Patent ID: 6058032
Filing Date: 2000-05-02
Classification: B60L,H02J,H02M,Y02T

Abstract:
A multiple pulse-width modulation power conversion device for variable-speed drive of a three-phase AC motor, comprising:three units, each unit including n (n.gtoreq.2) batteries each made up of a DC power supply or at least one battery cell, n power converters for converting DC power of each of said batteries to single-phase AC power, and n residual capacitance detectors for detecting residual capacitance of said batteries;wherein single-phase AC terminals within each unit are connected in series, one of the single-phase AC terminals that is not connected to a single-phase terminal of another power converter is connected to a star connection, and the other single-phase AC terminal that is not connected is connected to a respective one of three input terminals of said three-phase AC motor;further comprising control circuits for controlling said power converters such that AC applied to single-phase AC terminals of said n power converters within each unit are of the same phase, and moreover, for effecting multiple pulse-width modulation such that AC outputs from the three units are separated by an electrical angle of 120.degree., andeach unit further comprising means for determining the ratio of fundamental wave amplitude of AC voltages from said n power converters connected in series, based on residual capacitance detected by each of said residual capacitance detectors.