Over-temperature protection method and device for motor of electric vehicle and electric vehicle

Abstract

The embodiment of the invention provides an over-temperature protection method and device for a motor of an electric vehicle and an electric vehicle. The over-temperature protection method comprises the following steps: collecting motor temperatures of an electric vehicle according to preset time intervals; judging whether the temperature is higher than or equal to the preset first-grade over-temperature protection threshold value; detecting the maximum value of the temperature when the temperature is higher than or equal to the first-grade over-temperature protection threshold value, and further limiting the maximum output power of the motor according to the power limiting coefficient corresponding to the maximum value, wherein when the temperature is higher than or equal to the first-grade over-temperature protection threshold value, the higher the temperature is, the bigger the corresponding power limiting coefficient is, and the larger the limitation to the maximum output power is, so that when the temperature is higher than or equal to the first-grade over-temperature protection threshold value, the maximum output power of the motor is limited by the power limiting coefficient corresponding to the maximum value of the temperature to be decreased only but not increased, the situation of frequent fluctuations of the maximum output power is avoided, shaking of the electric vehicle is avoided, and both the safety and the driving comfort of the electric vehicle are further improved.

Description

technical field [0001] The application belongs to the field of control, and more specifically relates to a motor over-temperature protection method and device of an electric vehicle and the electric vehicle. Background technique [0002] With the advancement of science and technology, electric vehicles have been widely recognized by people for their advantages of energy saving and environmental protection, and have been more and more popularized in people's daily life. [0003] Electric vehicles are driven by rechargeable power sources. When the motor works in the low-speed, high-torque and high-speed areas, the heat generated by the motor is relatively large, and the temperature of the motor rises a lot. At this time, the temperature of the motor should be limited. The maximum output power reduces the heating of the motor and avoids the occurrence of motor demagnetization and other failures due to excessive temperature. [0004] At present, when the motor temperature is be...

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Problems solved by technology

[0005] However, in the existing method, when the temperature of the motor is between the first-level over-temperature protection threshold and the second-level over-temperature protection threshold, if the heating of the motor is reduced due to the limitation of the maximum output power, the temperature will increase when the temperature drops a little. The maximum output power of the motor, when the heat generation increases and the temperature rises, the maximum output power of the motor will be reduced, which will cause the temperature of the motor to fluctuate around a certain temperature, and the maximum output power of the motor will also vary with the temperature. When it is near a certain power, it fluctuates frequently, which will cause the electric vehicle to vibrate when driving the electric vehicle with the maximum output power, and reduce the safety and driving comfort of the electric vehicle.

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