Patent ID: 7843706
Filing Date: 2010-11-30
Classification: H02H,H02M

Abstract:
1. An inrush current limiting circuit interposed between a d.c. power source and a combination of an inverter circuit and a smoothing capacitor, the circuit comprising: a limiting resistor connected to the inverter circuit and the smoothing capacitor in series, for limiting inrush current from the d.c. power source to the inverter circuit and the smoothing capacitor through the limiting resistor itself; a switching circuit for allowing and disallowing a flow of resistor current in the limiting resistor within a period during which the inrush current flows through the limiting resistor; and open circuit instructing means for instructing to open the switching circuit based on a resistor inter-terminal voltage of the limiting resistor and based on the resistor current, wherein the open circuit instructing means includes: fixed time reference voltage calculating means for calculating a reference capacitor inter-terminal voltage of the smoothing capacitor at a time point at which a reference time elapses, based on the resistor inter-terminal voltage and the resistor current at the time point at which the reference time elapses, after a start of energization with current supplied from the d.c. power source through the switching circuit and the limiting resistor at least in a stage of activating an inverter equipped with the inrush current limiting circuit, the inverter circuit and the smoothing capacitor; and voltage-basis open circuit determining means for determining whether or not the switching circuit is to be opened based on the reference capacitor inter-terminal voltage and a capacitor inter-terminal voltage of the smoothing capacitor at the time point at which the reference time elapses.