US 8,037,964 B2 · Electric power steering apparatus

Abstract

When stopping operation of an electric power steering apparatus, a motor relay is kept in an on-state even after a power supply relay is in an off-state. A drive control portion sets a target value of a d-axis current to a value other than zero and sets a target value of a q-axis current to zero, and performs a processing same as that at the time of rotating a motor. MOS-FETs contained in a motor driving circuit are controlled such that each of driving currents of the two phases or more is not zero and the brushless motor does not rotate even supplied with these driving currents. Electric charge accumulated in a capacitor is discharged via the MOS-FETs each in an on-state, a motor relay and the windings of the brushless motor. The electric charge accumulated in the capacitor may be discharged via the excitation coil of the motor relay.

Claims6

Dependent claims

An electric power steering apparatus which is coupled to a power supply in use, comprising:

a motor which generates a steering assist power to be applied to a steering mechanism of a vehicle;
a power supply switch;
a capacitor connected for absorbing current ripple in the power from the power supply;
a motor driving circuit which includes a plurality of switching elements and supplies a driving current to the motor;
a drive control portion which controls the switching elements;
and
means for causing an electric charge accumulated in the capacitor to flow into a part of a current path necessary for rotating the motor at a time after the power supply switch is changed in a non-conductive state.

4 more elements

Dependencies are inferred from the claim text.

Electric power steering apparatus

Life of this patent

Electric power steering apparatus

Life of this patent

Abstract

Claims6