| 摘要 |
PROBLEM TO BE SOLVED: To suppress superposition of harmonic voltages onto an output voltage regardless of fluctuation in the neutral potential. SOLUTION: A first carrier in a multiplex carrier generated from a carrier signal generation circuit Gc is multiplied by the voltage Vdcp across a capacitor C1 and a second carrier is multiplied by the voltage Vdcn across a capacitor C2 to produce first and second carriers Ec1, Ec2. More specifically, amplitude of the first carrier Ec1 is increased and the amplitude of the Ec2 is decreased when Vdcp>Vdcn and the amplitude of the Ec1, Ec2 is regulated depending on the ratio of the detection voltages Vdcp, Vdcn. Pulse width of a pulse width modulation signal is then regulated based on the comparison results of these carriers and a modulation wave voltage command value Vu*. |
