Anti-tow protection device and method, electric machine drive system, powertrain and vehicle

Abstract

The application discloses a reverse towing protection device for an electric machine, which comprises a first converter configured to convert high voltage generated across a DC bus capacitor when a vehicle is reversely towed into a target low voltage, a wake-up circuit comprising a first input connected to an output of the first converter and a second input connected to a starting battery of the vehicle, the wake-up circuit being configured to output a wake-up voltage to an electric machine controller based on the target low voltage, and an electric machine controller configured to be activated upon receiving the wake-up voltage from the wake-up circuit, the electric machine controller being capable of monitoring wheel speed in real time when activated and causing the electric machine to enter an active short-circuit mode when the wheel speed is greater than a predetermined speed threshold. The application also discloses an electric machine driving system comprising the reverse towing protection device, a power assembly comprising the electric machine driving system, a vehicle comprising the power assembly, and a reverse towing protection method for an electric machine.

Description

Technical Field

[0001] This invention relates to the field of anti-towing protection for vehicles, and more specifically, to an anti-towing protection device for an electric motor, an electric motor drive system including the anti-towing protection device, a powertrain including the electric motor drive system, a vehicle including the powertrain, and a corresponding anti-towing protection method. Background Technology

[0002] Currently, with the development of new energy technologies, traditional fuel vehicles are gradually being replaced by electric vehicles. However, existing technologies have at least one of the following problems: they cannot perform safety monitoring of components / modules such as motors and circuits; motors are prone to overheating, damaging components of motor controllers and drive circuits; and overheating of motors can also easily lead to vehicle fires. Summary of the Invention

[0003] In view of this, a first aspect of the present invention provides a reverse drag protection device for a motor, wherein the reverse drag protection device comprises:

[0004] A first converter is connected in parallel with the DC bus capacitor in the motor drive circuit and is configured to convert the high voltage generated across the DC bus capacitor when the vehicle is towed backwards into a target low voltage.

[0005] A wake-up circuit, comprising a first input connected to the output of the first converter and a second input connected to the vehicle's starting battery, is configured to output a corresponding wake-up voltage to the motor controller based on a target low voltage output by the first converter.

[0006] A motor controller is configured to be activated upon receiving a wake-up voltage from the wake-up circuit. When activated, the motor controller is capable of monitoring the wheel speed in real time and causing the motor to enter an active short-circuit mode when the wheel speed exceeds a predetermined speed threshold.

[0007] The wake-up circuit includes a first resistor, a second resistor, a third resistor, a first switching transistor, and a second switching transistor. Each switching transistor includes a control input terminal, a power input terminal, and a power output terminal.

[0008] In this circuit, the first end of the first resistor is connected to the first converter as the first input terminal of the wake-up circuit; the first end of the second resistor is connected to the vehicle's starter battery as the second input terminal of the wake-up circuit; and the second end of the second resistor is connected to the first end of the third resistor.

[0009] In this configuration, the control input terminal of the first switching transistor is connected to the second terminal of the first resistor, the power input terminal of the first switching transistor is connected to the second terminal of the second resistor, and the power output terminal of the first switching transistor is grounded.

[0010] The control input terminal of the second switch is connected to the second terminal of the third resistor, the power input terminal of the second switch is connected to the vehicle's starting battery, and the power output terminal of the second switch is connected to the motor controller.

[0011] When the vehicle is towed backwards, the first switch and the second switch are turned on in sequence to output a wake-up voltage to the motor controller.

[0012] The first switching transistor is an NPN transistor, and the second switching transistor is a PNP transistor.

[0013] Wherein, the resistance value of the first resistor is less than the resistance value of the third resistor, and the resistance value of the third resistor is less than the resistance value of the second resistor.

[0014] The motor drive circuit includes a three-phase inverter bridge, and the motor controller is configured to turn on all three upper or three lower arms of the three-phase inverter bridge when the wheel speed is greater than a predetermined speed threshold, thereby causing the motor to enter an active short-circuit mode.

[0015] According to a second aspect of the invention, a motor drive system including the anti-drag protection device as described above is also provided.

[0016] According to a third aspect of the invention, a powertrain including the motor drive system described above is also provided.

[0017] According to a fourth aspect of the invention, a vehicle comprising the powertrain described above is also provided.

[0018] According to a fifth aspect of the present invention, a method for anti-drag protection of a motor is also provided, the method being implemented using the anti-drag protection device described above, wherein the method includes the following steps:

[0019] The first converter converts the high voltage generated across the DC bus capacitor when the vehicle is towed into the target low voltage.

[0020] Based on the target low voltage output by the first converter, a corresponding wake-up voltage is output to the motor controller via the wake-up circuit, and

[0021] The motor controller is activated by the wake-up voltage output by the wake-up circuit, and the wheel speed is monitored in real time by means of the motor controller. When the wheel speed is greater than a predetermined speed threshold, the motor enters an active short-circuit mode.

[0022] The method also includes: when the motor enters the active short-circuit mode, activating the safety monitoring function of the motor controller to monitor the motor's operating status in real time.

[0023] The method further includes: when the motor enters the active short-circuit mode, monitoring the PCB board temperature of the motor drive circuit in real time, and performing a cooling operation when the PCB board temperature of the motor drive circuit exceeds a predetermined temperature threshold.

[0024] The anti-drag protection device and method according to the present invention can achieve at least one of the following advantages:

[0025] 1) When the vehicle is being towed backwards, the motor controller can be activated by adding a simple wake-up circuit using the vehicle's existing converter, thus putting the motor into ASC mode.

[0026] 2) When the motor enters ASC mode, the motor controller can activate the safety monitoring function to monitor the motor's operating status in real time, thereby preventing overheating of circuit components caused by excessive short-circuit current and thus avoiding damage to the components. Attached Figure Description

[0027] By incorporating the figures in this article and subsequently the accompanying figures Figure 1 The specific embodiments used to illustrate certain principles of the invention will make other features and advantages of the device of the invention clearer or more specifically explained.

[0028] Figure 1 A schematic diagram of a reverse drag protection device for an electric motor according to an exemplary embodiment of the present invention is shown.

[0029] Figure 2 An operational flowchart of an anti-drag protection method for a motor according to an exemplary embodiment of the present invention is shown. Detailed Implementation

[0030] The anti-drag protection device and method for an electric motor according to the present invention will now be described with reference to the accompanying drawings and embodiments. In the following description, numerous specific details are set forth to enable those skilled in the art to gain a more complete understanding of the invention. However, it will be apparent to those skilled in the art that implementation of the invention may not include some of these specific details. Instead, the invention may be practiced with any combination of the following features and elements, regardless of whether they relate to different embodiments. Therefore, the following aspects, features, embodiments, and advantages are illustrative only and should not be considered as elements or limitations of the claims.

[0031] The applicant's research found that when a vehicle malfunctions or loses power, towing assistance is required. Because towing services for electric vehicles are not yet well-developed, traditional gasoline-powered vehicle towing teams are not very familiar with electric vehicles and still use traditional gasoline-powered vehicle towing methods to tow electric vehicles.

[0032] The applicant's further research revealed that the transmission mechanism of electric vehicles is directly connected to the motor, without a clutch between them. Therefore, when the vehicle is towed in reverse, the motor will rotate. Many electric vehicles use permanent magnet synchronous motors. When such a permanent magnet synchronous motor rotates, according to Faraday's law of electromagnetic induction, the conductor moves within a magnetic field, cutting magnetic field lines, thereby generating a current in the conductor, which in turn generates an induced electromotive force.

[0033] When towing an electric vehicle, the back electromotive force generated by the motor charges the DC bus capacitor C. Excessive back electromotive force can damage the motor drive circuit. Automakers design motor controllers with a certain margin of safety, allowing for towing of electric vehicles at speeds between 5 km / h and 30 km / h over short distances and for short periods.

[0034] When the vehicle speed reaches its maximum limit, for example, when the resulting back electromotive force of the motor is ≥180V, the motor will be forced into Active Short Circuit (ASC) mode. At this time, although the motor controller is constantly powered, it is not activated and therefore cannot monitor the ASC status. Without safety monitoring, prolonged high-speed traction can cause the motor to overheat, damaging the motor controller and drive circuit components. Furthermore, this overheating can potentially lead to vehicle fire.

[0035] To address the aforementioned technical problems, this invention proposes an anti-towing protection device and method for motors. According to the anti-towing protection device and method of this invention, when a vehicle is towed, the motor is in generator mode, and the DC bus capacitor is charged. First, a converter transforms the high voltage across the DC bus capacitor into a 5V low voltage. Then, based on this 5V low voltage, a 12V wake-up voltage is output to the motor controller (MCU) to wake it up. After the MCU is actively woken up, it can monitor the wheel speed in real time. When the wheel speed reaches its upper limit, the MCU can put the motor into ASC state. Simultaneously, the MCU continues to monitor the motor's operating condition. For example, the MCU can monitor the PCB temperature of the motor drive circuit in real time and send a cooling request to the VCU when the PCB temperature exceeds a predetermined value. Upon receiving the cooling request, the VCU can control the water pump to operate, thereby activating a cooling circulation loop to cool the motor and prevent damage to circuit components due to overheating.

[0036] Figure 1 A schematic diagram of a reverse drag protection device for a motor according to an exemplary embodiment of the present invention is shown. Figure 1 As shown, the motor 10 includes three-phase windings U, V, and W, and is driven by a drive circuit. In this example, the motor drive circuit is constructed as a three-phase inverter bridge 20 consisting of six switching transistors, which is connected between the vehicle's power battery HV+ / HV- and the motor 10. The three-phase inverter bridge 20, and in particular the control input of each of its switching transistors, is connected to the motor controller 30.

[0037] The motor controller 30 is powered via a constant power line KL30, which is connected to the vehicle's 12V starter battery. Additionally, the motor controller 30 includes a wake-up terminal connected to the starter line KL15, which is also connected to the vehicle's 12V starter battery. Unlike KL30, KL15 is equipped with a start switch S1. When the driver operates the vehicle, operating the start switch S1 activates the main relay (…). Figure 1 (Not shown) is powered on, thereby waking up the motor controller 30, enabling it to monitor and control the operation of the motor.

[0038] Specifically, when the vehicle is started, the motor controller 30 is woken up / activated by the start switch S1, putting it into working state. In working state, the motor controller 30 can alternately keep some of the six switching transistors of the three-phase inverter bridge 20 on and others off, thereby switching the current flow through each phase winding of the motor and thus controlling the operation of the motor.

[0039] However, this article discusses a scenario that is entirely different from the normal operating conditions of the vehicle described above. The following section will combine... Figure 1This article will elaborate on the applicable scenarios:

[0040] First, those skilled in the art will understand that the vehicles mentioned in this article may refer to new energy vehicles such as "electric vehicles," and there are no restrictions on this. When an electric vehicle malfunctions or runs out of power, it needs to be towed to a designated station for repair or charging by a rescue vehicle.

[0041] When the vehicle is towed backwards, it drives the motor to rotate, and in this situation, the motor is in generator mode. At the same time, the vehicle's power battery contactors S2 and S3 are open, and the back electromotive force generated by the motor charges the DC bus capacitor C through the freewheeling diode in the three-phase bridge arm.

[0042] To prevent DC bus overvoltage, this invention proposes a reverse drag protection device that can wake up the motor controller when the vehicle is not started, so that the motor enters active short circuit (ASC) mode. The motor controller can monitor the motor's operating status in ASC mode in real time, thus avoiding damage to circuit components when the short circuit current is too large.

[0043] like Figure 1 As shown, the reverse drag protection device includes a first converter 40, which is connected in parallel across the DC bus capacitor C to convert the high voltage generated across the DC bus capacitor when the motor is reverse dragged into a target low voltage, especially a low voltage of 5V.

[0044] For cost-saving purposes, the existing transformer T in the vehicle can be used to convert the DC bus voltage to a low 5V voltage, eliminating the need for additional voltage conversion equipment. However, to wake up the motor controller, this low 5V voltage needs to be further converted to the motor controller's wake-up voltage, typically 12V.

[0045] Therefore, the anti-drag protection device according to this embodiment further includes a wake-up circuit 50, which is configured to output a 12V wake-up voltage to the motor controller 30 based on a target low voltage output by the first converter. The wake-up circuit 50 includes two input terminals: a first input terminal, also called an enable input terminal, is connected to the output terminal of the first converter 40; the second input terminal, also called a power supply input terminal, is connected to the vehicle's starting battery. The output terminal of the wake-up circuit 50 is connected to the wake-up terminal (WAKE UP) of the motor controller 30.

[0046] Figure 1 An exemplary illustration shows the internal circuitry of a wake-up circuit 50. Specifically, the wake-up circuit 50 may include a first resistor R1, a second resistor R2, a third resistor R3, a first switching transistor Q1, and a second switching transistor Q2 (e.g., an IGBT). Figure 1 In the embodiment shown, the resistance values ​​of resistors R1, R2, and R3 can be specified as 4.7K ohms, 22K ohms, and 10K ohms, respectively. The first switch Q1 is specified as an NPN transistor, and the second switch Q2 is specified as a PNP transistor. Each switch includes a control input terminal, a power input terminal, and a power output terminal.

[0047] like Figure 1 As shown, the first end of the first resistor R1 is used as the enable input of the wake-up circuit 50, which is connected to the output of the first converter 40; the first end of the second resistor R2 is used as the power supply input of the wake-up circuit 50, which is connected to the vehicle's starter battery; and the second end of the second resistor R2 is connected to the first end of the third resistor R3.

[0048] The base of the first switching transistor Q1 (i.e., the "control input terminal") is connected to the second terminal of the first resistor R1, the collector of the first switching transistor Q1 (i.e., the "power input terminal") is connected to the second terminal of the second resistor R2, and the emitter of the first switching transistor Q1 (i.e., the "power output terminal") is grounded.

[0049] The base of the second switch Q2 (i.e., the "control input terminal") is connected to the second terminal of the third resistor R3, the emitter of the second switch Q2 (i.e., the "power input terminal") is connected to the vehicle's starting battery, and the collector of the second switch Q2 (i.e., the "power output terminal") is connected to the motor controller 30.

[0050] When the motor is reverse-driven, the high voltage formed on the bus capacitor C is converted into a low voltage of 5V by the first converter. This voltage is applied to the base of Q1 through resistor R1, making the base-emitter junction of Q1 conduct, forming an input circuit. Simultaneously, the 12V voltage from the vehicle's starting battery is applied to the collector of Q1 through resistor R2, making the collector-emitter junction of Q1 conduct, forming an output circuit. At the same time, the 12V voltage from the vehicle's starting battery is also applied to the emitter of Q2, making the emitter-base junction of Q2 conduct, forming an input circuit; furthermore, it makes the emitter-collector junction of Q2 conduct, forming an output circuit, thereby outputting a wake-up voltage to the motor controller 30.

[0051] Upon receiving a wake-up voltage from the wake-up circuit 50, the motor controller 30 is activated, enabling it to monitor wheel speed in real time and put the motor into ASC mode when the wheel speed exceeds a predetermined speed threshold. For example, when the wheel speed exceeds 30 km / h, the motor controller 30 can turn on all three upper arms (or three lower arms) of the three-phase inverter bridge in the motor drive circuit, forming a short circuit with the U, V, and W phases of the motor, dissipating the generated back electromotive force through the motor windings.

[0052] In ASC mode, if the short-circuit current is too large, the switching transistors in the inverter bridge will be damaged due to overheating. Therefore, the motor controller 30 is also configured to activate a safety monitoring function when the motor enters ASC mode to monitor the operating status of the motor drive circuit in real time.

[0053] As an example, the motor controller 30 can monitor the PCB temperature of the motor drive circuit in real time, specifically the IGBT temperature within the motor drive circuit. The motor controller 30 is further configured to perform a cooling operation when the PCB temperature of the motor drive circuit exceeds a predetermined temperature threshold. Specifically, when the PCB temperature of the motor drive circuit exceeds the predetermined temperature threshold, the motor controller 30 can send a cooling request to the vehicle control unit (VCU) via the CAN bus. The VCU can then control the water pump to operate, thereby activating a cooling circulation loop to cool the motor and prevent damage to internal motor components due to overheating.

[0054] As another example, the motor controller 30 can also monitor the magnitude of the short-circuit current and / or the wheel speed in real time, and implement corresponding safety protection measures based on the monitoring results.

[0055] according to Figure 1 The anti-towing protection device of the exemplary embodiment shown can be integrated / included in the motor drive system of a vehicle. Those skilled in the art will understand that, in addition to the anti-towing protection device first presented in this embodiment, the motor drive system may also include / integrate conventional inverters, power batteries, power domains, etc. These examples are merely exemplary and not restrictive, and therefore do not constitute a constraint on the scope of protection of this application.

[0056] Furthermore, this application also relates to a powertrain including the motor drive system. This powertrain may be a power drive assembly integrating a motor and a motor drive system, or it may be a power drive assembly integrating a motor, a motor drive system, and a reducer. These examples are merely illustrative and not restrictive, and therefore do not constitute a constraint on the scope of protection of this application.

[0057] Figure 2 A flowchart illustrating the operation of a reverse drag protection method for a motor according to an exemplary embodiment of the present invention is shown. Referring below... Figure 2 The operation steps of this anti-drag protection method are described in detail.

[0058] When the vehicle is towed while the power is off (the motor controller MCU is in sleep mode), the back electromotive force generated by the motor, which acts as a generator, charges the DC bus capacitor.

[0059] To prevent DC bus overvoltage, the reverse drag protection method according to this exemplary embodiment of the present invention first converts the high voltage across the bus capacitor into a low voltage of 5V using a converter.

[0060] Subsequently, the 5V low voltage is further converted into a 12V wake-up voltage using a wake-up circuit, which activates the MCU. When the MCU is activated, it can monitor the wheel speed in real time. When the wheel speed exceeds the upper limit, the MCU puts the motor into ASC mode.

[0061] When the motor enters ASC mode, the MCU can also activate a safety monitoring function to monitor the operating status of the motor drive circuit in real time. For example, the MCU can monitor the PCB temperature of the motor drive circuit in real time, and when the PCB temperature reaches a predetermined value, the MCU can send a cooling request to the VCU via the CAN bus.

[0062] Upon receiving a cooling request from the MCU, the VCU can turn on the water pump to start the cooling circulation loop to cool the motor.

[0063] As described above, according to the anti-towing protection device and method of the present invention, when the vehicle is towed, the motor is in generator mode, and the DC bus capacitor is charged. First, the high voltage across the DC bus capacitor is converted to a low voltage of 5V using a converter. Then, based on this low voltage of 5V, a 12V wake-up voltage is output to the motor controller (MCU) to wake it up. After the MCU is actively woken up, it can monitor the wheel speed in real time. When the wheel speed reaches the upper limit, the MCU can put the motor into ASC state. At the same time, the MCU continues to monitor the motor's operating condition. For example, the MCU can monitor the PCB temperature of the motor drive circuit in real time and send a cooling request to the VCU when the PCB temperature exceeds a predetermined value. After receiving the cooling request, the VCU can control the water pump to work, thereby starting the cooling circulation loop to cool the motor and prevent the circuit components from being damaged due to overheating.

[0064] The anti-drag protection device according to the present invention can achieve at least one of the following advantages:

[0065] 1) When the vehicle is being towed backwards, the motor controller can be activated by adding a simple wake-up circuit using the vehicle's existing converter, thus putting the motor into ASC mode.

[0066] 2) When the motor enters ASC mode, the motor controller can activate the safety monitoring function to monitor the motor's operating status in real time, thereby preventing overheating of circuit components caused by excessive short-circuit current and thus avoiding damage to the components.

[0067] Those skilled in the art will understand that, in this invention, terms such as “first,” “second,” and “third” do not indicate the order of components or values ​​in terms of time, space, size, etc., but are merely used to distinguish each component or value.

[0068] While the present invention has been disclosed above with reference to preferred embodiments, it is not limited thereto. Any modifications and alterations made by those skilled in the art without departing from the spirit and scope of the invention should be included within the scope of protection of the invention. Therefore, the scope of protection of the invention should be determined by the scope defined in the claims.

Claims

1. A reverse drag protection device for an electric motor, wherein, The anti-drag protection device includes: A first converter is connected in parallel with the DC bus capacitor in the motor drive circuit and is configured to convert the high voltage generated across the DC bus capacitor when the vehicle is towed backwards into a target low voltage. A wake-up circuit, comprising a first input connected to the output of the first converter and a second input connected to the vehicle's starting battery, is configured to output a corresponding wake-up voltage to the motor controller based on a target low voltage output by the first converter. A motor controller is configured to be activated upon receiving a wake-up voltage from the wake-up circuit. When activated, the motor controller can monitor the wheel speed in real time and cause the motor to enter an active short-circuit mode when the wheel speed exceeds a predetermined speed threshold. The wake-up circuit includes a first resistor (R1), a second resistor (R2), a third resistor (R3), a first switch (Q1), and a second switch (Q2). Each switch includes a control input terminal, a power input terminal, and a power output terminal. In this circuit, the first end of the first resistor is connected to the first converter as the first input terminal of the wake-up circuit; the first end of the second resistor is connected to the vehicle's starter battery as the second input terminal of the wake-up circuit; and the second end of the second resistor is connected to the first end of the third resistor. In this configuration, the control input terminal of the first switching transistor is connected to the second terminal of the first resistor, the power input terminal of the first switching transistor is connected to the second terminal of the second resistor, and the power output terminal of the first switching transistor is grounded. The control input terminal of the second switching transistor is connected to the second terminal of the third resistor, the power input terminal of the second switching transistor is connected to the vehicle's starting battery, and the power output terminal of the second switching transistor is connected to the motor controller. When the vehicle is towed backwards, the first switch (Q1) and the second switch (Q2) are turned on in sequence to output a wake-up voltage to the motor controller.

2. The anti-drag protection device according to claim 1, wherein, The first switching transistor is an NPN transistor, and the second switching transistor is a PNP transistor.

3. The anti-drag protection device according to claim 1, wherein, The resistance value of the first resistor (R1) is less than the resistance value of the third resistor (R3), and the resistance value of the third resistor (R3) is less than the resistance value of the second resistor (R2).

4. The anti-drag protection device according to any one of claims 1 to 3, wherein, The motor drive circuit includes a three-phase inverter bridge, and the motor controller is configured to turn on all three upper or three lower arms of the three-phase inverter bridge when the wheel speed is greater than a predetermined speed threshold, thereby causing the motor to enter an active short-circuit mode.

5. A motor drive system comprising an anti-drag protection device according to any one of claims 1 to 4.

6. A powertrain comprising the electric motor drive system according to claim 5.

7. A vehicle comprising the powertrain according to claim 6.

8. A method for reverse drag protection of a motor, the method being implemented using a reverse drag protection device according to any one of claims 1 to 4, wherein, The method includes the following steps: The first converter converts the high voltage generated across the DC bus capacitor when the vehicle is towed into the target low voltage. Based on the target low voltage output by the first converter, a corresponding wake-up voltage is output to the motor controller via the wake-up circuit, and The motor controller is activated by the wake-up voltage output by the wake-up circuit, and the wheel speed is monitored in real time by means of the motor controller. When the wheel speed is greater than a predetermined speed threshold, the motor enters an active short-circuit mode.

9. The anti-drag protection method according to claim 8, wherein, The method also includes: When the motor enters active short-circuit mode, the safety monitoring function of the motor controller is activated to monitor the motor's operating status in real time.

10. The anti-drag protection method according to claim 9, wherein, The method also includes: When the motor enters the active short-circuit mode, the temperature of the PCB board of the motor drive circuit is monitored in real time, and a cooling operation is performed when the temperature of the PCB board of the motor drive circuit exceeds the predetermined temperature threshold.

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