Abstract: A motor drive device includes: an inverter circuit; a drive circuit which receives voltage supplied from a control power source; a first cutoff circuit which cuts off voltage supply from the control power source to the drive circuit; a second cutoff circuit connected between the first cutoff circuit and the drive circuit; a voltage detection circuit which detects a detection voltage corresponding to the voltage supplied from the control power source and which is capable of changing the detection voltage; a comparison circuit which, upon determination that the detection voltage is not within a predetermined range, cuts off the first cutoff circuit; and a diagnosis circuit which diagnoses the first cutoff circuit. The diagnosis circuit causes the comparison circuit to cut off the first cutoff circuit, diagnoses the first cutoff circuit, and upon diagnosing the operation of the first cutoff circuit as being abnormal, cuts off the second cutoff circuit.

Abstract: A motor drive device includes: an inverter circuit; a drive circuit which receives voltage supplied from a control power source; a first cutoff circuit which cuts off voltage supply from the control power source to the drive circuit; a second cutoff circuit connected between the first cutoff circuit and the drive circuit; a voltage detection circuit which detects a detection voltage corresponding to the voltage supplied from the control power source and which is capable of changing the detection voltage; a comparison circuit which, upon determination that the detection voltage is not within a predetermined range, cuts off the first cutoff circuit; and a diagnosis circuit which diagnoses the first cutoff circuit. The diagnosis circuit causes the comparison circuit to cut off the first cutoff circuit, diagnoses the first cutoff circuit, and upon diagnosing the operation of the first cutoff circuit as being abnormal, cuts off the second cutoff circuit.

Abstract: A motor drive device of the present invention includes a speed signal generator that generates a rotation speed signal indicating rotation speed; a PWM signal generator that acts on the power switch unit to control the power switch unit so as to generate coil-applied voltage; and a phase advance information generator that has characteristic curve information representing changes of rotation speed of and load on a brushless motor, preliminarily set. The phase advance information generator generates phase advance information according to the load characteristic curve to variably control the phase advance (the phase of voltage applied to the coils of the brushless motor, relative to the induced voltage phase) according to the load characteristic curve.

Abstract: A motor drive device of the present invention includes a speed signal generator that generates a rotation speed signal indicating rotation speed; a PWM signal generator that acts on the power switch unit to control the power switch unit so as to generate coil-applied voltage; and a phase advance information generator that has characteristic curve information representing changes of rotation speed of and load on a brushless motor, preliminarily set. The phase advance information generator generates phase advance information according to the load characteristic curve to variably control the phase advance (the phase of voltage applied to the coils of the brushless motor, relative to the induced voltage phase) according to the load characteristic curve.

Abstract: A motor drive device according to the present invention includes a motor having a rotor and a drive coil, a rotor position detector, a speed detector that converts position information into speed information, a direction detector that converts the position information into rotating direction information, and a drive unit that drives the motor. When any one of a case where a pulse of a rotor position detector signal is not inputted to the speed detector and another case where a change of rotating direction of the motor is detected by the direction detector in a state in which the rotor repeats a forward rotation and a backward rotation in a condition of the rotor is locked.