| 摘要 |
PURPOSE: To facilitate the overcurrent protection when a motor is locked without reducing the torque necessary for the start of the motor by a method wherein the energization of a motor coil is discontinued when a speed signal interval is longer than a specified value in a driving state and when a detected current is larger than a specified value in a stationary state. CONSTITUTION: An output signal L is outputted from a negative AND circuit 13 when a driving/stationary signal 5 is a signal H and, further, the output signal of an inversion circuit 12 is a signal H, i.e., when an excessive current flows in a stationary state. On the other hand, as the driving/stationary signal 5 is a signal L in a driving state, a signal H is outputted from the negative AND circuit 13. Therefore, when an excessive current flows in the stationary state of a motor, the output signal L of the negative AND circuit 13 is inverted into a signal H by an inversion circuit 14 and, in accordance with the output signal L from a negative OR circuit 15, the energization of motor coils 2-4 is discontinued by a driving circuit 1 to avoid damages caused by the heat generation from the driving circuit 1 and the motor coils 2-4. Moreover, the energization of the driving circuit 1 is continued even if an excessive current flows in the driving state, so that a starting torque is not reduced. |
