| 摘要 |
1,076,228. Control of A.C. motors. LICENTIA PATENT - VERWALTUNGS G.m.b.H. Oct. 2, 1964 [Oct. 3, 1963; Nov. 8, 1963; July 28, 1964], No. 40208/64. Heading H2J. An induction motor 24 has thyristors 1-12 in its stator circuit, the motor being operated in its forward direction by firing thyristors 1, 2, 6, 7, and 11, 12. For reversal, thyristors 4-9 are fired, the motor speed being varied in accordance with the firing times of the thyristors. D.C. braking is applied by firing thyristors 1, 3, 4, 9, 10, 12, to form a three-phase rectifier bridge, the braking-current being regulated by firing-time control. Rotor resistor 19 is supplied through rectifier 30 and reactor 17, the resistor being shunted by a pulse circuit comprising thyristor 13. D.C. braking operation may be followed by reverse-current braking, the stator thyristors being switched accordingly. In another arrangement, the rotor circuit returns current to the three-phase mains through a pulse-controlled inverter. Resistors in the rotor circuit may be bridged by a contactor which responds when the stator thyristors are fully conductive. The resistors may be connected to the rotor winding through a rectifier. In a further embodiment, mercury-arc rectifiers are included in the stator circuit, series-connected thyristors which are each shunted by a resistor being placed in the rotor circuit. |
