Electric power steering device

Abstract

An object of the present invention is to provide an electric power steering device which detects each phase current of a motor with a single-shunt current detection circuit, and reliably detects failures (abnormal states) in the current detection circuit with a simple configuration, thereby enhancing safety. The electric power steering device is provided with: a single-shunt resistor connected to an inverter; a control motor current detection circuit which is connected in a forward direction to both ends of the shunt resistor and detects the phase currents of a motor as control motor current detection values for assist control; and a diagnosis motor current detection circuit which is connected in a reverse direction to both ends of the shunt resistor and detects failures in the control motor current detection circuit. The electric power steering device detects each phase current of a motor with the single-shunt scheme to perform assist control, and has two systems of circuits which amplify the voltage across the ends of the shunt resistor.

Description

technical field [0001] The present invention relates to an electric power steering device that applies steering assist force to the steering system of a vehicle through a multi-phase motor driven and controlled by a PWM (pulse width modulation) duty cycle (Duty) command value, in particular to a high-performance An electric power steering device that provides a single current detection circuit (a shunt type current detection circuit) between a drive unit that performs PWM driving and a power supply (battery) to perform auxiliary control, and at the same time diagnoses failures and abnormalities of the current detection circuit, etc. to improve security. Background technique [0002] An electric power steering device that uses the rotational force of an electric motor to assist in controlling the steering system of a vehicle, and applies the driving force of the electric motor to the steering shaft or rack shaft through a transmission mechanism such as a gear or a belt throug...

AI Technical Summary

Problems solved by technology

[0008] In such a structure, although it is necessary to measure the drive current of the inverter 106 and even the motor current of the motor 20, as one of the requirements for miniaturization, weight reduction, and low cost of the control unit 100, there is a single unit of the current detection circuit 120. (a shunt current detection circuit)

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