Solar-powered battery charger and related system and method

• US 8,421,400 B1
• Filed: 10/30/2009
• Issued: 04/16/2013
• Est. Priority Date: 10/30/2009
• Status: Active Grant

• Current Assignee: National Semiconductor Corporation (Texas Instruments, Inc.)
• Original Assignee: National Semiconductor Corporation (Texas Instruments, Inc.)
• Inventors: Khanna, Ramesh
• Primary Examiner(s): Muralidar, Richard V
• Application Number:
  US12/589,984
• Time in Patent Office: 1,264 Days
• Field of Search: 320/101, 320/137, 320/140, 320/143, 320/144, 307/6, 307/45, 307/58, 307/82
• US Class Current: 320/101
• CPC Class Codes: B60L 53/51 Photovoltaic means
• CPC Class Codes: H02H 7/18 for batteries; for accumulators
• CPC Class Codes: H02J 2207/20 Charging or discharging characterised by the power electronics converter
• CPC Class Codes: H02J 2310/48 for electric vehicles [EV] or hybrid vehicles [HEV]
• CPC Class Codes: H02J 7/00 Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
• CPC Class Codes: H02J 7/00308 Overvoltage protection
• CPC Class Codes: H02J 7/007192 in response to temperature
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/7072 Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
• CPC Class Codes: Y02T 90/12 Electric charging stations

Abstract

A solar-powered charger includes a solar panel configured to generate electrical energy at a first voltage level. The charger also includes a converter configured to receive the electrical energy from the solar panel, perform temperature compensation, and output the electrical energy to a load at a second voltage level. The second voltage level could be between 13.2V and 14.4V, inclusive. The converter could be configured to output the electrical energy at the second voltage level with a substantially constant current over temperatures between 0° C. and 100° C., inclusive. The converter could be configured to be coupled to and recharge a lead acid battery, a lithium ion battery, or a nickel metal hydride battery.

Claims

1. A solar-powered charger comprising:

a solar panel configured to generate electrical energy at a first voltage level that varies with temperature; and

a two-stage converter configured to receive the electrical energy from the solar panel, perform temperature compensation, and output the electrical energy to a load at a second voltage level, including

a first converter stage responsive to the first voltage level to output electrical energy at an intermediate voltage level, the intermediate voltage level being adjusted in accordance with a first reference voltage corresponding to a temperature associated with the solar panel; and

a second converter stage responsive to the intermediate voltage level to output to the load a substantially constant current at the second voltage level, the substantially constant current being adjusted in accordance with a second reference voltage corresponding to the temperature associated with the solar panel.

2. The charger of claim 1, further comprising:

a restart circuit configured to disable at least a portion of the charger in response to a fault and to restart at least the portion of the charger after the fault has been removed.

3. The charger of claim 1, further comprising:

an over-voltage circuit configured to prevent the second voltage level from exceeding a specified amount.

4. The charger of claim 1, wherein the second voltage level is in a range between 13.2V and 14.4V.

5. The charger of claim 1, wherein the converter is configured to output the electrical energy at the second voltage level with a substantially constant current over temperatures in a range between 0°

C. and 100°

C.

6. The charger of claim 1, wherein the converter is configured to be coupled to at least one of:

a lead acid battery, a lithium ion battery, and a nickel metal hydride battery.

7. The charger of claim 1, wherein the converter is configured to be coupled to and recharge a battery via an on-board diagnostic connector port in a vehicle.

8. An electrical charging unit comprising:

an input terminal configured to be coupled to receive electrical energy from a solar panel configured to generate electrical energy at a first voltage level that varies with temperature;

an output terminal configured to be coupled to a load; and

a two-stage converter configured to receive the electrical energy from the input terminal, perform temperature compensation, and output the electrical energy to the load via the output terminal, including;

a first converter stage responsive to the first voltage level to output electrical energy at an intermediate voltage level, the intermediate voltage level being adjusted in accordance with a first reference voltage corresponding to a temperature associated with the solar panel; and

a second converter stage responsive to the intermediate voltage level to output a substantially constant current at a second voltage level, the substantially constant current being adjusted in accordance with a second reference voltage corresponding to the temperature associated with the solar panel.

9. The electrical charging unit of claim 8, further comprising:

a restart circuit configured to disable the second stage in response to a fault and to restart the second stage after the fault has been removed.

10. The electrical charging unit of claim 8, further comprising:

an over-voltage circuit configured to prevent the electrical energy output to the load from exceeding a specified energy level.

11. The electrical charging unit of claim 8, wherein the converter is configured to output the electrical energy at a voltage in a range between 13.2V and 14.4V.

12. The electrical charging unit of claim 11, wherein the converter is configured to output the electrical energy at a substantially constant current over temperatures in a range between 0°

C. and 100°

C.

13. The method of claim 8, further comprising:

preventing the electrical energy output to the load from exceeding a specified energy level.

14. A method comprising:

generating electrical energy using a solar panel at a first voltage that varies with temperature;

measuring a temperature of the solar panel and providing both a first reference voltage and a second reference voltage corresponding to the measured temperature;

outputting from a first stage, in response to the first voltage level, electrical energy at an intermediate voltage level, the intermediate voltage level being adjusted in accordance with the first reference voltage; and

outputting from a second stage, in response to the intermediate voltage level, electrical energy as a substantially constant current at a second voltage level, the substantially constant current being adjusted in accordance with the second reference voltage.

15. The method of claim 14, further comprising:

determining if a fault condition has occurred; and

in response to the fault condition, disabling the output of the electrical energy from the second stage.