Circuit board

Abstract

The invention provides a circuit board used for a motor control device and provided with an alternative unit of a power cut-off relay. A switch unit SW (7) is disposed on a power supply path from a power supply generation unit (6) to a pre-driver unit (1), the switch unit SW (7) cutting off / energizing the power supply from the power supply generation unit (6) to the pre-driver unit (1). The control circuit includes a motor drive unit (INV) (5) that supplies power from an external power source (BT) to a motor (15) and a pre-driver unit (pre-driver IC) (1) that outputs a drive signal to the INV (5), and when a failure or abnormality of the control circuit is detected, the control unit (3) causes the SW (7) to be in a non-conductive state and cuts off power supply to the pre-driver unit (1).

Description

technical field [0001] The present invention relates to a circuit board mounted, for example, in a motor control device such as an electric power steering device. Background technique [0002] An electric power steering apparatus includes an electric motor that generates assist torque for steering operation of a driver of a vehicle such as an automobile, a control device for the electric motor, and the like. The electric power steering device has an inverter control unit that receives a control signal from a control unit (CPU) to generate a motor drive signal (PWM signal), and an inverter that is connected to an external battery and supplies drive current to each motor coil of the electric motor. circuit (INV), etc. [0003] On the circuit board on which the control circuit of the electric power steering device is mounted, in order to prevent dangerous behavior such as overcurrent flowing in the inverter circuit due to a failure such as a short circuit of a semiconductor sw...

AI Technical Summary

Problems solved by technology

[0007] However, if the power relay for overcurrent cutoff is removed from the power line, as long as there is no other substitute function, when an abnormality such as a FET short circuit of the inverter occurs, an overcurrent may continue to flow to the inverter or automatic steering may occur. such problem

[0008] In the case of Patent Document 1, the failure of the short-circuit detection part of the FET is diagnosed at startup, but if a failure occurs in the short-circuit detection part of the FET after control starts, the FET of the short-circuit detection part of the FET may not be diagnosed normally. short circuit fault

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