Source shedding regulator

• US 4,327,318 A
• Filed: 10/31/1980
• Issued: 04/27/1982
• Est. Priority Date: 10/31/1980
• Status: Expired due to Term

• Current Assignee: Amoco/Enron Solar Co.
• Original Assignee: Exxon Research and Engineering Company (Exxon Mobil Corporation)
• Inventors: Kwon, Yiduk, Lawson, Paul
• Primary Examiner(s): HICKEY, ROBERT
• Application Number:
  US06/202,544
• Time in Patent Office: 543 Days
• Field of Search: 320/2-5, 320/39, 320/40, 320/61, 323/906
• US Class Current: 320/101
• CPC Class Codes: H02J 7/35 with light sensitive cells
• CPC Class Codes: Y02E 10/56 Power conversion systems, e.g. maximum power point trackers
• CPC Class Codes: Y10S 136/293 Circuits
• CPC Class Codes: Y10S 323/906 Solar cell systems

Abstract

A voltage regulator for controlling the photovoltaic charging of storage batteries selectively includes or sheds portions of the photovoltaic array into or from the charging system.

Claims

1. A voltage regulator system for controlling photovoltaic charging of rechargeable storage batteries, said system comprising:

an array of photovoltaic solar cells having x number of serially connected solar cells coupled in first through nth parallel connected strings, each said string having blocking diode means connected in series with each of said strings, coupled between said string and said storage batteries;

voltage monitor means responsive to a voltage across said storage batteries, said monitor providing first, second, third and fourth control signals corresponding to monitored battery voltages of

a. greater than or equal to V_normal ;

b. less than or equal to V_normal ;

c. greater than or equal to V_maximum ; and

d. less than or equal to V_minimum, respectively;

logic means, coupled to receive said first through third control signals, wherein response to said first control signal said logic means provides a first logic signal to initiate a sequential shedding of first through nth strings of said array, said first logic signal continuing until said monitoring battery voltage is less than about V_normal ; and

in response to said second control signal, said logic means provides a second level signal to initiate sequential re-inserting of array strings, said second logic signal continuing until the monitored battery voltage equals or exceeds V_normal ; and

in response to said third signal continuing for a predetermined time period RC, said logic means provides a third logic signal to initiate simultaneous shedding of first through nth array, strings, said third logic signal continuing until said monitored battery voltage is less than V_maximum ;

in response to said fourth signal continuing for a predetermined time period RC, said logic means provides a fourth logic signal to initiate simultaneous reinserting of first through nth array, strings, said fourth logic signal continuing until said monitored battery voltage is greater than V_minimum ;

switching means for each of said first through nth strings of said array, said switching means having a main current conduction path coupled to electrically disable each respective array string;

sequencing and driver means for providing sequential turn-on or turn-off signals to said first through th switching means, said sequencing means being responsive to said first logic signal to provide sequential turn-on signals to said switching means and responsive to said second logic signal to provide sequented turn-off signals to said switching means;

override and driver means for providing simultaneous turn on or turn off signals of first through nth switching means, said override being responsive to said third and fourth logic signals, respectively.

2. The regulator system for claim 1 wherein said photovoltaic solar cells comprise silicon solar cells.

3. The regulator system of claim 2 wherein said storage batteries comprise lead-acid batteries having number of cells per battery.

4. The regulator system of claim 3 wherein V_normal is equal to about 1 times 2.4 volts.

5. The regulator system of claim 4 wherein V_maximum is equal to about 1 times 2.5 volts.

6. The regulator system of claim 5 wherein V_minimum is equal to about 1 times 2.2 volts.

7. The regulator system of claim 1 wherein said switching means comprise bipolar switching transistors.

8. The regulator system of claim 7 wherein said switching transistors comprise Darlington switching transistors.

9. The regulator system of claim 1 wherein said sequencing means comprises a multi-stage, clock-driven switching register, said clock means providing variable rate sequencing of said shedding or re-inserting of said strings of the array.

10. The regulator system of claim 1 wherein said voltage monitoring means comprises:

a first comparator means having a predetermined reference voltage of about V_normal volts;

a second comparator means having a predetermined reference voltage of about V_minimum volts;

a third comparator means having a predetermined reference voltage of about V_maximum volts;

each said comparator means being coupled to compare the battery terminal voltage to the respective reference voltage and providing a signal corresponding to a differential between said battery voltage and said respective reference voltage.

11. The regulator system of claim 10 wherein said comparator means comprises an operational amplifier having an input coupled to a positive terminal of said storage batteries and a second input coupled to said reference voltage.

12. The regulator system of claim 11 wherein said reference voltages comprises a regulator integrated circuit as a voltage follower of built-in reference.

13. The regulator system of claim 10 wherein said comparator means further includes pulse shaping means for converting a slow rise/fall time signal into a rapid rise/fall time signal.

14. The regulator system of claim 13 wherein said pulse shaping means comprises a Schmitt trigger.