Rapid-charging circuit

• US 4,162,439 A
• Filed: 06/29/1977
• Issued: 07/24/1979
• Est. Priority Date: 08/03/1976
• Status: Expired due to Term

• Current Assignee: Rollei Werke Franke and Heidecke KG
• Original Assignee: Rollei Werke Franke and Heidecke KG
• Inventors: Schneider, Arthur
• Primary Examiner(s): Hickey, Robert J.
• Application Number:
  US05/811,058
• Time in Patent Office: 755 Days
• Field of Search: 320/21, 320/22, 320/31, 320/32, 320/39, 320/40, 320/DIG. 1
• US Class Current: 320/141
• CPC Class Codes: H02J 7/00302 Overcharge protection
• CPC Class Codes: H02J 7/00309 Overheat or overtemperature protection
• CPC Class Codes: H02J 7/0049 Detection of fully charged condition
• CPC Class Codes: H02J 7/007194 of the battery
• CPC Class Codes: H02J 7/02 for charging batteries from ac mains by converters

Abstract

A control circuit for rapid charging of an accumulator with a pulsating current includes a transistor arranged for switching the charge current on and off. The collector circuit of the transistor has an emitter resistor arranged to establish a control voltage that is substantially constant throughout each pulse of the charge current, and a comparator has an output connected to the base of the transistor and inputs from a reference voltage and the voltage on the accumulator so as to block the transistor when the charge voltage exceeds the reference voltage. The emitter resistor is preferably an incandescent lamp, a zener diode is preferably arranged in parallel with the lamp to provide a constant voltage for the base-emitter circuit of the transistor, and a complementary transistor is preferably connected with the switching transistor to form a two-stage transistor circuit.

Claims

1. A circuit for controlling rapid charging of an accumulator with a pulsating current, said circuit including an electronic switch arranged in a charging circuit of said accumulator to be switched on through a control electrode to charge said accumulator and to be blocked upon said accumulator reaching a voltage corresponding to an adjustable reference voltage, said circuit being characterized by:

(a) said electronic switch being formed as a transistor;

(b) an emitter resistor arranged relative to said transistor;

(c) means applying to said transistor a control voltage that is substantially constant at least during the duration of a pulse of said charge current;

(d) a comparator;

(e) a base of said transistor serving as said control electrode and being connected to the output of said comparator;

(f) one input of said comparator being connected to the charge voltage of said accumulator;

(g) another input of said comparator being connected to said reference voltage so that the output of said comparator assumes a potential that blocks said transistor when said charge voltage exceeds said reference voltage;

(h) two feed conductors connected to said accumulator;

(i) a first one of said conductors having a high potential and a second one of said conductors having a low potential;

(j) a potentiometer arranged to provide said reference voltage;

(k) a resistor connected in series with said potentiometer;

(l) said resistor having a negative temperature coefficient and being arranged in thermal communication with said accumulator;

(m) a constant voltage source arranged in parallel with said potentiometer and said resistor;

(n) said constant voltage source being formed as a series connection of two zener diodes connected to said feed conductors;

(o) a cathode of a first one of said zener diodes being connected with said potentiometer;

(p) an anode of a second one of said zener diodes being connected with said resistor; and

(q) a pnp transistor arranged in parallel with said second zener diode and having a base connected to a junction between said potentiometer and said resistor.

2. The invention defined in claim 1, further characterized by:

(r) a zener diode being connected in parallel with said emitter resistor;

(s) said emitter resistor being formed as an incandescent lamp; and

(t) a complementary transistor coupled with said switch transistor to form a two-stage transistor circuit.