| 摘要 |
<p>1,254,366. Inverting; control of A.C. motors. MEIDENSHA K.K. 4 Dec., 1969 [6 Dec., 1968 (2)], No. 59249/69. Headings H2F and H2J. In an inverter operable from a variable D.C. voltage source 1, an auxiliary D.C. source 19 is switched in by means of auxiliary thyristors 20, 21 so as to ensure correct commutation when the variable voltage source 1 has low value. As described, the main thyristors 3 . . . 6 are turned on in pairs by variable frequency pulses so as to control the speed of induction motor 2. The input voltage 1 is varied so that V#f. The main thyristors 3 . . . 6 are commutated by inductors 9, 10 resonating with capacitors 7, 8, switched in by thyristors 11 ... 14, 20, 21. In Fig. 3 (not shown) the eight inductors 9, 10 are replaced by four inductors each common to an appropriate pair of circuits. In Fig. 4 (not shown) only a single D.C. supply is employed being connected directly to the commutating thyristors 20, 21 and via a specified thyristor chopper circuit to the inverter. The bridge circuit shown may be replaced by a centre-tapped transformer type.</p> |
