| 摘要 |
PURPOSE:To allow an ordinary cable and photocoupler to be used even when a switching frequency is high by applying a pulse signal for controlling the conduction of a transisitor through a resistor. CONSTITUTION:A current command signal (a) which is fed from a control circuit passes through a wiring cable and photocoupler 13 to a comparator 8. The comparator 8 inputs the signal and the output of a current transformer 7, outputs a valtage of +DC when the signal is larger than the output signal of a converter, while outputs a voltage of -DC in case opposite to the above. Since the comparator 8 and the resistor 14 for handling the high frequency pulse signal are disposed at the high voltage side near transistors 1, 2, it does not need a signal insulating photocoupler therein. Further, since signal transmission delay and th noise problem do not exist, ordinary wiring cable and photocoupler can be used. |
