BATTERY CHARGER

• US 3,688,177 A
• Filed: 03/25/1971
• Issued: 08/29/1972
• Est. Priority Date: 03/25/1971
• Status: Expired due to Term

• Current Assignee: Gary O. Hitchins, John B. Reeves
• Original Assignee: Gary O. Hitchins, John B. Reeves
• Inventors: Reeves, John B., Hitchins, Gary O.
• Primary Examiner(s): Miller, J. D.
• Assistant Examiner(s): Hickey, R. J.
• Application Number:
  US05/127,875
• Time in Patent Office: 523 Days
• Field of Search: 320/22-24,31-33,39,40
• US Class Current: 320/141
• CPC Class Codes: H02J 2207/20 Charging or discharging characterised by the power electronics converter
• CPC Class Codes: H02J 7/00718 in response to charge current gradient
• CPC Class Codes: H02J 7/02 for charging batteries from ac mains by converters

Abstract

Battery charging apparatus providing different charging rates dependent upon the state of charge of the battery. The battery charging current and battery terminal voltage are sampled and applied to a control circuit. The control circuit changes the conduction duration of a controllable rectifier to change the battery charging current. The control circuit is adaptable to multiple-phase battery charging apparatus.

Claims

1. A battery charger comprising controllable rectifying means having input and output terminals, said output terminals being suitable for connection to the battery being charged, means of supplying alternating current to said input terminals of said controllable rectifying means, rectifier controlling means which controls the battery charging current by controlling the condition duration per cycle of said controllable rectifying means, said rectifier controlling means limiting the maximum battery charging current to a first predeterMined current value, said rectifier controlling means reducing the battery charging current to a second predetermined current value when the terminal voltage of the battery being charged increases to a first predetermined voltage value, apparatus including a bistable multivibrator in said rectifier controlling means for reducing the battery charging current to a third predetermined current value when the terminal voltage of the battery being charged increases to a second predetermined voltage value, said rectifier controlling means increasing the battery charging current if the terminal voltage of the battery decreases, and current transformer means in said controlling means responsive to said alternating current for controlling the maximum current delivered to said battery.

2. The battery charger of claim 1 wherein the third predetermined current value of battery charging current is equal to zero.

3. The battery charger of claim 1 wherein the rectifier controlling means comprises means for sampling a current proportional to the battery charging current, battery terminal voltage sampling means, battery charging current limiting means, reference voltage means comprising Zener diodes, and rectifier triggering means comprising a programmable unijunction transistor.

4. The rectifier controlling means of claim 3 wherein said bistable multi-vibrator circuit may be triggered to decrease or increase the battery charging current.

5. A battery charger comprising controllable multiple-phase rectifying means having input and output terminals, said output terminals being suitable for connection to the battery being charged, means of supplying multiple phase alternating current to said input terminals of said multiple-phase controllable rectifying means, multiple-phase rectifier controlling means which controls the battery charging current by controlling the conduction duration per cycle of said controllable rectifying means, said rectifier controlling means including current transformer apparatus coupled to one phase of said alternating current supplying means for limiting the maximum battery charging current to a first predetermined current value, said rectifier controlling means reducing the battery charging current to a second predetermined current value when the terminal voltage of the battery being charged increases to a first predetermined voltage value, said rectifier controlling means reducing the battery charging current to a third predetermined current value when the terminal voltage of the battery being charged increases to a second predetermined voltage value, and said rectifier controlling means increasing the battery charging current to said first predetermined current value if the terminal voltage of the battery decreases to a third predetermined voltage value.

6. A battery charger comprising controllable multiple-phase rectifying means having input and output terminals, said output terminals being suitable for connection to the battery being charged, means of supplying multiple-phase AC power to said input terminals of said multiple-phase controllable rectifying means, multiple-phase rectifier controlling means which controls the battery charging current by controlling the conduction duration per cycle for each phase of said controllable rectifying means, said multiple-phase rectifier controlling means comprising means for sampling a current which is proportional to the battery charging current, means for sampling the battery terminal voltage, said current and voltage sampling means being connected to voltage reference means, said voltage reference means producing a response when a predetermined magnitude of voltage is applied thereto, said response being applied to triggering means having an output, said triggering output being controlled by said voltage reference response, and said triggering output controlling said controllable rectifying means.

7. A battery charger comprising a three-phase full wave bridge rectifying circuit having input and output termInals, said three-phase rectifying circuit comprising silicon controlled rectifiers, said output terminals being suitable for connection to the battery being charged, a three-phase AC transformer having two secondary outputs, one of said outputs being connected to said three-phase rectifying circuit, the other of said secondary outputs having each phase thereof connected independently to a single-phase rectifier circuit, a control circuit which controls the battery charging current by controlling the conduction duration per cycle of said three-phase rectifying circuit, said control circuit comprising a current sampler having a current transformer and rectifier circuit, said current sampler producing a DC voltage proportional to the AC current in one phase of said three-phase transformer output which is connected to said three-phase rectifying circuit, a battery terminal voltage sampler, the output of said voltage sampler and said current sampler being connected to a limiting circuit comprising avalanche diodes and transistors, a rectifier trigger circuit comprising three programmable unijunction transistors, each of said programmable unijunction transistors having its gate electrode controlled in common by said limiting circuit.