GB1282082A - An excitation system for a brushless synchronous machine - Google Patents

Abstract

1282082 Automatic voltage and power factor control FUJI DENKI SEIZO K K 9 Jan 1970 [9 Jan 19691 1247/70 Heading G3R A brushless A.C. synchronous generator 3, having a field winding 5 supplied through a rectifier 6 mounted on its shaft from an A.C. exciter 7, is controlled by a regulator 16 whose output supplies the exciter field winding 8 through an amplifier 17 and whose input receives two signals, the first of which is derived by combining the outputs of error detecting units 12, 13 respectively representative of the deviation of the generator output voltage and power factor from pre-set values, and the second of which is derived from a voltage change detecting circuit 14, 15 and is produced when the generator output voltage changes beyond a predetermined value, the second signal being produced for an initial period of the voltage change during which it is superimposed on the first signal. The unit 14 comprises a rectifier receiving the generator output voltage and supplying an RC differentiating circuit, whose output is passed to the unit 15 comprising a pair of series-opposed Zener diodes which determine the predetermined value and are connected to a resistor from which the second signal is obtained, Fig. 3 (not shown). Operation of the circuit 14, 15 is explained for a sudden change of generator voltage below, Fig. 4 (not shown) or above, Fig. 5 (not shown) the normal value, the action of the second signal being to add a compensating differential function to the normal proportional integral characteristic of the regulator 16 for an initial period of the voltage change, Fig. 6 (not shown). Application of the invention to control a brushless A. C. motor is envisaged.