Fanless electric vehicle charger control circuit and method based on third-generation semiconductor

Abstract

The invention provides a fanless electric vehicle charger control circuit and method based on a third-generation semiconductor, and belongs to the technical field of switching power supplies. The control circuit comprises an anti-reverse-connection control circuit, an adjustable comparator unit, an oscillator unit, a logic gate unit and a driving signal generation unit, the adjustable comparator unit and the oscillator unit are connected with the logic gate unit, and the logic gate unit is connected with the driving signal generation unit. A first regulation voltage generation unit and a second regulation voltage generation unit of the adjustable comparator unit generate different regulation voltages, and a selection unit inputs the different regulation voltages into a temperature drift compensation end. The temperature drift of the comparator can be counteracted, accurate adjustment of the current of the charger is ensured, and abnormal heating of the charger caused by misjudgment of the comparator is avoided; meanwhile, a third-generation semiconductor device is used for constructing an anti-reverse-connection circuit and designing a corresponding control unit, so that the heat loss is further reduced, and simple and reliable anti-reverse-connection and anti-current-backflow control is realized.

Description

Technical Field

[0001] This invention belongs to the field of switching power supply technology, and particularly relates to a control circuit and method for a fanless electric vehicle charger based on third-generation semiconductors. Background Technology

[0002] Fanless electric vehicle chargers rely on a switching power supply to regulate the charging current of the electric vehicle battery, as detailed in the instruction manual. Figure 1 The process involves first converting 220V AC power into approximately 300V DC power through rectification, filtering, and EMI circuitry. This DC power is then input to the switching power supply. The secondary side of the switching power supply's rectification and filtering circuit converts the high-frequency AC power into stable DC power, which is then output to the electric vehicle battery after passing through a reverse connection protection circuit composed of SCRs. The comparator in the feedback control module compares the real-time output current and / or voltage signals fed back from the sampling circuit with a preset reference signal. Based on the comparison result, it dynamically adjusts the duty cycle of the PWM signal driving the switching power supply's MOSFET. When a higher charging current is needed, the control chip increases the PWM duty cycle, extending the MOSFET's on-time and allowing the high-frequency transformer to transfer more energy to the secondary side. When a lower current or constant current state is needed, the control chip decreases or locks the duty cycle, achieving precise current control by limiting energy transfer. The entire adjustment process uses a closed-loop feedback system composed of sampling resistors or Hall sensors to correct current deviations in real time, ensuring that the output current always conforms to the preset charging curve.

[0003] In the aforementioned reverse connection protection circuit composed of an SCR, the SCR is a unidirectional thyristor, mainly used as a power control switch in electric two-wheeler chargers to achieve rectification and reverse connection protection functions. Its operation consists of two stages: conduction and turn-off. Conduction: When the charger is powered on and the battery is correctly connected, the control circuit (such as an RC network or transistor) applies a trigger current pulse (typically 1-15mA) to the gate of the SCR. The SCR immediately switches from the off state to the on state, the voltage drop between the anode and cathode of the SCR decreases, and current begins to flow to the load (battery). Even if the gate trigger signal disappears, the SCR remains on. Turn-off: The SCR turns off depending on the current flowing through it dropping below the holding current (typically 20mA). Therefore, when the battery is fully charged or the circuit is abnormal, the control circuit will turn it off by reducing the load current or short-circuiting the thyristor. Specifically, when the battery is reverse-connected, the transistor is cut off, and there is no current at the SCR gate, thus achieving turn-off when the load current naturally crosses zero.

[0004] However, the above charger has the following problems: (1) The internal resistance of the SCR in the reverse connection protection circuit is large, so the on-state voltage drop is large and heat loss is easy to occur; if a traditional MOSFET is used instead of the SCR, at least two back-to-back MOSFETs are needed to realize the charger power control and reverse connection protection functions. Two back-to-back MOSFETs are prone to reverse current backflow; (2) The above charging current adjustment process depends on the comparator performance in the feedback control module. In the application scenario of fanless electric vehicle charger, since it relies entirely on natural heat dissipation and shell fin heat dissipation, the working environment temperature of the charger is relatively high. When the charger is in a high load working state or high temperature environment for a long time, the heat generated by the power device will be gradually conducted to the control board, causing the comparator's working temperature to rise significantly. At this time, it is very easy to cause the temperature drift phenomenon of the comparator module. This drift is essentially caused by the non-ideal characteristics of the threshold voltage, gain and other parameters of the transistor inside the comparator changing with temperature: when the temperature rises, the performance parameters of the differential circuit, buffer circuit and other circuits inside the comparator will shift, directly causing the preset reference signal level received to drift, that is, the abnormal rise or fall of the received external reference signal. Even a slight drift in the reference signal, amplified by the control loop, can directly reduce the adjustment accuracy of the PWM duty cycle, leading to fluctuations in the charging current. If the reference signal is too high, the comparator will incorrectly determine that the feedback current has not reached the target value, driving the control chip to increase the duty cycle, causing the actual output current to exceed the preset threshold, further increasing the charger's heat generation, affecting the battery's charging efficiency and lifespan, and thus hindering the development of fanless electric vehicles. Summary of the Invention

[0005] To address the aforementioned problems in existing technologies, this invention proposes a control circuit and method for a fanless electric vehicle charger based on third-generation semiconductors. By setting an adjustable comparator unit, temperature drift compensation of the comparator can be achieved, thereby controlling the charging current within a reasonable range and avoiding excessive heat generation in the fanless electric vehicle charger due to comparator misjudgment. Simultaneously, the use of third-generation semiconductor devices to construct a reverse connection protection circuit and design a corresponding control unit further reduces heat loss and achieves simple and reliable reverse connection and current backflow prevention control, providing a technical foundation for the further development of fanless electric vehicles.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a fanless electric vehicle charger control circuit based on third-generation semiconductors, including a reverse connection protection control circuit, an adjustable comparator unit, an oscillator unit, a logic gate unit, and a drive signal generation unit. The reverse connection protection control circuit is used to receive control signals and, according to the control signals, the MCU controls the third-generation semiconductor devices in the fanless electric vehicle charger reverse connection protection circuit to be turned on or off. The adjustable comparator unit and oscillator unit are both connected to the logic gate unit, which is connected to the drive signal generation unit. The adjustable comparator unit is used for closed-loop control of the output signal of the switching power supply in the charger. The oscillator unit is used to generate a clock signal. The logic gate unit is used to trigger the drive signal generation unit, which is used to generate a drive signal for the primary-side switching transistor of the switching power supply in the charger. The adjustable comparator unit includes a first adjustable voltage generation unit, a second adjustable voltage generation unit, a selection unit, and a comparator module. The first adjustable voltage generation unit is used to generate a first adjustable voltage, and the second adjustable voltage generation unit is used to generate a second adjustable voltage. The selection unit is used to input the first adjustable voltage or the second adjustable voltage to the temperature drift compensation terminal of the comparator module according to the temperature data of the adjustable comparator unit to compensate for the temperature drift of the comparator module.

[0007] Furthermore, the output of the adjustable comparator unit is connected to the first input of the logic gate unit, the output of the oscillator unit is connected to the second input of the logic gate unit, and the output of the logic gate unit is connected to one input of the drive signal generation unit. The drive signal generation unit is used to generate the drive signal for the switching power supply switching transistor in the fanless electric vehicle charger.

[0008] Furthermore, the logic gate unit is an AND gate unit.

[0009] Furthermore, the drive signal generation unit includes a first flip-flop and a second comparator. The S terminal of the first flip-flop is connected to the output terminal of the logic gate unit, the R terminal of the first flip-flop is connected to the output terminal of the second comparator, and the Q terminal of the first flip-flop outputs the drive signal of the switching power supply transistor in the fanless electric vehicle charger. The first input terminal of the second comparator is connected to the first terminal of the current sensing resistor, the second terminal of the current sensing resistor is grounded, the current sensing resistor is connected in series with the main switching transistor of the switching power supply, and the second input terminal of the second comparator is connected to the output feedback signal terminal of the switching power supply.

[0010] Further, the first input terminal of the comparator module is connected to the output feedback signal terminal of the switching power supply, the second input terminal of the comparator module is connected to a preset voltage signal, and the output terminal of the comparator module serves as the output terminal of the adjustable comparator unit. The comparator module includes an input signal preprocessing unit, a temperature drift compensation unit, and an output processing unit. The input signal preprocessing unit is connected to the temperature drift compensation unit, and the temperature drift compensation unit is connected to the output processing unit. The input signal preprocessing unit includes a first switching transistor, a second switching transistor, an eighth switching transistor, a first transistor, and a second transistor. The first terminal of the first switching transistor is connected to a preset voltage VREG, the second terminal of the first switching transistor is connected to the first terminal of the first transistor, the second terminal of the first transistor is connected to the first terminal of the eighth switching transistor, the second terminal of the eighth switching transistor is connected to a preset voltage VSS, the first terminal of the second switching transistor is connected to the preset voltage VREG, the second terminal of the second switching transistor is connected to the first terminal of the second transistor, and the second terminal of the second transistor is connected to the first terminal of the eighth switching transistor. The control terminal of the first transistor serves as the second input terminal of the comparator module, the control terminal of the second transistor serves as the first input terminal of the comparator module, and the control terminal of the eighth switching transistor is connected to a preset voltage bias signal.

[0011] Further, the temperature drift compensation unit includes a third switch, a fourth switch, a ninth switch, a tenth switch, an eleventh switch, and a twelfth switch; the first terminal of the third switch is connected to a preset voltage VREG, the second terminal of the third switch is connected to the first terminals of the ninth and tenth switches, the second terminal of the ninth switch is connected to the temperature drift compensation terminal, the second terminal of the tenth switch is connected to a preset voltage VSS, the first terminal of the fourth switch is connected to the preset voltage VREG, the second terminal of the fourth switch is connected to the first terminals of the eleventh and twelfth switches, the second terminal of the twelfth switch is connected to the temperature drift compensation terminal, the second terminal of the eleventh switch is connected to the preset voltage VSS, the control terminal of the third switch is connected to the control terminal of the second switch, the control terminal of the fourth switch is connected to the control terminal of the first switch, the control terminal of the tenth switch is connected to the second terminal of the fourth switch, and the control terminal of the eleventh switch is connected to the second terminal of the third switch.

[0012] Further, the output processing unit includes a fifth switch, a sixth switch, a seventh switch, a thirteenth switch, a fourteenth switch, and a fifteenth switch; the first terminal of the fifth switch is connected to a preset voltage VREG, the second terminal of the fifth switch is connected to the first terminal of the thirteenth switch, and the second terminal of the thirteenth switch is connected to a preset voltage VSS; the first terminal of the sixth switch is connected to the preset voltage VREG, the second terminal of the sixth switch is connected to the first terminal of the fourteenth switch, and the second terminal of the fourteenth switch is connected to the preset voltage VSS; the first terminal of the seventh switch is connected to the preset voltage VREG, the second terminal of the seventh switch is connected to the first terminal of the fifteenth switch, and the second terminal of the fifteenth switch is connected to the preset voltage VSS; the control terminal of the fifth switch is connected to the second terminal of the fifth switch and the control terminal of the sixth switch, the control terminal of the thirteenth switch is connected to the second terminal of the fourth switch, the control terminal of the fourteenth switch is connected to the second terminal of the third switch, the second terminal of the sixth switch is connected to the control terminals of the seventh switch and the fifteenth switch, and the second terminal of the seventh switch is the output terminal of the comparator module.

[0013] Furthermore, the third-generation semiconductor devices in the reverse connection protection circuit include bidirectional GaN switches K8, K9, and K10, diodes D1, D2, D3, D4, and D5, resistors R20 and R30. The bidirectional GaN switch K8 is connected in series in either the positive or negative output circuit of the fanless electric vehicle charger power supply. The anode of diode D1 is connected to one end of the bidirectional GaN switch K8, the cathode of diode D1 is connected to the cathode of diode D2, the anode of diode D2 is connected to the control terminal of the bidirectional GaN switch K8, and the anode of diode D3 is connected to the other end of the bidirectional GaN switch K8. At one end, the cathode of diode D3 is connected to the cathode of diode D4, and the anode of diode D4 is connected to the control terminal of bidirectional GaN switch K8. The control terminal of bidirectional GaN switch K8 is also connected to the other end of bidirectional GaN switch K8 through switch K9 and switch K10 connected in series. The control terminals of switch K9 and switch K10 are connected and then grounded through resistor R30. One end of resistor R20 is connected to the common terminal of switch K9 and switch K10, and the other end of resistor R20 is connected to the control terminal of switch K9. The anode of diode D5 is connected to the common terminal of switch K9 and switch K10, and the cathode of diode D5 is connected to the control terminal of switch K9.

[0014] Furthermore, the reverse connection protection control circuit includes a turn-on control circuit and a turn-off control circuit. The turn-on control circuit includes an optocoupler U2, resistors R1 and R2. One end of resistor R2 is connected to the control signal MCU, and the other end of resistor R2 is connected to pin 1 of optocoupler U2. Pin 2 of optocoupler U2 is grounded, and pin 3 of optocoupler U2 is connected to the auxiliary winding N3 of the switching power supply in the fanless electric vehicle charger. Pin 4 of optocoupler U2 outputs the control signal of the third-generation semiconductor device in the reverse connection protection circuit through resistor R1. The turn-off control circuit includes resistors R3, R4, R5, R6, R7, and R8, diodes D6, D7, D8, and D9, switching transistors K1 and K2, and capacitor C0. One end of resistor R3 is connected to the control signal MCU, and the other end of resistor R3 is connected to one end of resistor R4 and... The control terminal of switch K1, the other end of resistor R4 and the other end of switch K1 are grounded. One end of switch K1 is connected to the cathode of diode D6 through resistor R5. The anode of diode D6 is connected to the 5V power supply. One end of switch K1 is also connected to the control terminal of switch K2, the other end of resistor R6 and one end of resistor R7. The other end of resistor R7 is grounded. One end of resistor R6 is connected to the cathode of diode D7. The anode of diode D7 is connected to the output terminal of the switching power supply in the fanless electric vehicle charger. Diode D8 is connected in parallel with resistor R7. The other end of switch K2 is grounded. One end of switch K2 is connected to the cathode of diode D9. The anode of diode D9 is connected to one end of resistor R8. The other end of resistor R8 outputs the control signal of the third-generation semiconductor device in the reverse connection protection circuit. One end of capacitor C0 is connected to the other end of resistor R8. The other end of capacitor C0 is grounded.

[0015] This invention also proposes a control method for a fanless electric vehicle charger based on third-generation semiconductors, applied to the aforementioned control circuit for a fanless electric vehicle charger based on third-generation semiconductors. The control method includes the following steps: S1: Charge the electric vehicle using a fanless electric vehicle charger and detect the DC bus voltage of the fanless electric vehicle charger. S2: Determine whether the DC bus voltage is greater than the first threshold. If the DC bus voltage is greater than the first threshold, execute S3; otherwise, execute S7. S3: The MCU outputs a high level control signal, which uses the reverse connection protection control circuit to turn on the bidirectional GaN switch and execute S4. S4: Detect the temperature of the comparator module. When the temperature of the comparator module is higher than the preset upper temperature threshold, input the second adjustment voltage VB2 into the temperature drift compensation terminal of the comparator module. When the temperature of the comparator module is lower than the preset lower temperature threshold, input the first adjustment voltage VB1 into the temperature drift compensation terminal of the comparator module; and execute S5. S5: Uses an adjustable comparator unit, oscillator unit, logic gate unit and drive signal generation unit to generate drive signals, control the operation of the primary-side switching transistor of the switching power supply in the fanless electric vehicle charger, and adjust the charging current. S6: Detect the output voltage of the auxiliary winding of the fanless electric vehicle charger, determine whether the output voltage of the auxiliary winding is greater than the second threshold, and execute S7 when the output voltage of the auxiliary winding is not greater than the second threshold. S7: When the MCU outputs a low level control signal, the bidirectional GaN switch is turned off using the reverse connection protection control circuit, stopping the charging of the electric vehicle and outputting an alarm signal.

[0016] The beneficial technical effects of this invention compared with the prior art are as follows: (1) The first adjustment voltage or the second adjustment voltage is input to the temperature drift compensation terminal of the comparator module according to the temperature data of the adjustable comparator unit to offset the temperature drift of the comparator module, ensure the accuracy of the charger current adjustment, and avoid the overheating problem of the charger caused by the comparator misjudgment; (2) The charger anti-reverse connection circuit is constructed using third-generation semiconductor devices and a corresponding control unit is designed to further reduce heat loss and achieve simple and reliable anti-reverse connection and anti-current backflow control. Attached Figure Description

[0017] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0018] Figure 1 A simplified structural diagram of an existing electric vehicle charger; Figure 2 This is a simplified structural diagram of the feedback control circuit for the fanless electric vehicle charger of the present invention. Figure 3 A simplified structural diagram of the comparator topology after adding bias control in this invention; Figure 4 This is a simplified structural diagram of the third-generation semiconductor device in the reverse polarity protection circuit of the present invention; Figure 5 This is a simplified structural diagram of the conduction control circuit of the reverse connection protection control circuit of the present invention; Figure 6 This is a simplified structural diagram of the shutdown control circuit of the reverse connection protection control circuit of the present invention. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] The concepts involved in this application will first be described with reference to the accompanying drawings. It should be noted that the following descriptions of various concepts are only for the purpose of making the content of this application easier to understand and do not constitute a limitation on the scope of protection of this application; furthermore, the embodiments and features in the embodiments of this application can be combined with each other unless otherwise specified. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0021] Refer to the instruction manual. Figure 2 This invention proposes a control circuit for a fanless electric vehicle charger based on third-generation semiconductors, including an adjustable comparator unit 1, an oscillator unit OSC, a logic AND gate unit AND1, and a drive signal generation unit 2. The outputs of the adjustable comparator unit 1 and the oscillator unit OSC are both connected to the input of the logic AND gate unit AND1. The output of the logic AND gate unit AND1 is connected to one input of the drive signal generation unit. The adjustable comparator unit 1 is used for closed-loop control of the output signal of the switching power supply in the charger. The oscillator unit OSC is used to generate a clock signal. The logic AND gate unit AND1 is used to trigger the drive signal generation unit 2. The drive signal generation unit 2 is used to generate a drive signal for the primary-side switching transistor of the switching power supply in the charger.

[0022] The adjustable comparator unit includes a first adjustable voltage generation unit ( Figure 2 (not shown in the image), second regulating voltage generating unit ( Figure 2 (Not shown in the diagram) A selection unit S and a comparator module TCMP are used. The first regulating voltage generating unit generates a first regulating voltage VB1, and the second regulating voltage generating unit generates a second regulating voltage VB2. The temperature data of the adjustable comparator unit is detected using contact temperature detection units such as RTDs, thermocouples, and thermometers, or non-contact temperature detection units such as infrared temperature sensors, and compared with a preset temperature data threshold. The selection unit S is used to close the switch corresponding to the selection unit S based on the comparison result of the temperature data of the adjustable comparator unit and the temperature data threshold, thereby inputting the first regulating voltage VB1 or the second regulating voltage VB2 into the temperature drift compensation terminal Tcom of the comparator module to compensate for the temperature drift of the comparator module.

[0023] It should be noted that the first adjustment voltage VB1 is greater than the second adjustment voltage VB2. When the temperature of the comparator module is higher than the preset upper temperature threshold, causing the external reference voltage received by the comparator module to rise abnormally, the second adjustment voltage VB2 is input. When the temperature of the comparator module is lower than the preset lower temperature threshold, causing the external reference voltage received by the comparator module to drop abnormally, the first adjustment voltage VB1 is input. This is to compensate for the drift of the external reference voltage of the comparator module caused by temperature changes.

[0024] Further refer to the instruction manual appendix Figure 2 The drive signal generation unit includes a first flip-flop RS1 and a second comparator CMP2. The S terminal of the first flip-flop RS1 is connected to the output terminal of the AND gate unit AND1, and the R terminal of the first flip-flop RS1 is connected to the output terminal of the second comparator CMP2. The Q terminal of the first flip-flop RS1 outputs the drive signal DRV of the primary-side switching transistor of the power supply in the fanless electric vehicle charger. The first input terminal of the second comparator CMP2 is connected to the first terminal of a current sensing resistor, the second terminal of which is grounded. The current sensing resistor is connected in series with the primary-side switching transistor of the power supply, and the second input terminal of the second comparator CMP2 is connected to the output feedback signal terminal of the power supply. It can be understood that the current sensing resistor is the resistance between the primary-side switching transistor of the power supply and the ground terminal GND. The first input terminal of the second comparator CMP2 is connected to the common terminal of the primary-side switching transistor and the current sensing resistor, used to acquire the current signal flowing through the current sensing resistor and convert it into a voltage signal. The output feedback signal terminal of the power supply receives the output feedback signal transmitted by the output current detection unit on the secondary side of the power supply through an isolation device such as an optocoupler. This output feedback signal reflects the output current of the charger. The first input terminal of the comparator module TCMP is connected to the output feedback signal terminal of the switching power supply, the second input terminal of the comparator module TCMP is connected to the preset voltage signal VREF, and the output terminal of the comparator module TCMP serves as the output terminal of the adjustable comparator unit.

[0025] Refer to the instruction manual. Figure 3The comparator module TCMP of the present invention includes an input signal preprocessing unit, a temperature drift compensation unit, and an output processing unit. The input signal preprocessing unit is connected to the temperature drift compensation unit, and the temperature drift compensation unit is connected to the output processing unit. The input signal preprocessing unit includes a first switch M1, a second switch M2, an eighth switch M8, a first transistor N1, and a second transistor N2. The first terminal of the first switch M1 is connected to a preset voltage VREG, the second terminal of the first switch M1 is connected to the first terminal of the first transistor N1, the second terminal of the first transistor N1 is connected to the first terminal of the eighth switch M8, and the second terminal of the eighth switch M8 is connected to a preset voltage VSS. The first terminal of the second switch M2 is connected to the preset voltage VREG, the second terminal of the second switch M2 is connected to the first terminal of the second transistor N2, and the second terminal of the second transistor N2 is connected to the first terminal of the eighth switch M8. The control terminal of the first transistor N1 serves as the second input terminal of the comparator module, the control terminal of the second transistor N2 serves as the first input terminal of the comparator module, and the control terminal of the eighth switch M8 is connected to a preset voltage bias signal Vpre.

[0026] The temperature drift compensation unit includes a third switch M3, a fourth switch M4, a ninth switch M9, a tenth switch M10, an eleventh switch M11, and a twelfth switch M12. The first terminal of the third switch M3 is connected to a preset voltage VREG. The second terminal of the third switch M3 is connected to the first terminals of the ninth and tenth switches M9 and M10, respectively. The second terminal of the ninth switch M9 is connected to the temperature drift compensation terminal Tcom. The second terminal of the tenth switch M10 is connected to a preset voltage VSS. The first terminal of the fourth switch M4 is connected to the preset voltage VREG. The second terminal of the fourth switch M4 is connected to the first terminals of the eleventh and twelfth switches M11 and M12, respectively. The second terminal of the twelfth switch M12 is connected to the temperature drift compensation terminal Tcom. The second terminal of the eleventh switch M11 is connected to the preset voltage VSS. The control terminal of the third switch M3 is connected to the control terminal of the second switch M2, and the control terminal of the fourth switch M4 is connected to the control terminal of the first switch M1. Figure 3(Point a in the diagram), the control terminal of the tenth switch M10 is connected to the second terminal of the fourth switch M4, and the control terminal of the eleventh switch M11 is connected to the second terminal of the third switch M3. By inputting the first regulating voltage VB1 or the second regulating voltage VB2 through the temperature drift compensation terminal Tcom, the gate-source voltages of the ninth switch M9 and the twelfth switch M12 are adjusted, changing the current matching degree between the ninth switch M9 and the eleventh switch M11, and between the tenth switch M10 and the twelfth switch M12, thereby changing the current flowing through the first transistor N1, thus achieving the effect of adjusting the preset voltage signal VREF input to the comparator module TCMP.

[0027] The output processing unit includes a fifth switch M5, a sixth switch M6, a seventh switch M7, a thirteenth switch M13, a fourteenth switch M14, and a fifteenth switch M15. The first terminal of the fifth switch M5 is connected to a preset voltage VREG, and the second terminal of the fifth switch M5 is connected to the first terminal of the thirteenth switch M13, which in turn is connected to a preset voltage VSS. The first terminal of the sixth switch M6 is connected to the preset voltage VREG, and the second terminal of the sixth switch M6 is connected to the first terminal of the fourteenth switch M14, which in turn is connected to the preset voltage VSS. The first terminal of the seventh switch M7 is connected to... The comparator module is connected to a preset voltage VREG. The second terminal of the seventh switch M7 is connected to the first terminal of the fifteenth switch M15, and the second terminal of the fifteenth switch M15 is connected to the preset voltage VSS. The control terminal of the fifth switch M5 is connected to the second terminal of the fifth switch M5 and the control terminal of the sixth switch M6. The control terminal of the thirteenth switch M13 is connected to the second terminal of the fourth switch M4. The control terminal of the fourteenth switch M14 is connected to the second terminal of the third switch M3. The second terminal of the sixth switch M6 is connected to the control terminals of the seventh switch M7 and the fifteenth switch M15. The second terminal of the seventh switch M7 is the output terminal O of the comparator module.

[0028] The first switch M1 to the fifteenth switch M15 are MOS transistors, and the first transistor N1 and the second transistor N2 are NPN transistors.

[0029] The present invention also includes a reverse connection protection circuit constructed from third-generation semiconductor devices, and a reverse connection protection control circuit. Further details can be found in the appendix to this specification. Figure 4The third-generation semiconductor devices in the reverse connection protection circuit include bidirectional GaN switches K8, K9, and K10, diodes D1, D2, D3, D4, and D5, resistors R20 and R30. The bidirectional GaN switch K8 is connected in series in either the positive or negative output circuit of the fanless electric vehicle charger's switching power supply. The anode of diode D1 is connected to one end of the bidirectional GaN switch K8, the cathode of diode D1 is connected to the cathode of diode D2, the anode of diode D2 is connected to the control terminal of the bidirectional GaN switch K8, and the anode of diode D3 is connected to the other end of the bidirectional GaN switch K8. The cathode of diode D3 is connected to the cathode of diode D4. The anode of diode D4 is connected to the control terminal of bidirectional GaN switch K8. The control terminal of bidirectional GaN switch K8 is also connected to the other end of bidirectional GaN switch K8 through switches K9 and K10 connected in series. The control terminals of switches K9 and K10 are connected and then grounded through resistor R30. One end of resistor R20 is connected to the common terminal of switches K9 and K10, and the other end of resistor R20 is connected to the control terminal of switch K9. The anode of diode D5 is connected to the common terminal of switches K9 and K10, and the cathode of diode D5 is connected to the control terminal of switch K9. The above-mentioned third-generation semiconductor device can directly replace the one attached to the instruction manual. Figure 1 The SCR and its control circuit section in the system reduce heat loss and achieve simple and reliable power supply reverse connection protection and load current backflow protection control.

[0030] The reverse connection protection control circuit of this invention includes a conduction control circuit and a shutdown control circuit, as detailed in the appendix to the specification. Figure 5 The reverse connection protection control circuit includes an optocoupler U2, resistors R1 and R2. One end of resistor R2 is connected to the control signal MCU, and the other end is connected to pin 1 of optocoupler U2. Pin 2 of optocoupler U2 is grounded. Pin 3 of optocoupler U2 is connected to the auxiliary winding N3 of the switching power supply in the fanless electric vehicle charger. Pin 4 of optocoupler U2 outputs the control signal Vgate of the third-generation semiconductor device in the reverse connection protection circuit through resistor R1 to turn on the third-generation semiconductor device. (Refer to the attached manual.) Figure 6The reverse connection protection control circuit includes resistors R3, R4, R5, R6, R7, and R8, diodes D6, D7, D8, and D9, switching transistors K1 and K2, and capacitor C0. One end of resistor R3 is connected to the control signal MCU, and the other end of resistor R3 is connected to one end of resistor R4 and the control terminal of switching transistor K1. The other ends of resistor R4 and switching transistor K1 are grounded. One end of switching transistor K1 is connected to the cathode of diode D6 through resistor R5, and the anode of diode D6 is connected to a 5V power supply. One end of switching transistor K1 is also connected to the control terminal of switching transistor K2. One end of resistor R6 and the other end of resistor R7 are connected to the power supply. The other end of resistor R7 is grounded. One end of resistor R6 is connected to the cathode of diode D7. The anode of diode D7 is connected to the output terminal of the switching power supply in the fanless electric vehicle charger. Diode D8 is connected in parallel with resistor R7. The other end of switching transistor K2 is grounded. One end of switching transistor K2 is connected to the cathode of diode D9. The anode of diode D9 is connected to one end of resistor R8. The other end of resistor R8 outputs the control signal Vgate of the third-generation semiconductor device in the reverse connection protection circuit to turn off the third-generation semiconductor device. One end of capacitor C0 is connected to the other end of resistor R8. The other end of capacitor C0 is grounded.

[0031] Furthermore, it should be noted that the reverse connection protection circuit and reverse connection protection control circuit constructed from third-generation semiconductor devices proposed in this invention are also applicable to electric vehicle chargers with fans.

[0032] This invention also proposes a control method for a fanless electric vehicle charger based on third-generation semiconductors, applied to the aforementioned control circuit for a fanless electric vehicle charger based on third-generation semiconductors. The control method includes the following steps: S1: Charge the electric vehicle using a fanless electric vehicle charger and detect the DC bus voltage of the fanless electric vehicle charger. S2: Determine whether the DC bus voltage is greater than the first threshold. If the DC bus voltage is greater than the first threshold, execute S3; otherwise, execute S7. S3: The MCU outputs a high level control signal, which uses the reverse connection protection control circuit to turn on the bidirectional GaN switch and execute S4. S4: Detect the temperature of the comparator module. When the temperature of the comparator module is higher than the preset upper temperature threshold, input the second adjustment voltage VB2 into the temperature drift compensation terminal of the comparator module. When the temperature of the comparator module is lower than the preset lower temperature threshold, input the first adjustment voltage VB1 into the temperature drift compensation terminal of the comparator module; and execute S5. S5: Uses an adjustable comparator unit, oscillator unit, logic gate unit and drive signal generation unit to generate drive signals, control the operation of the primary-side switching transistor of the switching power supply in the fanless electric vehicle charger, and adjust the charging current. S6: Detect the output voltage of the auxiliary winding of the fanless electric vehicle charger, determine whether the output voltage of the auxiliary winding is greater than the second threshold, and execute S7 when the output voltage of the auxiliary winding is not greater than the second threshold. S7: When the MCU outputs a low level control signal, the bidirectional GaN switch is turned off using the reverse connection protection control circuit, stopping the charging of the electric vehicle and outputting an alarm signal to remind the electric vehicle that the charging process is abnormal.

[0033] In the above control method, when the DC bus voltage is detected to be no greater than the first threshold, it indicates that the polarity of the charger input power supply is incorrect (reverse connection exists). At this time, the bidirectional GaN switch is turned off, thereby cutting off the input circuit to protect the charger circuit. At the same time, the control terminal level of the bidirectional GaN switch K8 is forcibly pulled low by the switches K9 and K10 to achieve hardware and software shutdown interlocking and ensure the reliable shutdown of the bidirectional GaN switch K8. When the output voltage of the auxiliary winding is detected to be no greater than the second threshold, it indicates that the charger is in standby mode or the charger input power supply voltage is abnormal. At this time, the bidirectional GaN switch is turned off to stop charging. Furthermore, since the bidirectional GaN switch is a unipolar device (essentially without a body diode), it can achieve bidirectional blocking when it is turned off, thereby effectively preventing battery current from flowing back into the charger.

[0034] The embodiments and / or implementation methods described above are merely preferred embodiments and / or implementation methods for implementing the technology of the present invention, and are not intended to limit the implementation methods of the technology of the present invention in any way. Any person skilled in the art can make some modifications or alterations to other equivalent embodiments without departing from the scope of the technical means disclosed in the content of the present invention, but they should still be regarded as the technology or embodiments that are substantially the same as the present invention.

[0035] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. The above descriptions are only preferred embodiments of this application. It should be noted that due to the limitations of written expression, while there are objectively infinite specific structures, those skilled in the art can make several improvements, modifications, or changes without departing from the principles of this application, and can also combine the above technical features in an appropriate manner. These improvements, modifications, changes, or combinations, or the direct application of the inventive concept and technical solution to other situations without modification, should all be considered within the scope of protection of this application.

Claims

1. A fanless electric vehicle charger control circuit based on third generation semiconductor, comprising an anti-reverse connection control circuit, an adjustable comparator unit, an oscillator unit, a logic gate unit and a drive signal generation unit, the anti-reverse connection control circuit is used for connecting a control signal and controlling the third generation semiconductor device in the fanless electric vehicle charger anti-reverse connection circuit to be turned on or turned off according to the control signal. The adjustable comparator unit and the oscillator unit are connected to the logic gate unit, the logic gate unit is connected to the driving signal generation unit, the adjustable comparator unit is used for closed-loop control of the output signal of the switching power supply in the charger, the oscillator unit is used for generating a clock signal, the logic gate unit is used for triggering the driving signal generation unit, and the driving signal generation unit is used for generating a driving signal of the primary side switch tube of the switching power supply in the charger, characterized in that, The adjustable comparator unit comprises a first adjusting voltage generation unit, a second adjusting voltage generation unit, a selection unit and a comparator module, the first adjusting voltage generation unit is used for generating a first adjusting voltage, the second adjusting voltage generation unit is used for generating a second adjusting voltage, and the selection unit is used for inputting the first adjusting voltage or the second adjusting voltage into the temperature drift compensation end of the comparator module according to the temperature data of the adjustable comparator unit, so as to offset the temperature drift of the comparator module.

2. The third-generation semiconductor-based fan-less electric vehicle charger control circuit according to claim 1, wherein, The output end of the adjustable comparator unit is connected with the first input end of the logic gate unit, the output end of the oscillator unit is connected with the second input end of the logic gate unit, the output end of the logic gate unit is connected with one input end of the drive signal generation unit, and the drive signal generation unit is used for generating the drive signal of the switch tube of the switching power supply in the fanless electric vehicle charger.

3. The third-generation semiconductor-based fan-less electric vehicle charger control circuit of claim 2, wherein, The logic gate unit is an AND gate unit.

4. The third-generation semiconductor-based fan-less electric vehicle charger control circuit of claim 2, wherein, The drive signal generation unit comprises a first flip-flop and a second comparator, the S end of the first flip-flop is connected with the output end of the logic gate unit, the R end of the first flip-flop is connected with the output end of the second comparator, the Q end of the first flip-flop outputs the drive signal of the switch tube of the switching power supply in the fanless electric vehicle charger, the first input end of the second comparator is connected with the first end of a current detection resistor, the second end of the current detection resistor is grounded, the current detection resistor is connected with the main switch tube of the switching power supply in series, and the second input end of the second comparator is connected with the output feedback signal end of the switching power supply.

5. The third-generation semiconductor-based fan-less electric vehicle charger control circuit of claim 4, wherein, The first input end of the comparator module is connected with the output feedback signal end of the switching power supply, the second input end of the comparator module is connected with a preset voltage signal, and the output end of the comparator module serves as the output end of the adjustable comparator unit; the comparator module comprises an input signal preprocessing unit, a temperature drift compensation unit and an output processing unit. The input signal preprocessing unit is connected with the temperature drift compensation unit, and the temperature drift compensation unit is connected with the output processing unit. The input signal preprocessing unit includes a first switch tube, a second switch tube, an eighth switch tube, a first transistor and a second transistor, the first end of the first switch tube is connected with a preset voltage VREG, the second end of the first switch tube is connected with the first end of the first transistor, the second end of the first transistor is connected with the first end of the eighth switch tube, the second end of the eighth switch tube is connected with a preset voltage VSS, the first end of the second switch tube is connected with a preset voltage VREG, the second end of the second switch tube is connected with the first end of the second transistor, the second end of the second transistor is connected with the first end of the eighth switch tube, the control end of the first transistor is used as the second input end of the comparator module, the control end of the second transistor is used as the first input end of the comparator module, and the control end of the eighth switch tube is connected with a preset voltage bias signal.

6. The third-generation semiconductor-based fan-less electric vehicle charger control circuit of claim 5, wherein, The temperature drift compensation unit includes a third switch tube, a fourth switch tube, a ninth switch tube, a tenth switch tube, an eleventh switch tube and a twelfth switch tube, the first end of the third switch tube is connected with a preset voltage VREG, the second end of the third switch tube is connected with the first end of the ninth switch tube and the tenth switch tube, the second end of the ninth switch tube is connected with the temperature drift compensation end, the second end of the tenth switch tube is connected with a preset voltage VSS, the first end of the fourth switch tube is connected with a preset voltage VREG, the second end of the fourth switch tube is connected with the first end of the eleventh switch tube and the twelfth switch tube, the second end of the twelfth switch tube is connected with the temperature drift compensation end, the second end of the eleventh switch tube is connected with a preset voltage VSS, the control end of the third switch tube is connected with the control end of the second switch tube, the control end of the fourth switch tube is connected with the control end of the first switch tube, the control end of the tenth switch tube is connected with the second end of the fourth switch tube, and the control end of the eleventh switch tube is connected with the second end of the third switch tube.

7. The third-generation semiconductor-based fan-less electric vehicle charger control circuit of claim 6, wherein, The output processing unit includes a fifth switch tube, a sixth switch tube, a seventh switch tube, a thirteenth switch tube, a fourteenth switch tube and a fifteenth switch tube, the first end of the fifth switch tube is connected with a preset voltage VREG, the second end of the fifth switch tube is connected with the first end of the thirteenth switch tube, the second end of the thirteenth switch tube is connected with a preset voltage VSS, the first end of the sixth switch tube is connected with a preset voltage VREG, the second end of the sixth switch tube is connected with the first end of the fourteenth switch tube, the second end of the fourteenth switch tube is connected with a preset voltage VSS, the first end of the seventh switch tube is connected with a preset voltage VREG, the second end of the seventh switch tube is connected with the first end of the fifteenth switch tube, and the second end of the fifteenth switch tube is connected with a preset voltage VSS. The control end of the fifth switch tube is connected with the second end of the fifth switch tube and the control end of the sixth switch tube, the control end of the thirteenth switch tube is connected with the second end of the fourth switch tube, the control end of the fourteenth switch tube is connected with the second end of the third switch tube, the second end of the sixth switch tube is connected with the control ends of the seventh switch tube and the fifteenth switch tube, and the second end of the seventh switch tube is the output end of the comparator module.

8. The third-generation semiconductor-based fan-less electric vehicle charger control circuit of claim 1, wherein, The third generation semiconductor device in the anti-reverse connection circuit comprises a bidirectional GaN switch tube K8, a switch tube K9, a switch tube K10, a diode D1, a diode D2, a diode D3, a diode D4, a diode D5, a resistor R20 and a resistor R30. The bidirectional GaN switch tube K8 is connected in series in the output positive loop or the output negative loop of the fanless electric vehicle charger switching power supply. One end of the bidirectional GaN switch tube K8 is connected with the anode of the diode D1, the cathode of the diode D1 is connected with the cathode of the diode D2, the anode of the diode D2 is connected with the control end of the bidirectional GaN switch tube K8, the other end of the bidirectional GaN switch tube K8 is connected with the anode of the diode D3, the cathode of the diode D3 is connected with the cathode of the diode D4, the anode of the diode D4 is connected with the control end of the bidirectional GaN switch tube K8, the control end of the bidirectional GaN switch tube K8 is also connected with the other end of the bidirectional GaN switch tube K8 through the series connection of the switch tube K9 and the switch tube K10, the control end of the switch tube K9 is connected with the control end of the switch tube K10 and then grounded through the resistor R30, one end of the resistor R20 is connected with the common end of the switch tube K9 and the switch tube K10, the other end of the resistor R20 is connected with the control end of the switch tube K9, the anode of the diode D5 is connected with the common end of the switch tube K9 and the switch tube K10, and the cathode of the diode D5 is connected with the control end of the switch tube K9.

9. The third-generation semiconductor-based fan-less electric vehicle charger control circuit of claim 8, wherein, The anti-reverse connection control circuit includes a conduction control circuit and an off control circuit. The conduction control circuit includes a photo-coupler U2, a resistor R1 and a resistor R2. One end of the resistor R2 is connected to a control signal MCU, and the other end of the resistor R2 is connected to the pin 1 of the photo-coupler U2. The pin 2 of the photo-coupler U2 is grounded. The pin 3 of the photo-coupler U2 is connected to an auxiliary winding N3 of a switching power supply in the fanless electric vehicle charger. The pin 4 of the photo-coupler U2 outputs a conduction control signal of a third generation semiconductor device in the anti-reverse connection circuit through the resistor R1. The off control circuit includes a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a diode D6, a diode D7, a diode D8, a diode D9, a switch K1, a switch K2 and a capacitor C0. One end of the resistor R3 is connected to the control signal MCU. The other end of the resistor R3 is connected to one end of the resistor R4 and a control end of the switch K1. The other end of the resistor R4 and the other end of the switch K1 are grounded. One end of the switch K1 is connected to the cathode of the diode D6 through the resistor R5. The anode of the diode D6 is connected to a 5V power supply. One end of the switch K1 is also connected to a control end of the switch K2, the other end of the resistor R6 and one end of the resistor R7. The other end of the resistor R7 is grounded. One end of the resistor R6 is connected to the cathode of the diode D7. The anode of the diode D7 is connected to an output end of the switching power supply in the fanless electric vehicle charger. The diode D8 is connected in parallel with the resistor R7. The other end of the switch K2 is grounded. One end of the switch K2 is connected to the cathode of the diode D9. The anode of the diode D9 is connected to one end of the resistor R8. The other end of the resistor R8 outputs an off control signal of the third generation semiconductor device in the anti-reverse connection circuit. One end of the capacitor C0 is connected to the other end of the resistor R8. The other end of the capacitor C0 is grounded.

10. A control method of the fanless electric vehicle charger based on the third generation semiconductor, applied to the control circuit of the fanless electric vehicle charger based on the third generation semiconductor as claimed in any one of claims 1-9, characterized in that, The control method includes the following steps: S1: charging an electric vehicle by using the fanless electric vehicle charger, and detecting a DC bus voltage of the fanless electric vehicle charger; S2: judging whether the DC bus voltage is greater than a first threshold value. When the DC bus voltage is greater than the first threshold value, S3 is executed. Otherwise, S7 is executed; S3: the control signal MCU outputs a high level. The conduction control circuit of the anti-reverse connection control circuit makes the bidirectional GaN switch conductive, and S4 is executed; S4: detecting the temperature of the comparator module. When the temperature of the comparator module is higher than a preset upper temperature threshold value, the second regulating voltage VB2 is input to the temperature drift compensation end of the comparator module. When the temperature of the comparator module is lower than a preset lower temperature threshold value, the first regulating voltage VB1 is input to the temperature drift compensation end of the comparator module, and S5 is executed; S5: generating a driving signal by using the adjustable comparator unit, the oscillator unit, the logic gate unit and the driving signal generation unit, controlling the primary side switch of the switching power supply in the fanless electric vehicle charger to work, and adjusting the charging current; S6: detecting the output voltage of the auxiliary winding of the fanless electric vehicle charger, and judging whether the output voltage of the auxiliary winding is greater than a second threshold value. When the output voltage of the auxiliary winding is not greater than the second threshold value, S7 is executed. S7: the control signal MCU outputs low level, the off control circuit of the anti-reverse connection control circuit makes the bidirectional GaN switch tube off, stops charging the electric vehicle and outputs an alarm signal.

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