Patent ID: 8223521

Claim:
An inverter device comprising: an inverter main circuit obtained by connecting, in a three-phase bridge-like manner, three arms formed by coupling, in series with a direct-current power source, two switching elements which perform mutually opposite on/off operations, to apply three-phase pseudo alternating-current voltages of a three-phase PWM system to an electric motor; shunt resistors connected to the direct-current power source in series with at least two of the three arms of the inverter main circuit; and control means for detecting currents flowing through the shunt resistors in a predetermined cycle to control the on/off operations of the switching elements of the inverter main circuit based on the detected currents, wherein the control means determines if the on-time of the switching element is continuously not more than a predetermined value, and if the control means determines that the on-time of the switching element is not more than a predetermined value, the control means converts, into the current value of a specific angle range, a current value detected at a time before approximately 180° corresponding to the specific angle range and then uses the converted current value.