DRIVE PULSE OUTPUT LIMITER CIRCUIT

摘要

PROBLEM TO BE SOLVED: To materialize an ideal switching which has no excessive surge current stress due to an excessive drive pulse width even with all the oscillation frequencies and all the impedance conditions. SOLUTION: When charging current or discharging current flows in a capacitor 11 connected between both ends of a switching element 3 or between both ends of a winding of a main transformer 7, potentials appear across the switching elements 2 and 3. Therefore, by detecting a pulse voltage appearing across an impedance element 13 which is serially connected to the capacitor 11 by means of a charging current detecting circuit 32 or a discharging current detecting circuit 35 and then applying the outputs of the circuits 32 and 35 to pulse limiter circuits 30 and 31 and then blocking drive input signals into drive circuits of the switching elements 2 and 3, drive pulse widths of the switching elements are so limited that they may be driven only after the pulse voltages across the switching elements decrease to about zero volt.