| 摘要 |
PURPOSE:To effectively commutate a thyristor by enhancing a reverse voltage applied when the thyristor is turned OFF, and sufficiently increasing a reverse voltage applying time as compared with the turning OFF time of the thyristor. CONSTITUTION:The output of a power source E is applied through a thyristor SCR triggered by a trigger circuit Trg to an oscillation transformer T, and an output is led from the secondary winding N2. In the trigger circuit Trg, a capacitor C3 is charged only when the transistor Tr2 is turned OFF. Since the transistor Tr1 is turned ON if the potential of the capacitor C2 at the thyristor side is lower than the other end side potential, a transistor Tr2 is turned OFF during the time. Accordingly,the voltage of the capacitor C3 can arrive at the breakover voltage of a diac DI only when the voltage of the capacitor C2 is positive, and the reverse voltage applying time becomes sufficiently longer than the turning OFF time of the thyristor SCR. |
