1 Advantages of permanent magnet synchronous motor
Compared with DC motor, permanent magnet synchronous motor has no disadvantages such as commutator and brush of DC motor. Compared with asynchronous motor, it does not need reactive excitation current, so it has high efficiency, high power factor, large moment of inertia ratio, reduced stator current and stator resistance loss, measurable rotor parameters and good control performance.
Compared with the common synchronous motor, the permanent magnet synchronous motor saves the excitation device, simplifies the structure and improves the efficiency. The vector control system of permanent magnet synchronous motor can realize high precision, high dynamic performance and wide range of speed regulation or positioning control.
2. Disadvantages of permanent magnet synchronous motor
Compared with asynchronous motor, permanent magnet synchronous motor has some disadvantages, such as relatively high cost and difficult starting.
Control mode of permanent magnet synchronous motor
The constant voltage frequency ratio control method of permanent magnet synchronous motor is similar to that of AC induction motor, which controls the amplitude and frequency of motor input voltage to change at the same time, so that the motor flux linkage is constant, and the constant voltage frequency ratio control method can meet the requirements of large-scale speed regulation system.
Permanent magnet synchronous motor can still achieve certain control accuracy without feeding back physical signals such as current, voltage or position, which is the biggest advantage of constant voltage-frequency ratio control method. Constant voltage frequency ratio control method has simple control algorithm and low hardware cost, and has been widely used in the field of general frequency converters.