<p>The problem of large-capacity multiphase motor system high-frequency vibration and noise caused by pulse-width modulation (PWM) is prominent. At present, carrier phase-shift PWM is a good method to suppress high-frequency vibration. However, further research is required to determine whether the chosen carrier phase-shift angle is optimal. In addition, the current imbalance problem has not been reported with carrier phase shift in multiphase motor systems. First, a multiphase motor mathematical model of electromagnetic (EM) force is built, and a total harmonic energy analytic expression of EM force is proposed for solving optimal carrier phase-shift angle. This expression obtained the best high-frequency vibration suppression effect. Second, a current balance control method considering carrier phase-shifting high-frequency vibration suppression is proposed. Third, the current imbalance problem of multiphase motor systems caused by carrier phase shifting is analyzed. A fundamental phase compensation strategy is proposed to solve the imbalance of motor winding current after carrier phase shifting for high-frequency vibration suppression. The correctness of the proposed strategy is verified by a 15-phase/tens of MW motor system. This study provides a solution for optimal high-frequency vibration suppression strategy and output current balance control of multiphase large-capacity motor systems after adopting carrier phase shifting.</p>