| 摘要 |
PURPOSE:To prevent the influence of load conditions, etc., to be exerted upon a switching frequency by comparing a load current with a current command value, and delaying the compared output and applying on-off control to an electric valve. CONSTITUTION:A DC power source 1 is brought under the on-off control of the electric valve 2 such as a transistor (TR) to control a current flowing to a load 3. This load current is detected by a current detector 5. Its detected current and a command value are compared with each other by a comparator 9 through a subtracter 6 to obtain a signal corresponding to the polarity of their deviation. This signal is passed through a delay circuit 10 and is supplied to a driving circuit 8 as a signal delayed by a set time to perform the on-off control over said electric valve 2. Consequently, the switching frequency of the electric valve 2 is determined by the delay time of the delay circuit 10 to eliminate the dependency on power source condition and load condition. |
