Patent GB-650724-A (GB)
Title: Regulating apparatus for the automatic charging of an accumulator battery in two stages
IPC: H02J7/32
Filed: 1947-07-01
Abstract: 650,724. Automatic control systems for battery-charging apparatus. COMPAGNIE GENERALE D'ELECTRICITE. July 1, 1947, Nos. 17321 and 17322. Convention dates, Aug. 10, 1945, and Nov. 27, 1945. [Class 38 (iv)] In a two-stage batterycharging system as described in Specification 604,402, in which the first stage is one at constant current and the second is one at constant voltage equal to the voltage attained at the end of the first stage, the first stage is terminated either when the battery reaches a predetermined voltage U or at the end of a given time T- whichever occurs the earlier -and the voltage regulator for the second stage, which is normally set to regulate to the value U, is associated with means responsive to battery volts which so modify the setting that regulation during the second stage is to the voltage reached by the battery at the end of time T if the voltage U has not been attained. As shown in Fig. 1 a battery B is charged by a generator G under the control of a current regulator R2 and a voltage regulator R1, both in the form of a solenoid having a spring- loaded core P2 or P1. During the first stage, deviation of the charging current from the prescribed value causes core P2 to move a rheostat r1 of a bridge r1-r4 suppying a second winding E2 of the voltage regulator. The change of excitation of this winding causes core P1 to move in a corrective sense a rheostat C1 in the generator field circuit. The second stage is initiated by locking core P2 by a device A, whereby variation of excitation of winding E2 is prevented and the rheostat C1 is solely controlled by the voltage winding E1 of regulator R1 which then maintains the generator voltage equal to that reached at the end of the first stage. When the charging source is a dry rectifier or a grid-controlled rectifier the core P1 may act on a rheostat forming one element of a bridge, similar to r1-r4, the D.C. output of which controls the impedance of a saturable reactor connected either in the A.C. supply to the dry rectifier or in the grid control circuit of the controlled rectifier. Fig. 3 shows another A.C. charging arrangement in which a saturable reactor T, either controlling the excitation of a grid-controlled charging rectifier or arranged in series with the A.C. side of a dry rectifier G, is controlled by a transductor T3, R3 having in addition to a self-magnetizing winding: (1) a voltage-excited winding connected directly across the battery and solely effecting regulation during the second stage; and (2) a " current " winding effecting control during the first charging stage at constant current. The last winding is excited through a rectifier R2 fed with the opposed secondary voltages of transformers P1, P2, an air gap in the core of the latter being adjusted to vary the secondary voltage during the first stage by a reversible motor M having opposing fields e1, e2 and the balance, or otherwise, of which is governed by a saturable reactor T2 controlled by a transductor T1, R1 having a winding which carries the charging current. A contactor A in the motor field supply circuit opens at the end of the first stage and terminates " current " control of transductor T3. In other arrangements, Figs. 4 and 6 (not shown), completely independent regulators, which may be either of the solenoid and core, or transductor types, are utilized for the two stages, a relay or contact-making galvanometer closing its contacts at the end of the first stage and bringing about the actuations of contactors which terminate control by the " current " regulator and initiate control by the " voltage " regulator. The relay or galvanometer is energized in series with the control coil or winding of the voltage regulator, and the relay or galvanometer contacts may close either by the battery attaining a prescribed voltage or by the closing of a time- or amperehour-controlled switch which starts a motor for reducing resistance in series with the relay or galvanometer coil.