Drive motor system principle

The vehicle's drive motor is its unique power source, responsible for converting electrical energy into mechanical energy to propel the vehicle forward or backward. Depending on the vehicle's operating status, the drive motor of a new energy vehicle has two working modes: electric drive and energy recovery.

In electric drive mode, the DC power generated by the power battery is transmitted to the motor controller, which then converts it into AC power and transmits it to the drive motor. The drive motor converts electrical energy into mechanical energy and generates torque to propel the vehicle.

At present, the types of drive motors commonly used in new energy vehicles are mainly permanent magnet synchronous motors and induction asynchronous motors. Permanent magnet synchronous motors have excellent performance in electric vehicle driving due to their high efficiency, precise control, high torque density, good stability, low vibration and low noise. They have attracted great attention in the electric vehicle field at home and abroad and are one of the most competitive electric vehicle drive motors.

Induction asynchronous motors, also known as induction motors, generate a lot of heat because their rotor winding current is generated by induction. Compared with permanent magnet synchronous motors, their power density is lower, but their high-speed performance is better than that of permanent magnet synchronous motors. In addition, with the wide application of induction asynchronous motors in electric drive systems, their industrial chain is more controllable and their costs are lower. They are also widely used in new energy vehicles abroad and some new energy vehicles in China.

From the perspective of the maintenance market, the structure and control of these two motors are basically similar, so this article will take the permanent magnet synchronous motor as an example for a brief introduction.

Permanent magnet synchronous motors are usually composed of components such as motor housing, stator core, stator winding, rotor, front and rear end covers, and cooling system.

The motor housing is generally cast with aluminum alloy, and a cooling duct is cast in the middle part. The coolant circulates in the motor housing, taking away the heat generated by the motor and ensuring that the drive motor operates within a reasonable temperature range.

The stator core is usually made of laminated silicon steel sheets and embedded in the motor housing, which has excellent magnetic conductivity. A certain number of slots are opened on the inner wall of the stator core, and the stator winding is wound in these slots according to a specific rule.

The motor rotor is made of permanent magnetic material, does not require external power supply, and has its own magnetic field. The rotor is equipped with bearings at both ends to support smooth rotation. The front cover effectively seals the drive motor to ensure that the motor has good protection performance.