Direct-current to three-phase alternating-current inverter system

摘要

A direct-current to three-phase alternating-current inverter system includes a three-phase motor, a plurality of switching elements, an inverter circuit for the three-phase motor, a capacitor, a direct-current power source and a control circuit. The switching elements arranged in the inverter circuit serve as upper and lower arms for the respective three phases of the three-phase motor, respectively. The capacitor is connected in parallel to the respective pairs of the upper and lower arms. The direct-current power source is arranged between the neutral-point of the three-phase motor and the respective lower arms or the respective upper arms. The control circuit controls the switching elements such that at least the switching frequency of one pair of the switching elements for one phase through which the current having the greatest value flows is lower than the switching frequencies of the other pairs of the switching elements for the other phases.