GB1347098A - Threephase generating system - Google Patents

Abstract

1347098 Vehicle supply systems NIPPONDENSO KK 19 April 1971 [3 April 1970 9 April 1970 (3) 21 April 1970] 26078/71 Heading H2H A system comprising a three phase starconnected generator which is drivable at greatly varying speeds and a rectifier device is provided with means whereby the rectifier device is switched from operation in a full wave mode to operation in a half wave mode in dependence on the generator speed and/or generator output current, the star point of the alternator windings being permanently connected to one of the D.C. output terminals by a diode. A battery 5 is charged and the electrical loads 6 of a motor vehicle supplied by a star connected three phase alternator 1 by way of a rectifier device 2, the alternator being driven by the engine of the vehicle. A regulator 4 is provided to govern the field winding 1e of the alternator thereby to control its output and a further control device 9 is provided which controls the operation of a relay 7. When the engine speed, and hence the alternator speed, is low, the relay 7 is unenergized, the contact 7c thus making on contact 7a. In this instance the rectifier device 2 operates in a full wave manner whereupon the system develops an output current as is shown in curve a in Fig. 2. At the same time the voltage at the star point 1d is subjected to half wave rectification by the diode 8 so as to produce a current which is added to that obtained by the rectifier 2 to give the current curve b in Fig. 2. As the alternator speed is increased a point is reached at which the regulator 9 causes energization of the relay 7 to move the contact 7c to fixed contact 7b. In this position the D.C. supply line 11 is connected directly to the star point 1d of the alternator 1 whereupon the rectifier elements 2d, 2e, 2f are rendered inoperative and the rectifier device 2 operates in a half wave mode, the output current having a characteristic shown by the curve c in Fig. 2. The regulator 9 may be arranged to be responsive to the alternator speed and/or the alternator output current and the diode 8 is also effective to reduce arcing at the contacts 7a, 7b, 7c. The contact 7b may be dispensed with if the diode 8 has a large current capacity. If desired a diode 12, of opposite polarity to the diode 8, may be introduced so that fluctuations in the voltage at the star point 1d are full wave rectified such that the current curve d in Fig. 2 is obtained. Other embodiments are described in which certain of the elements of the rectifier bridge 2 are controlled rectifier elements and in which the full wave to half wave switching relay may be placed in the A.C. side of the bridge rectifier 2.