Gallium nitride sound equipment high-power switching power supply

Abstract

The high-power switching power supply comprises an input rectification filtering module, a gallium nitride PFC module, a main control module, an LLC power conversion module, a synchronous rectification output module and a feedback module. The input end of the input rectification filtering module is connected with an external power supply; the gallium nitride PFC module is respectively connected with the output end of the input rectification filtering module, the input end of the LLC power conversion module and the main control module; the synchronous rectification output module is connected between the output end of the LLC power conversion module and a load; the feedback module is connected between the output end of the synchronous rectification output module and the main control module; through the structure, the switching power supply has the advantages of low heat generation, high output efficiency and small size, when the switching power supply is used in a narrow space, the heat generation is low, the output power is very stable, and the stability of a power amplifier power supply is ensured.

Description

Technical Field

[0001] The utility model relates to the technical field of high-power audio switching power supplies, in particular to a gallium nitride audio high-power switching power supply. Background Art

[0002] With the development of technology, audio equipment has become an indispensable part of people's daily lives. Currently, well-known audio brands such as Sonos and Bno have begun to launch miniature high-power amplifiers. These amplifiers are popular among consumers due to their small size and high power. However, due to the relatively high power of the power supply used in high-power audio amplifiers, the heat of the power supply components is difficult to dissipate, which reduces the lifespan of the power components. Excessive component temperature causes high temperature of the machine casing, which can easily burn people. However, traditional audio switching power supplies have problems such as low efficiency, large size, and heavy weight. Therefore, a gallium nitride audio high-power switching power supply is urgently needed to solve these problems. Utility Model Content

[0003] The present invention aims to solve at least one of the technical problems in the prior art. To this end, the present invention provides a gallium nitride audio high-power switching power supply.

[0004] An embodiment of the present invention solves the technical problem by adopting a technical solution: a gallium nitride audio high-power switching power supply, comprising an input rectifier and filter module, a gallium nitride PFC module, a main control module, an LLC power conversion module, a synchronous rectifier output module, and a feedback module;

[0005] The input end of the input rectifier filter module is connected to the external power supply;

[0006] The GaN PFC module is connected to the output end of the input rectifier and filter module, the input end of the LLC power conversion module, and the main control module respectively;

[0007] The synchronous rectification output module is connected between the output end of the LLC power conversion module and the load;

[0008] The feedback module is connected between the output end of the synchronous rectification output module and the main control module;

[0009] The external power signal is transmitted to the GaN PFC module through the input rectifier and filter module to convert the power signal into a high-frequency pulse signal. After voltage conversion by the LLC power conversion module, a stable voltage signal is output through the synchronous rectifier output module. The main control module controls the working state of the GaN PFC module based on the feedback signal from the feedback module to achieve stable control of the output voltage.

[0010] As one of the preferred embodiments of the present invention, the gallium nitride PFC module includes a gallium nitride switching device Q5, an inductor T2, diodes D5-D6, a diode D8, a resistor RT1, a resistor R3, a resistor R12, a resistor R34, a resistor R38, a resistor R41-R42, a capacitor EC5 and a capacitor EC6, one end of the inductor T2 is respectively connected to the input rectifier filter module and the anode of the diode D5, the other end of the inductor T2 is respectively connected to the anode of the diode D6 and the input end of the gallium nitride switching device Q5, the cathode of the diode D5 is respectively connected to the cathode of the diode D6 and one end of the resistor RT1, and the control end of the gallium nitride switching device Q5 is connected to the cathode of the diode D6 and one end of the resistor RT1. They are respectively connected to the anode of diode D8, one end of resistor R3 and one end of resistor R42. The cathode of diode D8 is connected to the other end of resistor R3 and connected to the main control module via resistor R12. The output end of gallium nitride switching device Q5 is respectively connected to the other end of resistor R42, one end of resistor EC5 and one end of capacitor EC6. The other end of capacitor EC5 is respectively connected to the other end of capacitor EC6, the other end of resistor RT1, one end of capacitor C16, one end of resistor R34 and the LLC power conversion module. The other end of resistor R34 is connected to the other end of capacitor C16 and connected to the main control module via resistor R38 and resistor R41.

[0011] As one of the preferred embodiments of the present utility model, the LLC power conversion module includes a first drive circuit, a second drive circuit, a gallium nitride switch device Q4, a gallium nitride switch device Q6, an inductor T3, a transformer T4 and a capacitor C32. The first drive circuit is connected between the main control module and the control end of the gallium nitride switch device Q4, the second drive circuit is connected between the main control module and the control end of the gallium nitride switch device Q6, the input end of the gallium nitride switch device Q4 is connected to VBUS, the output end of the gallium nitride switch device Q4 is respectively connected to the input end of the gallium nitride switch device Q6 and one end of the inductor T3, the other end of the inductor T3 is connected to one end of the primary winding of the transformer T4, the other end of the primary winding of the transformer T4 is respectively connected to the main control module and one end of the capacitor C32, the other end of the capacitor C32 is grounded, and the secondary winding of the transformer T4 is connected to the synchronous rectification output module.

[0012] As one of the preferred embodiments of the present utility model, the first drive circuit includes a resistor R24, a resistor R29, a resistor R31 and a diode D7. One end of the resistor R24 ​​is respectively connected to the main control module and one end of the resistor R29. The other end of the resistor R29 is respectively connected to the other end of the diode R24, one end of the resistor R31 and the control end of the gallium nitride switching device Q4 through the diode D7. The other end of the resistor R31 is connected to the output end of the gallium nitride switching device Q4.

[0013] As one of the preferred embodiments of the present invention, the second drive circuit includes a resistor R39, a resistor R43, a resistor R45 and a diode D9. One end of the resistor R39 is connected to the main control module and one end of the resistor R43 respectively. The other end of the resistor R39 is connected to the other end of the diode R39, one end of the resistor R45 and the control end of the gallium nitride switching device Q6 respectively through the diode D9. The other end of the resistor R45 is connected to the output end of the gallium nitride switching device Q6.

[0014] As one of the preferred embodiments of the present utility model, the feedback module includes a resistor R20, a resistor R21, a resistor R25, a resistor R26, a resistor R32, a voltage regulator ZD2, an optocoupler U6 and a control chip U8. One end of the resistor R21 is connected to the output end of the synchronous rectification output module, and the other end of the resistor R21 is connected to one end of the resistor R32 and the control end of the control chip U8 via the resistor R26. The output end of the control chip U8 and the other end of the resistor R32 are grounded. The input end of the control chip U8 is connected to one end of the resistor R25 and one end of the optocoupler U6 light emitter respectively. The other end of the optocoupler U6 light emitter is connected to the other end of the resistor R25 and to the output end of the synchronous rectification output module via the resistor R20 and the voltage regulator ZD2. One end of the optocoupler U6 light receiver is connected to the main control module and the other end is grounded.

[0015] The beneficial effects of the present invention are as follows: a gallium nitride audio high-power switching power supply comprises an input rectifier and filter module, a gallium nitride PFC module, a main control module, an LLC power conversion module, a synchronous rectifier output module and a feedback module; the input end of the input rectifier and filter module is connected to an external power supply; the gallium nitride PFC module is respectively connected to the output end of the input rectifier and filter module, the input end of the LLC power conversion module and the main control module; the synchronous rectifier output module is connected between the output end of the LLC power conversion module and the load; the feedback module is connected between the output end of the synchronous rectifier output module and the main control module; the above structure makes the switching power supply have the advantages of low heat generation, high output efficiency and small size. When used in a narrow space, the heat generation is low and the output power is very stable, thereby ensuring the stability of the power amplifier power supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0017] Figure 1 This is a circuit schematic diagram of a gallium nitride audio high-power switching power supply;

[0018] Figure 2 This is the circuit schematic diagram of the input rectifier and filter module;

[0019] Figure 3A circuit schematic diagram of a gallium nitride PFC module;

[0020] Figure 4 A circuit schematic diagram of a main control module;

[0021] Figure 5 A circuit schematic diagram of an LLC power conversion module;

[0022] Figure 6 A circuit schematic diagram of a synchronous rectification output module;

[0023] Figure 7 A circuit schematic diagram of a feedback module. DETAILED DESCRIPTION

[0024] This part will describe the specific embodiments of the present application in detail, the preferred embodiments of the present application are shown in the drawings, the role of the drawings is to supplement the description of the text part with graphics, so that people can intuitively and visually understand each technical feature and the overall technical scheme of the present application, but it cannot be understood as a limitation on the protection scope of the present application.

[0025] In the description of the present application, the meaning of multiple is more than two, greater than, less than, more than, etc. is not included in the number, above, below, etc. is included in the number. If there is a description of the first, second, it is only used for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features or implicitly indicating the sequence of indicated technical features.

[0026] In the description of the present application, it is understood that the position description is involved, for example, the position or location relationship indicated by up, down, front, back, left, right, etc. is based on the position or location relationship shown in the drawings, which is only for the convenience of describing the present application and simplifying the description, and is not used to indicate or imply that the device or element indicated must have a specific position, be constructed and operated in a specific position, so it cannot be understood as a limitation on the present application.

[0027] In the present application, unless otherwise explicitly limited, the words "set", "install", "connect" and the like should be broadly understood, for example, they can be directly connected, or indirectly connected through an intermediate medium; can be fixedly connected, or can be detachably connected, or can be integrally formed; can be mechanically connected; can be the internal communication or interaction relationship of two elements. The skilled in the art can reasonably determine the specific meaning of the above words in the present application in combination with the specific content of the technical scheme.

[0028] Reference Figures 1 to 7A gallium nitride audio high-power switching power supply includes an input rectification and filtering module 10, a gallium nitride PFC module 20, a main control module 30, an LLC power conversion module 40, a synchronous rectification output module 50, and a feedback module 60;

[0029] The input end of the input rectifier and filter module 10 is connected to the external power supply;

[0030] The GaN PFC module 20 is connected to the output end of the input rectifier filter module 10, the input end of the LLC power conversion module 40, and the main control module 30 respectively;

[0031] The synchronous rectification output module 50 is connected between the output terminal of the LLC power conversion module 40 and the load;

[0032] The feedback module 60 is connected between the output end of the synchronous rectification output module 50 and the main control module 30;

[0033] The external power signal is transmitted to the GaN PFC module 20 via the input rectifier and filter module 10, which converts the power signal into a high-frequency pulse signal. After voltage conversion by the LLC power conversion module 40, a stable voltage signal is output through the synchronous rectifier output module 50. The main control module 30 controls the operating state of the GaN PFC module 20 based on the feedback signal from the feedback module 60 to achieve stable control of the output voltage.

[0034] In this utility model, the working principle is as follows:

[0035] 1) Reference Figures 1-2 In some embodiments, the input rectifier filter module 10 includes a fuse F1, an inductor LF3, an inductor LF4, a capacitor XC1, a capacitor XC2, a rectifier bridge BD1, a capacitor C14, a resistor R33, and a resistor R36. The fuse F1 is connected between one end of the external power supply and the fourth end of the inductor LF4, the third end of the inductor LF4 is connected to the other end of the external power supply, the second end of the inductor LF4 is respectively connected to one end of the capacitor XC2 and the second end of the inductor LF3, the first end of the inductor LF4 is respectively connected to the other end of the capacitor XC2 and the inductor LF 3, the first end of the inductor LF3 is respectively connected to one end of the capacitor XC1 and the second end of the rectifier bridge BD1, the third end of the inductor LF3 is respectively connected to the other end of the capacitor XC1 and the third end of the rectifier bridge BD1, the first end of the rectifier bridge BD1 is respectively connected to one end of the capacitor C14 and the gallium nitride PFC module 20, the fourth end of the rectifier bridge BD1 is respectively connected to the other end of the capacitor C14, one end of the resistor R33, one end of the resistor R36 and the main control module 30, and the other end of the resistor R33 and the other end of the resistor R36 are grounded.

[0036] Specifically, CON1 is the AC power input, which passes through fuse F1, filters (inductor LF3 and inductor LF4), and X capacitors (capacitor XC1 and capacitor XC2) and then enters rectifier bridge BD1 for rectification, converting the AC power into DC power. Capacitor C14 is a DC filter capacitor, and resistors R33 and R36 are current-limiting resistors used to detect current and provide protection when the current exceeds the limit.

[0037] 2) Reference Figure 1 、 Figure 3 In some embodiments, the gallium nitride PFC module 20 includes a gallium nitride switch device Q5, an inductor T2, diodes D5-D6, a diode D8, a resistor RT1, a resistor R3, a resistor R12, a resistor R34, a resistor R38, resistors R41-R42, a capacitor EC5, and a capacitor EC6. One end of the inductor T2 is connected to the input rectifier filter module 10 and the anode of the diode D5, respectively. The other end of the inductor T2 is connected to the anode of the diode D6 and the input end of the gallium nitride switch device Q5, respectively. The cathode of the diode D5 is connected to the cathode of the diode D6 and one end of the resistor RT1, respectively. The control end of the gallium nitride switch device Q5 is connected to the diode D6 and one end of the resistor RT1, respectively. The anode of the diode D8 is connected to one end of the resistor R3 and one end of the resistor R42. The cathode of the diode D8 is connected to the other end of the resistor R3 and is connected to the main control module 30 via the resistor R12. The output end of the gallium nitride switching device Q5 is respectively connected to the other end of the resistor R42, one end of the resistor EC5 and one end of the capacitor EC6. The other end of the capacitor EC5 is respectively connected to the other end of the capacitor EC6, the other end of the resistor RT1, one end of the capacitor C16, one end of the resistor R34 and the LLC power conversion module 40. The other end of the resistor R34 is connected to the other end of the capacitor C16 and is connected to the main control module 30 via the resistor R38 and the resistor R41.

[0038] Specifically, diode D5 and resistor RT1 pre-charge capacitors EC5 and EC6 to reduce the instantaneous charging current impact of the PFC circuit; inductor T2 is a PFC inductor, and diode D6 is a PFC rectifier diode. When the gallium nitride switching device Q5 is working, diode D6 rectifies and outputs a 380-400V voltage to charge capacitors EC5 and EC6. After full charge, the voltage on capacitors EC5 and EC6 reaches 380V-400V, which is provided to the subsequent LLC power conversion module 40 for power supply; resistors R34, R38, R41 and R50 form a voltage divider circuit, and the divided voltage is provided to the control chip U9 in the main control module 30 for voltage detection to determine that the output voltage cannot exceed 400V.

[0039] 3) Reference Figure 1 、 Figures 5-6In some embodiments, the LLC power conversion module 40 comprises a first driving circuit 41, a second driving circuit 42, a gallium nitride switching device Q4, a gallium nitride switching device Q6, an inductor T3, a transformer T4, and a capacitor C32. The first driving circuit 41 is connected between the main control module 30 and the control terminal of the gallium nitride switching device Q4. The second driving circuit 42 is connected between the main control module 30 and the control terminal of the gallium nitride switching device Q6. The input terminal of the gallium nitride switching device Q4 is connected to VBUS. The output terminal of the gallium nitride switching device Q4 is connected to the input terminal of the gallium nitride switching device Q6 and one end of the inductor T3, respectively. The other end of the inductor T3 is connected to one end of the primary winding of the transformer T4. The other end of the primary winding of the transformer T4 is connected to the main control module 30 and one end of the capacitor C32, respectively. The other end of the capacitor C32 is grounded. The secondary winding of the transformer T4 is connected to the synchronous rectification output module 50.

[0040] Specifically, the gallium nitride switching device Q4, the gallium nitride switching device Q6, the inductor T3, the capacitor C32, and the transformer T4 form an LLC half-bridge resonant circuit. The 7th pin and the 12th pin of the control chip U9 in the main control module 30 output PWM to the G-poles of the gallium nitride switching device Q4 and the gallium nitride switching device Q6 to control the conduction and cutoff of the gallium nitride switching device Q4 and the gallium nitride switching device Q6. The gallium nitride switching device Q4 is the upper half-bridge, the gallium nitride switching device Q6 is the lower half-bridge, and the MOS tubes Q3 and Q7 of the secondary winding of the transformer T4 are synchronous rectification MOS tubes. The full-wave rectification through the MOS tubes Q3 and Q7 obtains a stable DC power output.

[0041] In further embodiments, the first driving circuit 41 connected between the main control module 30 and the control terminal of the gallium nitride switching device Q4 and the second driving circuit 42 connected between the main control module 30 and the control terminal of the gallium nitride switching device Q6 are further included. Preferably, the first driving circuit 41 comprises a resistor R24, a resistor R29, a resistor R31, and a diode D7. One end of the resistor R24 is connected to the main control module 30 and one end of the resistor R29, respectively. The other end of the resistor R29 is connected to the other end of the diode R24, one end of the resistor R31, and the control terminal of the gallium nitride switching device Q4 through the diode D7. The other end of the resistor R31 is connected to the output terminal of the gallium nitride switching device Q4. The second driving circuit 42 comprises a resistor R39, a resistor R43, a resistor R45, and a diode D9. One end of the resistor R39 is connected to the main control module 30 and one end of the resistor R43, respectively. The other end of the resistor R39 is connected to the other end of the diode R39, one end of the resistor R45, and the control terminal of the gallium nitride switching device Q6 through the diode D9. The other end of the resistor R45 is connected to the output terminal of the gallium nitride switching device Q6.

[0042] 4) Refer to Figure 1、 Figure 7 In some embodiments, the feedback module 60 comprises a resistor R20, a resistor R21, a resistor R25, a resistor R26, a resistor R32, a voltage stabilizing tube ZD2, an optical coupler U6 and a control chip U8, one end of the resistor R21 is connected with the output end of the synchronous rectification output module 50, the other end of the resistor R21 is connected with one end of the resistor R32 and the control end of the control chip U8 through the resistor R26 respectively, the output end of the control chip U8 and the other end of the resistor R32 are grounded, the input end of the control chip U8 is connected with one end of the resistor R25 and the light emitter of the optical coupler U6 respectively, the other end of the light emitter of the optical coupler U6 is connected with the other end of the resistor R25 and the output end of the synchronous rectification output module 50 through the resistor R20 and the voltage stabilizing tube ZD2, one end of the light receiver of the optical coupler U6 is connected with the master control module, and the other end is grounded.

[0043] Specifically, the control chip U7 is a synchronous rectification control chip, used for controlling the conduction and cut-off of the MOS tube Q3 and the MOS tube Q7, after the rectified direct-current power supply is detected by voltage division through the resistor R21, the resistor R26 and the resistor R32, the conduction and cut-off of the optical coupler U6 are controlled through the control chip U8, so that the stable output direct-current voltage is supplied to the power amplifier.

[0044] 5) The external power supply signal is transmitted to the gallium nitride PFC module 20 through the input rectification filtering module 10, so as to convert the power supply signal into a high-frequency pulse signal; after voltage conversion through the LLC power conversion module 40, the voltage signal is stabilized through the synchronous rectification output module 50; the master control module 30 controls the working state of the gallium nitride PFC module 20 according to the feedback signal of the feedback module 60, so as to realize stable control on the output voltage; the advantages of the utility model lie in that the above structure makes the switching power supply have the advantages of low heat generation, high output efficiency and small size, when used in a narrow space, the heat generation is low, and the output power size is very stable, which guarantees the stability of the power amplifier power supply.

[0045] Of course, the utility model is not limited to the above-mentioned implementation manners, and those skilled in the art can also make equivalent transformations or replacements without departing from the spirit of the utility model, and these equivalent transformations and replacements are all included in the range defined by the claims of the present application.

Claims

1. A gallium nitride audio high-power switching power supply, characterized by: It includes an input rectification and filtering module (10), a gallium nitride PFC module (20), a main control module (30), an LLC power conversion module (40), a synchronous rectification output module (50), and a feedback module (60); The input end of the input rectifier filter module (10) is connected to an external power supply; The gallium nitride PFC module (20) is respectively connected to the output end of the input rectification and filtering module (10), the input end of the LLC power conversion module (40), and the main control module (30); The synchronous rectification output module (50) is connected between the output end of the LLC power conversion module (40) and the load; The feedback module (60) is connected between the output end of the synchronous rectification output module (50) and the main control module (30); The external power supply signal is transmitted to the gallium nitride PFC module (20) via the input rectifier filter module (10) to convert the power supply signal into a high-frequency pulse signal; after voltage conversion by the LLC power conversion module (40), the voltage signal is stabilized by the synchronous rectifier output module (50); and the main control module (30) controls the working state of the gallium nitride PFC module (20) according to the feedback signal of the feedback module (60) to achieve stable control of the output voltage.

2. The gallium nitride audio high-power switching power supply according to claim 1, characterized in that: The gallium nitride PFC module (20) includes a gallium nitride switch device Q5, an inductor T2, diodes D5-D6, a diode D8, a resistor RT1, a resistor R3, a resistor R12, a resistor R34, a resistor R38, resistors R41-R42, a capacitor EC5, and a capacitor EC6. One end of the inductor T2 is respectively connected to the input rectifier filter module (10) and the anode of the diode D5. The other end of the inductor T2 is respectively connected to the anode of the diode D6 and the input end of the gallium nitride switch device Q5. The cathode of the diode D5 is respectively connected to the cathode of the diode D6 and one end of the resistor RT1. The control end of the gallium nitride switch device Q5 is respectively connected to the anode of the diode D8. , one end of the resistor R3 and one end of the resistor R42, the cathode of the diode D8 is connected to the other end of the resistor R3 and is connected to the main control module (30) via the resistor R12, the output end of the gallium nitride switch device Q5 is respectively connected to the other end of the resistor R42, one end of the resistor EC5 and one end of the capacitor EC6, the other end of the capacitor EC5 is respectively connected to the other end of the capacitor EC6, the other end of the resistor RT1, one end of the capacitor C16, one end of the resistor R34 and the LLC power conversion module (40), the other end of the resistor R34 is connected to the other end of the capacitor C16 and is connected to the main control module (30) via the resistor R38 and the resistor R41.

3. The gallium nitride audio high-power switching power supply according to claim 1, characterized in that: The LLC power conversion module (40) comprises a first drive circuit (41), a second drive circuit (42), a gallium nitride switch device Q4, a gallium nitride switch device Q6, an inductor T3, a transformer T4 and a capacitor C32. The first drive circuit (41) is connected between the main control module (30) and the control end of the gallium nitride switch device Q4, the second drive circuit (42) is connected between the main control module (30) and the control end of the gallium nitride switch device Q6, the input end of the gallium nitride switch device Q4 is connected to VBUS, the output end of the gallium nitride switch device Q4 is respectively connected to the input end of the gallium nitride switch device Q6 and one end of the inductor T3, the other end of the inductor T3 is connected to one end of the primary winding of the transformer T4, the other end of the primary winding of the transformer T4 is respectively connected to the main control module (30) and one end of the capacitor C32, the other end of the capacitor C32 is grounded, and the secondary winding of the transformer T4 is connected to the synchronous rectification output module (50).

4. The gallium nitride audio high-power switching power supply according to claim 3, characterized in that: The first drive circuit (41) includes a resistor R24, a resistor R29, a resistor R31, and a diode D7. One end of the resistor R24 ​​is connected to the main control module (30) and one end of the resistor R29 respectively. The other end of the resistor R29 is connected to the other end of the diode R24, one end of the resistor R31, and the control end of the gallium nitride switch device Q4 respectively through the diode D7. The other end of the resistor R31 is connected to the output end of the gallium nitride switch device Q4.

5. The gallium nitride audio high-power switching power supply according to claim 3, characterized in that: The second drive circuit (42) includes a resistor R39, a resistor R43, a resistor R45, and a diode D9. One end of the resistor R39 is connected to the main control module (30) and one end of the resistor R43 respectively. The other end of the resistor R39 is connected to the other end of the diode R39, one end of the resistor R45, and the control end of the gallium nitride switch device Q6 respectively through the diode D9. The other end of the resistor R45 is connected to the output end of the gallium nitride switch device Q6.

6. The gallium nitride audio high-power switching power supply according to claim 1, characterized in that: The feedback module (60) includes a resistor R20, a resistor R21, a resistor R25, a resistor R26, a resistor R32, a voltage regulator ZD2, an optocoupler U6, and a control chip U8. One end of the resistor R21 is connected to the output end of the synchronous rectification output module (50), and the other end of the resistor R21 is connected to one end of the resistor R32 and the control end of the control chip U8 via the resistor R26. The output end of the control chip U8 and the other end of the resistor R32 are grounded. The input end of the control chip U8 is connected to one end of the resistor R25 and one end of the light emitter of the optocoupler U6, respectively. The other end of the light emitter of the optocoupler U6 is connected to the other end of the resistor R25 and is connected to the output end of the synchronous rectification output module (50) via the resistor R20 and the voltage regulator ZD2. One end of the light receiver of the optocoupler U6 is connected to the main control module (30), and the other end is grounded.

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