Power supply control device for inductive loads

A power supply control device for inductive loads, comprising:

• a plurality of power switching elements that are provided between a DC power supply having a negative terminal connected to a ground circuit and a plurality of inductive loads and that are connected between a positive terminal of the DC power supply and a positive terminal of each of the plurality of inductive loads so as to be intermittently driven;
• and
• a microprocessor that performs switching control of at least the plurality of power switching elements,
• wherein electric power is supplied from the DC power supply to the power supply control device for inductive loads through a power supply terminal and a ground terminal,
• a constant voltage power supply that supplies a predetermined stabilization control voltage to the microprocessor, a power capacitor, and a voltage dividing resistor are connected in parallel to each other between the power supply terminal and the ground terminal,
• a commutation diode is connected between an output end of each of the plurality of power switching elements and the ground terminal,
• in a state where one of the plurality of power switching elements is closed and an excitation current flows through one of the plurality of inductive loads, when the closed power switching element is opened, the commutation diode is connected in a relationship in which the excitation current is commutated and attenuates through the ground terminal and the commutation diode,
• when a disconnection abnormality of a ground wiring line between the ground terminal and the ground circuit occurs, the excitation current flowing through one of the plurality of inductive loads flows back and attenuates through the DC power supply, the power capacitor, and the commutation diode, and the power capacitor is charged by the return current, and
• when a monitoring voltage that is a voltage across the power capacitor rises and a monitoring divided voltage divided by the voltage dividing resistor exceeds a predetermined threshold voltage, occurrence of a disconnection abnormality of the ground wiring line between the ground terminal and the ground circuit is detected and stored, and driving command signals for the plurality of power switching elements are simultaneously stopped according to the detection and storage of the disconnection abnormality.