Magnet configurations and current control for high torque to current ratio in interior permanent magnet synchronous motors

Usually, Permanent Magnet Synchronous Motors (PMSM) are designed so that they may induce the sinusoidal electromotive force (EMF), at least for the line-to-line voltage, because of necessity to suppress the torque ripples when they are driven by sinusoidal current. Thus, the size for using the magnets is restricted. In this paper an extended magnet type (thickness of magnet is not changed) interior PMSM (IPMSM) inducing the non sinusoidal EMF is proposed. Two suitable, current waveforms will be calculated that maximizing of torque, minimizing of copper losses and torque ripple less have been taken into the consideration. The calculated performance of this type IPMSM model is compared with that of conventional sinusoidal EMF type IPMSM model driven by sinusoidal current. We found that the torque increased about 15% while the width of magnet had been increased about 20%, and we could confirm that the ripple less output torque was given when the motor was driven by the non sinusoidal current.