Torque Ripple Minimization in Interior PM Machines using FEM and Multiple Reference Frames

Abstract

Pulsating torque exists in interior permanent magnet (IPM) machines due to non-sinusoidal flux density distribution around the air-gap. These torque pulsations are reflected as speed ripple, noise and vibration, which degrade the IPM drive performance and should be minimized. Firstly, the paper proposes a mathematical model of IPM machine that takes into account space harmonics of inductances and flux linkages related to permanent magnets as a function of rotor position. The space harmonics are analyzed by the 2D finite-element method (FEM) and the motor parameters of the model are determined. Then, the pulsating torque is compensated by generating an inverse torque component through the stator current, and this procedure to predetermine the adequate current reference is based on maximum torque per ampere characteristic (MTPA). Because of the periodic nature of torque ripple, this paper presents a current control scheme that solves bandwidth limits of conventional PI controllers by means of multiple reference frames. Two different motor structures have been studied and verification for them is given.

A model predictive control scheme with torque ripple mitigation for permanent magnet motors

“…Closed-loop approaches are based on the on-line identification of the torque ripple based on measurements and on (a simpler) machine model [5]. In most cases, the torque or current controller must present a high dynamic performance in order to effectively mitigate the torque harmonics [2]- [4].…”

“…Various active torque ripple mitigation techniques have been investigated so far. The methods can be roughly classified in open loop approaches [2]- [4] and closed-loop approaches. Open loop approaches require a fine modeling (machine geometry and magnetic materials characteristic [4]) or accurate measurements of the parameters that determine the torque ripple, such as the induced voltage waveform [3].…”

Torque ripple compensation based on instantaneous torque estimation in permanent magnet synchronous motors

“…However, the transducer is very expensive and it is affected by mechanical resonance. In [5] [6], mathematical models have been applied to the torque estimation. The model is obtained from an analysis of the spatial harmonics by finite element analysis (FEA) and fast Fourier transform (FFT).…”

Advanced Torque Control of Permanent Magnet Synchronous Motor Using Finite Element Analysis Based Motor Model with a Real-time Simulator

“…The strict torque model of PMSM has been reported to analysis the actual output torque and some torque ripples reduction techniques have been proposed by calculating optimal current reference to reduce torque ripples (1) (2) . However, they are usually developed with a current regulator.…”