Principle of Drive Motor System
The driving motor of a vehicle is its unique source of power, responsible for converting electrical energy into mechanical energy to propel the vehicle forward or backward. According to the operating status of the vehicle, the drive motors of new energy vehicles have 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 driving motor. The driving motor converts electrical energy into mechanical energy, generating torque to propel the vehicle.
In energy recovery mode, the rotation of the wheels drives the electric motor into generator mode, generating three-phase alternating current. Subsequently, the motor controller converts AC power to DC power and sends the electrical energy back to the power battery for charging under the guidance of the control unit.
Currently, the commonly used types of drive motors for new energy vehicles are permanent magnet synchronous motors and induction asynchronous motors. Permanent magnet synchronous motors have shown outstanding 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 high attention in the field of electric vehicles at home and abroad and are one of the most competitive electric vehicle driving motors.
Induction asynchronous motor, also known as induction motor, generates a large amount of heat due to the induction of rotor winding current. Compared to permanent magnet synchronous motors, the power density is lower, but its high-speed performance is better than that of permanent magnet synchronous motors. With the widespread application of induction asynchronous motors in electric drive systems, their industrial chain is more controllable and their cost is 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 types of motors are basically similar, so this article will briefly introduce them using permanent magnet synchronous motors as an example.
Permanent magnet synchronous motors are usually composed of components such as motor housing, stator core, stator winding, rotor, front and rear end caps, cooling system, etc.
The motor housing is generally made of aluminum alloy casting, and the middle part is cast with cooling pipes. The cooling liquid circulates inside the motor housing, taking away the heat generated by the motor and ensuring that the driving motor operates within a reasonable temperature range.
The stator core is usually made of laminated silicon steel sheets, embedded in the motor housing, and has excellent magnetic conductivity. There are a certain number of slots on the inner wall of the stator core, and the stator winding is wound in these slots according to specific rules.
The motor rotor is made of permanent magnet material and does not require external power supply, with 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, ensuring that the motor has good protective performance.