SYSTEM AND METHOD FOR CELL BALANCING AND CHARGING

• US 20100295509A1
• Filed: 12/31/2009
• Published: 11/25/2010
• Est. Priority Date: 05/22/2009
• Status: Active Grant

• Current Assignee: Intersil Americas LLC (Renesas Electronics Corporation)
• Original Assignee: Intersil Americas LLC (Renesas Electronics Corporation)
• Inventors: ALLEN, TONY, MOUSSAOUI, ZAKI
• Granted Patent: US 9,397,508 B2
• Time in Patent Office: Days
• US Class Current: 320/118
• CPC Class Codes: H02J 7/00 Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
• CPC Class Codes: H02J 7/0014 Circuits for equalisation of charge between batteries
• CPC Class Codes: H02J 7/0016 using shunting, discharge or bypass circuits
• CPC Class Codes: H02J 7/0018 using separate charge circuits
• CPC Class Codes: H02J 7/0019 using switched or multiplexed charge circuits
• CPC Class Codes: H02J 7/007184 in response to battery voltage gradient

Abstract

An apparatus for charging a plurality of series connected battery cells, includes a first and second input terminals for providing a charging voltage to the plurality of series connected battery cell. A transformer includes a primary side associated with the charging voltage and a secondary side includes a plurality of portions. Each of the plurality of portions is connected across at least one of the plurality of series connected battery cell. A switch in series between each of the plurality of portions of the secondary side and the at least one of the plurality of series connected battery cells increases an impedance between the portion of the secondary side and the associated one of the plurality of series connected battery cells in a first state and decreases the impedance between the portion of the secondary side and the associated one of the plurality of series connected battery cells in a second state.

Claims

1. An apparatus for charging a plurality of series connected battery cells, comprising:

first and second input terminals for providing a charging voltage to the plurality of series connected battery cells;

a transformer including a primary side associated with the charging voltage and a secondary side including a plurality of portions, each of the plurality of portions connected across at least one of the plurality of series connected battery cells; and

a switch in series between each of the plurality of portions of the secondary side and the at least one of the plurality of series connected battery cells for increasing an impedance between the portion of the secondary side and the at least one of the plurality of series connected battery cells in a first state and for decreasing the impedance between the portion of the secondary side and the at least one of the plurality of series connected battery cells in a second state.

2. The apparatus of claim 1, wherein in a charging mode charge on the primary side is transferred to the plurality of portions of the secondary side, the voltage from the primary side divided amongst the plurality of portions of the secondary side in proportion to an amount of charge needed by the at least one battery cell associated with the portion of the secondary side and in a discharging mode an input to the primary side of the transformer comprises a total series voltage of the plurality of series connected battery cells.

3. The apparatus of claim 1 further including a resonant circuit connected between the primary side of the transformer and the first and second input terminals.

4. The apparatus of claim 3 further including switching circuit, the switching circuit comprising:

a first switch connected between the first input terminal and the resonant circuit; and

a second switch connected between the second input terminal and the resonant circuit.

5. The apparatus of claim 3 further including:

a first diode connected between the first input terminal and the resonant circuit; and

a second diode connected between the second input terminal and the resonant circuit.

6. The apparatus of claim 1, wherein the switch comprises a MOSFET transistor.

7. The apparatus of claim 1, further comprising a capacitor in parallel with the switch in series between each of the plurality of portions of the secondary side and the at least one of the plurality of series connected battery cells.

8. The apparatus of claim 1, further comprising:

wherein each of the at least one of the plurality of series connected battery cells comprises a second plurality of series connected battery cells;

second and third input terminals for providing a second charging voltage to the second plurality of series connected battery cells;

a second transformer including a second primary side associated with the second charging voltage and a second secondary side including a second plurality of portions, each of the second plurality of portions connected across an associated battery cell of the second plurality of series connected battery cells; and

a second switch in series between each of the second plurality of portions of the secondary side and the associated battery cell for increasing an impedance between the second portion of the secondary side and the battery cell in a first state and for decreasing the impedance between the second portion of the secondary side and the associated battery cell in a second state.

9. An apparatus for charging a plurality of series connected battery cells, comprising:

first and second input terminals for providing a charging voltage to the plurality of series connected battery cells;

a transformer including a primary side associated with the charging voltage and a secondary side including a plurality of portions, each of the plurality of portions connected across at least one of the plurality of series connected battery cells;

a resonant circuit connected between the primary side of the transformer and the first and second input terminals;

a switch in series between each of the plurality of portions of the secondary side and the at least one of the plurality of series connected battery cells for increasing an impedance between the portion of the secondary side and the at least one of the plurality of series connected battery cells in a first state and for decreasing the impedance between the portion of the secondary side and the at least one of the plurality of series connected battery cells in a second state; and

wherein in a charging mode charge on the primary side is transferred to the plurality of portions of the secondary side, the voltage from the primary side divided amongst the plurality of portions of the secondary side in proportion to an amount of charge needed by the at least one battery cell associated with the portion of the secondary side and in a discharging mode an input to the primary side of the transformer comprises a total series voltage of the plurality of series connected battery cells.

10. The apparatus of claim 9 further including switching circuit, the switching circuit comprising:

a first switch connected between the first input terminal and the resonant circuit; and

a second switch connected between the second input terminal and the resonant circuit.

11. The apparatus of claim 9 further including:

a first diode connected between the first input terminal and the resonant circuit; and

a second diode connected between the second input terminal and the resonant circuit.

12. The apparatus of claim 9, wherein the switch comprises a MOSFET transistor.

13. The apparatus of claim 9, further comprising a capacitor in parallel with the switch in series between each of the plurality of portions of the secondary side and the at least one of the plurality of series connected battery cells.

14. The apparatus of claim 9, further comprising:

wherein each of the at least one of the plurality of series connected battery cells comprises a second plurality of series connected battery cells;

second and third input terminals for providing a second charging voltage to the second plurality of series connected battery cells;

a second transformer including a second primary side associated with the second charging voltage and a second secondary side including a second plurality of portions, each of the second plurality of portions connected across an associated battery cell of the second plurality of series connected battery cells; and

a second switch in series between each of the second plurality of portions of the secondary side and the associated battery cell for increasing an impedance between the second portion of the secondary side and the battery cell in a first state and for decreasing the impedance between the second portion of the secondary side and the associated battery cell in a second state.

15. A method for charging a plurality of series connected battery cells, comprising the steps of:

receiving a charging voltage for the plurality of series connected battery cells;

transferring from a primary side of a transformer to a plurality of portions of a secondary side in a charging mode;

dividing the voltage from the primary side amongst the plurality of portions of the secondary side in proportion to an amount of charge needed by at least one battery cell associated with the portion of the secondary side;

transferring a total series voltage of the plurality of series connected battery cells to the primary side of the transformer in a discharging mode;

increasing an impedance between the portion of the secondary side and the at least one of the plurality of series connected battery cells in a first state; and

decreasing the impedance between the portion of the secondary side and the at least one of the plurality of series connected battery cells in a second state.

16. The method of claim 15 further including the step of generating a resonant input to the primary side of the transformer responsive to the charging voltage.

17. The method of claim 16 further including step of switching the charging voltage to a resonant circuit providing the resonant input.