| 摘要 |
PURPOSE:To reduce the cost of a transistor chopper device by conducting a charging transistor for a short time from when a chopper current is switched from ON to OFF to charging a base current controlling capacitor, thereby enabling the use of a low withstand voltage charging capacitor. CONSTITUTION:When a current flow rate command 204 becomes from H to L, the potential of the connecting point between resistors 90 and 98 is lowered via a differentiating circuit 124, a transistor 96 is interrupted, and a charging transistor 104 is simultaneously conducted. When the output of a differentiating circuit 124 is eliminated thereafter, the transistor 96 and the charging transistor 104 are reset to the original state. Accordingly, the transistor 104 is shortcircuited for a short time after the chopper current 200 is switched from ON to OFF, an instantaneous current produced by the voltage induced in an inductance flows through the transistor 104, and flows to a base current controlling capacitor 108. As a result, a large voltage is not applied to the transistor 104, but the transistor having low withstand voltage can be used therefor. |
