Patent ID: 7859207

Claim:
A method for adjusting a motor current supplied to an electric motor using an inverter device, the inverter device including an inverter circuit and a capacitor connected to an input of the inverter circuit, the method comprising: setting a maximum acceptable motor current value using a map or an expression representing a relationship between a temperature of the capacitor and a maximum value of the motor current that prevents a component of the inverter device from being damaged by a surge voltage produced by an equivalent series resistance of the capacitor; estimating a rotational position of a rotor of the electric motor and controlling the inverter circuit in such a manner as to supply a direct electric current smaller than the maximum acceptable motor current value to the electric motor as a d-axis electric current if the temperature of the capacitor is in a range in which the maximum acceptable motor current value is smaller than a value at which a torque necessary for starting the electric motor is produced; and controlling the inverter circuit in such a manner as to supply an alternating electric current to the electric motor after the temperature of the capacitor reaches a temperature at which the maximum acceptable motor current value becomes greater than or equal to the value at which the torque necessary for starting the electric motor is produced.