| 摘要 |
PURPOSE:To facilitate a DC brake by sorting a rectifier for generating an overcurrent of an induction motor driven by an inverter, and driving other power element connected with power bus reverse to the element. CONSTITUTION:A speed command signal 20 is processed by a processor 19 to form 6 PWM signals 18, and outputs a signal 16 for driving the bases of power transistors 2-7 through a base drive circuit 17. A base driver 17 insulates a main circuit power source and a control power source through a pulse transformer or a photocoupler to detect the overcurrent of the transistor. A protecting circuit 21 base blocks 22a'-f' by overcurrent signals 22a-f from the driver 17 to turn OFF the abnormal transistor. Then, the pulse width for driving the base of the power transistor not abnormal is controlled. Thus, a brake current is flowed to a motor 1 to prevent the motor 1 from idling. |
