| 摘要 |
PURPOSE:To control the braking of a brushless motor at a high speed by an electronic switch of small capacity by controlling the input side of a motor winding drive circuit of a SEPP structure and employing a SEPP output stage transistor as a switch for flowing a shortcircuiting current in the motor winding. CONSTITUTION:An electronic switch ESW1 is opened, an electronic switch ESW2 is closed to ground the input of a drive amplifier 3, thereby applying an electromagnetic brake. Since the bases of transistors T1, T2 of the amplifier 3 are ground voltage, the transistor T2 is turned ON when a counterelectromotive force +VE which is higher than the ground voltage is generated in response to the rotating speed of a rotor at the terminal E of a motor winding 4 to discharge the counterelectromotive force through a - power source, and the transistor T1 is turned ON when a counterelectromotive force -VE which is lower than the ground voltage is generated, and the counterelectromotive force is absorbed to the + power source side. In other words, the electromagnetic brake is acted by the shortcircuiting current. The continuous variation of a brake torque can be performed by varying the conduction duty ratio of the switch ESW2. |
