| 摘要 |
PURPOSE:To improve the efficiency of electric power as well as the characteristics of rush current, by connecting the coil of a relay which controls a rush current preventing resistance connected to the primary side of a transformer to the secondary side of the transformer and by controlling the rush current preventing resistance with a current flowing to the secondary winding. CONSTITUTION:A rush current produced when a start switch SW is applied is suppressed by a resistance R2. The time during the application of the start switch SW through the closure of a contact rl' of a relay RL' is increased as long as a constant current circuit consisting of a comparator COMP and a control circuit PWM has no start with ON of an earth switch ASW. As a result, the voltage charged to a capacitor C2 approximates to the level of the power supply voltage E. Thus the rush current produced when the contact rl' is closed is also reduced. Furthermore the coil RL' functions together with a resistance R4 as a protecting resistance that works when the load 6 is short-circuited. This can improve both of the power efficiency and the characteristics of rush current. |
