Patent ID: 8842455

Claim:
An electric-power conversion apparatus comprising: a chopper circuit; a current sense resistor that detects a first output current of the chopper circuit; a differential detection circuit that outputs, as a differential detection signal, an electric potential difference across the current sense resistor; and a calculation means that corrects the differential detection signal from the differential detection circuit by use of a control signal so as to calculate a second output current of the chopper circuit; wherein the calculation means calculates a switching signal for turning on or off the chopper circuit based on a phase width signal, which is the control signal for the chopper circuit, and calculates the second output current of the chopper circuit based on the differential detection signal; wherein the chopper circuit is configured with an upper stage power semiconductor device connected between a first electric potential and a second electric potential and a lower stage power semiconductor device connected between the second electric potential and a reference electric potential; wherein the current sense resistor is connected between the second electric potential and a third electric potential; wherein the differential detection circuit detects the electric potential difference between the second electric potential and the third electric potential, wherein the calculation means is provided with a first correction amount and a second correction amount and selects, as a correction amount for calculating the second output current of the chopper circuit, one of the first correction amount and the second correction amount in accordance with on/off of the switching signal, and wherein the calculation means is provided with a carrier-wave generator that generates a carrier wave for obtaining the switching signal and a holder that holds the differential detection signal in synchronization with the carrier wave, and selects one of the first correction amount and the second correction amount in accordance with the switching signal at a time point when the differential detection signal is held.