Equipment classification of electric vehicle motors
Posted by Admin | 26 Nov
The drive motors used in electric vehicles are different from conventional industrial motors. The drive motor of an electric vehicle usually requires frequent start/stop, acceleration/deceleration, high torque at low speed or climbing, low torque at high speed, and a wide range of speed changes. Industrial motors are usually optimized at the rated operating point. Therefore, the drive motors of electric vehicles are unique and should be classified separately.
For brushless motors, according to whether the motor has a position sensor, it is divided into a position sensorless brushless motor and a position sensorless brushless motor. For a brushless motor without a position sensor, the vehicle must be pedaled up first. After the motor has a certain rotation speed, the controller can recognize the phase of the brushless motor, and then the controller can supply power to the motor. Since the position sensorless brushless motor cannot achieve zero-speed start, it is less used in electric vehicles produced after 2000. Brushless motors used in the electric vehicle industry generally use position sensor brushless motors. Rotate 180°, the coil does not move, and the Hall element induces the S pole magnetic field. At this time, P1 and R2 are cut off, and P2 and R1 are turned on. It can be seen that the current i'flows from the positive pole of the battery through R1, coil, and P2 to the negative pole of the battery. The direction of current i'at point A in the energized coil is the direction towards the terminal (the vector direction is opposite to the i'vector direction). The magnetic steel receives the reaction force of the coil, and also produces a counterclockwise rotating torque.
The number of magnets in brushless motors for electric vehicles is relatively large. Generally, there are 3 sets of coils, and each set of coils has a corresponding Hall element (3 phase coils have 3 Hall elements), so that the motor rotates more smoothly and efficiently. higher. When the magnetic steel rotates, the Hall element senses the change in the direction of the magnetic field and gives a corresponding control signal. The brushless controller controls the on and off of the upper 3 and lower 3 power tubes according to this signal.