Power conversion device and motor drive device including power conversion device

摘要

A power conversion device includes a power-supply shunt resistance that is provided between an inverter and the negative-voltage side of a DC power supply, and respective-phase lower-arm shunt resistances that are provided between the power-supply shunt resistance and respective-phase lower-arm switching elements. Respective-phase lower-arm voltages, that are respective voltages between the negative-voltage side of the DC power supply and connection points between the respective-phase lower-arm switching elements and the respective-phase lower-arm shunt resistances, are detected to calculate respective-phase currents that flow through a load device in accordance with detection values of the respective-phase lower-arm voltages, and to control a carrier frequency of a carrier signal, which serves as a reference frequency of each drive signal, according to a change in a specific control parameter A.

主权项

1. A power conversion device to convert DC power supplied from a DC power supply to AC power, and to supply the AC power to a load device, the power conversion device comprising:
an inverter that is configured by connecting arms in parallel, each of which is made up of an upper-arm switching element and a lower-arm switching element; a shunt resistance that is provided at least between a negative-voltage side of the DC power supply and the respective-phase lower-arm switching elements; a voltage detection unit to detect a voltage between the respective-phase lower-arm switching elements and the negative-voltage side of the DC power supply; and a control unit to generate drive signals corresponding to the respective-phase upper-arm switching elements and the respective-phase lower-arm switching elements in accordance with values detected by the voltage detection unit, wherein the control unit changes a carrier frequency of a carrier signal, which serves as a reference frequency of the drive signals, according to a change in a specific control parameter, and wherein the control unit controls the carrier frequency to become high when an output frequency of the inverter is high, and controls the carrier frequency to become low when the output frequency is low.