Patent ID: 9446790
Filing Date: 2016-09-20
CPC Classification: B62D

Claim Text:
1. An electric power steering system, comprising: an electric motor that generates assist torque based on steering torque; a main power supply that supplies electric power to the electric motor; an auxiliary power supply device including an auxiliary power supply connected to the main power supply and capable of discharging electric power to the electric motor; and a control device that controls an operation of the auxiliary power supply device, wherein: the control device switches a mode, as a mode of connection between the main power supply and the auxiliary power supply device, among a first supply mode in which the main power supply and the auxiliary power supply are connected in series with each other and a high-potential side of the auxiliary power supply is connected to the electric motor, a second supply mode in which the main power supply and the auxiliary power supply are connected in series with each other and a low-potential side of the auxiliary power supply is connected to the electric motor, and a main power supply charging mode in which the main power supply and the auxiliary power supply are connected in parallel to each other, the main power supply charging mode being a mode in which the auxiliary power supply charges the main power supply.