxiliary diode is connected to the first terminal of the auxiliary capacitor, the second auxiliary winding is inductively coupled to the energy storage inductor, one end of the second auxiliary winding is connected to the cathode of the second auxiliary diode, and the other end of the second auxiliary winding is connected to the second terminal of the auxiliary capacitor.

[0059] The auxiliary device in the above embodiments can be connected to the primary winding or the secondary winding, and the primary winding is particularly applied to the second to fourth embodiments. By connecting the auxiliary device to the secondary winding, it is not necessary to place a diode between the energy storage inductor and the secondary winding of the voltage conversion device of the forward converter. Therefore, compared with the structure of the auxiliary device connected to the primary winding, the present invention can have a simpler circuit structure.

[0060] Referring to Fig. 17, Fig. 17 is a diagram illustrating waveforms of voltage (Volt) and current (ampere) at the alternating current (AC) input terminal of the secondary current of the forward power factor corrector of the forward converter according to one embodiment of the present invention. As shown in Fig. 17, the voltage V s and the AC input terminal current I s The current harmonics are small, and it can be seen that the forward power factor corrector can effectively perform demagnetization according to the demagnetization interval d1 of the secondary current I2.

[0061] Referring to Fig. 18, Fig. 18 is a diagram illustrating a relationship between the duty cycle (D) of the switch and the output voltage (Volt) of the forward power factor corrector according to one embodiment of the present invention. The relationship between the duty cycle of the switch and the output voltage can be expressed by the following equation (1). V o =D / (1-D)|V s | (1) Here, as shown in FIG. o is the output voltage, V s is the AC input voltage and D is the switch duty cycle.

[0062] Considering the above description, the forward converter according to one or more embodiments of the present invention can use the auxiliary device to have the advantages of high conversion efficiency, meet the demagnetization requirements of the winding of the voltage converter, provide the compensation voltage, and be smaller and lighter without adding any additional complex and high-cost structure. In addition to the above advantages, the forward power factor corrector including the above-mentioned forward converter of the present invention can also reduce the current dead band through the compensation voltage of the auxiliary device, and achieve the effects of high power factor and low harmonic factor.

Claims

1. a voltage conversion device including a primary winding and a secondary winding, for converting an input voltage into an output voltage; a switch connected to the voltage conversion device and configured to switch whether or not the input voltage is supplied to the voltage conversion device; an auxiliary device connected to the voltage converter, storing electrical energy discharged by the voltage converter, generating a compensation voltage when the switch is turned off, and providing the compensation voltage when the switch is turned on; Equipped with The compensation voltage and the input voltage have the same polarity; Forward converter.

2. 2. The forward converter of claim 1, wherein the auxiliary device is an auxiliary capacitor.

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

4. The voltage conversion device further includes an energy storage inductor that outputs the output voltage. the auxiliary diode is a first auxiliary diode, the auxiliary winding is a first auxiliary winding, The auxiliary device includes: a second auxiliary diode having an anode connected to the first terminal of the auxiliary capacitor; a second auxiliary winding inductively coupled to the energy storage inductor, one end of which is connected to the cathode of the second auxiliary diode and the other end of which is connected to the second terminal of the auxiliary capacitor; The forward converter of claim 3 further comprising:

5. The voltage conversion device further includes an energy storage inductor that outputs the output voltage. The auxiliary device includes: an auxiliary diode having an anode connected to the first terminal of the auxiliary capacitor; an auxiliary winding inductively coupled to the energy storage inductor, one end connected to the cathode of the auxiliary diode and the other end connected to the second terminal of the auxiliary capacitor; The forward converter of claim 2 further comprising:

6. The voltage conversion device further includes an energy storage inductor; a first terminal of the energy storage inductor configured to output the output voltage; The auxiliary device terminals are connected to the secondary winding; 2. The forward converter of claim 1, wherein another terminal of the auxiliary device is connected to a second terminal of the energy storage inductor.

7. The auxiliary device further comprises an auxiliary capacitor; a first terminal of the auxiliary capacitor connected to the secondary winding; 7. The forward converter of claim 6, wherein the second terminal of the auxiliary capacitor is connected to the second terminal of the energy storage inductor.

8. The auxiliary device includes: an auxiliary diode having an anode connected to the first terminal of the auxiliary capacitor; an auxiliary winding inductively coupled to the energy storage inductor, one end connected to the cathode of the auxiliary diode and the other end connected to the second terminal of the auxiliary capacitor; The forward converter of claim 7 further comprising:

9. The auxiliary device includes: an auxiliary diode having an anode connected to the first terminal of the auxiliary capacitor; an auxiliary winding inductively coupled to the primary winding and the secondary winding, the auxiliary winding having one end connected to the cathode of the auxiliary diode and the other end connected to the second terminal of the auxiliary capacitor; The forward converter of claim 7 further comprising:

10. the auxiliary diode is a first auxiliary diode, the auxiliary winding is a first auxiliary winding, The auxiliary device includes: a second auxiliary diode having an anode connected to the first terminal of the auxiliary capacitor; a second auxiliary winding inductively coupled to the energy storage inductor, one end of which is connected to the cathode of the second auxiliary diode and the other end of which is connected to the second terminal of the auxiliary capacitor; The forward converter of claim 9 further comprising:

11. one end of the auxiliary device is configured to receive the input voltage; The forward converter of claim 1 , wherein the other end of the auxiliary device is connected to the primary winding.

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

13. The voltage converter further comprises an energy storage inductor configured to output the output voltage; the auxiliary diode is a first auxiliary diode, the auxiliary winding is a first auxiliary winding, The auxiliary device includes: a second auxiliary diode having an anode connected to the first terminal of the auxiliary capacitor; a second auxiliary winding inductively coupled to the energy storage inductor, one end of which is connected to the cathode of the second auxiliary diode and the other end of which is connected to the second terminal of the auxiliary capacitor; The forward converter of claim 12 further comprising:

14. A forward converter according to claim 1; a rectifier connected to the forward converter and configured to receive a power source and rectify the power source to generate the input voltage.

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