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US 10,703,404 B2Granted
Electric power steering device
AssigneeMitsubishi Electric Corporation
InventorsMunenori Yamamoto, Hiroshi Nishimura
Life of this patent
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Abstract
In an electric power steering device, if a semiconductor switching element is used between a battery and a bridge circuit for opening and closing a current path, this arises a problem of generation of heat by an ON resistance; for this reason, a current flowing through the semiconductor switching element is limited if a difference between the gate voltage and the source voltage of the semiconductor switching element is smaller than or equal to a predetermined value.
Claims3
An electric power steering device comprising:
- a motor;
- a bridge circuit that supplies a current to the motor and comprises a switching element;
- an opening and closing unit that includes a semiconductor switching element and performs supply and interruption of a current to the bridge circuit from a battery by the semiconductor switching element;
- and
- a microcomputer that performs control so as to limit a current flowing through the semiconductor switching element when a difference between a gate voltage and a source voltage of the semiconductor switching element is smaller than or equal to a predetermined value,
- wherein the current flowing through the semiconductor switching element is limited by limiting a drive Duty ratio of the switching element when a vehicle speed is less than or equal to a threshold speed and by limiting a motor current when the vehicle speed is greater than the threshold speed.
3 more elements
Dependencies are inferred from the claim text.