IPM and SPM motor

Introduction

Permanent magnets of SPM rotor are arranged on the surface, IPM is a built-in permanent magnet motor, and its permanent magnets are distributed inside the rotor.

SPM magnetic steel surface mount and IPM magnetic steel embedded are permanent magnet synchronous motors.

SPM: 

IPM:

Difference

SPM motor uses less permanent magnets and has fewer harmonic components of flux linkage, which makes it easier to produce sinusoidal magnetomotive force.

IPM motor can produce large inductance, torque and suspension force.

Built-in rotor structure can make full use of the reluctance torque produced by asymmetric rotor magnetic circuit, and improve the power density of motor, which makes the dynamic performance of motor better than that of surface-mounted rotor structure, and the manufacturing process is simpler, but the magnetic leakage coefficient and manufacturing cost are larger than those of surface-mounted rotor structure.

At the same time, for the rotor magnetic circuit structure of tangential IPM, two adjacent magnetic poles are connected in parallel to provide magnetic flux at one pole distance. Therefore, a larger magnetic flux per pole can be obtained. When the number of pole pairs of the motor is large, the structure is more prominent. The reluctance torque of the motor with tangential structure accounts for 40% of the total electromagnetic torque of the motor. The radial PMSM has small magnetic flux leakage coefficient, and does not need to take isolation measures. The polar arc coefficient is easy to control, the rotor strength is high, and the permanent magnet is not easy to deform. The PMSM with tangential structure has large magnetic leakage coefficient, which requires isolation measures. It has large magnetic flux per pole, many poles and large reluctance torque.

Application

1. The control strategy.

IPM: MTP+A field weakening control is used more.

SPM: id=0 vector control is more.

2. In the application field.

The applications of SPM motor are mostly industrial control, and the IPM motor is mostly used in electric vehicles, which seems to indicate that the power density of IPM motor is stronger than that of SPM motor, while the control performance of SPM motor is stronger than that of IPM.

3. On the inductance of DQ axis.

The inductances of D and Q axes of SPM motor are equal.

The inductances of D and Q axes of IPM motor are different, and Lq is greater than LD.