Patent ID: 7129663

Claim:
An electric power steering apparatus, comprising: a booster circuit outputting an output voltage, the output voltage being obtained by boosting a power supply voltage, the booster circuit comprising: a booster coil having a first end and a second end, the power supply voltage being applied to the first end of the booster coil; a first switching element connected to the second end of the booster coil, the first switching element selectively causing the second end to be grounded and ungrounded; an output terminal connected to a node between the second end of the booster coil and the first switching element; a second switching element provided between the node and the output terminal, the second switching element selectively connects and disconnects the node with the output terminal; and a smoothing capacitor connected to the output terminal; a motor being controlled according to power that is supplied based on the output voltage of the booster circuit, wherein the electric power steering apparatus uses the motor as a driving source to apply assisting force to a steering system; and a control section that drives the first and second switching elements such that the first and second switching elements are selectively turned on and off during application of assisting force to the steering system, thereby controlling the output voltage of the booster circuit, wherein, when application of assisting force to the steering system is stopped, the control section holds the second switching element on until the output voltage of the booster circuit becomes equal to a predetermined voltage.