Control principles of permanent magnet synchronous motor (PMSM),
induction motor (IM) and flat wire motor
In the motor control of electric vehicles, the control principles of permanent magnet synchronous motor (PMSM), induction motor (IM) and flat wire motor are crucial.
These three types of motors have their own characteristics in the motor control system, and the technical means used, such as PWM (pulse width modulation), feedback control, etc., are also different. This article will explore the control principles and related technologies of these three motors from the perspective of maintenance engineers.
Permanent magnet synchronous motor (PMSM) is one of the types of motors widely used in electric vehicles. Its core working principle is to rely on the permanent magnets on the rotor to generate a stable magnetic field, and the stator generates a rotating magnetic field through three-phase alternating current, so that the rotor and stator rotate synchronously.
The motor control adopts PWM technology to accurately control the speed and torque of the motor by adjusting the duty cycle of the stator current. In the closed-loop control system, the actual speed and torque of the motor are fed back by the sensor and compared with the set value. The controller continuously adjusts the output current according to the feedback signal to maintain the stable operation of the motor.
The functions of the motor controller include adjusting the current, monitoring the motor status and protecting the motor. In the motor drive, the controller provides the required current to the motor to achieve precise acceleration and deceleration. Overload protection and temperature management are achieved by monitoring current and temperature. When the motor operating temperature exceeds the set threshold, the system will automatically reduce the output power or shut down to ensure the safety of the motor.
Induction motor (IM) is another widely used motor, and its working principle relies on electromagnetic induction. The rotating magnetic field generated by the stator induces current in the rotor, and the rotor and stator magnetic fields interact to generate torque. IM control also uses PWM technology to control the speed by adjusting the frequency and amplitude of the input current. Due to the slip of IM, its speed is usually slightly lower than the speed of the stator magnetic field. In a closed-loop control system, the feedback signal can help the controller adjust the current in real time to adapt to load changes and ensure the stability of the motor. The function of the motor controller is similar to that of PMSM, which is responsible for receiving sensor signals, monitoring the operating status of the motor, and preventing overload. The overload protection mechanism of IM is also achieved by monitoring temperature and current to ensure that the motor operates within a safe range.
The design of flat wire motor uses flat windings, which gives it higher power density and better heat dissipation performance. The control principle of the flat wire motor is similar to that of PMSM and IM, and also uses PWM technology to control the current input accurately. The feedback control system also adjusts the control strategy by monitoring the motor status in real time. The functions of the motor controller cover current regulation, status monitoring and protection. In terms of motor drive, the controller ensures that the motor can operate efficiently under different operating conditions. The overload protection and temperature management of the flat wire motor rely on sensor feedback. When the motor temperature is too high, the control system will take corresponding measures to protect the motor.
