Power converter
Patent Information
- Application Number
- TW114105789
- Authority / Receiving Office
- TW · TW
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2025-02-17
- Publication Date
- 2026-09-01
- Estimated Expiration
- 2045-02-16
Smart Images
Figure TWG2TA001073662_001 
Figure TWG2TA001073662_002 
Figure TWG2TA001073662_003
Abstract
Description
[Technical Field]
[0001] The present invention relates to a power converter, and more particularly to a power converter that can maintain optimal efficiency by reducing the output voltage under light load operation. [Previous Technology]
[0002] Current power supply designs have increasingly higher efficiency requirements under light loads. In addition to selecting low-power components, the supply voltage of integrated circuits (ICs) can also be reduced in the design, thereby reducing IC losses. The most intuitive approach is to directly reduce the output voltage, for example, by reducing the output voltage from 20 volts to 15 volts, in order to reduce losses.
[0003] Please refer to Figures 1, 2A, and 2B, which are respectively a block diagram of an existing charger circuit, a circuit diagram of the AC-to-DC rectifier and primary-side conversion circuit in Figure 1, and a circuit diagram of the secondary-side circuit in Figure 1. The power conversion circuit shown in Figure 1, taking the charger circuit as an example, includes an AC-to-DC rectifier 91, a primary-side conversion circuit 92, and a secondary-side circuit 93. The AC mains power is converted into DC voltage by the AC-to-DC rectifier 91, and then the DC voltage is boosted to a high voltage by the primary-side conversion circuit 92, for example, but not limited to 400 volts. This 400-volt high voltage then powers the resonant circuit (LLC). Furthermore, the resonant circuit (LLC) transfers energy to the secondary side through a transformer, and the output voltage is stabilized at, for example, but not limited to, 20 volts by the operation of the secondary-side circuit 93.
[0004] However, for power converter architectures with power factor correction (PFC) and resonant circuits (LLC), due to the influence of the LLC's resonant tank, the PFC's output voltage must also be reduced synchronously when the output voltage decreases, for example, from 400 volts to 300 volts, in order to maintain the optimal design of the resonant tank and keep the power converter's efficiency optimal. In other words, if the output voltage is reduced to cope with the system under light load conditions, but the PFC's output voltage is not reduced synchronously, the light load efficiency will not be improved.
[0005] Therefore, how to design a power converter to solve the problems and technical bottlenecks of the existing technology is an important research topic for the inventors of this case. [Summary of the Invention]
[0006] The purpose of this invention is to provide a power converter. The power converter includes a primary-side module and a secondary-side module. The primary-side module includes a boost unit, a first regulating unit, a conversion unit, and a first control unit. The secondary-side module includes a second regulating unit, a feedback circuit, a detection unit, and a second control unit. The boost unit provides a preceding voltage. The first regulating unit is coupled to the boost unit. The first regulating unit outputs a first voltage divider signal based on the preceding voltage and a first feedback signal. The conversion unit receives the preceding voltage and outputs an output voltage. The first control unit is coupled to the boost unit, the first regulating unit, and the conversion unit. The first control unit controls the boost unit to regulate the preceding voltage based on the first voltage divider signal and controls the conversion unit to regulate the output voltage based on a second feedback signal. The secondary-side module electrically isolates the primary-side module. The second regulating unit outputs a second voltage divider signal based on the output voltage and a first control signal. The feedback circuit provides a first feedback signal based on the first control signal. The detection unit outputs a status voltage based on the load state at the output of the conversion unit. The second control unit is coupled to the second adjustment unit, the detection unit, and the feedback circuit. The second control unit outputs a first control signal based on the state voltage and the reference voltage, and outputs a second control signal based on the second voltage divider signal.
[0007] In one embodiment, the first regulating unit includes a first voltage divider circuit and a first transformer circuit. The first voltage divider circuit is coupled to the boost unit and outputs a first voltage divider signal. The first transformer circuit is coupled to the first voltage divider circuit and receives a first feedback signal.
[0008] In one embodiment, the first voltage divider circuit includes a first resistor and a second resistor connected in series. The first end of the first resistor is coupled to the boost unit, and the first end of the second resistor is coupled to the ground terminal of the primary side module; the second end of the first resistor, the second end of the second resistor, the first control unit, and the first transformer circuit are coupled together and output a first voltage divider signal.
[0009] In one embodiment, the first transformer circuit includes a first transformer resistor and a first switching element. The first transformer resistor is connected in parallel with a first voltage divider circuit. A first terminal of the first switching element is coupled to a second terminal of the first resistor and a second terminal of the second resistor; a second terminal of the first switching element is coupled to the first transformer resistor; a control terminal of the first switching element is coupled to a second coupling element. When the first switching element is turned off according to a first feedback signal, the first transformer resistor is not connected to either the first resistor or the second resistor.
[0010] In one embodiment, the second adjustment unit includes a second voltage divider circuit and a second transformer circuit. The second voltage divider circuit outputs a second voltage divider signal based on the output voltage. The second transformer circuit is coupled to the second voltage divider circuit and receives a first control signal.
[0011] In one embodiment, the second voltage divider circuit includes a third resistor and a fourth resistor connected in series; the first end of the third resistor is coupled to the output terminal, and the first end of the fourth resistor is coupled to the ground terminal of the secondary side module; the second end of the third resistor, the second end of the fourth resistor, the second control unit and the second transformer circuit are coupled together and output a second voltage divider signal.
[0012] In one embodiment, the second transformer circuit includes a second transformer resistor and a second switching element. The second transformer resistor is connected in parallel with a second voltage divider circuit. A first terminal of the second switching element is coupled to a second terminal of a third resistor and a second terminal of a fourth resistor; a second terminal of the second switching element is coupled to the second transformer resistor; a control terminal of the second switching element is used to receive a first control signal. When the second switching element is turned off according to the first control signal, the second transformer resistor is not connected to the third resistor or the fourth resistor.
[0013] In one embodiment, the feedback circuit includes a second coupling element and a third switching element. The second coupling element includes a second transmitting end and a second receiving end. The second transmitting end is coupled to an output end. The second receiving end is coupled to a control end of a first switching element. The control end of the third switching element is coupled to a second control unit and receives a first control signal to control the third switching element to be turned on or off; a first end of the third switching element is coupled to a ground end of a secondary-side module; a second end of the third switching element is coupled to a second transmitting end. When the third switching element is off, the second transmitting end provides a first feedback signal.
[0014] In one embodiment, the primary-side module further includes a first coupling element. The first coupling element includes a first transmitter and a first receiver. The first transmitter is coupled to a second control unit. The first receiver is coupled to the first control unit. The first transmitter provides a second feedback signal to the first receiver according to a second control signal.
[0015] In one embodiment, the detection unit includes a detection element. The detection element is coupled between the output terminal and the second control unit, and is used to detect the load state of the output terminal to output a state voltage.
[0016] Accordingly, the present invention has the following features and advantages: under light load operation, the efficiency of the power converter is optimized by simultaneously reducing the front voltage of the primary side module and the output voltage of the secondary side module.
[0017] In order to further understand the technology, means and effects adopted by the present invention to achieve the intended purpose, please refer to the following detailed description and drawings of the present invention. It is believed that the purpose, features and characteristics of the present invention can be understood in depth and in detail from these drawings. However, the accompanying drawings are provided for reference and illustration only and are not intended to limit the present invention.
Implementation Method
[0018] The technical content and detailed description of the present invention are described below with reference to the accompanying drawings.
[0019] Please refer to Figure 3, which is a circuit block diagram of the power converter of the present invention. The power converter 100 includes a primary-side module 10 and a secondary-side module 20. The primary-side module 10 includes a boost unit 11, a first regulation unit 12, a conversion unit 13, and a first control unit 14. The secondary-side module 20 includes a second regulation unit 21, a feedback circuit 22, a detection unit 23, and a second control unit 24.
[0020] The boost unit 11 provides a preamp voltage V1. In an embodiment of the invention, the boost unit 11 includes a power factor correction (PFC) unit. A first adjustment unit 12 is coupled to the boost unit 11. The first adjustment unit 12 receives the preamp voltage V1 provided by the boost unit 11 and outputs a first voltage divider signal Sdv1 based on the preamp voltage V1 and a first feedback signal Sf1. The conversion unit 13 receives the preamp voltage V1 provided by the boost unit 11 and outputs an output voltage Vo. In an embodiment of the invention, the conversion unit 13 includes a resonant (LLC) unit.
[0021] The first control unit 14 is coupled to the boost unit 11, the first regulating unit 12, and the conversion unit 13. The first control unit 14 receives a first voltage divider signal Sdv1 provided by the first regulating unit 12, and controls the boost unit 11 to adjust the preceding voltage V1 according to the first voltage divider signal Sdv1, and controls the conversion unit 13 to adjust the output voltage Vo according to the second feedback signal Sf2. In an embodiment of the present invention, the first control unit 14 is a control IC shared by the boost unit 11 (i.e., including PFC) and the conversion unit 13 (i.e., including LLC).
[0022] The primary side module 10 further includes a first coupling element 15. Therefore, the first control unit 14 receives the second feedback signal Sf2 provided by the first coupling element 15 to control the conversion unit 13 to adjust the output voltage Vo. The operation of the first coupling element 15 will be described in detail later.
[0023] Referring again to Figure 3, the secondary-side module 20 electrically isolates the primary-side module 10 through the conversion unit 13 and the feedback circuit 22. The secondary-side module 20 includes a second adjustment unit 21, a feedback circuit 22, a detection unit 23, and a second control unit 24. The second adjustment unit 21 receives the output voltage Vo provided by the conversion unit 13 of the primary-side module 10, and outputs a second voltage divider signal Sdv2 according to the output voltage Vo and the first control signal Sc1.
[0024] The feedback circuit 22 provides a first feedback signal Sf1 to the first adjustment unit 12 of the primary side module 10 according to the first control signal Sc1. The detection unit 23 outputs a state voltage Vst according to the load state of the output terminal OUT of the conversion unit 13 of the primary side module 10, that is, according to the magnitude of the output current Io of the conversion unit 13.
[0025] The second control unit 24 is coupled to the second adjustment unit 21, the detection unit 23, and the feedback circuit 22. The second control unit 24 receives the state voltage Vst provided by the detection unit 23, and outputs a first control signal Sc1 to the second adjustment unit 21 and the feedback circuit 22 according to the state voltage Vst and the reference voltage Vref. It also receives the second voltage divider signal Sdv2 provided by the second adjustment unit 21, and outputs a second control signal Sc2 according to the second voltage divider signal Sdv2.
[0026] Please refer to Figures 4A and 4B, which are circuit diagrams of the primary side module and secondary side module of the power converter of the present invention, respectively, and the circuit block diagram of the power converter shown in Figure 3.
[0027] In Figure 4A, the first regulating unit 12 includes a first voltage divider circuit 121 and a first transformer circuit 122. The first voltage divider circuit 121 is coupled to the boost unit 11 and outputs a first voltage divider signal Sdv1. Specifically, the first voltage divider circuit 121 includes a first resistor R11 and a second resistor R12 connected in series. The first end of the first resistor R11 is coupled to the boost unit 11 to receive the preceding voltage V1 generated by the boost unit 11, i.e., the high voltage output obtained after the boost unit 11 boosts and converts the voltage, for example, but not limited to 400 volts. The first end of the second resistor R12 is coupled to the ground terminal G1 of the primary side module 10, i.e., the first end of the second resistor R12 is not coupled to the first end of the first resistor R11. The second end of the first resistor R11, the second end of the second resistor R12, the first control unit 14, and the first transformer circuit 122 are coupled, and the first voltage divider signal Sdv1 is output at the coupled node.
[0028] The first transformer circuit 122 is coupled to the first voltage divider circuit 121 and receives the first feedback signal Sf1 provided by the feedback circuit 22. In FIG. 4A, the first transformer circuit 122 includes a first transformer resistor R13 and a first switching element S11. The first transformer resistor R13 is connected in parallel with the first voltage divider circuit 121. The first terminal of the first switching element S11 is coupled to the second terminal of the first resistor R11 and the second terminal of the second resistor R12. The second terminal of the first switching element S11 is coupled to the first transformer resistor R13. The control terminal of the first switching element S11 is coupled to the second coupling element 221 to receive the first feedback signal Sf1 provided by the feedback circuit 22. Therefore, when the first switching element S11 is turned off according to the first feedback signal Sf1, the first transformer resistor R13 is not connected to the first resistor R11 or the second resistor R12. Specifically, in this embodiment, the second coupling element 221 can be an optical coupler (or optocoupler, optoisolator), which has a second transmitting end 2211 and a second receiving end 2212.
[0029] In Figure 4B, the second adjustment unit 21 includes a second voltage divider circuit 211 and a second transformer circuit 212. The second voltage divider circuit 211 outputs a second voltage divider signal Sdv2 based on the output voltage Vo. Specifically, the second voltage divider circuit 211 includes a third resistor R21 and a fourth resistor R22 connected in series. The first end of the third resistor R21 is coupled to the output terminal OUT to receive the output voltage Vo. The first end of the fourth resistor R22 is coupled to the ground terminal G2 of the secondary side module 20. The second ends of the third resistor R21, the fourth resistor R22, the second control unit 24, and the second transformer circuit 212 are coupled together, and the second voltage divider signal Sdv2 is output at the coupled nodes.
[0030] The second transformer circuit 212 is coupled to the second voltage divider circuit 211 and receives the first control signal Sc1 provided by the second control unit 24. In FIG. 4B, the second transformer circuit 212 includes a second transformer resistor R23 and a second switching element S21. The second transformer resistor R23 is connected in parallel with the second voltage divider circuit 211. The first terminal of the second switching element S21 is coupled to the second terminal of the third resistor R21 and the second terminal of the fourth resistor R22. The second terminal of the second switching element S21 is coupled to the second transformer resistor R23. The control terminal of the second switching element S21 is used to receive the first control signal Sc1 provided by the second control unit 24. Therefore, when the second switching element S21 is turned off according to the first control signal Sc1, the second transformer resistor R23 is not connected to the third resistor R21 or the fourth resistor R22.
[0031] In Figure 4B, the feedback circuit 22 includes a second coupling element 221 and a third switching element S22. The second coupling element 221 includes a second transmitting terminal 2211 and a second receiving terminal 2212 (see Figure 4A). The second transmitting terminal 2211 is coupled to the output terminal OUT to receive the output voltage Vo. The second receiving terminal 2212 is coupled to the control terminal of the first switching element S11 of the first transformer circuit 122. The control terminal of the third switching element S22 is coupled to the second control unit 24 and receives the first control signal Sc1 provided by the second control unit 24 to control the conduction or deactivation of the third switching element S22. The first terminal of the third switching element S22 is coupled to the ground terminal G3 of the secondary side module 20. The second terminal of the third switching element S22 is coupled to the second transmitting terminal 2211 of the second coupling element 221. Therefore, when the third switching element S22 is turned off, the second transmitting end 2211 of the second coupling element 221 provides a first feedback signal Sf1 for the second receiving end 2212 of the second coupling element 221 to receive.
[0032] Please refer to Figures 4A and 4B. As previously described, the first coupling element 15 includes a first transmitter 151 (see Figure 4B) and a first receiver 152 (see Figure 4A). The first transmitter 151 is coupled to the second control unit 24, and the first receiver 152 is coupled to the first control unit 14. When the first transmitter 151 is turned off according to the second control signal Sc2, it provides a second feedback signal Sf2 to the first receiver 152.
[0033] Furthermore, referring to Figure 4B, the detection unit 23 of the secondary module 20 includes a detection element R24, which is, for example, but not limited to, a resistor. The detection element R24 is coupled between the output terminal OUT and the second control unit 24 to detect the load state of the output terminal OUT, thereby outputting a state voltage Vst. For example, if the detection element R24 is a resistor, then according to the current flowing through it (i.e., the output current Io), the larger the output current Io, the larger the voltage across the detection element R24 (i.e., the state voltage Vst); conversely, the smaller the output current Io, the smaller the voltage across the detection element R24. Therefore, the larger the state voltage Vst, the heavier the system load; conversely, the smaller the state voltage Vst, the lighter the system load. Thus, the load state of the system can be detected through the use of the detection element R24.
[0034] Hereinafter, the power converter of the present invention will be described in order to simultaneously reduce the front voltage V1 of the primary side module 10 and the output voltage Vo of the secondary side module 20 under light load conditions, so as to optimize the efficiency of the power converter.
[0035] Under normal heavy load conditions, the output current Io of the secondary module 20 flows through the detection element R24, and a detection voltage V24 is generated across the detection element R24. When the second control unit 24 determines that it is operating under heavy load based on the state voltage Vst (i.e., the corresponding detection voltage V24), for example, if the second control unit 24 determines that the state voltage Vst is greater than the reference voltage Vref, the second control unit 24 provides a first control signal Sc1, such as a high-level signal, to turn on the third switching element S22. Since the third switching element S22 is turned on, the second transmitting end 2211 of the second coupling element 221 sends a first feedback signal Sf1 to the second receiving end 2212, causing the first switching element S11 to turn on. Therefore, the first transformer resistor R13 is connected in parallel with the second resistor R12.
[0036] Simultaneously, the second control unit 24 provides a high-level first control signal Sc1 to turn on the second switching element S21. At this time, the second transformer resistor R23 is connected in parallel with the fourth resistor R22.
[0037] Further, under heavy load conditions, to stabilize the output voltage Vo at, for example, but not limited to, 20 volts, the first control unit 14 receives the second feedback signal Sf2 provided by the first coupling element 15, and adjusts the duty cycle of the control signals of the upper switch QH and the lower switch QL of the conversion unit 13 according to the second feedback signal Sf2, that is, adjusting the duty cycle of the upper switch control signal HG (controlling the upper switch QH) and the lower switch control signal LG (controlling the lower switch QL). For example, if the output voltage Vo decreases, the duty cycle of the upper switch control signal HG and the lower switch control signal LG is increased to improve the output energy of the conversion unit 13, thereby increasing the output voltage Vo. Conversely, if the output voltage Vo increases, the duty cycle of the upper switch control signal HG and the lower switch control signal LG is decreased to reduce the output energy of the conversion unit 13, thereby decreasing the output voltage Vo, thereby maintaining the output voltage Vo at 20 volts under heavy load conditions.
[0038] Conversely, when the second control unit 24 determines that it is operating under light load based on the state voltage Vst (i.e., the corresponding detection voltage V24), for example, if the second control unit 24 determines that the state voltage Vst is less than the reference voltage Vref, the second control unit 24 provides a first control signal Sc1, such as a low-level signal, to turn off the third switching element S22, or it does not provide the first control signal Sc1, which also turns off the third switching element S22. Since the third switching element S22 is turned off, the second transmitting end 2211 of the second coupling element 221 does not send the first feedback signal Sf1 to the second receiving end 2212, causing the first switching element S11 to turn off. Therefore, the first transformer resistor R13 is not connected to the first resistor R11 or the second resistor R12. Based on this, since the first transformer resistor R13 removes its parallel connection with the second resistor R12, the first transformer resistor R13 no longer participates in the voltage division of the preceding voltage V1. Therefore, the first voltage division signal Sdv1 undergoes a transient voltage change. However, in order to maintain the voltage of the first voltage divider signal Sdv1 at a specific voltage, such as, but not limited to, 2.5 volts, the first control unit 14 must control the output voltage V1 of the boost unit 11 to decrease accordingly when the system is operating under light load, for example, from 400 volts to 300 volts, in order to maintain the first voltage divider signal Sdv1 at this specific voltage.
[0039] Simultaneously, the second control unit 24 provides a low-level first control signal Sc1 (or does not provide a first control signal Sc1) to turn off the second switching element S21. In this case, the second transformer resistor R23, which was originally connected in parallel with the fourth resistor R22, is removed from the parallel connection with the fourth resistor R22. Based on this, since the voltage of the second voltage divider signal Sdv2 is fixed, for example, but not limited to 2.5 volts, the output voltage Vo is reduced due to the removal of the parallel connection of the resistors. Thus, when the system is operating under light load, the output voltage Vo is also reduced accordingly, for example, but not limited to 15 volts.
[0040] Similarly, under light load conditions, in order to stabilize the output voltage Vo at, for example, but not limited to, 15 volts, the first control unit 14 receives the second feedback signal Sf2 provided by the first coupling element 15, and adjusts the duty cycle of the control signals of the upper switch QH and the lower switch QL of the switching unit 13 according to the second feedback signal Sf2, that is, adjusts the duty cycle of the upper switch control signal HG (controlling the upper switch QH) and the lower switch control signal LG (controlling the lower switch QL), thereby maintaining the output voltage Vo at 15 volts under light load conditions.
[0041] In summary, the present invention has the following features and advantages: under light load operation, by simultaneously reducing the front voltage of the primary side module and the output voltage of the secondary side module, the efficiency of the power converter is optimized.
[0042] The above description is only a detailed description and drawings of preferred embodiments of the present invention. However, the features of the present invention are not limited thereto and are not intended to limit the present invention. The scope of the present invention should be determined by the following claims. All embodiments that are in line with the spirit of the claims and similar variations thereof should be included in the scope of the present invention. Any variations or modifications that can be easily conceived by those skilled in the art within the field of the present invention can be covered by the following claims. [Simplified Explanation of the Diagram]
[0043] Figure 1: is a block diagram of an existing charger circuit.
[0044] Figure 2A: This is a circuit diagram of the AC to DC rectifier and the primary side conversion circuit in Figure 1.
[0045] Figure 2B: is a circuit diagram of the secondary side circuit in Figure 1.
[0046] Figure 3: is a circuit block diagram of the power converter of the present invention.
[0047] Figure 4A: is a circuit diagram of the primary side module of the power converter of the present invention.
[0048] Figure 4B: is a circuit diagram of the secondary side module of the power converter of the present invention.
Claims
1. A power converter, comprising: A primary-side module includes: a boost unit providing a preamp voltage; a first regulating unit coupled to the boost unit, the first regulating unit outputting a first voltage divider signal based on the preamp voltage and a first feedback signal; a conversion unit receiving the preamp voltage and outputting an output voltage; and a first control unit coupled to the boost unit, the first regulating unit, and the conversion unit, the first control unit controlling the boost unit to regulate the preamp voltage based on the first voltage divider signal, and controlling the conversion unit to regulate the output voltage based on a second feedback signal; and a secondary-side module electrically isolating the primary-side module, the secondary-side module including: a second regulating unit outputting a second voltage divider signal based on the output voltage and a first control signal; wherein the second regulating unit includes: a second voltage divider circuit outputting the second voltage divider signal based on the output voltage; and a second transformer circuit coupled to the second voltage divider circuit and receiving the first control signal; A feedback circuit provides the first feedback signal based on the first control signal; a detection unit outputs a state voltage based on a load state at an output of the conversion unit; and a second control unit coupled to the second adjustment unit, the detection unit, and the feedback circuit, the second control unit outputting the first control signal based on the state voltage and a reference voltage, and outputting a second control signal based on the second voltage divider signal.
2. The power converter as claimed in claim 1, wherein the first regulating unit comprises: A first voltage divider circuit is coupled to the boost unit and outputs the first voltage divider signal; And a first transformer circuit, coupled to the first voltage divider circuit, and receiving the first feedback signal.
3. The power converter as claimed in claim 2, wherein the first voltage divider circuit includes a first resistor and a second resistor connected in series; a first end of the first resistor is coupled to the boost unit, and a first end of the second resistor is coupled to a ground terminal of the primary side module; a second end of the first resistor, a second end of the second resistor, the first control unit and the first transformer circuit are coupled together and output the first voltage divider signal.
4. The power converter as claimed in claim 3, wherein the first transformer circuit comprises: A first transformer resistor is connected in parallel with the first voltage divider circuit; The first switching element has a first terminal coupled to the second terminal of the first resistor and the second terminal of the second resistor; a second terminal of the first switching element is coupled to the first transformer resistor; and a control terminal of the first switching element is coupled to a second coupling element; wherein, when the first switching element is turned off according to the first feedback signal, the first transformer resistor is not connected to the first resistor or the second resistor.
5. The power converter as claimed in claim 1, wherein the second voltage divider circuit includes a third resistor and a fourth resistor connected in series; a first end of the third resistor is coupled to the output terminal, and a first end of the fourth resistor is coupled to a ground terminal of the secondary side module; a second end of the third resistor, a second end of the fourth resistor, the second control unit, and the second transformer circuit are coupled together and output the second voltage divider signal.
6. The power converter as claimed in claim 5, wherein the second transformer circuit comprises: A second transformer resistor is connected in parallel with the second voltage divider circuit; And a second switching element, a first terminal of the second switching element being coupled to the second terminal of the third resistor and the second terminal of the fourth resistor; a second terminal of the second switching element being coupled to the second transformer resistor; a control terminal of the second switching element being used to receive the first control signal; wherein, when the second switching element is turned off according to the first control signal, the second transformer resistor is not connected to the third resistor or the fourth resistor.
7. The power converter as claimed in claim 4, wherein the feedback circuit includes: The second coupling element includes: a second transmitting end coupled to the output end; a second receiving end coupled to the control end of the first switching element; and a third switching element, a control end of the third switching element coupled to the second control unit and receiving the first control signal to control the third switching element to be turned on or off; a first end of the third switching element coupled to a ground end of the secondary side module; and a second end of the third switching element coupled to the second transmitting end; wherein, when the third switching element is turned off, the second transmitting end provides the first feedback signal.
8. The power converter as claimed in claim 1, further comprising a first coupling element, including: A first transmitter is coupled to the second control unit of the secondary side module; and a first receiver coupled to the first control unit of the primary side module; wherein the first transmitter provides the second feedback signal to the first receiver according to the second control signal.
9. The power converter as claimed in claim 1, wherein the detection unit includes a detection element coupled between the output terminal and the second control unit, the detection element being used to detect the load state of the output terminal in order to output the state voltage.