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|1. (WO2018198740) MOTOR DRIVE DEVICE, AND ELECTRIC POWER STEERING DEVICE|
|Title:||MOTOR DRIVE DEVICE, AND ELECTRIC POWER STEERING DEVICE|
A motor drive device having a control unit that controls driving of a motor, wherein: the control unit has a control part for outputting instruction signals pertaining to the amount by which the motor is to be driven, a drive part for supplying to the motor a current supplied from an external power supply on the basis of the outputted instruction signal, a current detection part for detecting the current that flows to the drive part, and a first temperature detection part for detecting the temperature of the drive part; the control part calculates the heat storage amount inside the control unit at a prescribed period; when the calculated heat storage amount is greater than a prescribed threshold value, the control part outputs an instruction signal of a driving amount that is smaller than the driving amount at the time of calculation; and the heat storage amount Qn calculated the nth time (where n is an integer of 1 or greater) by the control part is a value for which, when Q0 is taken as a prescribed initial value, an estimated value of the heat generation amount obtained on the basis of the external power supply voltage, the prescribed period, and the detected current value is added to a heat storage amount Qn–1, and is a value from which the estimated value of the heat dissipation amount obtained on the basis of the difference between the temperature detected by the first temperature detection part and a prescribed temperature is subtracted.