Bidirectional electric vehicle charging device

Abstract

The utility model provides a bidirectional electric automobile charging device, which comprises a charging main circuit and a charging control circuit, and is characterized in that the charging main circuit comprises a PFC converter and a CLLC resonant converter which are of a cascade structure; the front end of the PFC converter is connected with an alternating current charging interface, the rear end of the PFC converter is connected with the primary side of the CLLC resonant converter, and the secondary side of the CLLC resonant converter is connected with an automobile battery; the charging control circuit comprises three single-chip microcomputers, and the three single-chip microcomputers correspondingly control the PFC converter, the primary side of the CLLC resonant converter and the secondary side of the CLLC resonant converter respectively. The forward and reverse working states of the charging device are controlled by the two single-chip microcomputers respectively, the two single-chip microcomputers are in isolated communication, transmit key signals such as the charging state and the discharging state and communicate with the upper computer at the same time, and the upper computer can obtain key signals such as circuit output voltage, charging current and discharging current. Therefore, the circuit is monitored in real time.

Description

Technical Field

[0001] The utility model relates to a bidirectional electric vehicle charging device. Background Art

[0002] Conventional charging devices are generally composed of a cascade of a "PFC converter + full-bridge converter". The first-stage PFC converter completes the function of power factor correction; the second-stage full-bridge converter converts the DC high-voltage bus voltage into a wide-range battery voltage of 200 - 450 VDC to realize charging and discharging of the vehicle battery. In this structure, soft switching of the switching tubes is achieved during forward charging, but when discharging in the reverse direction, it works in a traditional full-bridge converter, and the circuit operating efficiency is low.

[0003] Since the bidirectional CLLC resonant converter can achieve soft-switching control both in the forward and reverse operations, it can overcome the defect of low operating efficiency of the full-bridge converter. However, the forward and reverse operating characteristics of the CLLC resonant converter are not the same, so it is still necessary to solve the problem of coordinating the consistency of bidirectional operation. Summary of the Utility Model

[0004] The utility model provides a bidirectional electric vehicle charging device, which adopts a cascade structure of a PFC converter and a CLLC resonant converter to meet the requirements of soft-switching control for both the forward and reverse directions of the bidirectional charging circuit, and is specifically realized by the following technical means:

[0005] A bidirectional electric vehicle charging device includes a charging main circuit and a charging control circuit. The charging main circuit includes a PFC converter and a CLLC resonant converter in a cascade structure;

[0006] The front end of the PFC converter is connected to an AC charging interface, and the rear end is connected to the primary side of the CLLC resonant converter. The secondary side of the CLLC resonant converter is connected to the vehicle battery;

[0007] The charging control circuit includes three single-chip microcomputers, which respectively control the PFC converter, the primary side of the CLLC resonant converter, and the secondary side of the CLLC resonant converter.

[0008] In one or more embodiments of the utility model, the CLLC resonant converter includes a first H-bridge provided on its primary side and a second H-bridge provided on its secondary side;

[0009] The first bridge arm of the first H-bridge includes a first MOS tube and a third MOS tube connected in series, and its second bridge arm includes a second MOS tube and a fourth MOS tube connected in series. A resonant inductor and a first resonant capacitor are provided between the output end of the first bridge arm of the first H-bridge and one end of the primary coil. The other end of the primary coil is connected to the output end of the second bridge arm of the first H-bridge, and an exciting inductor is also connected in parallel across both ends of the primary coil;

[0010] The first arm of the second H-bridge includes a fifth MOS transistor and a seventh MOS transistor connected in series, and its second arm includes a sixth MOS transistor and an eighth MOS transistor connected in series. The output terminals of the first arm and the second arm of the second H-bridge are respectively connected to both ends of the secondary coil; a second resonant capacitor is provided between one end of the secondary coil and the output terminal of the second arm of the second H-bridge;

[0011] The PFC converter includes a third H-bridge. The first arm of the third H-bridge includes a ninth MOS transistor and an eleventh MOS transistor connected in series, and its second arm includes a tenth MOS transistor and a twelfth MOS transistor connected in series;

[0012] The single-chip microcomputer includes a first single-chip microcomputer for controlling the operation of the first H-bridge, a second single-chip microcomputer for controlling the operation of the second H-bridge, and a third single-chip microcomputer for controlling the operation of the third H-bridge. The first single-chip microcomputer communicates with the second single-chip microcomputer.

[0013] In one or more embodiments of the present invention, the charging control circuit further includes a current sensor CT1 provided on the primary side of the CLLC resonant converter to obtain the primary side resonant current, a current sensor CT2 provided on the secondary side of the CLLC resonant converter to obtain the secondary side resonant current, a current sensor CT3 provided at the connection end between the CLLC resonant converter and the vehicle battery to obtain the charging current, and a current sensor CT4 provided at the connection end between the PFC converter and the CLLC resonant converter to obtain the discharge current;

[0014] The output terminals of the current sensor CT1 and the current sensor CT3 are respectively connected to the first single-chip microcomputer, and the output terminals of the current sensor CT2 and the current sensor CT4 are respectively connected to the second single-chip microcomputer; the output terminal of the current sensor CT4 is also connected to the third single-chip microcomputer.

[0015] In one or more embodiments of the present invention, a current sampling circuit is respectively provided between each current sensor and the single-chip microcomputer. The current sampling circuit includes a first operational amplifier. A negative feedback connection is provided between the negative phase terminal and the output terminal of the first operational amplifier, and its positive phase input terminal is connected to the output terminal of the current sensor and an RC filtering module is provided at the positive phase input terminal.

[0016] In one or more embodiments of the present invention, an output overcurrent protection circuit is further provided. The output overcurrent protection circuit includes a second operational amplifier and a first diode. A positive feedback connection is provided between the output terminal and the positive phase terminal of the second operational amplifier, and a comparison voltage is input to the positive phase terminal. The negative phase terminal of the second operational amplifier is connected to the output terminal of the current sensor CT3 to obtain the charging current. The cathode of the first diode is connected to the output terminal of the second operational amplifier, and its anode is connected to the first single-chip microcomputer.

[0017] In one or more embodiments of the present utility model, isolation drive circuits are respectively provided between the first single-chip microcomputer and the first H-bridge, between the second single-chip microcomputer and the second H-bridge, and between the third single-chip microcomputer and the third H-bridge. The isolation drive circuit includes a first drive branch for driving the first bridge arm of the H-bridge and a second drive branch for driving the second bridge arm of the H-bridge;

[0018] The first drive branch includes a first isolation transformer. The primary side of the first isolation transformer is connected to a PWM signal terminal of the single-chip microcomputer. The secondary side thereof is provided with two secondary coils. A NPN triode is connected in parallel at both ends of each secondary coil, and the emitter of the NPN triode is connected to the gate of the controlled MOS tube;

[0019] The second drive branch includes a second isolation transformer. The primary side of the second isolation transformer is connected to another PWM signal terminal of the single-chip microcomputer. The secondary side thereof is provided with two secondary coils. A NPN triode is connected in parallel at both ends of each secondary coil, and the emitter of the NPN triode is connected to the gate of the controlled MOS tube.

[0020] In one or more embodiments of the present utility model, an over-temperature protection circuit is further provided. The over-temperature protection circuit includes a third operational amplifier. A positive feedback connection is provided between the output terminal and the non-inverting terminal of the third operational amplifier, and a comparison voltage is input to the non-inverting terminal. The inverting terminal of the third operational amplifier is connected to a temperature sensing element, and the output terminal of the third operational amplifier is connected to the second single-chip microcomputer.

[0021] In one or more embodiments of the present utility model, a heat dissipation control circuit is further provided. The heat dissipation control circuit includes a fourth operational amplifier, a second diode, a first voltage stabilizer diode, and a first switching tube. A positive feedback connection is provided between the output terminal and the non-inverting terminal of the fourth operational amplifier, and a comparison voltage is input to the non-inverting terminal. The inverting terminal of the fourth operational amplifier is connected to a temperature sensing element. The cathode of the second diode is connected to the output terminal of the fourth operational amplifier, and its anode is connected to the anode of the first voltage stabilizer diode. The cathode of the first voltage stabilizer diode is connected to the base of the first switching tube, and the collector of the first switching tube is connected to a heat dissipation device.

[0022] Compared with the prior art, the advantages of the present utility model are reflected in: adopting a cascaded structure of a PFC converter and a CLLC resonant converter to meet the requirements of positive and negative soft-switching control of the bidirectional charging circuit; at the same time, the primary and secondary sides of the CLLC resonant converter are respectively controlled by two single-chip microcomputers, and the two single-chip microcomputers coordinate and communicate with each other, which is convenient for realizing real-time adjustment of the working mode of the resonant converter. For example, stage charging switching of three charging modes of constant current, constant power, and constant voltage for the storage battery is implemented, thereby improving the overall circuit efficiency. Description of the Drawings

[0023] Figure 1 It is a schematic diagram of the topological structures of the main charging circuit and the charging control circuit.

[0024] Figure 2 It is a schematic diagram of the first driving branch of the isolation driving circuit.

[0025] Figure 3 It is a schematic diagram of the second driving branch of the isolation driving circuit.

[0026] Figure 4 It is a schematic diagram of the output overcurrent protection circuit.

[0027] Figure 5 It is a schematic diagram of the current sampling circuit.

[0028] Figure 6 It is a schematic diagram of the auxiliary power supply VCC circuit.

[0029] Figure 7 It is a schematic diagram of the overtemperature protection circuit.

[0030] Figure 8 It is a schematic diagram of the heat dissipation control circuit. Specific implementation manners

[0031] As described below in conjunction with the attached Figures 1 to 8 , the solution of the present application is further described:

[0032] Referring to the attached Figure 1 , the bidirectional electric vehicle charging device includes a main charging circuit and a charging control circuit. The main charging circuit includes a PFC converter and a CLLC resonant converter with a cascaded structure. The front end of the PFC converter is connected to the AC charging interface, and its rear end is connected to the primary side of the CLLC resonant converter. The secondary side of the CLLC resonant converter is connected to the vehicle battery. The charging control circuit includes three single-chip microcomputers, which respectively control the PFC converter, the primary side of the CLLC resonant converter, and the secondary side of the CLLC resonant converter. This device adopts the cascaded structure of the PFC converter and the CLLC resonant converter to meet the requirements of positive and reverse soft-switching control of the bidirectional charging circuit, and each converter is controlled by an independent single-chip microcomputer, so the response performance and coordination performance are both improved.

[0033] When working in the forward direction, the PFC converter realizes power factor correction, rectifies the single-phase grid voltage of 100~240VAC into a 400V DC bus voltage to supply power to the CLLC resonant converter, and then charges the vehicle battery. When working in the reverse direction, the vehicle battery discharges through the CLLC resonant converter and the DC bus, and the PFC converter inversely converts the DC bus voltage into a grid voltage output of 100~240VAC;

[0034] Specifically, the CLLC resonant converter includes a first H-bridge disposed on its primary side and a second H-bridge disposed on its secondary side; the first arm of the first H-bridge includes a first MOS transistor Q1 and a third MOS transistor Q3 connected in series, and its second arm includes a second MOS transistor Q2 and a fourth MOS transistor Q4 connected in series. A resonant inductor Lr and a first resonant capacitor Cr1 are provided between the output end of the first arm of the first H-bridge and one end of the primary coil. The other end of the primary coil is connected to the output end of the second arm of the first H-bridge, and an exciting inductor Lm is also connected in parallel across both ends of the primary coil.

[0035] The first arm of the second H-bridge includes a fifth MOS transistor Q5 and a seventh MOS transistor Q7 connected in series, and its second arm includes a sixth MOS transistor Q6 and an eighth MOS transistor Q8 connected in series. The output ends of the first arm and the second arm of the second H-bridge are respectively connected to both ends of the secondary coil; a second resonant capacitor Cr2 is provided between one end of the secondary coil and the output end of the second arm of the second H-bridge.

[0036] The above CLLC resonant converter designs the magnetic integrated resonant inductor in a decoupled manner, that is, the resonant inductor is integrated into the transformer, reducing the number of magnetic components, lowering the circuit loss, and improving the circuit efficiency.

[0037] The PFC converter includes a third H-bridge. The first arm of the third H-bridge includes a ninth MOS transistor and an eleventh MOS transistor connected in series, and its second arm includes a tenth MOS transistor and a twelfth MOS transistor connected in series.

[0038] It should be noted that the "output end of the first arm" and "output end of the second arm" mentioned above are described based on the structure of the basic H-bridge circuit. Whether the electrical signal at this point is input or output depends on the actual energy flow direction.

[0039] The single-chip microcomputer includes a first single-chip microcomputer MCU1 for controlling the operation of the first H-bridge, a second single-chip microcomputer MCU2 for controlling the operation of the second H-bridge, and a third single-chip microcomputer MCU3 for controlling the operation of the third H-bridge. The first single-chip microcomputer MCU1 and the second single-chip microcomputer MCU2 communicate with each other.

[0040] The primary and secondary sides of the CLLC resonant converter are controlled by the first single-chip microcomputer MCU1 and the second single-chip microcomputer MCU2 respectively: during forward charging, the first single-chip microcomputer MCU1 works, samples the output voltage and charging current of the battery, processes the sampled signals to obtain the driving signals for MOS transistors Q1 - Q4, and the driving signals drive MOS transistors Q1 - Q4 through isolation by a driving transformer; at this time, the second single-chip microcomputer MCU2 changes the output driving signal to a low level and sends it to the MOS transistors Q5 - Q8 on the secondary side to turn them off. During reverse discharging, the second single-chip microcomputer MCU2 works, samples the PFC output side and the discharging current, and the driving signals control MOS transistors Q5 - Q8. At this time, the first single-chip microcomputer MCU1 sends a turn-off signal to MOS transistors Q1 - Q4.

[0041] The two single-chip microcomputers communicate with each other in a coordinated manner, which is convenient for realizing real-time adjustment of the working mode of the resonant converter. For example, it can realize staged charging switching among three charging modes of constant current, constant power, and constant voltage for the storage battery, thereby improving the overall circuit efficiency. At the same time, the single-chip microcomputer can also communicate with the host computer, and the host computer can obtain key signals such as the circuit output voltage, charging current, and discharging current, so as to monitor the circuit in real time.

[0042] The charging control circuit further includes a current sensor CT1 provided on the primary side of the CLLC resonant converter to obtain the primary side resonant current, a current sensor CT2 provided on the secondary side of the CLLC resonant converter to obtain the secondary side resonant current, a current sensor CT3 provided at the connection end between the CLLC resonant converter and the vehicle battery to obtain the charging current, and a current sensor CT4 provided at the connection end between the PFC converter and the CLLC resonant converter to obtain the discharging current;

[0043] The output ends of the current sensor CT1 and the current sensor CT3 are respectively connected to the first single-chip microcomputer MCU1, and the output ends of the current sensor CT2 and the current sensor CT4 are respectively connected to the second single-chip microcomputer MCU2; the output end of the current sensor CT4 is also connected to the third single-chip microcomputer MCU3. And current sampling circuits are respectively provided between each current sensor and the single-chip microcomputer.

[0044] Taking the current sampling circuit between the current sensor CT1 and the third single-chip microcomputer MCU1 as an example:

[0045] See Appendix Figure 5, the current sampling circuit includes a first operational amplifier IC15. The negative phase terminal of the first operational amplifier IC15 is connected to its output terminal through a resistor R83 to achieve negative feedback connection. Its positive phase input terminal is connected to the output terminal of the current sensor CT1, and an RC filtering module composed of a resistor R80 and a capacitor C57 is provided at the positive phase input terminal, thereby realizing the transformation of the current signal into a voltage signal. After being processed by the first operational amplifier IC15, it is sent to the first single-chip microcomputer MCU1 for real-time control of the circuit.

[0046] An output overcurrent protection circuit is provided to detect the situation of overcurrent during charging. See the appendix Figure 4 , the output overcurrent protection circuit includes a second operational amplifier IC2 and a first diode D19. The output terminal of the second operational amplifier IC2 is connected to its positive phase terminal through a resistor R69 to achieve positive feedback connection, and a comparison voltage is input to the positive phase terminal. The comparison voltage is obtained by series voltage division of a resistor R71 and a resistor R72; the negative phase terminal of the second operational amplifier IC2 is connected to the output terminal of the current sensor CT3 to obtain the charging current Iout_CS. The cathode of the first diode D19 is connected to the output terminal of the second operational amplifier IC2, and its anode is connected to the first single-chip microcomputer MCU1 to feedback the overcurrent signal Iout_P. The first single-chip microcomputer MCU1 judges whether to disconnect the circuit according to the overcurrent signal Iout_P. That is, when the current detected by the current sensor CT3 is too large, the second operational amplifier IC2 outputs a low level, the diode D19 conducts, and the overcurrent signal Iout_P output by the second operational amplifier IC2 becomes a low-level signal and is sent to the first single-chip microcomputer MCU1, so that the output PWM wave becomes a low level, turning off the MOS transistor to stop the circuit from working.

[0047] To meet the requirements of driving force and isolation protection, isolation drive circuits are respectively provided between the first single-chip microcomputer MCU1 and the first H-bridge, between the second single-chip microcomputer MCU2 and the second H-bridge, and between the third single-chip microcomputer MCU3 and the third H-bridge to solve the problems of isolation drive and floating ground drive of each MOS transistor.

[0048] Taking the isolation drive circuit between the first single-chip microcomputer MCU1 and the first H-bridge as an example:

[0049] See the appendix Figure 2 and the appendix Figure 3 , the isolation drive circuit includes a first drive branch for driving the first bridge arm of the first H-bridge and a second drive branch for driving the second bridge arm of the first H-bridge;

[0050] The first driving branch includes a first isolation transformer T1. The primary side of the first isolation transformer T1 is connected to a PWM signal terminal of a first single-chip microcomputer MCU1 through a diode D22. Two secondary coils (i.e., two sets of taps) are provided on the secondary side for respectively controlling a first MOS transistor Q1 and a fourth MOS transistor Q4. An NPN triode VT1 is connected in parallel across the two ends of the secondary coil between tap 3 and tap 4. The emitter of the NPN triode VT1 is connected to the gate of the first MOS transistor Q1. A diode D21 is provided between the emitter of the NPN triode VT1 and one end of the secondary coil. A diode D23 and a resistor R5 are connected in series and then connected in parallel with the secondary coil between tap 3 and tap 4. The cathode of the diode D23 is connected to the base of the NPN triode VT1. An NPN triode VT2 is connected in parallel across the two ends of the secondary coil between tap 5 and tap 6. The emitter of the NPN triode VT2 is connected to the gate of the fourth MOS transistor Q4. A diode D24 is provided between the emitter of the NPN triode VT2 and one end of the secondary coil. A diode D25 and a resistor R9 are connected in series and then connected in parallel with the secondary coil between tap 5 and tap 6. The cathode of the diode D25 is connected to the base of the NPN triode VT2.

[0051] Similarly, the second driving branch includes a second isolation transformer T2. The primary side of the second isolation transformer T2 is connected to another PWM signal terminal of the first single-chip microcomputer MCU1. Two secondary coils (i.e., two sets of taps) are provided on the secondary side for respectively controlling a second MOS transistor Q2 and a third MOS transistor Q3. An NPN triode VT3 is connected in parallel across the two ends of the secondary coil between tap 3 and tap 4. The emitter of the NPN triode VT3 is connected to the gate of the second MOS transistor Q2. A diode D26 is provided between the emitter of the NPN triode VT3 and one end of the secondary coil. A diode D27 and a resistor R16 are connected in series and then connected in parallel with the secondary coil between tap 3 and tap 4. The cathode of the diode D27 is connected to the base of the NPN triode VT3. An NPN triode VT4 is connected in parallel across the two ends of the secondary coil between tap 5 and tap 6. The emitter of the NPN triode VT4 is connected to the gate of the third MOS transistor Q3. A diode D29 is provided between the emitter of the NPN triode VT4 and one end of the secondary coil. A diode D30 and a resistor R15 are connected in series and then connected in parallel with the secondary coil between tap 5 and tap 6. The cathode of the diode D30 is connected to the base of the NPN triode VT4.

[0052] An overtemperature protection circuit is provided to detect the overtemperature situation during charging and discharging. See the appendix Figure 7, the over-temperature protection circuit includes a third operational amplifier IC13. A positive feedback connection is established between the output terminal of the third operational amplifier IC13 and the non-inverting terminal via a resistor R79, and a comparison voltage is input to the non-inverting terminal. The comparison voltage is obtained by series voltage division of a resistor R77 and a resistor R78; the inverting terminal of the third operational amplifier IC13 is connected to a temperature sensing element (e.g., a thermistor NTC), and the output terminal of the third operational amplifier IC13 is connected to a second single-chip microcomputer MCU2 to feedback an over-temperature signal OTP. The second single-chip microcomputer MCU2 determines whether to completely disconnect the circuit according to the over-temperature signal OTP. That is, when the temperature sensing element detects that the temperature is higher than the set value, the over-temperature signal OTP output by the third operational amplifier IC13 becomes a low level and is sent to the second single-chip microcomputer MCU2, making the output PWM wave become a low level, turning off the MOS transistor and stopping the circuit from working.

[0053] A heat dissipation control circuit is provided to dissipate heat from the device in case of over-temperature. See the appendix Figure 8 , the heat dissipation control circuit includes a fourth operational amplifier IC14, a second diode D20, a first voltage regulator Z12, and a first switching transistor VT10. A positive feedback connection is established between the output terminal of the fourth operational amplifier IC14 and the non-inverting terminal via a resistor R73, and a comparison voltage is input to the non-inverting terminal. The comparison voltage is obtained by series voltage division of a resistor R74 and a resistor R75; the inverting terminal of the fourth operational amplifier IC14 is connected to a temperature sensing element (e.g., a thermistor NTC), the cathode of the second diode D20 is connected to the output terminal of the fourth operational amplifier IC14, its anode is connected to the anode of the first voltage regulator Z12, and the cathode of the first voltage regulator Z12 is connected to the base of the first switching transistor VT10 to control the on / off of the first switching transistor VT10. The collector of the first switching transistor VT10 is connected to a heat dissipation device (e.g., a fan). That is, when the temperature sensing element detects that the temperature is within the set temperature range, the output of the fourth operational amplifier IC14 is a high level, the diode D20 is cut off, and thus the first switching transistor VT10 is also cut off, and the fan stops working; when the temperature is higher than the set value, the output of the fourth operational amplifier IC14 becomes a low level, the diode D20 conducts, the first switching transistor VT10 also conducts, and the FANC signal becomes a high level to control the fan to work.

[0054] An auxiliary power supply VCC circuit is provided to meet the power supply requirements of the circuit. For specific implementation, refer to the appendix Figure 6 The circuit shown. The power circuit adopts a flyback converter, and the control chip adopts a single-chip integrated IC. The circuit is simple, with few components, low cost. The auxiliary power supply VCC circuit outputs four different voltages to provide working voltages for the single-chip microcomputer and each chip of the circuit.

[0055] The above preferred embodiments should be regarded as illustrative examples of the implementation of the solution of this application. Any technical deductions, substitutions, improvements, etc. that are identical, similar to, or based on the solution of this application should be regarded as within the protection scope of this patent.

Claims

1. A bidirectional electric vehicle charging device, comprising a main charging circuit and a charging control circuit, characterized in that, The main charging circuit includes a PFC converter and a CLLC resonant converter with a cascaded structure; The front end of the PFC converter is connected to the AC charging interface, and its rear end is connected to the primary side of the CLLC resonant converter. The secondary side of the CLLC resonant converter is connected to the vehicle battery; The charging control circuit includes three single-chip microcomputers, which respectively control the PFC converter, the primary side of the CLLC resonant converter, and the secondary side of the CLLC resonant converter.

2. The bidirectional electric vehicle charging device according to claim 1, characterized in that, The CLLC resonant converter includes a first H-bridge provided on its primary side and a second H-bridge provided on its secondary side; The first bridge arm of the first H-bridge includes a first MOS transistor and a third MOS transistor connected in series. Its second bridge arm includes a second MOS transistor and a fourth MOS transistor connected in series. A resonant inductor and a first resonant capacitor are provided between the output end of the first bridge arm of the first H-bridge and one end of the primary coil. The other end of the primary coil is connected to the output end of the second bridge arm of the first H-bridge. An exciting inductor is also connected in parallel across the two ends of the primary coil; The first bridge arm of the second H-bridge includes a fifth MOS transistor and a seventh MOS transistor connected in series. Its second bridge arm includes a sixth MOS transistor and an eighth MOS transistor connected in series. The output ends of the first bridge arm and the second bridge arm of the second H-bridge are respectively connected to the two ends of the secondary coil; A second resonant capacitor is provided between one end of the secondary coil and the output end of the second bridge arm of the second H-bridge; The PFC converter includes a third H-bridge. The first bridge arm of the third H-bridge includes a ninth MOS transistor and an eleventh MOS transistor connected in series. Its second bridge arm includes a tenth MOS transistor and a twelfth MOS transistor connected in series; The single-chip microcomputer includes a first single-chip microcomputer for controlling the operation of the first H-bridge, a second single-chip microcomputer for controlling the operation of the second H-bridge, and a third single-chip microcomputer for controlling the operation of the third H-bridge. The first single-chip microcomputer and the second single-chip microcomputer communicate with each other.

3. The bidirectional electric vehicle charging device according to claim 2, characterized in that, The charging control circuit further includes a current sensor CT1 provided on the primary side of the CLLC resonant converter to obtain the primary side resonant current, a current sensor CT2 provided on the secondary side of the CLLC resonant converter to obtain the secondary side resonant current, a current sensor CT3 provided at the connection end between the CLLC resonant converter and the vehicle battery to obtain the charging current, and a current sensor CT4 provided at the connection end between the PFC converter and the CLLC resonant converter to obtain the discharge current; The output ends of the current sensor CT1 and the current sensor CT3 are respectively connected to the first single-chip microcomputer. The output ends of the current sensor CT2 and the current sensor CT4 are respectively connected to the second single-chip microcomputer; The output end of the current sensor CT4 is also connected to the third single-chip microcomputer.

4. The bidirectional electric vehicle charging device according to claim 3, characterized in that, Current sampling circuits are respectively provided between each current sensor and the single-chip microcomputer. The current sampling circuit includes a first operational amplifier. A negative feedback connection is provided between the negative phase end and the output end of the first operational amplifier. Its positive phase input end is connected to the output end of the current sensor and an RC filtering module is provided at the positive phase input end.

5. The bidirectional electric vehicle charging device according to claim 3, characterized in that, An output overcurrent protection circuit is also provided. The output overcurrent protection circuit includes a second operational amplifier and a first diode. There is a positive feedback connection between the output terminal and the non-inverting terminal of the second operational amplifier, and a comparison voltage is input to the non-inverting terminal. The inverting terminal of the second operational amplifier is connected to the output terminal of a current sensor CT3 to obtain the charging current. The cathode of the first diode is connected to the output terminal of the second operational amplifier, and its anode is connected to the first single-chip microcomputer.

6. The bidirectional electric vehicle charging device according to claim 2, wherein, Isolation drive circuits are respectively provided between the first single-chip microcomputer and the first H-bridge, between the second single-chip microcomputer and the second H-bridge, and between the third single-chip microcomputer and the third H-bridge.

7. The bi-directional electric vehicle charging device according to claim 6, wherein, The isolation drive circuit includes a first drive branch for driving the first bridge arm of the H-bridge and a second drive branch for driving the second bridge arm of the H-bridge. The first drive branch includes a first isolation transformer. The primary side of the first isolation transformer is connected to a PWM signal terminal of the single-chip microcomputer. There are two secondary coils on the secondary side. A NPN transistor is connected in parallel at both ends of each secondary coil, and the emitter of the NPN transistor is connected to the gate of the controlled MOS transistor. The second drive branch includes a second isolation transformer. The primary side of the second isolation transformer is connected to another PWM signal terminal of the single-chip microcomputer. There are two secondary coils on the secondary side. A NPN transistor is connected in parallel at both ends of each secondary coil, and the emitter of the NPN transistor is connected to the gate of the controlled MOS transistor.

8. The bidirectional electric vehicle charging device according to claim 2, characterized in that, An overtemperature protection circuit is also provided. The overtemperature protection circuit includes a third operational amplifier. There is a positive feedback connection between the output terminal and the non-inverting terminal of the third operational amplifier, and a comparison voltage is input to the non-inverting terminal. The inverting terminal of the third operational amplifier is connected to a temperature sensing element, and the output terminal of the third operational amplifier is connected to the second single-chip microcomputer.

9. The bidirectional electric vehicle charging device according to claim 1, wherein A heat dissipation control circuit is also provided. The heat dissipation control circuit includes a fourth operational amplifier, a second diode, a first voltage regulator diode, and a first switching transistor. There is a positive feedback connection between the output terminal and the non-inverting terminal of the fourth operational amplifier, and a comparison voltage is input to the non-inverting terminal. The inverting terminal of the fourth operational amplifier is connected to a temperature sensing element. The cathode of the second diode is connected to the output terminal of the fourth operational amplifier, and its anode is connected to the anode of the first voltage regulator diode. The cathode of the first voltage regulator diode is connected to the base of the first switching transistor, and the collector of the first switching transistor is connected to a heat dissipation device.

10. The bidirectional electric vehicle charging device according to claim 1, wherein, An auxiliary power supply VCC circuit is also provided.

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