WO2023040236A1 - Overvoltage protection circuit, overvoltage protection method, and motor controller - Google Patents

Abstract

Provided are an overvoltage protection circuit, an overvoltage protection method, and a motor controller, relating to the technical field of high voltage. The overvoltage protection circuit comprises a voltage sampling circuit (100), an overvoltage comparison circuit (200), a signal processing circuit (300), and a driving execution circuit (400) which are connected in sequence; the voltage sampling circuit (100) performs voltage sampling on a direct current bus to generate a voltage sampling signal; the overvoltage comparison circuit (200) performs voltage comparison on the voltage sampling signal and a first reference voltage, and generates an overvoltage signal when the sampling voltage of the voltage sampling signal is larger than or equal to the first reference voltage; the signal processing circuit (300) performs signal processing according to the overvoltage signal, and generates an enable signal and an active short-circuit signal; and the driving execution circuit (400) controls the motor controller to enter a safe state according to the enable signal and the active short-circuit signal.

Description

Overvoltage protection circuit, overvoltage protection method and motor controller

This application claims the priority of Chinese Patent Application No. 202111096382.9 filed on September 17, 2021, the entire contents of which are hereby incorporated by reference.

technical field

The present application relates to the field of high voltage technology, in particular to an overvoltage protection circuit, an overvoltage protection method and a motor controller.

Background technique

When the vehicle is running at high speed and the main contactor of the battery is disconnected abnormally, the voltage at both ends of the DC bus capacitor connected to the drive motor controller will be overvoltage due to the impact of the back electromotive force of the permanent magnet synchronous motor. The phenomenon will be aggravated with the increase of the back EMF of the motor and the increase of the power generation. When the overvoltage occurs, it is necessary to adopt overvoltage protection to avoid equipment damage or safety accidents.

At present, the driving motor controller usually needs to switch from the normal operation mode to the safe mode within tens of microseconds to hundreds of microseconds, and the operating time of the existing hardware overvoltage protection scheme is tens of microseconds to hundreds of microseconds. However, when the back EMF of the permanent magnet synchronous motor is much higher than the withstand voltage value of the internal high-voltage components of the drive motor control system or the power generated by the vehicle is large, the drive motor controller needs to switch from the normal operation mode to the safe mode in a shorter time .

The above content is only used to assist in understanding the technical solution of the present application, and does not mean that the above content is admitted as prior art.

technical problem

The main purpose of this application is to provide an overvoltage protection circuit, an overvoltage protection method and a motor controller, aiming to solve the technical problem that the prior art cannot effectively guarantee the high voltage safety of the high voltage components inside the drive motor controller.

technical solution

In order to achieve the above purpose, the application provides an overvoltage protection circuit, the overvoltage protection circuit includes a voltage sampling circuit, an overvoltage comparison circuit, a signal processing circuit and a drive execution circuit connected in sequence;

The voltage sampling circuit is configured to perform voltage sampling on the DC bus to generate a voltage sampling signal;

The overvoltage comparison circuit is configured to compare the voltage sampling signal with a first reference voltage, and generate an overvoltage signal when the sampling voltage of the voltage sampling signal is greater than or equal to the first reference voltage;

The signal processing circuit is configured to perform signal processing according to the overvoltage signal to generate an enable signal and an active short circuit signal;

The driving execution circuit is configured to control the motor controller to enter a safe state according to the enabling signal and the active short-circuit signal;

The voltage sampling circuit is configured to perform voltage sampling on the DC bus to generate a voltage sampling signal;

The overvoltage comparison circuit is configured to compare the voltage sampling signal with a first reference voltage, and generate an overvoltage signal when the sampling voltage of the voltage sampling signal is greater than or equal to the first reference voltage;

The signal processing circuit is configured to perform signal processing according to the overvoltage signal to generate an enable signal and an active short circuit signal;

The drive execution circuit is configured to control the motor controller to enter a safe state according to the enable signal and the active short-circuit signal.

In one embodiment, the signal processing circuit includes a digital isolation circuit and a logic inversion circuit connected in parallel;

The digital isolation circuit is configured to perform signal processing according to the overvoltage signal to generate an enable signal;

The logic negation circuit is configured to perform signal processing according to the overvoltage signal to generate an active short circuit signal.

In one embodiment, the logic negation circuit includes a switch tube;

The control end of the switch tube is connected to the overvoltage comparison circuit, the first end of the switch tube is connected to the power supply, and the second end of the switch tube is connected to the DC bus.

In an implementation manner, the logic inversion circuit further includes a delay circuit.

In one embodiment, the delay circuit includes a first resistor and a first capacitor;

The first end of the first resistor is connected to the overvoltage comparison circuit, the second end of the first resistor is connected to the control end of the switch tube; the first end of the second capacitor is connected to the first The second end of a resistor is connected, and the second end of the second capacitor is connected with the second end of the switch tube.

In one embodiment, the overvoltage signal input end of the digital isolation circuit and the overvoltage signal input end of the logic negation circuit are respectively connected to the overvoltage signal output end of the overvoltage comparison circuit, and the digital isolation circuit The low-voltage-side enable signal output end of the circuit is connected to the low-voltage-side enable signal input end of the drive execution circuit, and the high-voltage-side enable signal output end of the logic inversion circuit is respectively connected to the high-voltage side enable signal of the drive execution circuit. can be connected to the signal input terminal.

In addition, in order to achieve the above purpose, the present application also provides an overvoltage protection method, the overvoltage protection method is applied to the above-mentioned overvoltage protection circuit, and the overvoltage protection circuit includes: a voltage sampling circuit, an overvoltage Comparing circuit, signal processing circuit and driving execution circuit;

The overvoltage protection method includes:

The voltage sampling circuit performs voltage sampling on the DC bus to generate a voltage sampling signal;

The overvoltage comparison circuit compares the voltage sampling signal with a first reference voltage, and generates an overvoltage signal when the sampling voltage of the voltage sampling signal is greater than or equal to the first reference voltage;

The signal processing circuit performs signal processing according to the overvoltage signal to generate an enable signal and an active short circuit signal;

The drive execution circuit controls the motor controller to enter a safe state according to the enable signal and the active short circuit signal.

In one embodiment, the drive execution circuit controls the motor controller to enter a safe state according to the enable signal and the active short-circuit signal, including:

When the sampling voltage is greater than the first reference voltage, the drive execution circuit controls all the bridge arms of the motor controller to be turned off according to the enable signal, and according to the preset time delay of the active short-circuit signal time, controlling the conduction of the upper bridge arm or the lower bridge arm of the motor controller;

During the process of the sampling voltage dropping from the first reference voltage to the second reference voltage, the upper bridge arm or the lower bridge arm of the motor controller is kept turned on.

In an embodiment, after the upper bridge arm or the lower bridge arm of the motor controller is kept turned on during the process of the sampling voltage dropping from the first reference voltage to the second reference voltage, it includes:

When the sampling voltage is lower than the second reference voltage, all the bridge arms of the motor controller are controlled to be turned off according to the enabling signal, and the motor controller is controlled according to the preset delay time of the active short-circuit signal. The upper or lower bridge arm of the motor controller is turned off;

During the process of the sampling voltage rising from the second reference voltage to the first reference voltage, all bridge arms of the motor controller are kept turned off.

In addition, in order to achieve the above purpose, the present application also provides a motor controller, the motor controller includes the above-mentioned overvoltage protection circuit, or is applied to the above-mentioned overvoltage protection method.

Beneficial effect

The overvoltage protection circuit of the present application includes a voltage sampling circuit, an overvoltage comparison circuit, a signal processing circuit, and a drive execution circuit connected in sequence. The voltage sampling circuit performs voltage sampling on the DC bus to generate a voltage sampling signal, and the overvoltage comparison circuit converts the voltage sampling signal Perform voltage comparison with the first reference voltage, generate an overvoltage signal when the sampling voltage of the voltage sampling signal is greater than or equal to the first reference voltage, and the signal processing circuit performs signal processing according to the overvoltage signal to generate an enable signal and an active short circuit signal, The drive execution circuit controls the motor controller to enter a safe state according to the enable signal and the active short circuit signal. In the present application, by sampling the voltage of the DC bus, when the sampling voltage of the voltage sampling signal exceeds the first reference voltage, the driving motor control system is controlled to enter a safe state, so as to realize fast hardware overvoltage protection only through hardware.

Description of drawings

FIG. 1 is a schematic structural diagram of the first embodiment of the overvoltage protection circuit of the present application;

FIG. 2 is a schematic structural diagram of the second embodiment of the overvoltage protection circuit of the present application;

Fig. 3 is the circuit diagram of an embodiment of the overvoltage protection circuit of the present application;

4 is a schematic flow diagram of an embodiment of the overvoltage protection circuit of the present application;

FIG. 5 is a logic diagram of safe state mode switching in an embodiment of the overvoltage protection method of the present application.

Explanation of reference numbers:

label	name	label	name
100	voltage sampling circuit	300	signal processing circuit
200	Overvoltage comparator circuit	400	drive execution circuit
R1~R6	1st~6th resistor	101	first divider unit
C1~C2	1st ~ 2nd capacitance	102	second voltage divider unit
HVDC_P	DC bus high voltage positive terminal	301	digital isolation circuit
HVDC_N	DC bus high voltage negative terminal	302	logic negation circuit
Vref	reference voltage	CP1	Digital Isolation Chip
Safe state	security status	CP2	driver chip
ASC	active short circuit	T1	Triode
Freewheeling	freewheeling state	A1	Comparators
U1	first reference voltage	VDD	Power supply
U2	second reference voltage	Udc	DC bus voltage

The realization, functional features and advantages of the present application will be further described in conjunction with the embodiments and with reference to the accompanying drawings.

Embodiments of the present invention

It should be understood that the specific embodiments described here are only used to explain the present application, not to limit the present application.

An embodiment of the present application provides an overvoltage protection circuit. Referring to FIG. 1 , FIG. 1 is a schematic structural diagram of a first embodiment of the overvoltage protection circuit of the present application.

The overvoltage protection circuit includes a voltage sampling circuit 100 , an overvoltage comparison circuit 200 , a signal processing circuit 300 and a drive execution circuit 400 connected in sequence.

It should be noted that the voltage sampling terminal of the voltage sampling circuit 100 is connected to the high-voltage electrode terminal of the DC bus, the voltage sampling signal output terminal of the voltage sampling circuit 100 is connected to the voltage sampling signal input terminal of the overvoltage comparison circuit 200, and the overvoltage comparison The overvoltage signal output end of the circuit 200 is connected to the overvoltage signal input end of the signal processing circuit 300, and the enable signal output end of the signal processing circuit 300 is connected to the enable signal input end of the drive execution circuit 400, and the control of the drive execution circuit 400 The terminal is connected with the control terminal of the drive motor control system.

It is easy to understand that when high-speed power generation occurs and the battery main contactor is abnormally disconnected, the overvoltage protection circuit controls the drive motor control system, and can switch from the normal operation mode to the safe state (active short circuit state) within ten microseconds ), quickly cut off the energy transfer circuit between the permanent magnet synchronous motor and the high-voltage DC bus, and control the voltage on both sides of the high-voltage DC bus within the withstand voltage range of the high-voltage components to meet the high-voltage safety target of the vehicle.

The voltage sampling circuit 100, the voltage sampling circuit, is configured to perform voltage sampling on the DC bus to generate a voltage sampling signal.

It should be understood that the voltage sampling circuit 100 can sample the voltage of the DC bus by means of resistance voltage division, the voltage sampling signal can include the sampled voltage of the DC bus, that is, the voltage sampling result, and the voltage division resistance can be determined according to the voltage level of the DC bus. It is determined to ensure the safe use of the overvoltage protection circuit while realizing accurate voltage sampling.

The overvoltage comparison circuit 200 is configured to compare the voltage sampling signal with a first reference voltage, and generate an overvoltage signal when the sampling voltage of the voltage sampling signal is greater than or equal to the first reference voltage.

It can be understood that the overvoltage comparison circuit 200 may first filter the voltage sampling signal to remove redundant clutter in the sampling process, and then compare the sampling voltage in the filtered voltage sampling signal with the provided first reference voltage , the first reference voltage may be the minimum value within the withstand voltage range of the internal high-voltage components of the drive motor controller.

It is easy to understand that, through voltage comparison, when the sampling voltage of the DC bus is greater than or equal to the first reference voltage, the overvoltage signal generated by the overvoltage comparison circuit 200 can be a low-level signal, and when the signal is low, it indicates that an overvoltage has occurred Correspondingly, when the sampling voltage does not exceed the first reference voltage, the overvoltage signal generated by the overvoltage comparison circuit 200 can be a high-level signal. When the signal is high, it indicates that the overvoltage fault has not occurred or the overvoltage fault has disappeared.

The signal processing circuit 300 is configured to perform signal processing according to the overvoltage signal to generate an enable signal and an active short circuit signal.

It can be understood that the signal processing circuit 300 can perform signal isolation or logic inversion on the overvoltage signal. When the generated enable signal acts on the low-voltage side of the drive execution circuit 400, if the enable signal is a high-level signal, the drive execution circuit 400 can be enabled, so that the drive execution circuit 400 performs pulse width modulation transmission, If the enable signal is a low-level signal, the driving execution circuit 400 can be turned off, thereby prohibiting the driving execution circuit 400 from performing pulse width modulation transmission.

It should be understood that, by inverting the logic of the overvoltage signal, when the generated active short circuit signal acts on the high voltage side of the driving execution circuit 400 , the driving execution circuit 400 can output a high level. The priority of the high-voltage-side active short-circuit signal (high-voltage-side enable signal) is higher than that of the low-voltage-side enable signal.

The driving execution circuit 400 is configured to control the motor controller to enter a safe state according to the enable signal and the active short circuit signal.

It is easy to understand that the drive execution circuit 400 can first make its own enable pin in a low-level invalid state according to the enable signal on the low-voltage side, and then control the drive motor control system to enter a safe state according to the active short-circuit signal on the high-voltage side. Before exceeding the maximum value in the withstand voltage range of the internal high-voltage components of the drive motor controller, it enters a safe state within ten microseconds, realizing fast hardware overvoltage protection.

The overvoltage protection circuit of this embodiment includes a voltage sampling circuit 100, an overvoltage comparison circuit 200, a signal processing circuit 300, and a drive execution circuit 400 connected in sequence. The voltage sampling circuit 100 performs voltage sampling on the DC bus to generate a voltage sampling signal. The comparison circuit 200 compares the voltage sampling signal with the first reference voltage, and generates an overvoltage signal when the sampling voltage of the voltage sampling signal is greater than or equal to the first reference voltage, and the signal processing circuit 300 performs signal processing according to the overvoltage signal to generate The enable signal and the active short-circuit signal, the drive execution circuit 400 controls the motor controller to enter a safe state according to the enable signal and the active short-circuit signal. In the present application, by sampling the voltage of the DC bus, when the sampling voltage of the voltage sampling signal exceeds the first reference voltage, the driving motor control system is controlled to enter a safe state, so as to realize fast overvoltage protection only through hardware.

Based on the first embodiment of the present application, the second embodiment of the overvoltage protection circuit of the present application is proposed. Referring to FIG. 2 and FIG. 3, FIG. 2 is a schematic structural diagram of the second embodiment of the overvoltage protection circuit of the present application, and FIG. A schematic circuit diagram of an embodiment of an overvoltage protection circuit.

In the second embodiment, the voltage sampling circuit 100 includes a first voltage dividing unit 101 and a second voltage dividing unit 102 .

The voltage input terminal of the first voltage dividing unit 101 is connected to the high voltage positive terminal of the DC bus, the voltage input terminal of the second voltage dividing unit 102 is connected to the high voltage negative terminal of the DC bus, and the first The voltage output terminal of the voltage dividing unit 101 and the voltage output terminal of the second voltage dividing unit 102 are respectively connected to the voltage sampling signal input terminal of the overvoltage comparison circuit 200 .

It should be understood that both the first voltage dividing unit 101 and the second voltage dividing unit 102 include several voltage dividing resistors, and the number of voltage dividing resistors is determined by the DC bus voltage level. The first voltage dividing unit 101 and the second voltage dividing unit 101 The voltage dividing resistors in the unit 102 can be set to the same number or different numbers.

It is easy to understand that HVDC_P is the positive high voltage terminal of the DC bus, and HVDC_N is the negative high voltage terminal of the DC bus. The voltage comparison circuit 200, the voltage sampling signal may include the sampling voltage of the DC bus, that is, the voltage sampling result, so as to ensure the safe use of the overvoltage protection circuit while realizing accurate voltage sampling.

In the second embodiment, the overvoltage comparison circuit 200 includes a third resistor R3, a second capacitor C2 and a comparator A1.

The first end of the third resistor R3 is connected to the voltage sampling signal output end of the voltage sampling circuit 100, and the second end of the third resistor R3 is respectively connected to the first end of the second capacitor C2 and the The negative input terminal of the comparator A1 is connected to the ground, the second terminal of the second capacitor C2 is connected to the ground, and the output terminal of the comparator A1 is connected to the overvoltage signal input terminal of the signal processing circuit 300 .

It should be noted that the voltage sampling signal is sent to the negative input terminal of the comparator A1 after filtering, the reference voltage can be input from the positive input terminal of the comparator A1, and the voltage value of the reference voltage can be the first reference voltage, that is, the drive motor controller The comparator A1 compares the sampled voltage in the filtered voltage sampling signal with the provided reference voltage, and outputs the overvoltage signal, that is, the comparison result, to the signal processing circuit 300 .

It is easy to understand that the third resistor R3 and the second capacitor C2 filter the voltage sampling signal. When the sampling voltage of the DC bus is greater than or equal to the first reference voltage, the overvoltage signal generated by the overvoltage comparator circuit 200 can be a low-level signal. When the signal is low, it indicates that an overvoltage fault has occurred. Correspondingly, when the sampling voltage does not exceed When the first reference voltage is used, the overvoltage signal generated by the overvoltage comparator circuit 200 can be a high-level invalid signal. When the signal is high, it means that no overvoltage fault occurs or the overvoltage fault has disappeared.

In the second embodiment, the signal processing circuit 300 includes a digital isolation circuit 301 and a logic negation circuit 302 connected in parallel.

The digital isolation circuit 301 is configured to perform signal processing according to the overvoltage signal to generate an enabling signal.

The logic negation circuit 302 is configured to perform signal processing according to the overvoltage signal to generate an active short circuit signal.

The overvoltage signal input end of the digital isolation circuit 301 and the overvoltage signal input end of the logic negation circuit 302 are respectively connected to the overvoltage signal output end of the overvoltage comparison circuit 200, and the digital isolation circuit 301 The low voltage side enable signal output end is connected to the low voltage side enable signal input end of the drive execution circuit 400, and the high voltage side enable signal output end of the logic inversion circuit 302 is respectively connected to the high voltage side of the drive execution circuit 400. Enable signal input connection.

Further, the low voltage side enable signal output end of the digital isolation circuit 301 is respectively connected to the upper bridge wall low voltage side enable signal input end and the lower bridge wall low voltage side enable signal input end of the drive execution circuit, and the high voltage side of the logic inversion circuit 302 The side enable signal output end is connected to the active short-circuit signal input end of the upper bridge wall high-voltage side or the active short-circuit signal input end of the lower bridge wall high-voltage side of the drive execution circuit.

It is easy to understand that the digital isolation circuit 301 can be set to digitally isolate the overvoltage signal to generate an enable signal for driving the low-voltage side of the execution circuit 400, and the logic negation circuit 302 can be set to perform logic takeover according to the overvoltage signal. Conversely, to generate an active short-circuit signal acting on the high-voltage side of the drive execution circuit 400, first the enable signal on the low-voltage side can make the enable pin of the drive execution circuit 400 be in a low-level inactive state, and then the drive execution circuit 400 according to the high-voltage side The active short-circuit signal controls the drive motor control system to enter a safe state, wherein the priority of the active short-circuit signal at the high-voltage side is higher than that of the enable signal at the low-voltage side.

The digital isolation circuit 301 includes a digital isolation chip CP1.

The overvoltage signal input end of the digital isolation chip CP1 is connected to the overvoltage signal output end of the overvoltage comparison circuit 200, and the low voltage side enable signal output end of the digital isolation chip CP1 is respectively connected to the upper bridge of the drive execution circuit. The enable signal input terminal of the low-voltage side of the wall is connected to the enable signal input terminal of the low-voltage side of the lower bridge wall, and the enable signal is active at high level.

It should be understood that the digital isolation circuit 301 may include a digital isolation chip CP1 and peripheral circuits of the digital isolation chip CP1, the peripheral circuits assist the operation of the digital isolation chip CP1, and the digital isolation chip CP1 has a digital isolation function. The enable signal generated by the digital isolation chip CP1 can act on the low-voltage side of the drive execution circuit 400. If the enable signal is a high-level signal, the drive execution circuit 400 can be enabled, so that the drive execution circuit 400 performs pulse width modulation. For wave generation, if the enable signal is a low-level signal, the drive execution circuit 400 can be turned off, thereby prohibiting the drive execution circuit 400 from performing pulse width modulation wave generation.

In the second embodiment, the logic inversion circuit includes a switch tube; the control terminal of the switch tube is connected to the overvoltage comparison circuit, the first end of the switch tube is connected to the power supply, and the switch tube The second terminal is connected to the DC bus.

The logic negation circuit also includes a delay circuit; the delay circuit includes a first resistor and a first capacitor;

The first end of the first resistor is connected to the overvoltage comparison circuit, the second end of the first resistor is connected to the control end of the switch tube; the first end of the second capacitor is connected to the first The second end of a resistor is connected, and the second end of the second capacitor is connected with the second end of the switch tube.

In a specific implementation, the logical inversion circuit 302 includes a first resistor R1, a first capacitor C1, a second resistor R2 and a transistor T1, the switch tube may be the transistor T1, and the DC bus provides the output voltage of the power supply.

The first terminal of the first resistor R1 is connected to the overvoltage signal output terminal of the overvoltage comparator circuit 200, and the second terminal of the first resistor R1 is respectively connected to the first terminal of the first capacitor C1 and the The base of the triode T1 is connected, the emitter of the triode T1 and the second end of the first capacitor C1 are respectively grounded, the first end of the second resistor R2 is connected to the voltage output end of the power supply, and the The second end of the second resistor R2 is connected to the collector of the triode T1 , and the collector of the triode T1 is connected to the high voltage side enabling signal input end of the driving execution circuit 400 .

It can be understood that the overvoltage signal is sent to the base of the transistor T1 after being filtered and delayed, and after the logic is reversed, the active short circuit signal on the high voltage side is sent to the upper three bridges (or the lower three bridges) to drive the actuator circuit 400 on the high voltage side. When the active short-circuit signal generated by the logic inversion circuit 302 acts on the high voltage side of the driving execution circuit 400, the driving execution circuit 400 can output a high level. Among them, the first resistor R1 and the first capacitor C1 filter and briefly delay the overvoltage signal, the purpose of which is to ensure that when the high voltage side enable signal is active, the low voltage side enable signal is already at low level, thereby prohibiting the drive The execution circuit 400 executes pulse width modulation wave generation, so as to prevent the through-through damage of the upper and lower bridge switch tubes. The second resistor R2 is the collector current limiting resistor of the triode T1, and the power supply provides the power supply voltage for the triode T1.

In a specific implementation, the overvoltage comparison circuit 200 further includes a fourth resistor R4, a fifth resistor R5 and a sixth resistor R6.

The first terminal of the fourth resistor R4 is connected to the voltage output terminal of the reference voltage source, and the second terminal of the fourth resistor R4 is respectively connected to the positive input terminal of the comparator A1 and the first terminal of the fifth resistor R5. One end is connected, the second end of the fifth resistor R5 is connected to the output end of the comparator A1, the first end of the sixth resistor R6 is connected to the voltage output end of the power supply, and the sixth resistor R6 The second terminal of is connected to the output terminal of the comparator A1.

It can be understood that Vref is a reference voltage, and the reference voltage output by the reference voltage source is connected to the positive input terminal of the comparator A1 through the fourth resistor R4, and the fourth resistor R4 and the fifth resistor R5 jointly determine the threshold voltage range of the comparator A1 value. VDD is the power supply, and the output power supply voltage of the power supply is connected to the output terminal of the comparator A1 through the sixth resistor R6, and the sixth resistor R6 is a pull-up resistor at the output terminal of the comparator A1.

In the second embodiment, the driving execution circuit 400 includes a driving chip CP2.

The enabling signal input end of the driving chip CP2 is connected to the enabling signal output end of the signal processing circuit 300 , and the control end of the driving chip CP2 is connected to the control end of the driving motor control system.

It is easy to understand that when an overvoltage fault occurs, the drive chip CP2 of all bridge arms first makes all the enable pins in a low-level inactive state according to the low-voltage side enable signal, and the drive chip CP2 prohibits the low-voltage side pulse width modulation transmission. Wave command, and then control the drive motor control system to enter a safe state according to the enable signal on the high-voltage side. Before the DC bus voltage exceeds the maximum value in the withstand voltage range of the internal high-voltage components of the drive motor controller, it will enter the safe state within ten microseconds, realizing fast Hardware overvoltage protection.

In this embodiment, when the vehicle is running at high speed and the battery main contactor is abnormally disconnected, according to the DC bus voltage threshold and slope change rule, the control system of the driving motor can quickly enter an accurate safe state, so as to ensure the DC bus in the whole process. The voltage is always lower than the maximum value of the withstand voltage range of the internal high-voltage device of the drive motor controller, which finally meets the high-voltage safety target of the vehicle and ensures the safety of people and vehicles. The cost of the overvoltage protection circuit is low, and the control logic is simple and clear, with high Sampling and control accuracy, strong reliability, and fast response speed can meet the rapid overvoltage protection of different permanent magnet synchronous motor back EMF and power generation systems.

Further, the embodiment of the present application also provides an overvoltage protection method. Referring to FIG. 4, FIG. 4 is a schematic flow chart of an embodiment of the overvoltage protection method of the present application. A voltage protection circuit, the overvoltage protection circuit includes: a voltage sampling circuit, an overvoltage comparison circuit, a signal processing circuit and a drive execution circuit.

In this embodiment, the overvoltage protection method includes the following steps:

Step S10: the voltage sampling circuit performs voltage sampling on the DC bus to generate a voltage sampling signal.

It is easy to understand that when high-speed power generation occurs and the battery main contactor is abnormally disconnected, the overvoltage protection circuit controls the drive motor control system, and can switch from the normal operation mode to the safe state (active short circuit state) within ten microseconds ), quickly cut off the energy transfer circuit between the permanent magnet synchronous motor and the high-voltage DC bus, and control the voltage on both sides of the high-voltage DC bus within the withstand voltage range of the high-voltage components to meet the high-voltage safety target of the vehicle.

It should be understood that the voltage sampling circuit can sample the voltage of the DC bus by means of resistor division, and the voltage sampling signal can include the sampled voltage of the DC bus, that is, the voltage sampling result, and the voltage division resistance can be determined according to the voltage level of the DC bus , to ensure the safe use of the overvoltage protection circuit while realizing accurate voltage sampling.

Step S20: The overvoltage comparison circuit compares the voltage sampling signal with a first reference voltage, and generates an overvoltage signal when the sampling voltage of the voltage sampling signal is greater than or equal to the first reference voltage.

It can be understood that the overvoltage comparison circuit may first filter the voltage sampling signal to remove redundant clutter in the sampling process, and then compare the sampling voltage in the filtered voltage sampling signal with the provided first reference voltage, The first reference voltage may be the minimum value within the withstand voltage range of the internal high-voltage components of the drive motor controller.

It is easy to understand that, through voltage comparison, when the sampling voltage of the DC bus is greater than or equal to the first reference voltage, the overvoltage signal generated by the overvoltage comparison circuit can be a low-level signal, and when the signal is low, it indicates that an overvoltage fault has occurred Correspondingly, when the sampling voltage does not exceed the first reference voltage, the overvoltage signal generated by the overvoltage comparison circuit may be a high-level signal, and when the signal is high, it indicates that no overvoltage fault has occurred or the overvoltage fault has disappeared.

Step S30: The signal processing circuit performs signal processing according to the overvoltage signal to generate an enable signal and an active short circuit signal.

It can be understood that the signal processing circuit can perform signal isolation or logic inversion on the overvoltage signal. When the generated enable signal acts on the low-voltage side of the drive execution circuit, if the enable signal is a high-level signal, the drive execution circuit can be enabled, so that the drive execution circuit performs pulse width modulation. If the signal is a low-level signal, the drive execution circuit can be turned off, thereby prohibiting the drive execution circuit from executing pulse width modulation and sending waves.

It should be understood that, by inverting the logic of the overvoltage signal, when the generated active short-circuit signal acts on the high voltage side of the drive execution circuit, the drive execution circuit can output a high level. The priority of the high-voltage-side active short-circuit signal (high-voltage-side enable signal) is higher than that of the low-voltage-side enable signal.

Step S40: the driving execution circuit controls the motor controller to enter a safe state according to the enabling signal and the active short circuit signal.

It is easy to understand that the drive execution circuit can first make its own enable pin in a low-level invalid state according to the enable signal on the low-voltage side, and then control the drive motor control system to enter a safe state according to the active short-circuit signal on the high-voltage side. Before the maximum value in the withstand voltage range of the internal high-voltage components of the drive motor controller, it enters a safe state within ten microseconds, realizing fast hardware overvoltage protection.

Further, the step S40 includes: when the sampling voltage is greater than the first reference voltage, the driving execution circuit controls all the bridge arms of the motor controller to be turned off according to the enabling signal, and according to the The preset delay time of the active short-circuit signal controls the conduction of the upper bridge arm or the lower bridge arm of the motor controller.

During the process of the sampling voltage dropping from the first reference voltage to the second reference voltage, the upper bridge arm or the lower bridge arm of the motor controller is kept turned on.

After the step S40, it includes: when the sampling voltage is lower than the second reference voltage, controlling all the bridge arms of the motor controller to be turned off according to the enabling signal, and controlling all bridge arms of the motor controller to be turned off according to the active short circuit signal. A delay time is set to control the upper bridge arm or the lower bridge arm of the motor controller to be turned off.

During the process of the sampling voltage rising from the second reference voltage to the first reference voltage, all bridge arms of the motor controller are kept turned off.

It should be noted that, as shown in FIG. 5 , FIG. 5 is a logic diagram of safe state mode switching in an embodiment of the overvoltage protection circuit of the present invention. A voltage sampling signal is measured on the DC bus. When the sampling voltage in the voltage sampling signal is greater than or equal to U1 (the first reference voltage), the overvoltage signal is at a low level, which first passes isolation and then makes the low voltage side enable pins of the drive chip CP2 of all bridge arms at a low level Ping invalid mode, at the same time, after a short delay and logic inversion, it is sent to the enable pin of the high-voltage side of the driver chip CP2 of the upper three bridges (or the lower three bridges), and the drive motor controller immediately enters the safe state, that is, the ASC state (active short circuit state ), when the sampling voltage drops from U1 to U2 (from the first reference voltage to the second reference voltage), the drive motor controller will remain in the ASC state; when the sampling voltage is less than or equal to U2, the overvoltage signal is High level, after isolation, the low-voltage side enable pins of the drive chip CP2 of all bridge arms are in high-level active mode (at this time, the drive chip CP2 should prohibit sending pulse width modulation wave commands to prevent the drive from the upper and lower bridges to pass through ), at the same time, the overvoltage signal is sent to the enable pin of the high-voltage side of the driver chip CP2 of the upper three bridges (or the lower three bridges) after a short delay and logic inversion, and the drive motor controller immediately exits the ASC state and enters the Freewheeling state to continue In the current state, when the DC bus voltage rises from U2 to U1 (the second reference voltage rises to the first reference voltage), the motor controller will remain in the Freewheeling state of the safe state. At this point, the safe state mode will follow the DC bus It can be switched arbitrarily due to voltage changes and has strong anti-interference ability. Among them, Safe state represents the safe state, Udc represents the DC bus voltage, U1 and U2 of the DC bus voltage can be two different reference voltages at both ends of the DC bus capacitor of the drive motor controller, and the amplitude of the DC bus voltage U1 is greater than or equal to the DC The amplitude of the bus voltage U2; the threshold width between the DC bus voltage U1 and the DC bus voltage U2 can be adjusted by changing the resistance values of the second resistor R2 and the third resistor R3.

In this embodiment, the voltage sampling circuit performs voltage sampling on the DC bus to generate a voltage sampling signal. The overvoltage comparison circuit compares the voltage sampling signal with the first reference voltage. When the sampling voltage of the voltage sampling signal is greater than or equal to the first reference voltage When the overvoltage signal is generated, the signal processing circuit performs signal processing according to the overvoltage signal to generate an enable signal and an active short circuit signal, and the drive execution circuit controls the motor controller to enter a safe state according to the enable signal and the active short circuit signal. In this embodiment, by performing voltage sampling on the DC bus, when the sampling voltage of the voltage sampling signal exceeds the first reference voltage, the driving motor control system is controlled to enter a safe state, thereby realizing fast hardware overvoltage protection.

In addition, the embodiment of the present application also provides a motor controller, the motor controller includes the above-mentioned overvoltage protection circuit, or is applied to the above-mentioned overvoltage protection method.

Since the motor controller adopts all the technical solutions of the above-mentioned embodiments, it has at least all the functions brought by the technical solutions of the above-mentioned embodiments, and will not repeat them here.

It should be understood that the above is only an example, and does not constitute any limitation to the technical solution of the present application. In a specific application, those skilled in the art can make settings according to needs, and the present application does not limit this.

It should be noted that the workflow described above is only illustrative and does not limit the scope of protection of this application. In practical applications, those skilled in the art can select part or all of them to implement according to actual needs. The purpose of the scheme of this embodiment is not limited here.

In addition, for technical details that are not described in detail in this embodiment, refer to the overvoltage protection circuit, overvoltage protection method, and motor controller provided in any embodiment of the present application, and will not be repeated here.

Furthermore, it should be noted that in this document, the term "comprises", "comprises" or any other variation thereof is intended to cover a non-exclusive inclusion such that a process, method, article or system comprising a set of elements includes not only those elements, but also other elements not expressly listed, or elements inherent in such a process, method, article, or system. Without further limitations, an element defined by the phrase "comprising a..." does not preclude the presence of additional identical elements in the process, method, article or system comprising that element.

The serial numbers of the above embodiments of the present application are for description only, and do not represent the advantages and disadvantages of the embodiments.

Through the description of the above embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus a necessary general-purpose hardware platform, and of course also by hardware, but in many cases the former is better implementation. Based on this understanding, the technical solution of the present application can be embodied in the form of a software product in essence or the part that contributes to the prior art, and the computer software product is stored in a storage medium (such as a read-only memory (Read-only memory) Only Memory, ROM)/RAM, magnetic disk, optical disk), including several instructions to enable a terminal device (which can be a mobile phone, computer, server, or network device, etc.) to execute the methods described in various embodiments of this application.

The above are only optional embodiments of the application, and are not intended to limit the patent scope of the application. Any equivalent structure or equivalent process transformation made by using the specification and drawings of the application, or directly or indirectly used in other related technologies fields, are all included in the scope of patent protection of this application in the same way.

Claims (10)

1. An overvoltage protection circuit, wherein the overvoltage protection circuit includes a voltage sampling circuit, an overvoltage comparison circuit, a signal processing circuit, and a drive execution circuit connected in sequence;

   The voltage sampling circuit is configured to perform voltage sampling on the DC bus to generate a voltage sampling signal;

   The overvoltage comparison circuit is configured to compare the voltage sampling signal with a first reference voltage, and generate an overvoltage signal when the sampling voltage of the voltage sampling signal is greater than or equal to the first reference voltage;

   The signal processing circuit is configured to perform signal processing according to the overvoltage signal to generate an enable signal and an active short circuit signal;

   The drive execution circuit is configured to control the motor controller to enter a safe state according to the enable signal and the active short-circuit signal.
2. The overvoltage protection circuit according to claim 1, wherein the signal processing circuit comprises a digital isolation circuit and a logic negation circuit connected in parallel;

   The digital isolation circuit is configured to perform signal processing according to the overvoltage signal to generate an enabling signal;

   The logic negation circuit is configured to perform signal processing according to the overvoltage signal to generate an active short circuit signal.
3. The overvoltage protection circuit according to claim 2, wherein the logic negation circuit comprises a switch tube;

   The control end of the switch tube is connected to the overvoltage comparison circuit, the first end of the switch tube is connected to the power supply, and the second end of the switch tube is connected to the DC bus.
4. The overvoltage protection circuit according to claim 3, wherein the logic inversion circuit further comprises a delay circuit.
5. The overvoltage protection circuit according to claim 4, wherein the delay circuit comprises a first resistor and a first capacitor;

   The first end of the first resistor is connected to the overvoltage comparison circuit, the second end of the first resistor is connected to the control end of the switch tube; the first end of the second capacitor is connected to the first The second end of a resistor is connected, and the second end of the second capacitor is connected with the second end of the switch tube.
6. The overvoltage protection circuit according to claim 2, wherein the overvoltage signal input terminal of the digital isolation circuit and the overvoltage signal input terminal of the logic negation circuit are respectively connected with the overvoltage signal of the overvoltage comparison circuit The output terminal of the low-voltage side of the digital isolation circuit is connected to the input terminal of the low-voltage side enabling signal of the drive execution circuit, and the output terminal of the high-voltage side of the logic inversion circuit is respectively connected to the The high-voltage side enable signal input terminal of the above-mentioned drive execution circuit is connected.
7. An overvoltage protection method, wherein the overvoltage protection method is applied to the overvoltage protection circuit according to any one of claims 1 to 6, the overvoltage protection circuit comprising: a voltage sampling circuit, an overvoltage comparison circuit, signal processing circuit and drive execution circuit, the overvoltage protection method includes:

   The voltage sampling circuit performs voltage sampling on the DC bus to generate a voltage sampling signal;

   The overvoltage comparison circuit compares the voltage sampling signal with a first reference voltage, and generates an overvoltage signal when the sampling voltage of the voltage sampling signal is greater than or equal to the first reference voltage;

   The signal processing circuit performs signal processing according to the overvoltage signal to generate an enable signal and an active short circuit signal;

   The drive execution circuit controls the motor controller to enter a safe state according to the enable signal and the active short circuit signal.
8. An overvoltage protection method according to claim 7, wherein the drive execution circuit controls the motor controller to enter a safe state according to the enabling signal and the active short circuit signal, comprising:

   When the sampling voltage is greater than the first reference voltage, the drive execution circuit controls all the bridge arms of the motor controller to be turned off according to the enable signal, and according to the preset time delay of the active short-circuit signal time, controlling the conduction of the upper bridge arm or the lower bridge arm of the motor controller;

   During the process of the sampling voltage dropping from the first reference voltage to the second reference voltage, the upper bridge arm or the lower bridge arm of the motor controller is kept turned on.
9. The overvoltage protection method according to claim 8, wherein, during the process of the sampling voltage dropping from the first reference voltage to the second reference voltage, the upper bridge arm of the motor controller is kept Or after the lower bridge arm is turned on, including:

   When the sampling voltage is lower than the second reference voltage, all the bridge arms of the motor controller are controlled to be turned off according to the enabling signal, and the motor controller is controlled according to the preset delay time of the active short-circuit signal. The upper or lower bridge arm of the motor controller is turned off;

   During the process of the sampling voltage rising from the second reference voltage to the first reference voltage, all bridge arms of the motor controller are kept turned off.
10. A motor controller, wherein the motor controller includes the overvoltage protection circuit according to any one of claims 1 to 6, or is applied to the overvoltage protection method according to any one of claims 7 to 9.