GB1450238A - Circuit arrangement for charging a battery of storage cells - Google Patents

Abstract

1450238 Automatic control of voltage and current SIEMENS AG 3 June 1974 [25 March 1974] 24561/74 Heading G3R [Also in Division H2] A circuit for charging a battery 2 comprises a voltage increasing circuit 6 and a comparator 13 for controlling the output voltage Uc of the voltage increasing circuit, the comparator receiving at its first input a voltage U* equal to the gassing voltage of the battery and at its second input the charging voltage Uc of the battery. The battery may be in an aircraft provided with a D.C. generator 3 the output voltage Un of which may not be sufficient to charge the battery at its gassing voltage particularly since the gassing voltage varies with temperature. The reference gassing voltage U* supplied by a potentiometer 14 is therefore corrected by a temperature dependent voltage U*z supplied by a thermistor 17 and compared with the charging voltage Ub in the comparator 13. The output of the comparator is supplied to a circuit 12 which controls the mark-space ratio of the output signal of a circuit 11. The circuit 11 controls the switching of a thyristor or transistor 8 in the voltage increasing circuit 6 which includes a choke 7 and a capacitor 10. The voltage Uc across the capacitor exceeds the supply voltage Un by an amount dependent on the mark-space ratio of the output signal from the circuit 11 so that the charging voltage for the battery always equals the gassing voltage at the ambient temperature. A charge current limiting circuit including a thyristor or transistor 23 is also provided, the current flowing through a resistor 21 and a limit value current set by a potentiometer 22 being supplied to a circuit 20 which controls the transistor. If the supply voltage Un should exceed the permissible battery charging voltage, a diode 19 enables a signal to be supplied from the comparator to the circuit 20 to switch off the transistor 23.