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The rotor magnetic circuit structure of the permanent magnet synchronous motor is different, so the operation characteristics and control system of the motor are also different. According to the different positions of the permanent magnets on the rotor, permanent magnet synchronous motors can be mainly divided into: surface type and interior type. In the surface-type permanent magnet synchronous motor, the permanent magnets are usually tile-shaped and located on the outer surface of the rotor core. The important feature of this motor is that the main inductances of the straight and orthogonal axes are equal;
The interior permanent magnet is located inside the rotor, and there is a pole piece made of ferromagnetic material between the outer surface of the permanent magnet and the inner circle of the stator core, which can protect the permanent magnet. The important feature of this permanent magnet motor is that the main inductances of the straight and quadrature axes are not equal. Therefore, the performance of these two motors is different.
Permanent magnet synchronous motor has simple structure, small size, light weight, low loss and high efficiency. Compared with DC motor, it does not have the shortcomings of DC motor such as commutator and brush. Compared with asynchronous motors, it does not need reactive excitation current, so it has high efficiency, high power factor, large moment-to-inertia ratio, reduced stator current and stator resistance losses, and measurable rotor parameters and good control performance; Compared with asynchronous motors, there are also disadvantages such as high cost and difficulty in starting. Compared with the common synchronous motor, it saves the excitation device, simplifies the structure and improves the efficiency. The permanent magnet synchronous motor vector control system can achieve high precision, high dynamic performance, and wide range of speed regulation or positioning control. Therefore, the permanent magnet synchronous motor vector control system has attracted extensive attention from scholars at home and abroad.
