The harmonics of the induced voltage under load conditions cause the deterioration of the motor performance. It occurs when the peak value of the demand voltage exceeds the DC link voltage. In this paper, thus, to reduce the induced voltage harmonics under load conditions, an asymmetric rotor design method using the advanced inverse cosine function (AICF) is proposed. Using this method, the rotor shape is determined by considering the armature reaction under certain load condition. As a result, an improved concentrated flux synchronous motor (CFSM) achieving the required performance is designed. Lastly, the induced voltages waveforms of the proposed motors under the load conditions are compared through finite-element analysis (FEA) as well as experiments.