Patent ID: 7432616
Filing Date: 2008-10-07
Classification: G01R,H02M

Abstract:
1. An inverter device comprising: an electrolytic capacitor serving as a DC power source; an inverter main circuit which has switching elements, and which converts a DC voltage of said electrolytic capacitor to an AC voltage; a switching control circuit which outputs a control signal for ON/OFF-controlling said switching elements of said inverter main circuit; and an electrolytic capacitor electrostatic capacitance calculator which calculates an electrostatic capacitance of said electrolytic capacitor, wherein when a power source connected to said electrolytic capacitor is interrupted, said switching control circuit controls said switching elements of said inverter main circuit to operate to supply a current to a load, thereby discharging charges of said electrolytic capacitor, and said electrolytic capacitor electrostatic capacitance calculator calculates the electrostatic capacitance of said electrolytic capacitor, on the basis of a discharged charge amount which is obtained from an inverter output current that is detected by a current detector disposed on a side of an output of said inverter main circuit, ON/OFF time ratio of said switching elements of said inverter main circuit, and a discharge voltage which is a voltage drop from a beginning of discharging of said electrolytic capacitor.