01 asynchronous motor working principle
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Through the relative motion of the rotating magnetic field generated by the stator and the rotor winding, the rotor winding cuts the magnetic induction line to generate an induced electromotive force, thereby generating an induced current in the rotor winding. The induced current in the rotor winding interacts with the magnetic field to generate electromagnetic torque that causes the rotor to rotate.
When the rotor speed gradually approaches the synchronous speed, the induced current gradually decreases, and the generated electromagnetic torque also decreases accordingly. When the asynchronous motor operates in the motor state, the rotor speed is less than the synchronous speed.
Asynchronous motors are the most widely used in electric vehicles. Compared with DC motors, they have a wider range of speeds, so that they can meet the needs of high-speed cruising of vehicles even without a secondary differential or gearbox.
The asynchronous motor has the ability of variable frequency speed regulation, and its effect is equivalent to the linear relationship between the engine speed and the vehicle speed when the vehicle equipped with the continuously variable transmission is understood to accelerate.
Asynchronous motors are also easier to achieve kinetic energy recovery. When the vehicle is coasting or braking, the wheel reverses the motor to rotate. Under this condition, the motor can generate electricity and recover the electric energy into the battery, thereby extending the cruising range of the vehicle.
Tesla MODELS uses asynchronous motors, and currently includes a variety of hybrids such as the Roewe 550Plug-in. The reason why the asynchronous motor is selected is because of its anti-interference ability and high-speed weak magnetic field running ability, although the power is large, the structure is simple, and the work is reliable.
