| 摘要 |
1,128,735. Generating systems for vehicles. ROBERT BOSCH G.m.b.H. 20 July, 1967 [21 July, 1966], No. 33296/67. Heading H2H. A three-phase generating system for road vehicles and the like comprises means for changing the phase windings of the three-phase generator from star to delta connection when the speed of the generator or its output current exceeds a predetermined value. A three-phase generator 10 driven at widely varying speeds supplies a load circuit 24, 25 by way of a rectifier 23, the generator field winding 14 being energized from the generator output by way of an auxiliary rectifier 26 and a voltage regulator 27. The connections of the generator output windings 11, 12, 13 are controlled by a relay 15, the contacts of which are shown in the positions wherein the generator is stationary or rotating at slow speeds and delivering a low output current. In these positions the windings 11, 12, 13 are in star connection. As the load taken by the output circuit increases the output of the current transformer 28 and rectifier 29 increases until the breakdown point of a Zener diode 35 is reached whereupon a transistor 32 conducts to energize the relay 15 thus changing the contact positions to connect the windings 11, 12, 13 in delta. Contact 20 of the relay 15 opens before, and closes after, contacts 17-19 so that these latter contacts operate under no-load conditions. The operation of relay 15 may be made responsive only to the generator speed. In the case of generators having a small current output the current transformer 28 may be dispensed with and the Zener diode 35 and transistor 32 made responsive to the voltage drop across a resistor 37. Furthermore a resistor may be placed in series with the variable resistor 34 to obtain switching hysteresis. |
