| 摘要 |
A current instruct value generating section including a motor speed range determining unit for detecting a locked state of a motor; a time calculating unit for, if the locked state of the motor is detected, calculating a time required for the transistor junction temperature to reach a preset upper limit; a timer unit for setting the timer to the calculated time and counting the set time; and a current limiting unit for limiting the current instruct value when the timer times out. When the locked state of the motor is detected, the time calculating unit calculates a time required for the transistor junction temperature to reach the upper limit. When the timer counts up that time, the current limiting unit limits the current instruct value, thereby preventing concentration of excessively large loads on the transistors even when the motor is locked while the motor is being supplied with phase current.
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