VOLTAGE BALANCE CIRCUIT FOR RECHARGEABLE BATTERIES

• US 20090167247A1
• Filed: 12/22/2008
• Published: 07/02/2009
• Est. Priority Date: 12/29/2007
• Status: Active Grant

• Current Assignee: BYD Semiconductor Co., Ltd. (BYD Company Limited)
• Original Assignee: BYD Company Limited
• Inventors: BAI, QingGang, WU, ZhengDong, ZHOU, Jun
• Granted Patent: US 8,228,032 B2
• Time in Patent Office: Days
• US Class Current: 320/134
• CPC Class Codes: H02J 7/0016 using shunting, discharge or bypass circuits

Abstract

Voltage balance circuit for dual cell rechargeable battery having a balancing circuit coupled to an integrated control circuit. The balancing circuit can be configured to charge and discharge current during a voltage balancing process allowing a higher charged cell to discharge or dissipate excess capacity to a lower charged cell. The integrated control circuit, having a plurality of modules, can be configured to output balancing directional and timing control signals for signaling the activation and deactivation of the voltage balancing process.

Claims

1. A voltage balance circuit for a dual cell rechargeable battery comprising:

a balancing circuit configured to charge and discharge current during a voltage balancing process for the rechargeable battery; and

an integrated control circuit adaptable to being turned on or off based on charging and discharging current and voltage generated by the balancing circuit during the voltage balancing process for the rechargeable battery.

2. The circuit of claim 1, wherein the activation threshold for initiating the voltage balancing process for the rechargeable battery is greater than or equal to 40 mV.

3. The circuit of claim 1, wherein the balancing circuit includes:

an inductor;

a resistor coupled to the inductor, the resistor capable of detecting an amount of current flow within the inductor; and

PMOS and NMOS circuits coupled to the inductor and resistor, wherein the MOS circuits, inductor and resistor are capable of forming closed circuits during the voltage balancing process for the rechargeable battery.

4. The circuit of claim 3, wherein the integrated control circuit includes:

a voltage detection module capable of detecting voltage differences and outputting balancing activation and directional signals;

a delay control module coupled to the voltage detection module, the delay control module configured to output a balancing timing control signal in response to the balancing activation signal;

a direct current (DC) modulation module coupled to the voltage detection and delay control modules, the DC modulation module adaptable to being activated or deactivated by the balancing directional and timing control signals; and

a driver amplification module coupled to the DC modulation module, the driver amplification module operable to amplify signals from the DC modulation module without altering its logic state.

5. The circuit of claim 4, wherein the amplified signals from the driver amplification module are operable to activate and deactivate the balancing circuit.

6. The circuit of claim 4, wherein the voltage detection module includes:

first, second, third and fourth divider resistors;

first, second and third comparators, wherein the first and second divider resistors are coupled to the cathode of the first and second comparators and the anode of the third comparator, and the third and fourth divider resistors are coupled to the anode of the first and second comparators and the cathode of the third comparator; and

a first logic controller coupled to the three comparators, the first logic controller configured to output the balancing activation and directional signals in response to input signals from the three comparators.

7. The circuit of claim 4, wherein the delay control module includes:

a reference-voltage circuit adaptable to provide power;

a bias circuit coupled to the reference-voltage circuit, the bias circuit capable of generating a corresponding current based on the reference-voltage circuit;

an oscillation frequency divider coupled to the bias circuit, the oscillation frequency divider operable to output a control signal based on the current generated by the bias circuit; and

a logic delay coupled to the oscillation frequency divider, the logic delay operable to output the balancing timing control signal in response to the control signal from the oscillation frequency divider.

8. The circuit of claim 7, wherein the balancing timing control signal has 40 s periods, rectangular waves and 50% duty cycle, and wherein the balancing timing control signal outputs a low logic signal 0 during the voltage balancing process and a high logic signal 1 during a voltage detection process, the voltage balancing and detection processes each being 20 s.

9. The circuit of claim 4, wherein the DC modulation module includes a maximum reference voltage and a minimum reference voltage.

10. The circuit of claim 9, wherein the maximum reference voltage is the product of the resistor and the maximum current within a charging-discharging circuit loop during the voltage balancing process for the rechargeable battery while the minimum reference voltage is the product of the resistor and the minimum current within the charging-discharging circuit loop during the voltage balancing process for the rechargeable battery.

11. The circuit of claim 4, wherein the DC modulation module includes:

first and second error amplifiers, each amplifier operable to amplify voltage on the resistor, wherein activation of the amplifier depends on the balancing directional signal from the voltage detection module;

fourth, fifth, sixth and seventh comparators, wherein the fourth and fifth comparators are coupled to the first error amplifier and the sixth and seventh comparators are coupled to the second error amplifier, the fourth comparator adaptable to compare the amplified signal from the first error amplifier with the minimum reference voltage, the fifth comparator adaptable to compare the amplified signal from first error amplifier with the maximum reference voltage, the sixth comparator adaptable to compare the amplified signal from the second error amplifier with the maximum reference voltage, the seventh comparator adaptable to compare the amplified signal from the second error amplifier with the minimum reference voltage; and

a second logic controller coupled to the four comparators, the second logic controller configured to receive input from the comparators and output logic signals for activating and deactivating the voltage balancing process for the rechargeable battery.

12. A voltage balance circuit for a dual cell rechargeable battery comprising:

a balancing circuit configured to charge and discharge current during a voltage balancing process for the rechargeable battery, the balancing circuit comprising;

an inductor;

a resistor coupled to the inductor, the resistor configured to detect current flow within the inductor; and

PMOS and NMOS circuits coupled to the inductor and resistor, wherein the MOS circuits, inductor and resistor are capable of forming closed circuits during the voltage balancing process for the rechargeable battery; and

an integrated control circuit capable of being activated or deactivated depending on charging and discharging current and voltage generated by the balancing circuit during the voltage balancing process for the rechargeable battery, the integrated control circuit comprising;

a voltage detection module operable to detect voltage differences and output balancing activation and directional signals;

a delay control module coupled to the voltage detection module, the delay control module operable to output a balancing timing control signal in response to the balancing activation signal;

a direct current (DC) modulation module coupled to the voltage detection and delay control modules, the DC modulation module operable to being activated and deactivated by the balancing directional and timing control signals; and

a driver amplification module coupled to the DC modulation module, the driver amplification module operable to amplify signals from the DC modulation module without altering its logic state.

13. The circuit of claim 12, wherein the activation threshold for initiating the voltage balancing process for the rechargeable battery is greater than or equal to 40 mV.

14. The circuit of claim 12, wherein the amplified signals from the driver amplification module are operable to activate and deactivate the balancing circuit.

15. The circuit of claim 12, wherein the voltage detection module includes:

first, second, third and fourth divider resistors;

first, second and third comparators, wherein the first and second divider resistors are coupled to the cathode of the first and second comparators and the anode of the third comparator, and the third and fourth divider resistors are coupled to the anode of the first and second comparators and the cathode of the third comparator; and

a first logic controller coupled to the three comparators, the first logic controller operable to output the balancing activation and directional signals in response to input signals from the three comparators.

16. The circuit of claim 15, wherein the delay control module includes:

a reference-voltage circuit adaptable to provide a source of power;

a bias circuit coupled to the reference-voltage circuit, the bias circuit operable to generate a corresponding current based on the reference-voltage circuit;

an oscillation frequency divider coupled to the bias circuit, the oscillation frequency divider operable to receive the current from the bias circuit and output a control signal; and

a logic delay coupled to the oscillation frequency divider, the logic delay configured to output the balancing timing control signal in response to the control signal from the oscillation frequency divider.

17. The circuit of claim 16, wherein the balancing timing control signal has 40 s periods, rectangular waves and 50% duty cycle, and wherein the balancing timing control signal outputs a low logic signal 0 during the voltage balancing process and a high logic signal 1 during a voltage detection process, the voltage balancing and detection processes each being 20 s.

18. The circuit of claim 17, wherein the DC modulation module includes a maximum reference voltage and a minimum reference voltage, the maximum reference voltage being the product of the resistor and the maximum current within a charging-discharging circuit loop during the voltage balancing process for the rechargeable battery, and the minimum reference voltage being the product of the resistor and the minimum current within the charging-discharging circuit loop during the voltage balancing process for the rechargeable battery.

19. The circuit of claim 18, wherein the DC modulation module includes:

first and second error amplifiers, each amplifier configured to amplify voltage on the resistor, wherein activation and selection of the amplifier depends on the balancing directional signal of the voltage detection module;

fourth, fifth, sixth and seventh comparators, wherein the fourth and fifth comparators are coupled to the first error amplifier and the sixth and seventh comparators are coupled to the second error amplifier, the fourth comparator capable of comparing the amplified signal from the first error amplifier with the minimum reference voltage, the fifth comparator capable of comparing the amplified signal from first error amplifier with the maximum reference voltage, the sixth comparator capable of comparing the amplified signal from the second error amplifier with the maximum reference voltage, the seventh comparator capable of comparing the amplified signal from the second error amplifier with the minimum reference voltage; and

a second logic controller coupled to the four comparators, the second logic controller adaptable to receive input from the comparators and output logic signals for activating and deactivating the voltage balancing process for the rechargeable battery.

20. A voltage balance circuit for a dual cell rechargeable battery comprising:

a balancing circuit having an inductor, a resistor coupled to the inductor for detecting current within the inductor, and PMOS and NMOS circuits coupled to the inductor and resistor, wherein the MOS circuits, inductor and resistor are capable of forming closed circuits for charging and discharging current during a voltage balancing process for the rechargeable battery; and

an integrated control circuit comprising;

a voltage detection module capable of detecting voltage differences, the voltage detection module having first, second, third and fourth divider resistors, first, second and third comparators, wherein the first and second divider resistors are coupled to the cathode of the first and second comparators and the anode of the third comparator, and the third and fourth divider resistors are coupled to the anode of the first and second comparators and the cathode of the third comparator, and a first logic controller coupled to the three comparators, the first logic controller operable to output balancing activation and directional signals;

a delay control module coupled to the voltage detection module, the delay control module having a reference-voltage circuit adaptable to provide power, a bias circuit coupled to the reference-voltage circuit for generating a corresponding current based on the reference-voltage circuit, an oscillation frequency divider coupled to the bias circuit, the oscillation frequency divider operable to output a control signal in response to the current received from the bias circuit, and a logic delay coupled to the oscillation frequency divider, the logic delay operable to output a balancing timing control signal in response to the control signal from the oscillation frequency divider;

a direct current (DC) modulation module coupled to the voltage detection and delay control modules, the DC modulation module having first and second error amplifiers, each amplifier capable of amplifying voltage on the resistor, wherein selection of the amplifier pathway depends on the balancing directional signal from the voltage detection module, fourth, fifth, sixth and seventh comparators, wherein the fourth and fifth comparators are coupled to the first error amplifier and the sixth and seventh comparators are coupled to the second error amplifier, the fourth comparator capable of comparing the amplified signal from the first error amplifier with a minimum reference voltage, the fifth comparator capable of comparing the amplified signal from first error amplifier with a maximum reference voltage, the sixth comparator capable of comparing the amplified signal from the second error amplifier with the maximum reference voltage, the seventh comparator adaptable to compare the amplified signal from the second error amplifier with the minimum reference voltage, and a second logic controller coupled to the four comparators, the second logic controller configured to receive input from the comparators and output logic signals for activating and deactivating the voltage balancing process for the rechargeable battery; and

a driver amplification module coupled to the DC modulation module, the driver amplification module operable to amplify signals from the DC modulation module without altering its logic state.