The authors present a new design of rotor shape of interior permanent magnet motor. Improvements of the flux concentration combined with the Pulse Width Modulation (PWM) method are applied in this article. The significantly selected harmonic contents of the air-gap flux density are reduced by this technique. Therefore, an obtained back Electromotive Forces (EMF) are of better quality. The essential consideration allows reducing the eddy current losses in the solid rotor as same as in the magnets.