Control device and failure determination method

A method of determining a failure of a current sensor performed by a control device that controls a motor via an inverter circuit that supplies power converted from direct current to three-phase alternating current to the motor,

• wherein a current sensor that detects alternating current of each phase of three-phase alternating current is provided at an output of the inverter circuit,
• the method comprising, by the control device,
• calculating estimated DC current values by using a duty value of a PWM signal for controlling switching of the inverter circuit and an AC current value of two phases among three phases detected by the current sensor, and
• by the control device, determining a failure of the current sensor on the basis of a change in the estimated DC current values that have been calculated, the control device configured to determine that the current sensor fails in a phase having a smallest difference between a maximum value and a minimum value of the estimated DC current values that have been calculated.

A control device that controls a motor via an inverter circuit that supplies power converted from direct current to three-phase alternating current to the motor, the control device comprising:

• a current sensor that detects AC current of each phase of three-phase alternating current provided at an output of the inverter circuit,
• wherein the control device calculates three estimated DC current values by using a duty value of a PWM signal for controlling switching of the inverter circuit and an AC current value of two phases among three phases detected by the current sensor, and determines a failure of the current sensor on the basis of a change in each of the estimated DC current values that have been calculated, the control device configured to:
• perform first determination of determining a phase in which the current sensor fails and a type of a failure by collating a change in each of the estimated DC current values that have been calculated, with a first determination table, and
• when the failure of the current sensor cannot be determined by the first determination, perform second determination of determining the phase in which the current sensor fails and the type of the failure by collating a change in each of the estimated DC current values that have been calculated, with a second determination table.