THREE-LEVEL POWER CONVERTER

PROBLEM TO BE SOLVED: To prevent discontinuous sound by controlling an output voltage of a three-level inverter from zero to maximum and realizing control of the generation of three-level pulse for continuously and smoothly performing an inverter output voltage. SOLUTION: This three-level power converter includes a power converter for converting a DC power into an AC phase voltage, having three-level potentials that are positive, negative, and intermediate voltages, and a controller for controlling acceleration/deceleration of an AC motor connected to the output side of the power converter. In a low-speed region in acceleration/deceleration control, a first pulse width modulation control region, in which positive/negative voltage pulses are alternately outputted via an intermediate voltage, is given for the whole region of the half period of the output voltage basic wave of the converter. In a high-speed region in the acceleration/deceleration control, a second pulse width modulation control region, which has a first period when the plurality of the voltage pulses of identical polarity are outputted continuously and a second period, when the positive and negative voltage pulses are alternately outputted via the intermediate voltage before/after the first period, is given in the half period of the output voltage basic wave of the converter. COPYRIGHT: (C)2005,JPO&NCIPI