CP signal control circuit of new energy automobile

Abstract

The utility model discloses a new energy automobile CP signal control circuit comprising a main control circuit comprising a main control chip U1; the CP signal control circuit comprises a triode Q13, a CP signal is connected with one end of a resistor R76, one end of a resistor R80, one end of a diode D17 and the positive electrode of a diode D16, the negative electrode of the diode D16 is connected with one end of a resistor R69, the other end of the resistor R69 is connected with one end of a resistor R70 and one end of a resistor R68, the other end of the resistor R68 is connected with a pin 3 of the main control chip U3, and the other end of the main control chip U3 is connected with a pin 4 of the main control chip U3. The other end of the resistor R76 is connected with a base electrode of a triode Q13 and one end of a capacitor C44, an emitter electrode of the triode Q13 is connected with a 12V voltage and one end of a resistor R78, and a collector electrode of the triode Q13 is connected with the other end of the resistor R78 and one end of a resistor R79; the utility model has the advantages of faster response speed, no light attenuation problem, more stable long-term use, and increased durability of the charging pile.

Description

Technical Field

[0001] This utility model relates to the field of electric vehicle charging pile technology, and in particular to a CP signal control circuit for new energy vehicles. Background Technology

[0002] During the charging process of electric vehicles, the transmission of communication and control protocols relies on the Control Guidance Signal (CP) circuit to complete the status detection and communication between the vehicle and the charging station. According to the IEC 61851 standard, the CP signal is typically generated by the charging station as a 1kHz variable duty cycle PWM signal. Through changes in resistance, voltage, and level logic, it identifies and controls the vehicle's connection status, charging request, and grounding status. Once charging is complete, the CP signal returns to a designated state, and the charging station disconnects from the vehicle to prevent battery overcharging. In this state, only by unplugging and replugging the charging gun can the charging station return to the communication state. This effectively prevents erroneous communication between the charging station and the vehicle after the battery is fully charged, avoiding hazards such as leakage and fire.

[0003] Currently, most AC charging piles on the market use optocouplers as the isolation and transmission medium for their mainstream CP signal control circuits. Optocouplers, widely used in the electronics field, are technologically mature, easy to use, and their signal control is straightforward, allowing for easy connection to an MCU. However, due to their inherent working principle, optocouplers experience significant communication delays and are prone to distortion at the edges of PWM signals. Furthermore, optocoupler communication relies on the illumination of LEDs in the preceding circuitry; prolonged use can lead to light decay, slowing the response of subsequent circuits and affecting the long-term stability of the charging pile. Utility Model Content

[0004] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the present invention.

[0005] In view of the problems existing in the above and / or existing charging pile PWM signal adjustment, this utility model is proposed.

[0006] Therefore, the purpose of this utility model is to provide a CP signal control circuit for new energy vehicles, which has a faster response speed, no light decay problem, is more stable in long-term use, and increases the durability of charging piles.

[0007] To solve the above-mentioned technical problems, this utility model provides the following technical solution: a CP signal control circuit for new energy vehicles, comprising,

[0008] The main control circuit includes the main control chip U1;

[0009] The CP signal control circuit includes a PNP transistor Q13. The CP signal is connected to one end of resistor R76, one end of resistor R80, one end of TVS diode D17, and the anode of diode D16. The cathode of diode D16 is connected to one end of resistor R69. The other end of resistor R69 is connected to one end of resistor R70 and one end of resistor R68. The other end of resistor R68 is connected to pin 3 of the main control chip U3. The other end of resistor R76 is connected to the base of transistor Q13 and one end of capacitor C44. The emitter of transistor Q13 is connected to a 12V voltage and one end of resistor R78. The collector of transistor Q13 is connected to the other end of resistor R78 and one end of resistor R79. The other end of resistor R79 is connected to an NPN transistor Q13. The collector of transistor Q12 is connected to one end of capacitor C40 and one end of resistor R71. The other end of resistor R80 and the other end of capacitor C44 are both connected to the collector of NPN transistor Q14. The base of transistor Q14 is connected to one end of resistor R81, one end of capacitor C45 and one end of resistor R82. The other end of capacitor C45 is connected to the collector of PNP transistor Q15. The base of transistor Q15 is connected to one end of resistor R84 and one end of resistor R85. The other ends of resistor R84, resistor R85, the emitter of transistor Q14 and the other end of resistor R82 are connected to a negative 12V voltage. The other end of TVS diode D17 and the emitter of transistor Q15 are both grounded.

[0010] As a preferred embodiment of the CP signal control circuit for new energy vehicles in this utility model, it further includes an abnormal monitoring circuit. The abnormal monitoring circuit includes a relay J1. Pin 2 of the relay J1 is connected to pin 45 of the main control chip U1. Pin 1 of the relay J1 is connected to the positive terminal of diode D21 and the drain of enhancement-mode field-effect transistor Q16. The gate of the field-effect transistor Q16 is connected to one end of resistor R94 and one end of R93. The other end of resistor R93 is connected to pin 20 of the main control chip U1. The other ends of resistor R81, resistor R71, and capacitor C40 are all connected to pin 3 of the relay J1. The negative terminal of diode D21 and pin 4 of the relay J1 are connected to a 12V voltage. The source of the field-effect transistor Q16 and the other end of resistor R94 are both grounded.

[0011] As a preferred embodiment of the CP signal control circuit for new energy vehicles in this utility model, it further includes a first power conversion circuit, which converts the externally input 220V voltage into the 12V voltage required by the CP signal control circuit.

[0012] As a preferred embodiment of the CP signal control circuit for new energy vehicles in this utility model, it further includes a second power conversion circuit, which converts the 12V voltage into the negative 12V voltage required by the CP signal control circuit.

[0013] As a preferred embodiment of the CP signal control circuit for new energy vehicles in this utility model, the first power conversion circuit includes a voltage conversion chip U19. The live wire of the mains power is connected to one end of capacitor C42, one end of resistor R75, and pin 2 of voltage conversion chip U19. The other end of capacitor C42 is connected to the ground wire of the mains power and one end of capacitor C43. The other end of capacitor C43, the other end of resistor R75, and pin 1 of voltage conversion chip U19 are connected to the neutral wire of the mains power. Pin 4 of voltage conversion chip U19 outputs 12V voltage and is connected to the positive terminal of LED6. The negative terminal of LED6 is connected to one end of resistor R77. The pin of voltage conversion chip U19 and the other end of resistor R77 are both grounded.

[0014] In a preferred embodiment of the CP signal control circuit for new energy vehicles in this utility model, the second power conversion circuit includes a voltage conversion chip U22. Pins 7, 8, and 1 of the voltage conversion chip U22 are respectively connected to one end of resistor R83. The 12V voltage is connected to the other end of resistor R83, pin 6 of the voltage conversion chip U22, and the positive terminal of the polarized capacitor C46. Pin 5 of the voltage conversion chip U22 is connected to one end of resistor R86, one end of resistor R87, and one end of capacitor C48. The other end of capacitor C48, the other end of resistor R87, one end of capacitor C47, pin 4 of voltage conversion chip U22, pin 3 of voltage conversion chip U22, the positive terminal of Schottky diode D18, and the negative terminal of polarized capacitor C49 are all connected to a negative 12V voltage. Pin 2 of voltage conversion chip U22 is connected to one end of inductor U21 and the negative terminal of Schottky diode D18. The positive terminal of polarized capacitor C49, the other end of inductor U21, the negative terminal of polarized capacitor C46, ​​and the other end of resistor R86 are all grounded.

[0015] Compared with the prior art, this utility model has the following technical effects: through the structural design of the CP signal control circuit, it has a faster response speed, no light decay problem, more stable long-term use, and increased durability of the charging pile; an abnormality monitoring circuit is set up to effectively deal with sudden situations caused by abnormal CP signals. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Among them:

[0017] Figure 1 This is the main control circuit diagram of this utility model.

[0018] Figure 2 This is a circuit diagram of the CP signal control of this utility model.

[0019] Figure 3 This is the circuit diagram for the anomaly monitoring of this utility model.

[0020] Figure 4 This is the first power conversion circuit diagram of this utility model.

[0021] Figure 5 This is the circuit diagram of the second power conversion circuit of this utility model.

[0022] Figure 6 This is a circuit diagram of the signal amplification circuit of this utility model.

[0023] Figure 7 Circuit diagram for CP signal and terminal connections.

[0024] Figure 8 This is a PWM waveform diagram acquired by the CP signal control circuit in this utility model.

[0025] Figure 9 This is a diagram of the rising edges of the PWM signal acquired by the CP signal control circuit in this utility model.

[0026] Figure 10 This is a diagram of the falling edge of the PWM signal acquired by the CP signal control circuit in this utility model. Detailed Implementation

[0027] To make the above-mentioned objectives, features and advantages of this utility model more apparent and understandable, the specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings.

[0028] Many specific details are set forth in the following description in order to provide a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0029] Secondly, the term "an embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that excludes other embodiments.

[0030] Example 1: Refer to Figures 1-5 This is the first embodiment of the present application. This embodiment discloses a CP signal control circuit for new energy vehicles, which has a faster response speed and improves the durability of charging piles.

[0031] A CP signal control circuit for a new energy vehicle includes a main control circuit and a CP signal control circuit. The main control circuit includes a main control chip U1. The peripheral circuit of the main control chip U1 is prior art and will not be described in detail in this application. (See reference...) Figure 1 The main control circuit includes the main control chip U1; the CP signal control circuit includes a PNP transistor Q13. The CP signal is connected to one end of resistor R76, one end of resistor R80, one end of TVS diode D17, and the anode of diode D16. The cathode of diode D16 is connected to one end of resistor R69. The other end of resistor R69 is connected to one end of resistor R70 and one end of resistor R68. The other end of resistor R68 is connected to pin 3 of the main control chip U3. The other end of resistor R76 is connected to the base of transistor Q13 and one end of capacitor C44. The emitter of transistor Q13 is connected to a 12V voltage and one end of resistor R78. The collector of transistor Q13 is connected to the other end of resistor R78 and one end of resistor R79. The other end of resistor R79 is connected to N... The collector of PN transistor Q12 and the base of transistor Q12 are connected to one end of capacitor C40 and one end of resistor R71. The other end of resistor R80 and the other end of capacitor C44 are both connected to the collector of NPN transistor Q14. The base of transistor Q14 is connected to one end of resistor R81, one end of capacitor C45 and one end of resistor R82. The other end of capacitor C45 is connected to the collector of PNP transistor Q15. The base of transistor Q15 is connected to one end of resistor R84 and one end of resistor R85. The other ends of resistor R84, resistor R85, the emitter of transistor Q14 and the other end of resistor R82 are connected to a negative 12V voltage. The other end of TVS diode D17 and the emitter of transistor Q15 are both grounded.

[0032] In the CP control circuit, CP_PWM_1 controls the on / off state of four transistors, determining whether the CP output is +12V or -12V. The microcontroller outputs a PWM wave with a specified duty cycle (compliant with national standards) to the transistors via CP_PWM_1. When the PWM wave is high, Q12 and Q14 are turned on, and Q13 and Q15 are turned off, at which point CP is -12V. When the PWM wave is low, Q12 and Q14 are turned off, and Q13 and Q15 are turned on, at which point CP is +12V.

[0033] The CP (Converter) is connected to the CP line of the charging gun via terminal CN2 to communicate with the vehicle. The vehicle will change the voltage divider resistor at the appropriate stage to convert the CP voltage to 9V and 6V. The CP_ADC will return the acquired CP voltage (the CP signal is first scaled by an operational amplifier to a voltage that will not damage the microcontroller; see below for a detailed explanation of the operational amplifier's working principle) to the microcontroller, which will then output a specified duty cycle based on the CP voltage value.

[0034] Specifically, it also includes a first power conversion circuit, which converts the externally input 220V voltage into the 12V voltage required by the CP signal control circuit. The specific structure of the first power conversion circuit is as follows: the first power conversion circuit includes a voltage conversion chip U19. The live wire of the mains power is connected to one end of capacitor C42, one end of resistor R75, and pin 2 of voltage conversion chip U19. The other end of capacitor C42 is connected to the ground wire of the mains power and one end of capacitor C43. The other end of capacitor C43, the other end of resistor R75, and pin 1 of voltage conversion chip U19 are connected to the neutral wire of the mains power. Pin 4 of voltage conversion chip U19 outputs 12V voltage and is connected to the positive terminal of LED6. The negative terminal of LED6 is connected to one end of resistor R77. The pin of voltage conversion chip U19 and the other end of resistor R77 are both grounded.

[0035] Specifically, it also includes a second power conversion circuit, which converts the 12V voltage into the negative 12V voltage required by the CP signal control circuit. The specific structure of the second power conversion circuit is as follows: the second power conversion circuit includes a voltage conversion chip U22. Pins 7, 8, and 1 of the voltage conversion chip U22 are respectively connected to one end of resistor R83. The 12V voltage is connected to the other end of resistor R83, pin 6 of the voltage conversion chip U22, and the positive terminal of the polarized capacitor C46. Pin 5 of the voltage conversion chip U22 is connected to one end of resistor R86, and the resistor... One end of R87 and one end of capacitor C48, the other end of capacitor C48, the other end of resistor R87, one end of capacitor C47, pin 4 of voltage conversion chip U22, pin 3 of voltage conversion chip U22, the positive terminal of Schottky diode D18 and the negative terminal of polarized capacitor C49 are respectively connected to a negative 12V voltage, pin 2 of voltage conversion chip U22 is connected to one end of inductor U21 and the negative terminal of Schottky diode D18, the positive terminal of polarized capacitor C49, the other end of inductor U21, the negative terminal of polarized capacitor C46 and the other end of resistor R86 are all grounded.

[0036] The main control circuit is used in conjunction with the CP control circuit to adjust the corresponding PWM output form based on the signals acquired by the microcontroller from the new energy vehicle. This application uses a CP circuit composed of several transistors. Through the operating characteristics of NPN and PNP transistors, a CP signal with a specified duty cycle is output according to the high and low levels given by the microcontroller. The transistors directly drive the CP signal, increasing the PWM rise time and fall time of the CP signal to approximately 1µs. Experiments demonstrate these effects. The black clip of channel one of the oscilloscope is grounded, and the probe is connected to pin 1 of terminal CN2 (CP is output on this pin). Following the communication method with the new energy vehicle, a tester is used to simulate the vehicle's operation. By dividing the 12V voltage to 6V to simulate the charging state of the new energy vehicle, the microcontroller outputs the specified duty cycle. The CP waveform acquired by channel one is observed, and the oscilloscope is paused to read the rise and fall times. Figures 8-10 The waveforms were acquired using an oscilloscope, with time on the horizontal axis and voltage on the vertical axis. Figure 8 This is the overall CP signal PWM waveform diagram. (From...) Figure 9 It can be seen that the rising edge response time of the PWM wave of the CP signal is about 1µs. Figure 10 It can be seen that the response time of the falling edge of the PWM wave of the CP signal is about 1µs, close to the nanosecond level. The above experiments show that using the CP circuit built with transistors in this invention can improve the response time of the rising and falling edges of the PWM waveform of the CP signal, improve the stability during charging, and avoid potential safety hazards.

[0037] In this application, the main control chip U1 is preferably a microcontroller, model STC8H3K64S2-45I-LQFP48, the voltage conversion chip U19 is model HLK-10M12, and the voltage conversion chip U22 is model MC34063; the mains power is converted into the voltage required by the CP signal control circuit through the first power conversion circuit and the second power conversion circuit.

[0038] Specifically, it also includes a signal amplification circuit, comprising operational amplifier U23 and Schottky diode D20. The CP signal is input to the positive terminal of Schottky diode D20. The negative terminal of Schottky diode D20 is connected to one end of resistor R91. The other end of resistor R91 is connected to pin 5 of operational amplifier U23 and one end of resistor R92. Pin 4 of operational amplifier U23 is connected to one end of resistor R90. The other end of resistor R90 is connected to the negative terminal of Schottky diode D19, one end of resistor R89, and capacitor C51. One end of the capacitor C52 and one end of the resistor R88 are connected to pin 7 of the operational amplifier U23, which is connected to the positive terminal of the Schottky diode D19. The 12V voltage is connected to pin 8 of the operational amplifier U23 and one end of the capacitor C50. The other end of the capacitor C50, pin 4 of the operational amplifier U23, and the other end of the resistor R89 ​​are connected to one end of the capacitor C53. The other ends of the capacitors C53, C51, C52, R88, and R92 are all grounded.

[0039] Signal amplifier circuit diagram as follows Figure 6 Operational amplifier U23 (preferred model: LM2904) is located between the CP signal output from the CP control circuit and the CP_ADC. Since the CP_ADC is directly input to the microcontroller, and the STM32 microcontroller operates at 3.3V, the operational amplifier acts as a scaler for a ±12V signal, protecting the MCU from burnout. Furthermore, it works in conjunction with capacitors in the external circuitry to filter and eliminate high-frequency interference. Pin 8 of operational amplifier U23 receives a +12V input, ensuring sufficient power and preventing saturation or distortion. Pin 5 of operational amplifier U23 receives the CP signal after voltage division (the CP signal may be 12V, 9V, or 6V depending on the state). After scaling and filtering, the signal is output from pin 7 to the CP_ADC pin of the main control chip U1 (see attached diagram). Figure 1 Pin 3 in the circuit is used to acquire the CP signal.

[0040] Example 2: Refer to Figure 6 This is the second embodiment of the present application. The difference between this embodiment and embodiment 1 is that this embodiment discloses a CP signal control circuit for new energy vehicles, which can realize emergency braking under abnormal conditions.

[0041] Specifically, it also includes an anomaly monitoring circuit, which includes a relay J1. Pin 2 of relay J1 is connected to pin 45 of the main control chip U1. Pin 1 of relay J1 is connected to the positive terminal of diode D21 and the drain of enhancement-mode field-effect transistor Q16. The gate of field-effect transistor Q16 is connected to one end of resistor R94 and one end of R93. The other end of resistor R93 is connected to pin 20 of the main control chip U1. The other ends of resistor R81, resistor R71, and capacitor C40 are all connected to pin 3 of relay J1. The negative terminal of diode D21 and pin 4 of relay J1 are connected to a 12V voltage. The source of field-effect transistor Q16 and the other end of resistor R94 are both grounded.

[0042] When the charging gun is connected to the vehicle's infotainment system, the voltage divider circuit on the vehicle's side causes the CP voltage to change accordingly. The main control chip U1 outputs a specified duty cycle based on the voltage collected by its pin 3. Pin 45 of the main control chip is connected to pin 2 of relay J1. When the collected CP signal value is the normal operating voltage, pin 20 (MAINRELAY port) of the main control chip U1 sends a closing command to relay J1, connecting pin 45 of the main control chip U1 to CP_PWM_1 in the CP control circuit (i.e., pins 2 and 3 of relay J1 are connected), enabling communication between the charging pile and the vehicle's infotainment system, allowing the charging pile to charge the vehicle's infotainment system. When the CP signal value collected by pin 3 of the main control chip U1 is abnormal, the main control chip U1 controls relay J1 through pin 20 to issue a command to disconnect and send a PWM signal, causing the charging pile to stop charging the vehicle's infotainment system.

[0043] The above circuitry enables abnormal monitoring of the CP signal. When the CP signal is abnormal, the CP communication between the vehicle and the charging station is disconnected to avoid potential safety hazards.

[0044] It should be noted that the above embodiments are only used to illustrate the technical solution of this utility model and are not intended to limit it. Although this utility model has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solution of this utility model without departing from the spirit and scope of the technical solution of this utility model, and all such modifications or substitutions should be covered within the scope of the claims of this utility model.

Claims

1. A CP signal control circuit for new energy vehicles, characterized in that: It includes, The main control circuit includes the main control chip U1; The CP signal control circuit includes a PNP transistor Q13. The CP signal is connected to one end of resistor R76, one end of resistor R80, one end of TVS diode D17, and the anode of diode D16. The cathode of diode D16 is connected to one end of resistor R69. The other end of resistor R69 is connected to one end of resistor R70 and one end of resistor R68. The other end of resistor R68 is connected to pin 3 of the main control chip U3. The other end of resistor R76 is connected to the base of transistor Q13 and one end of capacitor C44. The emitter of transistor Q13 is connected to a 12V voltage and one end of resistor R78. The collector of transistor Q13 is connected to the other end of resistor R78 and one end of resistor R79. The other end of resistor R79 is connected to an NPN transistor Q13. The collector of transistor Q12 is connected to one end of capacitor C40 and one end of resistor R71. The other end of resistor R80 and the other end of capacitor C44 are both connected to the collector of NPN transistor Q14. The base of transistor Q14 is connected to one end of resistor R81, one end of capacitor C45 and one end of resistor R82. The other end of capacitor C45 is connected to the collector of PNP transistor Q15. The base of transistor Q15 is connected to one end of resistor R84 and one end of resistor R85. The other ends of resistor R84, resistor R85, the emitter of transistor Q14 and the other end of resistor R82 are connected to a negative 12V voltage. The other end of TVS diode D17 and the emitter of transistor Q15 are both grounded.

2. The new energy vehicle CP signal control circuit as described in claim 1, characterized in that: It also includes an anomaly monitoring circuit, which includes a relay J1. Pin 2 of relay J1 is connected to pin 45 of the main control chip U1. Pin 1 of relay J1 is connected to the positive terminal of diode D21 and the drain of enhancement-mode field-effect transistor Q16. The gate of field-effect transistor Q16 is connected to one end of resistor R94 and one end of R93. The other end of resistor R93 is connected to pin 20 of the main control chip U1. The other ends of resistor R81, resistor R71, and capacitor C40 are all connected to pin 3 of relay J1. The negative terminal of diode D21 and pin 4 of relay J1 are connected to a 12V voltage. The source of field-effect transistor Q16 and the other end of resistor R94 are both grounded.

3. The new energy vehicle CP signal control circuit as described in claim 1 or 2, characterized in that: It also includes a first power conversion circuit, which converts the externally supplied 220V voltage into the 12V voltage required by the CP signal control circuit.

4. The new energy vehicle CP signal control circuit as described in claim 3, characterized in that: It also includes a second power conversion circuit, which converts the 12V voltage into the negative 12V voltage required in the CP signal control circuit.

5. The new energy vehicle CP signal control circuit as described in claim 4, characterized in that: The first power conversion circuit includes a voltage conversion chip U19. The live wire of the mains power is connected to one end of capacitor C42, one end of resistor R75, and pin 2 of voltage conversion chip U19. The other end of capacitor C42 is connected to the ground wire of the mains power and one end of capacitor C43. The other end of capacitor C43, the other end of resistor R75, and pin 1 of voltage conversion chip U19 are connected to the neutral wire of the mains power. Pin 4 of voltage conversion chip U19 outputs 12V voltage and is connected to the positive terminal of LED6. The negative terminal of LED6 is connected to one end of resistor R77. Pins of voltage conversion chip U19 and the other end of resistor R77 are both grounded.

6. The new energy vehicle CP signal control circuit as described in claim 5, characterized in that: The second power conversion circuit includes a voltage conversion chip U22. Pins 7, 8, and 1 of the voltage conversion chip U22 are connected to one end of resistor R83, respectively. A 12V voltage is connected to the other end of resistor R83, pin 6 of the voltage conversion chip U22, and the positive terminal of the polarized capacitor C46. Pin 5 of the voltage conversion chip U22 is connected to one end of resistor R86, one end of resistor R87, and one end of capacitor C48. The other end of capacitor C48, the other end of resistor R87, one end of capacitor C47, pins 4 and 3 of the voltage conversion chip U22, the positive terminal of Schottky diode D18, and the negative terminal of polarized capacitor C49 are connected to a negative 12V voltage. Pin 2 of the voltage conversion chip U22 is connected to one end of inductor U21 and the negative terminal of Schottky diode D18. The positive terminal of polarized capacitor C49, the other end of inductor U21, the negative terminal of polarized capacitor C46, ​​and the other end of resistor R86 are all grounded.

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