INCORPORATION BY REFERENCE

The disclosure of Japanese Patent Application No. 2018-164639 filed on Sep. 3, 2018 including the specification, drawings and abstract, is incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a vehicle control apparatus.

2. Description of Related Art

A control apparatus that controls a motor that is a source of an assist torque applied to a steering mechanism of a vehicle is conventionally known. For example, a control apparatus disclosed in Japanese Unexamined Patent Application Publication No. 2007-276706 (JP 2007-276706 A) includes a drive circuit, a power supply relay, and a control circuit. The drive circuit converts direct current (DC) power supplied from a battery into alternating current (AC) power and supplies the converted AC power to a motor. The power supply relay opens and closes a power supply path between the battery and the drive circuit. The control circuit controls operations of the drive circuit and the power supply relay. A capacitor for power supply stabilization is provided for the drive circuit.

The control circuit switches the power supply relay to on from off when triggered by turn-on of a power switch, e.g., an ignition switch. At this time, if an amount of power stored in the capacitor is small, inrush current into the capacitor from the battery may occur. A pre-charge circuit is provided in the control apparatus to reduce occurrence of the inrush current. The pre-charge circuit is a circuit for charging the capacitor before switching the power supply relay to on from off. The control circuit charges (pre-charges) the capacitor through the pre-charge circuit in advance and thereafter switches the power supply relay to on from off.

A control circuit that carries out what is generally referred to as initial check when power is turned on by operating a power switch is described in Japanese Patent No. 6109332 (JP 6109332 B), for example. The initial check is a check prior to starting power supply to the motor and is inspection for anomalies in parts, e.g., windings of the motor and the drive circuit, for driving the motor. When no anomaly is detected in the parts for driving the motor, the control circuit supplies power to the motor through the drive circuit. However, when an anomaly is detected in one of the parts for driving the motors, the control circuit may cause the abnormal part not to be used or shut off power supply, for example, depending on a type of the anomaly.

An operating voltage range may be set for the control circuit. The operating voltage range is a range of voltage within which the control circuit is guaranteed to operate in specifications. When a power supply voltage has entered the operating voltage range from outside the operating voltage range, the control circuit starts operating to carry out the initial check, for example, triggered by the change.

In a vehicle with an engine, for example, a drop in battery voltage may make it difficult to supply required power to an electrical load, such as a starter for starting the engine. In such a situation, what is generally referred to as jump start may be performed. Jump start means starting an engine of a disabled vehicle by connecting a battery of a rescue vehicle and a battery of the disabled vehicle with a jumper cable and supplying rescuing power to a starter of the disabled vehicle from the battery of the rescue vehicle. When the power switch of the disabled vehicle is turned off after the engine is started by the jump start, the following undesirable situation may arise. To perform the jump start, the battery of the disabled vehicle is connected to the battery of the rescue vehicle. As a result, a power supply voltage of the control circuit of the disabled vehicle may be held in an overvoltage condition where the power supply voltage is above the operating voltage range. When the power switch is turned off under the overvoltage condition, a power supply path between the battery and the control circuit is shut off, causing the power supply voltage of the control circuit to gradually decrease, eventually to a value below the operating voltage range. In this process, although for only a slight period of time, the power supply voltage stays within the operating voltage range by which an initial check start condition is satisfied.

There is some time lag from when the power switch is turned off to when the control circuit actually recognizes that the power switch is turned off. The control circuit recognizes that the power supply voltage is within the operating voltage range earlier than recognizing that the power switch is turned off. The control circuit then accordingly starts the initial check. The control circuit carries out the initial check by turning on the pre-charge circuit and, when triggered by completion of charging of the capacitor, turning on the power supply relay. As a result, power from the battery is supplied to a circuit downstream of the power supply relay. At this time, because the battery is connected to the battery of the rescue vehicle and therefore held in the overvoltage condition, a voltage above durable power of the pre-charge circuit may be applied to the pre-charge circuit.

SUMMARY OF THE INVENTION

An object of the invention is to provide a vehicle control apparatus capable of protecting a pre-charge circuit.

A vehicle control apparatus according to an aspect of the invention includes a drive circuit that supplies driving power based on a power supply voltage to a motor, a capacitor for power supply stabilization, the capacitor being connected in parallel with the drive circuit, a control circuit that controls an operation of the drive circuit, a power switch that opens and closes a first power supply path that connects between the control circuit and a power supply, a power supply relay that opens and closes a second power supply path that connects between the drive circuit and the power supply, and a pre-charge circuit that opens and closes a third power supply path that connects between the drive circuit and the power supply. After a lapse of a first preset period from when a voltage supplied through the first power supply path has entered an operating voltage range due to turning on of the power switch, the control circuit starts charging the capacitor by turning on the pre-charge circuit and, when the charging of the capacitor is completed, turns on the power supply relay.

By connecting the power supply of a disabled vehicle to a power supply of a rescue vehicle, for example, a power supply voltage of the control circuit of the disabled vehicle enters an overvoltage condition where the power supply voltage is above the operating voltage range. When the power switch of the disabled vehicle is turned off under the overvoltage condition, the first power supply path between the power supply and the control circuit is shut off, causing the power supply voltage of the control circuit to gradually decrease, eventually to a value within the operating voltage range. There is some time lag from when the power switch is turned off to when the control circuit actually recognizes that the power switch is turned off. Hence, the control circuit may recognize that the power supply voltage has entered the operating voltage range earlier than recognizing that the power switch is turned off. This may cause the control circuit to turn on the pre-charge circuit and, when triggered by completion of charging of the capacitor, to turn on the power supply relay. At this time, because the power supply of the disabled vehicle is connected to the power supply of the rescue vehicle and therefore the power supply voltage is held in the overvoltage condition, a voltage above durable power of the pre-charge circuit may be applied to the pre-charge circuit.

However, according to the above aspect, when the voltage supplied through the first power supply path has entered the operating voltage range, after the first preset period has elapsed from that time, the control circuit starts charging the capacitor by turning on the pre-charge circuit and, when charging of the capacitor is completed, turns on the power supply relay. Thus, even when the power switch is turned off under the overvoltage condition where the power supply voltage of the control circuit is above the operating voltage range and, as a result, the power supply voltage of the control circuit enters the operating voltage range, the control circuit does not turn on the pre-charge circuit immediately. If the power supply voltage of the control circuit decreases to a value below the operating voltage range before the first preset period elapses from when the power supply voltage of the control circuit has entered the operating voltage range, the control circuit does not turn on the pre-charge circuit. Furthermore, because the capacitor is not charged, the power supply relay is not turned on. Because no overvoltage is supplied to the pre-charge circuit, protecting the pre-charge circuit from an overvoltage is achieved.

