Inverters

Abstract

Abstract 1346310 Inverters SIEMENS AG 19 April 1971 [2 April 1970] 24765/71 Heading H2F An inverter comprises a parallel L-C oscillatory circuit 11, the inductance 12, 12a, 12b preferably being that of the load, a first S.C.R. circuit adapted to supply the circuit 11 with D.C. power from terminals 3, 4 comprising two series connected thyristors 1, 2 and a second S.C.R. circuit in series with the inductance and capacitance 12, 13 of the circuit 11 comprising two back-to-back thyristors 14, 15. Two inductances 5, 6 are connected in series with the thyristors 1, 2 and two capacitors 7, 8 in parallel, the circuit 11 being connected to the mid-points 9, 10 of the two series branches as shown. A thyristor 17 in series with inductance 18 is connected between the terminal 9 and a D.C. terminal 19 of preferably higher potential than that of terminal 4 and similarly a resistance 21 is connected between a preferably still higher terminal 22 and the terminal 9. A capacitance 20 is connected in parallel with the branch 17, 18. In operation, assuming the D.C. terminals to have the polarities indicated and the capacitors to be charged as indicated the S.C.R. 14 is activated and discharge of capacitor 13 occurs via the inductance 12. At the instant of maximum current in the inductance 12 and zero p.d. across capacitor 13, the thyristor 1 is switched on and the polarity of the capacitor 13 is rapidly caused to reverse and the current in 12 is rapidly diminished to zero. S.C.R. 15 is then fired and the charge on 13 is again reversed, the S.C.R. 2 being fired again at the instant of maximum current in 12 and quenched upon zero current being attained. For accelerating the recharging of capacitor 13 and for increasing its charge, the S.C.R. 17 is fired either together with or instead of S.C.R. 2. Power in the circuit 11 may be controlled by a variation of firing times of thyristors 1, 2 away from the instants of maximum current. The period of oscillation of circuits 13, 6 and 13, 5 is preferably less than half that of the circuit 11. The thyristors 1, 2 may also form part of a bridge.

Inventors

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