Patent ID: 7202618

Claim:
An inverter device, comprising: a plurality of switching elements which are provided in respective phases in a motor and which convert direct-current power into alternating-current power by being tuned on and off for driving the motor; a detecting unit for detecting a current in each phase in the motor; a control unit for controlling turning on and turning off of each of the plurality of switching elements, wherein: the control unit records, in advance, a current data table which specifies relationships between currents in the respective phases in the motor and positions of a rotor of the motor, and obtains, from the current data table, an initial position of the rotor corresponding to a current detected by the detecting unit before driving of the motor; the position of the rotor is a rotation angle of the rotor when one phase among the respective phases in the motor is a reference; the current data table is divided into a plurality of areas with respect to the rotation angle of the rotor in advance; and the control unit finds a current data table which corresponds to a relationship among the currents in the respective phases detected by the detecting unit, among the plurality of current data tables, and sets, as the initial position of the rotor, a value which can be obtained by substituting a current detected by the detecting unit into a linear equation with a slope corresponding to an increase or a decrease of a current specified by the found current data table.