Spectral Analysis of Output Current of PWM Inverter-Fed Multiple Three-Phase AC Motors

A multiple three-phase motor can be symmetrical or asymmetrical, depending on the phase displacement among the three stator winding sets. This paper investigates the output current spectrum of PWM inverter-fed multiple three-phase AC motors. The output current is analyzed by separating into current components that produce air-gap flux and current components that produce additional copper losses in the stator. The relationship with the symmetrical component theory is presented. The analysis is supported by experimental results.