GB1227630A - - Google Patents

Abstract

1,227,630. Battery charging systems. BRITISH AIRCRAFT CORP. Ltd. 3 Oct., 1969 [23 Aug., 1968], No. 40497/68. Heading H2H. [Also in Division G3] A method of monitoring and controlling the charging of an electric battery comprises generating an electric signal having a predetermined parameter which represents the current limits during a charging cycle and comparing the actual charging current with the signal so that the charging current is automatically terminated or reduced should the actual charging current exceed that represented by the signal of the corresponding point in the charging cycle. A battery to be charged is connected to an output terminal 66 fed from a D.C. supply 42 by way of current measuring circuits 48, 64, chopper circuits 50, 58, filters 44, 62 and a transformer 56 having eight separate output channels. The output level of the current at terminal 66 depends on the pulse width output of the chopper circuit 58 and this is governed by a control logic circuit 68 by way of a pulse width modulator 60. The logic circuit has a plurality of inputs, one from each of amplifiers 70, 74, 78, 80 wherein quantities are compared with the charging current measured by the circuit 64, one from an amplifier 88 and one from a polarity detector 108. The desired charging current characteristic of an initial constant portion and a subsequent linearly decreasing portion is generated by a circuit 72 the characteristic being related to the ampere hour capacity of the battery being charged by means of an input signal 86 fed into a current limiting reference circuit 76. From this circuit signals bearing different relationships with the battery capacity are fed to the generator 72, and thence to amplifier 70, and to the amplifiers 74, 78, 80. Should the charging current measured by the circuit 64 depart from the characteristic generated by the circuit 72 the logic circuit 68 becomes effective to terminate or to reduce the charging current. The polarity detector 108 inhibits operation of the circuit inter alia, by a relay 106 should the battery be connected wrongly and the amplifier 88 is effective to make the system responsive to the voltage of and type of battery being charged. A further signal fed to the circuit 76 by line 104 applies an override signal should the peak power taken from the system exceed a predetermined maximum thereby to reduce the power input. Indicator lamps are provided showing various conditions of the system.