In-vehicle electronic control unit and power feeding control method of the same

摘要

When a power supply switch is fed with power from a DC power supply and closed, a power supply unit starts power feeding to an opening and closing command generation unit and continues the power feeding by a self-hold command signal from the opening and closing command generation unit. A reverse connection protective element is a field-effect transistor connected in series to the power supply switch and driven to conduct current in an energization direction of an internal parasitic diode when the power supply is connected in proper polarity. Even when a supply fault abnormality is occurring due to fault contact between a positive-side wire of an in-vehicle electrical load connected to the reverse connection protective element and a positive-electrode wire of the DC power supply, the self-hold command signal is cancelled by determining that the power supply switch is opened while the reverse connection protective element is opened.

主权项

1. An in-vehicle electronic control unit, comprising:
a load opening and closing element which is connected in series to an in-vehicle electrical load and controls a power supply from a DC power supply to the in-vehicle electrical load; an opening and closing command generation unit which supplies an opening and closing command signal to the load opening and closing element, to close the load opening and closing element, and supplies a driving control signal to a gate of a drive transistor, to close the drive transistor; a reverse connection protective element which has an input wire connected to the DC power supply via a power supply switch and an output wire connected to the in-vehicle electrical load; a first monitor element which is connected to the input wire of the reverse connection protective element, monitors an input-side voltage on the input wire, and outputs a first monitor signal; and a power supply unit which feeds power to the opening and closing command generation unit by generating a predetermined stabilizing voltage when fed with the power from the DC power supply in response to the power supply switch being closed, wherein: the opening and closing command generation unit generates a self-hold command signal once the power supply switch is closed, to maintain a power feeding operation by the power supply unit when the power supply switch is subsequently opened, by maintaining the self-hold command signal; the reverse connection protective element includes a first field-effect transistor (FET), a parasitic diode is formed between a drain and a source of the first FET, the drive transistor is configured to apply a voltage to a gate of the first FET, in response to receiving the driving control signal, so that the reverse connection protective element is closed and conducts current in a same direction as a conduction direction of the parasitic diode when the DC power supply is connected in a proper polarity, whereas the reverse connection protective element does not conduct the current when the DC power supply is connected in a reversed polarity by an error and when the power supply unit stops the power feeding operation; the opening and closing command generation unit determines that the power supply switch is opened, in a first cycle, when the input-side voltage is less than a predetermined value based on the first monitor signal, and verifies that the power supply switch is closed, in a second cycle, when the input-side voltage is equal to or higher than the predetermined value by periodically cancelling the driving signal to the drive transistor to open the reverse connection protective element and monitoring the input-side voltage while the reverse connection protective element is opened; the opening and closing command generation unit stops the power feeding operation of the power supply unit by cancelling the self-hold command signal after a predetermined delay time upon detecting that the power supply switch is opened, and cancels the driving signal to open the drive transistor which opens the reverse connection protective element, so that the power supply unit is not started again while the power supply switch is opened due to the output wire of the reverse connection protective element and a positive-electrode wire of the DC power supply coming into contact with each other in an error.