| 摘要 |
PURPOSE: To prevent the damage of a motor and a transistor by detecting a current flowing at the time of the on-off of the transistor before the motor is operated and detecting the lifetime of a base drive circuit when the time up to a fixed current value exceeds the fixed time at the time of the rise or fall of the current. CONSTITUTION: A transistor (Tr) 6 is ignited, and the lag time of the on-off of a Tr 3 is obtained. A Tr 5 is ignited, and the lag time of the on-off of a Tr 4 is acquired. Trs 5, 6 are also turned on-off similarly, thus obtaining a lag time. Each lag time is compared with the threshold level of a predetermined lag time, a base drive circuit is determined as normality when all lag time is lower than the threshold level, and the lifetime of the power-transistor base drive circuit is decided to be expiration when even one of each lag time reaches the threshold level of more. |
