Patent ID: 7352598

Claim:
An inverter unit comprising a DC power source, an inverter circuit having a plurality of pairs of switching elements, in each pair of which the switching elements are coupled in series, and which pairs of switching elements are connected in parallel to said DC power source, so that a DC voltage of said DC power source is converted into a pulse train-like, pseudo-AC voltage output from said inverter circuit, and a PWM generator connected to said inverter circuit and capable of adjusting said pseudo-AC voltage by pulse width modulation, said inverter unit comprising: means for detecting an actual output voltage output from said inverter circuit; and means for controlling an output duty cycle, so that an output voltage detected by said means for detecting becomes a target output voltage; wherein said output duty cycle equals a target output voltage divided by a difference between a detected, high output voltage and a detected, low output voltage, and wherein said detected, high output voltage is a maximum voltage value detected in said pulse train-like, pseudo-AC voltage, and said detected, low output voltage is a minimum voltage value detected in said pulse train-like, pseudo-AC voltage.