Built-in permanent magnet motor

Abstract

The invention discloses a built-in permanent magnet motor. Main polar faces and interpolar faces of a rotor of the motor are formed by connecting a plurality of arcs of eccentric circles not concentric with the circle center of the rotor, so that an air gap is adjusted, and a purpose of reducing a cogging torque of the motor is achieved, and higher harmonic during motor operation is reduced according to regular hierarchic air gap thickness variation. According to the motor, quadrature-axis inductance of the motor is increased in a mode of adopting the air gap thickness of the specific interpolar face and keeping the preset widths of the interpolar faces, so that a reluctance torque of the motor is increased, and torsion of the motor is increased.

Description

technical field [0001] The invention relates to a motor rotor, and refers to a built-in permanent magnet motor rotor capable of increasing reluctance torque, reducing cogging torque and high-order harmonics. Background technique [0002] There is a built-in permanent magnet rotor motor with a uniform air gap. In order to increase its reluctance torque, a technical scheme of reducing the pole surface of the main magnetic pole is adopted. Another significance of this technical scheme is to expand the pole surface between poles. Increase the inductance ratio of the quadrature axis and the direct axis to increase the reluctance torque of the motor. However, the increase in the quadrature axis inductance leads to an increase in the cogging torque, and the cogging torque will lead to the generation of pulsating ripple torque, and the motor will generate vibration and noise, which has a great impact on the efficiency of the motor, especially for vehicle driving, When robot (or mec...

AI Technical Summary

Problems solved by technology

[0005] However, the above-mentioned various technical solutions for improving cogging torque will produce undesirable parasitic effects

For example, in the previous patent, because the air gap of the quadrature axis of the motor is increased, the inductance of the quadrature axis is greatly reduced, and the reluctance torque is also reduced accordingly.

When the cogging torque is lower than a certain level, the high-order harmonics of the induced voltage will increase instead, especially when using a strong magnet (rare earth magnet), the high-order harmonics of the induced voltage will cause thermal and electromagnetic losses of the rotor and stator , The noise increases when the motor is running under high load, and the radial force is generated to make the rotation force of the rotor uneven, and the bearing load increases, etc.

These higher harmonics will further deform the sine wave air gap magnetic circuit we hope, causing some parasitic torque waveforms, which will weaken the actual torque output of the motor

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