Power inverter

A power converting apparatus comprising a capacitor connected in series which serves to divide a DC voltage, a positive side main switching element and a positive side auxiliary switching element which have three electric potentials for setting the DC voltage to be a positive voltage, a negative voltage and an intermediate voltage by utilizing a node of the capacitor, and are inserted between the positive voltage side and an output terminal connected to a load and are connected to each other in series, a negative side main switching element and a negative side auxiliary switching element which are inserted between the negative voltage side and theoutput terminal and are connected to each other in series, a clamp diode connected between the intermediate voltage point and a node of the positive side main switching element and the positive side auxiliary switching element and between the intermediate voltage point and a node of the negative side main switching element and the negative side auxiliary switching element, and a plurality of free wheel diodes which is connected in parallel with each of the switching elements, and having, in a plurality of phases, a PWM inverter bridge for converting the DC voltage into an AC phase voltage having three electric potentials,

• wherein there is provided a zero voltage period having an intermediate voltage in which output phase voltages having all phases of the power converting apparatus become the intermediate voltage when a load current reaches a first overcurrent level.