A method for reducing bus voltage of a permanent magnet synchronous motor for a pump

Abstract

The present invention provides a method for processing bus voltage reduction of a permanent magnet synchronous motor of a pump type. The method adjusts the speed of the permanent magnet synchronous motor of the pump type in real time by detecting the actual value of the bus voltage of an electric drive vehicle. Specifically, in the speed adjustment process, by setting a critical value crossover zone of the bus voltage of the electric drive vehicle, the speed is switched only when the bus voltage is lower than or higher than the set voltage value during the falling and rising stages of the bus voltage. This can effectively avoid the phenomenon of speed instability, oscillation and frequent speed switching of the permanent magnet synchronous motor of the pump type near the critical value of the voltage. It can also avoid serious faults such as insufficient system cooling, over-temperature faults of key electrical components, lack of pressure in the brake system, insufficient lubrication of the transmission system, and even gear disengagement of the transmission when the permanent magnet synchronous motor of the pump type of the electric drive vehicle fails to supply voltage, while meeting the functional requirements of the electric drive system. This can also avoid other related problems.

Description

Technical Field

[0001] The present invention belongs to the technical field of fault processing and control of vehicle permanent magnet synchronous motors, and in particular relates to a method for processing bus voltage reduction of a pump-type permanent magnet synchronous motor. Background Art

[0002] The motor and its control system are key components of electric vehicles. Their control algorithms and fault emergency protection strategies have a direct impact on the performance of the vehicle. Permanent magnet synchronous motor control technology is one of the core technologies of electric vehicles. Due to its unique performance advantages and the abundant reserves of permanent magnet raw materials in my country, the research and application of permanent magnet synchronous motors in electric vehicle systems are becoming more and more extensive.

[0003] The application scenario of automotive permanent magnet synchronous motors for pumps is to drive key equipment such as oil pumps and water pumps in engines, gearboxes, brakes, etc. When a pump motor fails, it will stop working immediately, causing the oil pump, water pump and other equipment to stop quickly, which will lead to insufficient cooling of the vehicle system, over-temperature failure of key electrical components, lack of pressure in the brake system, insufficient lubrication of the transmission system, and even serious failures such as transmission disengagement, as well as other related problems. Therefore, the fault handling and control technology of automotive permanent magnet synchronous motors for pumps is very important.

[0004] The general way to deal with the undervoltage fault of the pump type permanent magnet synchronous motor is to turn off the IGBT and stop the motor to prevent the controller from failing due to excessive current. Electric vehicles have many electronic components, which are sensitive to temperature. The gearbox shifting also relies heavily on the pump type permanent magnet synchronous motor to drive the oil pump to establish oil pressure. The characteristic of the pump is that the load torque decreases as the speed decreases. Since the pump motor has a large load and a short deceleration time, once the oil pump and water pump stop working, the cooling system and hydraulic system of the electric drive vehicle will stop working immediately, which is easy to cause serious faults in the electric drive vehicle. Therefore, the traditional way to deal with the undervoltage fault of the pump type permanent magnet synchronous motor for vehicles is not suitable for the pump type permanent magnet synchronous motor for electric drive vehicles. Summary of the invention

[0005] In order to solve the above problems, the present invention provides a method for reducing the bus voltage of a pump-type permanent magnet synchronous motor. By setting a cross-zone of the critical value of the bus voltage of an electric drive vehicle, it can effectively avoid the phenomenon of unstable speed, oscillation and frequent speed switching of the pump-type permanent magnet synchronous motor near the voltage critical value.

[0006] A method for processing a bus voltage reduction of a pump-type permanent magnet synchronous motor, which adjusts the speed of the pump-type permanent magnet synchronous motor in real time by detecting the magnitude of the bus voltage U of an electric drive vehicle, thereby realizing undervoltage fault processing of the pump-type permanent magnet synchronous motor;

[0007] Among them, when the bus voltage U is not less than the set value U0, the pump-type permanent magnet synchronous motor operates at the rated speed value n0; when the bus voltage U drops to less than the set value U0, the magnitude of the bus voltage U and the set value U1 is judged again. If the bus voltage U is not less than U1, the pump-type permanent magnet synchronous motor continues to operate at the rated speed value n0, where U1 < U0; when the bus voltage U drops to less than the set value U1, the magnitude of the bus voltage U and the set value U2 is judged again. If the bus voltage U is not less than U2, the pump-type permanent magnet synchronous motor continues to operate at the rated speed value n0, where U2 < U1; when the bus voltage U drops to less than U2, the magnitude of the bus voltage U and the set value U3 is judged again, where U3 < U2. If the bus voltage value U is not less than U3, the pump-type permanent magnet synchronous motor operates at the set minimum speed value n1 and continuously compares with the set value U1. When the bus voltage U is higher than U1, the speed of the pump-type permanent magnet synchronous motor resumes to the rated speed value n0; when the bus voltage U drops to less than U3, the pump-type permanent magnet synchronous motor stops working.

[0008] Further, when the pump-type permanent magnet synchronous motor is used to drive the transmission oil pump on an electric drive vehicle, the rated speed value n0 of the pump-type permanent magnet synchronous motor is determined according to the relationship curve between the transmission oil pump flow and the speed; the minimum speed value n1 of the pump-type permanent magnet synchronous motor is determined according to the minimum flow demand of the transmission hydraulic system.

[0009] Further, when the pump-type permanent magnet synchronous motor is used to drive the brake oil pump on an electric drive vehicle, the rated speed value n0 of the pump-type permanent magnet synchronous motor is determined according to the hydraulic system flow required by the brake braking pressure; the minimum speed value n1 of the pump-type permanent magnet synchronous motor is determined according to the minimum flow demand of the brake hydraulic system.

[0010] Further, when the pump-type permanent magnet synchronous motor is used to drive the cooling water circulation pump on an electric drive vehicle, the rated speed value n0 of the pump-type permanent magnet synchronous motor is determined according to the relationship curve between the cooling water circulation pump flow and the speed; the minimum speed value n1 of the pump-type permanent magnet synchronous motor is determined according to the minimum flow demand of the components to be cooled on the electric drive vehicle.

[0011] Further, the set value U0 is the normal bus voltage value of the pump-type permanent magnet synchronous motor, and U0 is determined according to the voltage system adopted by the electric drive vehicle; the set value U1 is the minimum voltage value for the normal operation of the pump-type permanent magnet synchronous motor, and U1 is determined according to the back electromotive force of the rated speed value n0 of the pump-type permanent magnet synchronous motor; the set value U2 is determined according to the back electromotive force of the pump-type permanent magnet synchronous motor and the minimum speed value n1 of the pump-type permanent magnet synchronous motor; the set value U3 is determined according to the ability of the IGBT of the pump-type permanent magnet synchronous motor controller.

[0012] Beneficial effects:

[0013] 1. The present invention provides a method for processing bus voltage reduction of a permanent magnet synchronous motor of a pump type. By detecting the actual value of the bus voltage of an electric drive vehicle, the speed of the permanent magnet synchronous motor of the pump type is adjusted in real time. Specifically, in the speed adjustment process, by setting a critical value crossover zone of the bus voltage of the electric drive vehicle, the speed is switched only when the bus voltage is lower than or higher than the set voltage value in the decreasing and increasing stages of the bus voltage. This can effectively avoid the phenomenon of speed instability, oscillation and frequent speed switching of the permanent magnet synchronous motor of the pump type near the critical voltage value. It can also avoid serious faults such as insufficient system cooling, over-temperature faults of key electrical components, lack of brake system pressure, insufficient lubrication of the transmission system, and even transmission disengagement when the permanent magnet synchronous motor of the pump type of the electric drive vehicle fails to supply voltage, while meeting the functional requirements of the electric drive system. This can also avoid other related problems.

[0014] 2. The present invention provides a method for reducing the bus voltage of a permanent magnet synchronous motor of a pump type. The rated speed value n0 of the permanent magnet synchronous motor of the pump type and the minimum speed value n1 of the permanent magnet synchronous motor of the pump type are determined according to the use of the permanent magnet synchronous motor of the pump type in an electric drive vehicle. This method can better solve the undervoltage fault of the permanent magnet synchronous motor of the pump type in an electric drive vehicle under different working conditions.

[0015] 3. The present invention provides a method for reducing the bus voltage of a permanent magnet synchronous motor of a pump type, grades the bus voltage of the permanent magnet synchronous motor of a pump type, and provides a method for determining the critical value of each graded voltage, which can better solve the undervoltage fault of the permanent magnet synchronous motor of the pump type of an electric drive vehicle under different working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A flow chart of a method for reducing the bus voltage of a pump-type permanent magnet synchronous motor provided by the present invention;

[0017] Figure 2 A schematic diagram of speed change in a bus voltage critical value crossing zone provided by the present invention;

[0018] Figure 3 This is a schematic diagram of the speed recovery control method for a permanent magnet synchronous motor for a pump provided by the present invention. DETAILED DESCRIPTION

[0019] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application.

[0020] The present invention provides a method for reducing the bus voltage of a pump-type permanent magnet synchronous motor, aiming to reduce the working ability of the pump-type permanent magnet synchronous motor on the premise of meeting the functional requirements of the electric drive system, and尽可能地避免电驱动车辆泵类永磁同步电机欠压故障时,出现系统冷却不足、关键电气部件过温故障、制动系统压力缺失、传动系统润滑不足、甚至变速器脱挡等严重故障,以及其他关联性问题。尽可能地避免电驱动车辆泵类永磁同步电机欠压故障时,出现系统冷却不足、关键电气部件过温故障、制动系统压力缺失、传动系统润滑不足、甚至变速器脱挡等严重故障,以及其他关联性问题。

[0021] Specifically, as Figure 1 shown, a method for reducing the bus voltage of a pump-type permanent magnet synchronous motor includes the following steps:

[0022] First, the pump-type permanent magnet synchronous motor and its control system perform a power-on self-check.

[0023] After the self-check is completed without error, the pump-type permanent magnet synchronous motor operates under the normal bus voltage U0 of the electric drive vehicle, and the speed of the pump-type permanent magnet synchronous motor is maintained at n0.

[0024] The control system of the pump-type permanent magnet synchronous motor cyclically collects the bus voltage signal of the electric drive vehicle and the speed signal of the pump-type permanent magnet synchronous motor, and performs system fault diagnosis.

[0025] That is to say, the present invention adjusts the speed of the pump-type permanent magnet synchronous motor in real time by detecting the magnitude of the bus voltage U of the electric drive vehicle, so as to achieve the under-voltage fault handling of the pump-type permanent magnet synchronous motor.

[0026] Among them, as Figure 2 shown, when the bus voltage U is not less than the set value U0, the pump-type permanent magnet synchronous motor operates at the rated speed value n0; when the bus voltage U drops to less than the set value U0, the magnitude of the bus voltage U and the set value U1 are judged again. If the bus voltage U is not less than U1, the pump-type permanent magnet synchronous motor continues to operate at the rated speed value n0, where U1 < U0; when the bus voltage U drops to less than the set value U1, the magnitude of the bus voltage U and the set value U2 are judged again. If the bus voltage U is not less than U2, the pump-type permanent magnet synchronous motor continues to operate at the rated speed value n0, where U2 < U1; when the bus voltage U drops to less than U2, the magnitude of the bus voltage U and the set value U3 are judged again, where U3 < U2. If the bus voltage value U is not less than U3, the pump-type permanent magnet synchronous motor operates at the set minimum speed value n1 and continues to compare with the set value U1. When the bus voltage U is higher than U1, the speed of the pump-type permanent magnet synchronous motor resumes to the rated speed value n0; when the bus voltage U drops to less than U3, the pump-type permanent magnet synchronous motor stops working.

[0027] It should be noted that the present invention adopts voltage setting values ​​U0, U1, U2, and U3 to realize the classification of the bus voltage of the permanent magnet synchronous motor of the pump type, wherein the present invention determines the normal bus voltage value U0 of the permanent magnet synchronous motor of the pump type according to the voltage standard adopted by the electric drive vehicle; determines the minimum voltage value U1 for normal operation according to the back electromotive force of the rated speed value n0 of the permanent magnet synchronous motor of the pump type, and generally requires that the design value of the motor back electromotive force is not greater than the normal fluctuation value of the bus voltage; the voltage value U2 is determined according to the back electromotive force of the permanent magnet synchronous motor of the pump type and the minimum speed value n1 of the permanent magnet synchronous motor of the pump type; the voltage value U3 is determined according to the capacity of the IGBT of the controller of the permanent magnet synchronous motor of the pump type.

[0028] The following describes how to obtain the rated speed value n0, the minimum speed value n1, and the speed value n2 when the pump type permanent magnet synchronous motor stops working.

[0029] The rated speed value n0 of the permanent magnet synchronous motor for pumps, the minimum speed value n1 of the permanent magnet synchronous motor for pumps, and the stop speed value n2 of the permanent magnet synchronous motor for pumps are determined according to the use of the permanent magnet synchronous motor for pumps in electric drive vehicles. It should be noted that when the permanent magnet synchronous motor for pumps stops working, the stop speed value n2 is usually 0.

[0030] The first use: When a pump-type permanent magnet synchronous motor is used to drive a gearbox oil pump on an electric drive vehicle, the rated speed value n0 of the pump-type permanent magnet synchronous motor is determined based on the hydraulic system pressure that meets the gear establishment requirements of the gearbox, the hydraulic system flow that meets the gearbox lubrication requirements, and the oil pump flow that meets other requirements of the gearbox, combined with the oil pump's own flow and speed relationship curve; the minimum speed value n1 of the pump-type permanent magnet synchronous motor is determined based on meeting the minimum flow requirement of the gearbox hydraulic system.

[0031] The second use: When the pump type permanent magnet synchronous motor is used to drive the brake oil pump on an electric drive vehicle, the rated speed value n0 of the pump type permanent magnet synchronous motor is determined according to the hydraulic system flow that meets the brake pressure requirement; the minimum speed value n1 of the pump type permanent magnet synchronous motor is determined according to the minimum flow requirement of the brake hydraulic system.

[0032] The third use: When the permanent magnet synchronous motor of the pump type is used to drive the cooling water circulation pump on an electric drive vehicle, the rated speed value n0 of the permanent magnet synchronous motor of the pump type is determined based on the circulating water flow rate that meets the engine, motor, motor controller, power battery and other components that need cooling on the electric drive vehicle, combined with the relationship curve between the water pump flow rate and the speed; the minimum speed value n1 of the permanent magnet synchronous motor of the pump type is determined based on the minimum flow requirement of the components that need cooling on the electric drive vehicle.

[0033] It should be noted that the present invention detects the actual value of the bus voltage of the electric drive vehicle and adjusts the speed of the permanent magnet synchronous motor of the pump in real time, so as to avoid as much as possible the occurrence of serious faults such as insufficient system cooling, over-temperature failure of key electrical components, lack of brake system pressure, insufficient lubrication of the transmission system, and even transmission disengagement when the permanent magnet synchronous motor of the pump of the electric drive vehicle is undervoltage, as well as other related problems.

[0034] When it is detected that the bus voltage of the electric drive vehicle is the voltage value U0, the pump type permanent magnet synchronous motor operates at the speed value n0; in the continuous reduction stage of the bus voltage, before the bus voltage of the electric drive vehicle is reduced to the voltage value U1, the speed of the pump type permanent magnet synchronous motor is maintained at the speed value n0, and the speed of the pump type permanent magnet synchronous motor is not intervened until the bus voltage of the electric drive vehicle is reduced to the voltage value U2, and the speed of the pump type permanent magnet synchronous motor is reduced to the speed value n1; when the bus voltage of the electric drive vehicle is reduced to the voltage value U3, the pump type permanent magnet synchronous motor controller IGBT is turned off, the pump type permanent magnet synchronous motor stops working, and the speed of the pump type permanent magnet synchronous motor is reduced to the speed value n2, that is, the speed is 0.

[0035] Furthermore, when the bus voltage of the electric drive vehicle is lower than the normal voltage value U0, the undervoltage fault of the permanent magnet synchronous motor of the pump is handled according to the above method. In order not to affect the normal operation of the hydraulic system and cooling system of the electric drive vehicle, when the bus voltage of the electric drive vehicle is restored to the normal voltage value U0, the speed of the permanent magnet synchronous motor of the pump should also be restored to the rated speed value n0. When the bus voltage of the electric drive vehicle is at the critical value, that is, the voltage setting value U0, U1, U2, U3, the speed of the permanent magnet synchronous motor of the pump may be unstable and oscillate with the small fluctuation of the voltage, or even the speed may switch frequently.

[0036] In order to prevent this phenomenon from occurring, a critical value crossover zone of the bus voltage of the electric drive vehicle is set, and the bus voltage crossover zone range is [U2, U1]. Figure 2 As shown. When the bus voltage of the electric drive vehicle is in the range [U2, U0], the pump type permanent magnet synchronous motor works at the speed value n0; when the bus voltage of the electric drive vehicle is in the range [U1, U3], the pump type permanent magnet synchronous motor works at the speed value n1; when the bus voltage of the electric drive vehicle is lower than the voltage value U3, the pump type permanent magnet synchronous motor works at the speed value n2. It should be noted that in the decreasing stage of the bus voltage, when the bus voltage of the electric drive vehicle is lower than the voltage value U2, the speed of the pump type permanent magnet synchronous motor will be reduced to n1, and in the increasing stage of the bus voltage, when the bus voltage of the electric drive vehicle is higher than the voltage value U1, the speed of the pump type permanent magnet synchronous motor will be restored to n0, and when the bus voltage of the electric drive vehicle is lower than the voltage value U3, the speed of the pump type permanent magnet synchronous motor cannot be restored.

[0037] In summary, if Figure 3As shown, the present invention specifically provides a method for determining the speed of a pump-type permanent magnet synchronous motor, a bus voltage grading release, an undervoltage fault processing method, and a speed recovery control method. Compared with the prior art, the present invention provides a method for reducing the bus voltage of a pump-type permanent magnet synchronous motor. When the bus voltage of an electric drive vehicle is lower than the normal working voltage, the present invention detects the actual value of the bus voltage of the electric drive vehicle, adjusts the speed of the pump-type permanent magnet synchronous motor in real time, reduces the working capacity of the pump-type permanent magnet synchronous motor, and avoids the occurrence of serious faults such as insufficient system cooling, over-temperature faults of key electrical components, lack of pressure in the brake system, insufficient lubrication of the transmission system, and even transmission disengagement when the electric drive vehicle pump-type permanent magnet synchronous motor has an undervoltage fault, and other related problems. When the bus voltage of the electric drive vehicle is restored, the speed recovery control method of the pump-type permanent magnet synchronous motor provided by the present invention is used to restore the speed of the pump-type permanent magnet synchronous motor to a normal working state. The present invention can effectively avoid the phenomenon of unstable speed, oscillation, and frequent speed switching of the pump-type permanent magnet synchronous motor near the voltage critical value by setting a cross zone of the critical value of the bus voltage of the electric drive vehicle.

[0038] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art may certainly make various corresponding changes and modifications based on the present invention, but these corresponding changes and modifications should all fall within the scope of protection of the claims attached to the present invention.

Claims

1. A method for reducing the bus voltage of a pump-type permanent magnet synchronous motor, characterized in that: The speed of the permanent magnet synchronous motor for pumps is adjusted in real time by detecting the magnitude of the bus voltage U of the electric drive vehicle, so as to achieve the under-voltage fault handling of the permanent magnet synchronous motor for pumps; Among them, when the bus voltage U is not less than the set value U0, the permanent magnet synchronous motor for pumps operates at the rated speed value n0; when the bus voltage U drops to less than the set value U0, the magnitude of the bus voltage U and the set value U1 are judged again. If the bus voltage U is not less than U1, the permanent magnet synchronous motor for pumps continues to operate at the rated speed value n0, where U1 < U0; when the bus voltage U drops to less than the set value U1, the magnitude of the bus voltage U and the set value U2 are judged again. If the bus voltage U is not less than U2, the permanent magnet synchronous motor for pumps continues to operate at the rated speed value n0, where U2 < U1; when the bus voltage U drops to less than U2, the magnitude of the bus voltage U and the set value U3 are judged again, where U3 < U2. If the bus voltage value U is not less than U3, the permanent magnet synchronous motor for pumps operates at the set minimum speed value n1 and continues to be compared with the set value U1. When the bus voltage U is higher than U1, the speed of the permanent magnet synchronous motor for pumps resumes to the rated speed value n0; when the bus voltage U drops to less than U3, the permanent magnet synchronous motor for pumps stops working; The set value U0 is the normal bus voltage value of the permanent magnet synchronous motor for pumps, and U0 is determined according to the voltage system adopted by the electric drive vehicle; the set value U1 is the minimum voltage value for the normal operation of the permanent magnet synchronous motor for pumps, and U1 is determined according to the back electromotive force of the rated speed value n0 of the permanent magnet synchronous motor for pumps; the set value U2 is determined according to the back electromotive force of the permanent magnet synchronous motor for pumps and the minimum speed value n1 of the permanent magnet synchronous motor for pumps; the set value U3 is determined according to the capacity of the IGBT of the permanent magnet synchronous motor controller.

2. A method for reducing the bus voltage of a pump-type permanent magnet synchronous motor according to claim 1, characterized in that: When the permanent magnet synchronous motor for pumps is used to drive the transmission oil pump on the electric drive vehicle, the rated speed value n0 of the permanent magnet synchronous motor for pumps is determined according to the relationship curve between the transmission oil pump flow and the speed; the minimum speed value n1 of the permanent magnet synchronous motor for pumps is determined according to the minimum flow demand of the transmission hydraulic system.

3. The method for reducing the bus voltage of a pump-type permanent magnet synchronous motor according to claim 1, characterized in that: When the permanent magnet synchronous motor for pumps is used to drive the brake oil pump on the electric drive vehicle, the rated speed value n0 of the permanent magnet synchronous motor for pumps is determined according to the hydraulic system flow required by the brake braking pressure; the minimum speed value n1 of the permanent magnet synchronous motor for pumps is determined according to the minimum flow demand of the brake hydraulic system.

4. The method for reducing the bus voltage of a pump-type permanent magnet synchronous motor according to claim 1, characterized in that: When the permanent magnet synchronous motor for pumps is used to drive the cooling water circulation pump on the electric drive vehicle, the rated speed value n0 of the permanent magnet synchronous motor for pumps is determined according to the relationship curve between the cooling water circulation pump flow and the speed; the minimum speed value n1 of the permanent magnet synchronous motor for pumps is determined according to the minimum flow demand of the parts to be cooled on the electric drive vehicle.

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