| 摘要 |
PURPOSE:To prevent damage of a switching element, etc., due to an induced current at the time of reversing by turning OFF all switching elements when a speed command becomes near '0' of a speed thereby to feed all induced currents generated in an armature winding in a direction for charging a power source when a rotor is reversely rotated by an external force. CONSTITUTION:The three-phase DC brushless motor comprises a speed setter 50 and a comparator 52. The setter 50 is set to a predetermined speed range V0 near a speed '0' including a speed '0'. The comparator 52 compares V1 of a speed command 1 with a set speed V0, and judges ¦V1¦<V0 to output a stop signal S. A controller 3 so outputs a signal to drivers 28, 30 as to simultaneously turn OFF all transistors Tr1-T6 when the signal S is output. As a result, all the transistors Tr1-T6 are completely turned OFF, and an inverter 12 is protected. |
