Patent ID: 8786229

Claim:
A power consumption calculating method for a motor driving device configured to step down an input voltage inputted to a chopper circuit by the chopper circuit including a series circuit of a first switching element having one end connected to a positive voltage side of the inputted direct-current voltage, and a reactor having one end connected to the other end of the first switching element, and a second switching element disposed between the connection point between the other end of the first switching element and the one end of the reactor, and a negative voltage side of the input voltage, to convert a direct-current power outputted from the chopper circuit to an alternating-current power by driving an inverter by 120-degree conduction, to output to a motor, and to clamp a surge voltage generated at commutation of the inverter to the input voltage by a diode connected in inverse-parallel to the series circuit, the power consumption calculating method comprising: calculating a power consumption of the motor driving device at driving of the motor by a following equation (a) from the input voltage to the chopper circuit, a switching duty factor representing a ratio of an ON state of the first switching element to an ON/OFF cycle of the first switching element, a reactor current flowing in the reactor, a winding reactance of the motor, and a rotational speed of the motor, P = Vdc × BDuty · ( Idc - L m · Idc · N 5 · Vdc · Idc 3 ) ( a ) P; power consumption Vdc; input voltage BDuty; switching element switching duty factor Idc; reactor current L m ; motor winding reactor N; motor rotational speed.