PWM (Pulse Width Modulation) output circuit for automobile alternating current charging pile

Abstract

A PWM output circuit used for an automobile AC charging pile comprises a power supply conversion module, a PWM output detection module and a microprocessor. The PWM output detection module comprises a CP signal output circuit and a voltage detection circuit; the CP signal output circuit comprises an optical coupling isolation device, the input end of the optical coupling isolation device is connected with the microprocessor, and the output end of the optical coupling isolation device outputs CP signals through a first resistor and a fuse; the voltage detection circuit comprises a diode, the anode of the diode is connected between the first resistor and the fuse, and the cathode of the diode is connected with the sampling end of the microprocessor after being subjected to voltage division through a divider resistor. According to the utility model, additional high-cost chips and more components are not needed, the structure is simple, the cost is low, and a PWM circuit with + / -12V and frequency of 1KHz can be generated through the 3.3 V MCU, so that PWM voltage signals can be directly measured.

Description

Technical Field

[0001] The utility model relates to the technical field of AC charging piles, in particular to a PWM output circuit for an automobile AC charging pile. Background Art

[0002] With the rapid development of new energy vehicles, car charging piles have also ushered in development opportunities. Before using the charging pile for charging, existing new energy vehicles need to first confirm and detect whether the charging interface is reliably connected, otherwise it is easy to cause electric shock to people; when charging, the charging gun is inserted into the car charging interface, and the charging current is achieved by adjusting the PWM duty cycle. Therefore, when the charging pile is in the idle state, the gun is plugged in, and the charging state, the charging pile needs to generate a CP signal to realize the handshake communication of charging.

[0003] The existing AC charging pile PWM (CP) output circuit usually has more chips, such as optocoupler isolators, multiple transistors, operational amplifiers, etc., and the large number of components leads to complex circuit structure and high cost. Utility Model Content

[0004] The purpose of the utility model is to overcome the above-mentioned deficiencies of the prior art and to provide a PWM output circuit for an automobile AC charging pile with a simple structure, low cost and high reliability.

[0005] The technical solution of the utility model is: a PWM output circuit for an automobile AC charging pile, comprising a power conversion module, a PWM output detection module and a microprocessor; the PWM output detection module comprises a CP signal output circuit and a voltage detection circuit; the CP signal output circuit comprises an optocoupler isolation device, the input end of the optocoupler isolation device is connected to the microprocessor, and the output end of the optocoupler isolation device outputs the CP signal via a first resistor and a fuse; the voltage detection circuit comprises a diode, the anode of the diode is connected between the first resistor and the fuse, and the cathode is connected to the sampling end of the microprocessor after voltage division by a voltage divider resistor.

[0006] Furthermore, the power conversion module includes a power chip for converting DC12V into -12V to power the PWM output detection module.

[0007] Furthermore, one path of the power supply end of the optical coupling isolation device is connected to DC12V, and the other path is connected to DC-12V via the first protection switch, and the DC-12V is provided by the power conversion module.

[0008] Furthermore, the anode of the diode of the voltage detection circuit is connected between the resistor and the fuse, the cathode is divided by two voltage-dividing resistors and connected to the sampling end of the microprocessor through a second resistor, and a second protection switch is provided between the second resistor and the sampling end of the microprocessor.

[0009] Furthermore, a bidirectional TVS tube is connected between the first resistor and the fuse.

[0010] Furthermore, the first protection switch is a switching diode, one end of the switching diode is connected to DC12V, the other end is connected to DC-12V, and the middle end is connected between the first resistor and the fuse.

[0011] Furthermore, the output end of the optical coupling isolation device is connected to the connection socket via a first resistor and a fuse, and is connected to the automobile controller via the connection socket.

[0012] Furthermore, the output end of the power chip outputs DC-12V, and the output end is also grounded after passing through a parallel circuit of a capacitor and a bidirectional TVS tube.

[0013] Furthermore, the second protection switch is a switching diode, one end of the switching diode is grounded, the other end is connected to DC3.3V, and the middle end is connected to the second resistor and the sampling end of the microprocessor.

[0014] Furthermore, the CP signal output circuit is composed of an optocoupler isolation device, a first resistor and a fuse, and the rest are protection devices; the voltage detection circuit is composed of a diode, two voltage-dividing resistors and a second resistor, and the rest are protection devices.

[0015] The beneficial effects of the utility model are as follows: on the one hand, the PWM output detection module can form a CP signal output circuit only through the optocoupler isolation chip U14, resistor R30, resistor R26 and fuse F11, without the need for additional high-cost chips and more components. By connecting the optocoupler isolation chip to the MCU, a ±12V, 1KHz frequency PWM circuit can be generated through the 3.3V MCU, and the PWM voltage signal can be directly measured, which has a simple structure and low cost; on the other hand, the voltage detection circuit of the PWM output detection module can be realized by only a few voltage-dividing resistors and diodes, without the need to set up additional chips and more components, which greatly simplifies the circuit structure and reduces costs. In addition, the reliability of the circuit can be greatly improved through some protection devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of the circuit principle of the PWM output detection module of the embodiment of the utility model;

[0017] Figure 2 It is a schematic diagram of the circuit principle of the power conversion module of the embodiment of the utility model. DETAILED DESCRIPTION

[0018] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0019] A PWM output circuit for an automobile AC charging pile comprises a power conversion module, a PWM output detection module and an MCU (microprocessor); the power conversion module is used to supply power to the PWM output detection module.

[0020] Specifically, Figure 1 As shown: the PWM output detection module includes a CP signal output circuit and a voltage detection circuit. Among them, the CP signal output circuit includes an optocoupler isolation chip U14, a resistor R30, a resistor R26 and a fuse F11, and a protection device, namely a bidirectional TVS tube D2 and a switching diode D9, is also provided. The voltage detection circuit includes a diode D1, resistors R75, R76 and R77, and a protection device D6 (switching diode) is also provided. Specifically, the model of the optocoupler isolation chip U14 is TLP2745, and its pin 1 is connected to a 3.3V power supply via a resistor R30; pin 3 is connected to the output end of the MCU for generating a CP signal; pin 6 is connected to a +12V DC power supply, and VCC12V is also connected to a -12V DC power supply via a switching diode D9, that is, connected to the output end of the power conversion module. It can be understood that the +12V DC power supply of the PWM output detection module and the power conversion module can be obtained by converting the AC220V AC input into DC12V through other isolated power supply modules. The output end (pin 5) of U14 is connected to the connector CN8 through the resistor R26 and the fuse F11, and connected to the car controller through the connector CN8; one end of the bidirectional TVS tube D2 is connected between the resistor R26 and the fuse F11, and the other end is grounded. The anode of the diode D1 is connected between the resistor R26 and the fuse F11, and the cathode is divided into two branches after passing through the resistor R75. One branch is grounded after passing through the parallel circuit of the resistor R76 and the capacitor C49, and the other branch is connected to the sampling end of the MCU through the resistor R77; one end of the switch diode D6 is grounded, and the other end is connected to the 3.3V power supply, and the middle end is connected between the resistor R77 and the sampling end of the MCU.

[0021] like Figure 2 As shown: the power conversion module includes a power chip U21, for example, the power chip model of this embodiment is preferably MD7660. The BOOST pin of the power chip U21 is connected to a +12V DC power supply via a resistor R197, and the VDD terminal is also connected to a +12V DC power supply; external capacitors C61 and C62 are connected between the pins CAP+ and CAP-; the output terminal VOUT outputs a -12V DC power supply, and the output terminal VOUT is also grounded after passing through a parallel circuit of capacitors C21, C29 and a bidirectional TVS tube D7. Through the power chip U21, the +12V DC power supply can be converted into a -12V DC power supply to power the PWM output detection module.

[0022] The working principle of this embodiment is:

[0023] The CP signal of the AC charging pile realizes the handshake communication of charging through the PWM signal duty cycle and the PWM level. The PWM waveform is a 1KHz rectangular wave according to the national standard, and the charging current is realized by adjusting the PWM duty cycle. When the charging pile is in an idle state, the MCU generates a signal (CP_PWM_MCU) with a high level and transmits it to pin 3 of the optocoupler isolation chip U14. At this time, the optocoupler outputs +12V, and outputs a +12V high-level signal to the outside through R26 and F11. When the charging gun is connected to the car, the MCU detects the gun insertion signal (9V), and the MCU generates a 1KHzPWM, outputs a ±12V high-level signal through the optocoupler isolation chip U14, and generates a ±9V PWM (CP) signal at the connector CN8 through resistor R26 and fuse F11. The car controller of the charging car determines the charging current that the charging pile can provide through the PWM duty cycle. In the charging state, as with the principle of adding the charging gun mentioned above, a ±6V PWM (CP) signal is generated at the connector CN8.

[0024] In addition, the PWM (CP) signal is input to the MCU sampling end through the fuse F11, diode D1, resistors R75, R76 voltage divider and resistor R77 to form a PWM (CP) voltage detection circuit. D1 is a fast recovery diode, which is used to filter out the negative voltage in PWM. After the resistors R75 and R76 divider, the PWM (±12V) voltage is converted into a voltage range (0-3.3V) that can be collected by the MCU.

[0025] The PWM (CP) signal generated in this embodiment meets the national standard requirements for 7KW AC charging piles.

[0026] In summary, in the utility model, on one hand, the PWM output detection module can form a CP signal output circuit only through the optocoupler isolation chip U14, resistor R30, resistor R26 and fuse F11, without the need for additional high-cost chips and more components. By connecting the optocoupler isolation chip to the MCU, a ±12V, 1KHz frequency PWM circuit can be generated through the 3.3V MCU, and the PWM voltage signal can be directly measured, which has a simple structure and low cost; on the other hand, the voltage detection circuit of the PWM output detection module can be realized by only a few voltage-dividing resistors and diodes, without the need to set up additional chips and more components, which greatly simplifies the circuit structure and reduces costs. In addition, the reliability of the circuit can be greatly improved through some protection devices.

Claims

1. A PWM output circuit for an automobile AC charging pile, comprising a power conversion module, a PWM output detection module and a microprocessor; the PWM output detection module comprises a CP signal output circuit and a voltage detection circuit; characterized in that, The CP signal output circuit includes an optocoupler isolation device, the input end of the optocoupler isolation device is connected to the microprocessor, and the output end of the optocoupler isolation device outputs the CP signal through a first resistor and a fuse; the voltage detection circuit includes a diode, the anode of the diode is connected between the first resistor and the fuse, and the cathode is connected to the sampling end of the microprocessor after voltage division by a voltage divider resistor.

2. The PWM output circuit for an automobile AC charging pile according to claim 1, characterized in that: The power conversion module includes a power chip, which is used to convert DC12V into -12V to power the PWM output detection module.

3. The PWM output circuit for an automobile AC charging pile according to claim 1, characterized in that: One path of the power supply end of the optical coupling isolation device is connected to DC12V, and the other path is connected to DC-12V via the first protection switch, and the DC-12V is provided by the power conversion module.

4. The PWM output circuit for an automobile AC charging pile according to claim 1, characterized in that: The anode of the diode of the voltage detection circuit is connected between the resistor and the fuse, the cathode is divided by two voltage-dividing resistors and connected to the sampling end of the microprocessor through a second resistor, and a second protection switch is provided between the second resistor and the sampling end of the microprocessor.

5. The PWM output circuit for an automobile AC charging pile according to claim 1, characterized in that: A bidirectional TVS tube is also connected between the first resistor and the fuse.

6. The PWM output circuit for an automobile AC charging pile according to claim 3, characterized in that: The first protection switch is a switching diode, one end of the switching diode is connected to DC12V, the other end is connected to DC-12V, and the middle end is connected between the first resistor and the fuse.

7. The PWM output circuit for an automobile AC charging pile according to claim 1, characterized in that: The output end of the optical coupling isolation device is connected to the connection base via the first resistor and the fuse, and is connected to the automobile controller via the connection base.

8. The PWM output circuit for an automobile AC charging pile according to claim 2, characterized in that: The output end of the power chip outputs DC-12V, and the output end is also grounded after passing through a parallel circuit of a capacitor and a bidirectional TVS tube.

9. The PWM output circuit for an automobile AC charging pile according to claim 4, characterized in that: The second protection switch is a switching diode, one end of which is grounded, the other end is connected to DC3.3V, and the middle end is connected to the second resistor and the sampling end of the microprocessor.

10. The PWM output circuit for an automobile AC charging pile according to claim 1, characterized in that: The CP signal output circuit is composed of an optocoupler isolation device, a first resistor and a fuse, and the rest are protection devices; the voltage detection circuit is composed of a diode, two voltage-dividing resistors and a second resistor, and the rest are protection devices.

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