To provide a motor drive device and drive method capable of controlling a low-speed rotation.
An oscillation section 11 is composed of two oscillation portions of a first oscillation portion 11a and a second oscillation portion 11b having equal frequencies and different on-duty widths. An output of the first oscillation portion 11a and the second oscillation portion 11b is switched by a switching circuit 14 as a set pulse signal input into a PWM control portion 12. The switching circuit 14 is controlled by a low-speed control switching signal from a low-speed control switching signal terminal 13. The set pulse signal having an equal frequency and different on-duty is input into the PWM control portion 12. In the low-speed control, a current detection prohibition period is made short for removing a noise during switching the PWM control signal using the set pulse signal having a small on-duty to make a PWM minimum pulse width to be short. A current supplied to a DC brushless motor 7 can be reduced so that a generated torque of the DC brushless motor can be suppressed.
IWANAGA FUTOSHI
TANIMOTO KIYOTAKA
NISHINO HIDEKI
Next Patent: MOTOR DRIVE CONTROLLER AND ELECTRIC POWER STEERING APPARATUS THEREWITH