Patent ID: 7764051

Claim:
An alternating voltage generation apparatus comprising: first and second 3-phase coils, first and second inverters connected to said first and second 3-phase coils, respectively, to receive a direct-current voltage from a voltage supply line, a connector configured to allow connection with an external load receiving supply of alternating voltage from the alternating voltage generation apparatus, a relay circuit connected to a first neutral point of said first 3-phase coil and a second neutral point of said second 3-phase coil, and arranged between said first and second neutral points and said connector, and a control device controlling an operation of said first and second inverters and said relay circuit, wherein said first inverter responds to a first control signal from said control device to generate a first alternating voltage having a predetermined frequency at said first neutral point, said second inverter responds to a second control signal from said control device to generate at said second neutral point a second alternating voltage having said predetermined frequency, and corresponding to a phase-inverted version of said first alternating voltage, and said relay circuit responds to a third control signal from said control device to electrically connect said first and second neutral points with said connector, and provides to said connector a third alternating voltage having said predetermined frequency, and generated across said first and second neutral points.