Method and device for controlling an electric motor of an electric vehicle

Abstract

The group of inventions relates to a method for controlling an electric motor of an electric vehicle and a device for carrying out same. The method includes the steps of: activating and initiating self-testing of a motor control unit at a low voltage; subsequently activating the motor control unit at a high voltage; deactivating the motor control unit if it fails self-testing; receiving signals from an electric motor speed sensor and an electric motor current sensor; controlling the power consumption and generation modes; controlling the torque and speed of the electric motor; and controlling the torque of the electric motor on the basis of the operating parameters of the electric motor, insulated-gate bipolar transistors and a high-voltage circuit. The result is an increase in the safety of an electric vehicle.

Description

[0001]Description of the invention Method of controlling an electric motor of an electric vehicle and a device for implementing it Field of technology The claimed group of inventions relates to methods of controlling traction motors of vehicles and can be used in electric vehicles. A method of controlling the energy system of an all-wheel drive vehicle is known, which includes the following steps: - in response to the engine control unit (hereinafter referred to as the ECU) receiving a command to turn on, turning on the ECU with low voltage; - self-testing of the ECU; - in response to successful completion of the ECU self-test, turning on the ECU with high voltage,otherwise, issuing an error and disabling the ECU; - receiving a command by the ECU to control the torque of the electric motor from the vehicle control unit (hereinafter referred to as the VCU) and controlling the torque of the electric motor based on the received feedback signal from the electric motor current sensor; - receiving a command by the ECU to control the rotation speed of the electric motor from the VCU and controlling the rotation speed of the electric motor based on the received feedback signal from the electric motor speed sensor; - in response to receiving a command from the VCU to brake the electric motor, switching the electric motor to the power generation mode (patent WO 2023082854, published on 19.05.2023). A method for controlling an electric motor is known,implemented using the vehicle safety system and including the following steps: - switching off the electric motor by the safety module or limiting its output power during the current start after a specified period of time has elapsed if the correct safety code has not been provided; - permitting the power plant to operate if the correct safety code has been received (Patent RU 2509668, published on 20.03.2014. Bulletin No. 8). The closest in terms of the set of essential features - the prototype of the claimed invention in terms of the method for controlling an electric motor - is a method for controlling an electric motor, including the following steps: - in response to the ECU receiving a command to turn on, turning on the ECU with low voltage; - self-testing of the ECU; - in response to successful completion of the self-test of the ECU, turning on the ECU with high voltage,otherwise – issuing an error and disabling the ECU; - receiving signals from the electric motor speed sensor and the electric motor current sensor by the ECU and switching the electric motor operating mode between consumption and generation of electric power based on the received signals; - receiving a command by the ECU to control the electric motor torque from the BCU and controlling the electric motor torque based on the received signal with feedback from the electric motor current sensor; - receiving a command by the ECU to control the electric motor speed from the BCU and controlling the electric motor speed based on the received signal with feedback from the electric motor speed sensor; - in response to receiving a command from the BCU to brake the electric motor, switching the electric motor to the electric power generation mode (patent RU 2611592,Published on 28.02.2017. Bulletin No. 7). The general disadvantages of known solutions in terms of the method of controlling an electric motor include their limited capabilities, in terms of ensuring the safety of the ECU and the high-voltage circuit. A car power plant is known, including a battery, a battery heater, a battery control device connected to the batteries and the battery heater via a CAN bus, an electrical distribution box, an electric motor, an engine controller and a limiting inductor (patent RU 2611592, published on 28.02.2017. Bulletin 7). The closest in terms of the set of essential features - the prototype of the claimed invention in terms of the device for implementing the method of controlling an electric motor - is an electric motor control device including a BCU, ECU, capacitor, current-measuring sensor, rotation speed sensor, electric motor (patent RU 2657868,publ.18.06.2018. Bulletin No. 17). Common disadvantages of known solutions include the lack of devices for suppressing electromagnetic interference. Meanwhile, it is known that the source of such interference can be, in particular, transistors. Disclosure of the invention In the context of this application, the following concepts will be used as synonyms: - "electric motor of an electric vehicle", "traction electric motor of an electric vehicle", "engine"; - "vehicle", "car", "electric vehicle"; - "controller", "engine control unit". Low voltage will be understood as a voltage below or equal to 36 V, for example, 12 V,and high voltage means a voltage higher than 36 V. By switching on a high / low voltage element, it is meant connecting said element to a high or low voltage circuit. The high voltage circuit may differ from the low voltage circuit by the presence of a DC-DC step-up converter and / or a high voltage capacitor. The group of claimed inventions includes a method for controlling an electric motor of an electric vehicle and a device for implementing such a control method. The technical task of the claimed inventions that make up the group is to supplement the control algorithms of the traction electric motor of an electric vehicle with stages of additional monitoring of the traction electric motor parameters. The second technical task of the claimed inventions of the group is to increase the reliability of an electric vehicle by introducing devices into its design,suppressing electromagnetic interference. The technical result of implementing the proposed group of inventions consists in increasing the safety of operation of an electric vehicle. The solution to the first set technical problem is achieved by implementing a method for controlling a traction electric motor of an electric vehicle, including the following stages: stage 1: in response to the ECU receiving a command to turn on, turning on the ECU with low voltage; stage 2: self-testing of the ECU; stage 3: in response to successfully passing the self-test of the ECU, a preliminary charge of the high-voltage capacitor in the high-voltage circuit is performed, upon completion of which - a transition to the "READY" state; stage 4: authentication, including the sub-stages: sub-stage 4.1: after receiving a message about ignition activation, sending an authentication signal from the ECU to the ECU, the ECU waits for the specified signal from the ECU within a predetermined time interval; sub-stage 4.2: comparing the received signal with the reference signal in the ECU,which is generated in the ECU; if the result matches the reference signal, sending a signal from the ECU to the BCU to unlock the electric motor; if the signals do not match, the ECU waits for an authentication signal until a predetermined time interval has elapsed; if the authentication signal that matches the reference signal is not received, the ECU sends a signal to lock the electric motor to the BCU; sub-step 4.3: after the BCU receives the signal to unlock the engine, sending the signal (status) "UNLOCKED" from the BCU to the ECU and initiating the execution of the following steps. If the BCU receives the signal to lock the engine, sending the signal (status) "LOCKED" to the ECU by the BCU and initiating the active discharge of the high-voltage circuit. step 5: if the electric motor is unlocked, turning on the ECU with high voltage,otherwise, issuing an error and disabling the ECU; step 6: receiving signals from the electric motor speed sensor and the electric motor current sensor by the ECU and switching the electric motor operating mode between power consumption and generation based on the received signals; step 7: receiving a command from the ECU to control the electric motor torque and controlling the electric motor torque based on the received feedback signal from the electric motor current sensor by the ECU; step 8: receiving a command from the ECU to control the electric motor speed and controlling the electric motor speed based on the received feedback signal from the electric motor speed sensor; step 9: in response to receiving a command from the ECU to brake the electric motor,switching the electric motor to the power generation mode; step 10: in response to the ECU receiving a stop command or a motor blocking signal from the ACU, reducing the motor current to zero and sending an active discharge command from the ACU to the ECU; step 11: in response to the ECU receiving an active discharge command from the ACU, or in response to the loss of the signal from the CAN communication bus for a predetermined period of time and the ECU receiving a collision signal from the ACU, reducing the voltage in the high-voltage circuit by implementing an active phase-to-phase short circuit; step 12: in response to the successful completion of the active discharge and / or in response to the failure to receive a high-voltage grid operation signal for a predetermined period of time, disabling the ECU. The data for the authentication signal may be stored in the ACU memory or generated in the ACU based on the date, time,the data entered by the user and / or the cryptographic key stored in the memory of the ACU. The data for the reference signal may be stored in the memory of the ECU or generated in the ACU based on the date, time and the cryptographic key stored in the memory of the ECU. The order and repeatability of steps 6, 7, 8, 9, 10, 11, 12 is determined by the current traffic situation and / or a specific situation and is not the subject of protection under the present application. The order of listing steps 6, 7, 8, 9, 10, 11, 12 in the present application should not serve to indicate the only possible method for implementing the proposed invention. The novelty of the proposed technical solution, in terms of the method, is the introduction into the method of controlling the electric motor of an electric vehicle of three additional stages, indicated above under numbers “10”, “11”, “12”, namely: stage 10: in response to receiving a command from the ECU to stop or a signal to block the electric motor,reducing the electric motor current to zero and sending an active discharge command from the BCU to the ECU; step 11: in response to the ECU receiving an active discharge command from the BCU, or in response to the loss of a signal from the CAN communication bus for a predetermined period of time and the ECU receiving a collision signal from the BCU, reducing the voltage in the high-voltage circuit by implementing an active interphase short circuit; step 12: in response to the successful completion of the active discharge and / or in response to failure to receive a high-voltage network operation signal for a predetermined period of time, disabling the ECU. The solution to the second technical problem is achieved by introducing an electromagnetic filter in front of the high-voltage capacitor into the design of the electric vehicle. The novelty, in terms of the claimed device for implementing the method for controlling the electric motor of an electric vehicle,is the installation of an electromagnetic filter in front of the high-voltage capacitors, smoothing (suppressing) electromagnetic interference in the system. The specified features are new, essential, from the point of view of achieving the declared technical result, and industrially applicable, since they are based on known technologies. Brief description of the drawings Fig. 1 shows a block diagram of the stages of the proposed method for controlling the electric motor of an electric vehicle. Fig. 2 schematically shows a device for implementing the proposed method. The arrow shows the high-voltage input. Implementation of the invention The implementation of the proposed method for controlling the electric motor of an electric vehicle is illustrated by a block diagram, which indicates the main stages of implementing the method. The beginning of the implementation is shown as a conditional - zero - stage (marked "0"). The stages of controlling the electric motor of an electric vehicle, applied in the technical solutions used as analogues,and designated in Fig. 1 by numbers from 1 to 9, are known from the prior art. At stage 1, the ECU 17 is switched on with low voltage (Fig. 1, 2). At stage 2, the ECU 17 performs a self-test (Fig. 1, 2). As shown in Fig. 2, the self-test of the ECU 17 includes receiving wake-up signals from the modules included in the ECU 17, in particular the memory module, and the bipolar transistors with an insulated gate (hereinafter referred to as IGBT) 16, comparing the signals with the reference signals and, if they match, sending a message about the state of the ECU 17 to the ACU 18. Upon receipt of a response message, it is considered that the self-test has been completed successfully and they proceed to the next stage of switching on the ECU 17 with high voltage. The specified self-test stage allows ensuring the safety of the ECU 17 and the control system of the electric motor 23 as a whole,since it excludes the scenario of turning on the faulty ECU 17 with high voltage. At step 3, after the completion of the power-on of ECU 17 with low voltage and the absence of errors in ECU 17 is established, the pre-charging of the high-voltage capacitor 15 in the high-voltage circuit is started. In this case, the high voltage is supplied to the capacitor 15 through the electromagnetic filter 14. This allows to suppress electromagnetic interference and, due to this, increase the reliability of the device as a whole. After the charging is complete, ECU 17 goes into the "READY" state to complete the power-on of ECU 17 with high voltage. At step 4, authentication is performed. ACU 18 sends an authentication signal to ECU 17, and ECU 17 waits for said signal from ECU 18 within a preset time interval. As an example, which does not exclude other settings of the control system, ECU 18 sends said signal 250 ms after receiving the ignition activation message,and the ECU 17 waits for the specified signal for 600 ms. After receiving the authentication signal from the ACU 18, the ECU 17 compares it with the reference signal. If the result matches, it sends a signal to the ECU 18 to unlock the electric motor 23. If the signals do not match, the ECU 17 again waits for the authentication signal until the preset time interval has expired, and if it does not receive an authentication signal that matches the reference signal, it sends a signal to the ECU 18 to lock the electric motor 23. At step 5, if the electric motor is unlocked, the ECU 17 is switched on with high voltage, otherwise an error is issued and the ECU 17 is switched off. As noted above, the sequence and repeatability of steps 6, 7, 8, 9, 10, 11, 12 is determined by the current traffic situation and / or a specific situation and is not the subject of protection under the present application (Fig. 1). The order of listing steps 6, 7, 8, 9, 10, 11,12 in this application should not serve to indicate the only possible method for implementing the proposed invention. The mentioned stages relate to the operating engine of the electric vehicle, therefore they are conditionally combined in the block diagram into a set of stages enclosed in a dotted frame and designated by position 13 (Fig. 1). At stage 6, the ECU 17 receives signals from the speed sensor 21 of the electric motor 23 and the current sensor 20 of the electric motor 23 and switches the operating mode of the electric motor 23 between consumption and generation of electric power based on the received signals (Fig. 1,2). At stage 7, the ECU 17 receives a command to control the torque of the electric motor 23 from the BCU 18 and controls the torque of the electric motor 23 based on the received signal with feedback from the current-measuring sensor 20 of the electric motor 23. At stage 8, the ECU 17 receives a command to control the rotation speed of the electric motor 23 from the BCU 18 and controls the rotation speed of the electric motor 23 based on the received signal with feedback from the rotation speed sensor 21 of the electric motor 23. When the ECU 17 receives a command to control the speed, the ECU 17 converts it into a torque control command by means of proportional-integral regulation and carries out torque control with feedback from the current-measuring sensor 20 of the electric motor 23. Control of the torque and rotation speed with feedback from the current-measuring sensor 20 of the electric motor 23 makes it possible to create a closed automatic control system,continuously and in real time controlling the rotation speed and / or torque. At step 9, after the ECU 17 receives a command from the BCU 18 to brake the electric motor 23, the ECU 17 switches the electric motor 23 to the power generation mode. At step 10, after the ECU 17 receives a command from the BCU 18 to stop or a signal to block the electric motor 23, the ECU 17 reduces the current of the electric motor 23 to zero; the BCU 18 sends an active discharge command to the ECU 17. At step 11, after the ECU 17 receives an active discharge command from the BCU 18, or in response to a loss of a signal from the CAN communication bus for a predetermined period of time and the ECU 17 receives a collision signal from the BCU 18,The ECU 17 performs a voltage reduction in the high-voltage circuit by implementing an active interphase short circuit. At step 12, in response to a successful completion of the active discharge and / or in response to failure to receive a high-voltage network operation signal within a predetermined time, the ECU 17 is switched off. During normal operation, the ECU 17 monitors the operating parameters of the motor 23, the IGBT 16 and the high-voltage circuit and controls the torque of the electric motor 23 based on them. The ECU 17 receives signals from the temperature sensors 22 in the system, including the temperature sensors of the electric motor 23 and the temperature sensors of the IGBT 16, and in the event that any of the temperatures exceeds a predetermined threshold value, reduces the torque of the electric motor 23 until a safe state is reached,in which the temperature is below the specified threshold value. The ECU 17 also monitors the current in the high voltage circuit and the voltage at the terminals of the high voltage DC bus and, if any of the specified values ​​of the preset threshold values ​​are exceeded, carries out protection to protect the ECU 17 from damage, for example, by opening the ECU 17 circuit and / or connecting a shunt resistor and sending an error message to the ACU 18. In addition, if any of the specified values ​​of the preset threshold values ​​are exceeded, the ECU 17 can reduce the torque of the electric motor down to zero. The ECU 17 also monitors the rotation speed of the electric motor 23. If it is detected that the current rotation speed exceeds the preset threshold value,The ECU 17 reduces the torque of the electric motor 23. Due to the proposed additional control stages, the ECU 17 ensures protection of the electric motor 23 and the IGBT 16 from overheating, current and / or voltage overload, maintains the torque within safe limits, and also protects the electric motor 23 from overspeeding. In response to the ECU 17 receiving a command from the BCU 18 to brake, the ECU 17 switches the operation of the motor 23 to a mode in which the rotation speed is greater than zero and the torque is less than zero. In response to the ECU 17 receiving a command from the BCU 18 to stop or a signal to block the electric motor 23, the ECU 17 reduces the current of the electric motor 23 to zero and sends a message to the BCU 18 about stopping the electric motor 23. To turn off the ECU 17, which is required when turning off the power supply of the car or in the event of an emergency, such as a collision, it is necessary to first disconnect it from the high-voltage circuit or reduce the voltage in its circuit,for which an active discharge is used. During an active discharge, the energy of the high-voltage capacitors is discharged and / or the excess energy generated by the electric motor 23 is discharged, for example during braking at a high rotational speed of the electric motor 23, and dissipated on the braking resistor and / or the winding of the electric motor 23, in particular after the high-voltage contactor is disconnected. The active discharge ensures a safe low-voltage state in the high-voltage connecting line with which the non-insulated components of the ECU 17 may come into contact, which is particularly advantageous in the event of a collision or other emergency situation, and can also precede the process of disconnecting the power circuit of the electric motor 23. In addition, the active discharge system can be activated by the ECU 17 in response to detection of an excess of the rotational speed of the electric motor 23 in the energy generation mode of a preset rotational speed threshold and, therefore,exceeding the voltage in the high-voltage circuit of the preset threshold voltage value. Thus, the active discharge can be initiated by the ECU 17 in the event of receiving from the ECU 17 a corresponding command for active discharge (power-off scenario) or in the event of loss of communication with the CAN communication bus during a preset time interval and receiving a collision signal from the BCU 18 or directly from the collision sensors, for example, accelerometers (not shown in Fig. 2). In the active discharge mode, the ECU 17 sends to the BCU or to the battery control unit a signal to disconnect the main circuit of the storage battery (not shown in Fig. 2), disconnect the main relay and initiate an active interphase short circuit (Active Short Circuit). Preferably, if the rotation speed of the engine 23 exceeds 100 min-1, -1, until the DC bus voltage (not shown in Fig. 2) drops to a low voltage. During the power-off process, when the ECU 17 receives a command to stop the engine, i.e. a command to give it zero torque, or an authentication error, the torque of the engine 17 decreases to zero, and the ECU 17 goes into the "WORK END" operating mode. Also, the ECU 17 goes into the specified operating mode when the DC bus voltage drops to low voltage values ​​for a predetermined time interval, for example. The transition of the ECU 17 to the "WORK END" mode after a successful completion of the active discharge means a successful completion of the disconnection of the ECU 17 from the high-voltage circuit. After a successful disconnection of the ECU 17 from the high-voltage circuit, the ECU 17 can be disconnected from the low-voltage circuit and, accordingly, the ECU 17 can be turned off.Thus, the claimed method and device for its implementation provide for expansion of the electric motor control functionality, in particular, ensuring the safety of the electric motor and electrical components of the system. The proposed method for controlling the electric motor of an electric vehicle and the device for its implementation are focused on the use of existing serial technologies for the production of electric motors, electric vehicles and control devices, which allows us to speak about the industrial applicability of the proposed invention.

Claims

Invention formula Method for controlling an electric motor of an electric vehicle and a device for implementing the same 1. A method for controlling an electric motor of an electric vehicle, comprising the steps of switching on a low-voltage engine control unit upon a command from the electric vehicle control unit; self-testing the engine control unit; switching on, in the event of a successful self-test, a high-voltage engine control unit; issuing, in the event of a failure to pass the self-test, an error and switching off the engine control unit; receiving signals by the engine control unit from an electric motor speed sensor and an electric motor current-measuring sensor and switching the electric motor operating mode between consumption and generation of electric power based on the signals received;receiving by the engine control unit from the electric vehicle control unit a command to control the torque of the electric motor and controlling the torque of the electric motor based on a received feedback signal from the electric motor current sensor; receiving by the engine control unit from the electric vehicle control unit a command to control the rotation speed of the electric motor and controlling the rotation speed of the electric motor based on a received feedback signal from the electric motor rotation speed sensor; switching by the engine control unit, upon a command from the electric vehicle control unit to brake the electric motor, switching the electric motor to the power generation mode, characterized in that it includes monitoring the operating parameters of the electric motor, bipolar transistors with an insulated gate and a high voltage circuit;control of the electric motor torque on their basis and additionally contains authentication stages performed before switching on by the control unit; a high-voltage motor; blocking the electric motor after receiving a command from the electric vehicle control unit to stop or a signal to block the electric motor; reducing the current in the electric motor to zero and sending a command to the engine control unit for an active discharge; reducing upon a command for an active discharge from the electric vehicle control unit or in response to the loss of a signal from the CAN communication bus for a predetermined period of time and receiving by the engine control unit from the electric vehicle control unit a signal about a voltage collision in the high-voltage circuit by implementing an active interphase short circuit; disconnecting the engine control unit in response to the successful completion of the active discharge and / or in response to failure to receive a signal for the high-voltage network operation for a predetermined time.

2. The method according to claim1, characterized in that the operating parameters of the electric motor, the insulated-gate bipolar transistors, and the high-voltage circuit include the temperature of the electric motor and the insulated-gate bipolar transistors, the torque of the electric motor, the rotation speed of the electric motor, the current strength, and the voltage of the high-voltage circuit.

3. The method according to paragraphs. 1-2, characterized in that the data for the authentication signal is stored in the memory of the electric vehicle control unit or is generated in it based on the date, time, data entered by the user and / or the cryptographic key stored in the memory of the electric vehicle control unit, and the data for the reference signal can be stored in the memory of the engine control unit or is generated in the electric vehicle control unit based on the date, time, and the cryptographic key stored in the memory of the engine control unit.

4. A device for implementing the method for controlling the electric motor of an electric vehicle according to paragraph.1, including control unit. an electric vehicle, an engine control unit, a capacitor, a current-measuring sensor, a rotation speed sensor, an electric motor, characterized in that it additionally includes an electromagnetic filter installed in front of the high-voltage capacitors.

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