Steering control device
A steering control device capable of suitably handling a temporary drop in a supply voltage of a vehicle is provided. An ECU includes a microcomputer, a pre-driver, and an inverter. The microcomputer generates a command signal for the pre-driver. Upon being initialized by the microcomputer, the pre-driver becomes operable to generate a drive signal for the inverter based on the command signal. The inverter converts direct current power supplied from a battery into alternating current power for a motor by operating based on the drive signal. When a drop in a voltage of the battery is detected, the pre-driver transmits an abnormal-condition detection signal to the microcomputer and stops operating by resetting a state of the pre-driver to an initial state where the pre-driver is not initialized yet. When the abnormal-condition detection signal is received, the microcomputer re-initializes the pre-driver.
1. A steering control device that controls a motor depending on a steering state, the motor being a source of a driving force applied to a steering mechanism of a vehicle, the steering control device comprising:
a conversion circuit that converts direct current power supplied from a direct current power supply mounted in the vehicle to alternating current power supplied to the motor;
a pre-driver circuit that, upon being initialized, becomes operable to generate a drive signal that drives the conversion circuit, the pre-driver circuit including:
a voltage monitoring circuit configured to detect a drop in a voltage of the direct current power supply; and
a control circuit that, after initializing the pre-driver circuit, generates a command signal depending on the steering state, the command signal being a pulse width modulation signal for the pre-driver circuit, and the drive signal causing the conversion circuit to operate based on the generated command signal, wherein
when the drop in the voltage of the direct current power supply is detected by the voltage monitoring circuit, the pre-driver circuit (i) transmits an abnormal-condition detection signal to the control circuit and (ii) stops generating the drive signal by resetting a state of the pre-driver circuit to an initial state where the pre-driver circuit is not initialized yet, the abnormal-condition detection signal containing information indicating that the drop in the voltage of the direct current power supply has been detected and that the pre-driver has been reset to return to the initial state,
when the abnormal-condition detection signal is received by the control circuit, the control circuit re-initializes the pre-driver circuit by transmitting an initialization command to the pre-driver circuit, the initialization command being a signal for initializing the pre-driver circuit and including setting information for the pre-driver circuit, and
when the abnormal-condition detection signal is received even though the control circuit has re-initialized the pre-driver circuit, the control circuit performs a predetermined notification operation to notify a driver of the vehicle of the abnormal condition of the direct current power supply.
2. The steering control device according to claim 1 , wherein
the control circuit has an abnormal-condition detection function that detects an abnormal condition of the conversion circuit by monitoring an electric current supplied from the conversion circuit to the motor and a fail-safe function that stops generating the command signal when the abnormal condition of the conversion circuit is detected, and
the control circuit disables the abnormal-condition detection function when the abnormal-condition detection signal is received, and enables the abnormal-condition detection function when the abnormal-condition detection signal is not received after re-initializing the pre-driver circuit.
3. The steering control device according to claim 1 , wherein when the voltage of the direct current power supply goes below a threshold voltage, the pre-driver circuit detects a drop in the voltage of the direct current power supply.
4. The steering control device according to claim 1 , wherein the motor generates, as the driving force, an assistive force for assisting steering of the vehicle.