A motor electric brake control method and device for electric drive vehicles

Abstract

The invention discloses a motor electric braking control method and device for an electrically driven vehicle. The method steps include: S1. When the vehicle enters the braking condition, control and adjust the braking of the motor according to the torque mode with the torque as the following control target. Power torque to reduce the speed of the motor; S2. When the speed of the motor drops to the specified switching threshold, the control switches to the speed mode with the speed as the follow-up control target, and the speed of the motor is controlled to drop to zero speed according to the speed mode; S3. When After the speed of the motor is zero for a specified time, it will enter the position mode with the position as the follow-up control target, and control the position state of the motor rotor according to the position mode. The invention has the advantages of simple realization method, low cost, pure electric control braking, anti-rotation of wheels, good control effect and the like.

Description

technical field [0001] The present invention relates to the technical field of electric motor braking of electric drive vehicles, and in particular, to a method and device for controlling electric motor electric braking of electric drive vehicles. Background technique [0002] In vehicles powered by electric drive, a compound braking method is usually used, which uses the combined action of mechanical braking and electric braking, that is, when the vehicle needs to be braked, the electric braking is switched on first. , the electric braking force is gradually reduced, and the mechanical braking is gradually increased. Finally, when the speed reaches zero, the electric braking force is 0, and all the wheels are kept from rotating by the mechanical braking. However, the above-mentioned composite braking method of electric braking and mechanical braking must rely on mechanical braking, and mechanical braking may fail quickly, resulting in the reduction or failure of mechanical ...

AI Technical Summary

Problems solved by technology

However, the combined braking method of electric braking and mechanical braking mentioned above must rely on mechanical braking, and mechanical braking has a rapid failure of capacity, which leads to the reduction or failure of mechanical braking, and electric braking cannot complete the vehicle. The function of braking to zero, especially for special vehicles that often need to drive on complex roads, the mechanical brake is very easy to fail, which can easily lead to brake failure

[0003] As mentioned above, the vehicle is controlled in the torque mode during the electric braking process, and the control object of the torque mode is the torque. If it is considered that the braking is performed directly in accordance with the traditional electric braking control mode, when the speed is close to zero, Due to the need to still maintain torque, wheel spin problems may occur

And when the frequency converter is used to control the electricity, the motor is in the process of rotation, and the controlled current waveform is AC. When the motor speed is zero, the current becomes DC. Therefore, within a fixed period of time, the current will change from three IGBTs to three IGBTs respectively. The bridge arm is evenly shared (when rotating), and most of it is shared by one IGBT bridge arm (when locked) and the sum of the three-phase current is zero, which will cause the bridge arm IGBT to bear a large heat pressure, and may even Exceeding the limit affordability of the heat dissipation system, resulting in damage to the IGBT

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