| 摘要 |
1,128,013. Automatic voltage control. JOSEPH LUCAS (INDUSTRIES) Ltd. Dec. 1, 1965 [Dec. 9, 1964], No. 50042/64. Heading G3R. [Also in Division H2] A battery charging system has a currentresponsive circuit-breaker or fuse 34 in series with the control circuit of an alternator 21 and a voltage-responsive variable resistance device 37 across the control circuit. When over-voltage occurs, the device 37 conducts sufficient current to protect the components until the circuit breaker is operated or the fuse is blown. The device 37 may be a zener diode, a four layer diode or a non-linear resistance. The figure shows a vehicle battery charging circuit comprising the alternator 21 with a rectifier bridge circuit having diodes 25 and thyristors 23 having their gates connected to the secondary winding 43 of a transformer 39. The transformer has a primary winding 38 and a feedback winding 42, and forms with a transistor 41 an oscillator to render the thyristors conductive. When the voltage between lines 24, 26 reaches a predetermined value, a Zener diode 32 breaks down to render a transistor 33 conductive, which in turn renders the transistor 41 non conductive so that at the end of their conducting periods, the thyristors do not switch on. The voltage between the lines 24, 26 falls and when a capacitor 31 has discharged sufficiently the Zener diode 32 cuts off, so that the oscillator operates again. Should a fault occur, resulting in an excessively high voltage, a Zener diode 37 breaks down and a fuse 34 in series with the primary winding 38 blows and so renders the oscillator inoperative. |
