Electric power steering apparatus
AssigneeHonda Motor Co., Ltd.
InventorsHiroki Sagami, Kyoji Hamamoto, Hiroaki Horii, Fumihiro Morishita, Takuji Wada, Shinji Hironaka, Takashi Kuribayashi
Life of this patent
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Abstract
An electric power steering apparatus detects, as an abnormal phase, a phase other than a combination of phases whose interphase voltage is of nearly zero volts if a q-axis current is equal to or smaller than a first threshold value though a q-axis voltage is being applied. Alternatively, the electric power steering apparatus calculates a base electric angle at which the q-axis current is equal to or smaller than a third threshold value though the q-axis voltage is being applied, and determines an abnormal phase based on the base electric angle.
Claims3
An electric power steering apparatus comprising:
- an inverter for supplying three-phase AC electric power to three phases of an electric motor;
- a current coordinate converting unit for converting currents flowing in the three phases of the electric motor into d-q coordinate currents including a d-axis current as an exciting current component and a q-axis current as a torque current component;
- a voltage coordinate converting unit for converting three-phase voltages applied to the electric motor into a d-axis voltage and a q-axis voltage;
- an abnormal phase detecting unit for determining a combination of phases whose interphase voltage is of nearly zero volts in a state where the q-axis current is equal to or smaller than a first threshold value though the q-axis voltage is being applied, and detecting a phase other than the combination of phases as an abnormal phase;
- and
- a rotational speed detecting unit for detecting a rotational speed of the electric motor;
- wherein the abnormal phase detecting unit is operated when the rotational speed is equal to or smaller than a second threshold value,
- wherein the second threshold value comprises a threshold value for determining whether the electric motor is generating an excessive counter-electromotive force which makes accuracy of detecting the abnormal phase by the abnormal phase detecting unit inadequate.
Dependencies are inferred from the claim text.