Battery voltage balance apparatus and battery charge apparatus
In the related art, the measurement error due to the internal resistance of the battery is not considered in the battery balance method, such that the battery balance is not accurate, or the battery balance process is frequently started and stopped. In exemplary embodiments of the invention, detecting battery voltage and balancing battery voltage are performed in different time, such that the difference of charge current/discharge current among the batteries due to the battery voltage balance process do not affect the battery voltage detecting.
1. A battery voltage balance apparatus, comprising:
a timing control unit alternately determining a detecting timing and a balance timing, wherein the detecting timing and the balance timing do not overlap with each other;
a balance determining unit coupled to a plurality of battery units coupled in series and the timing control unit, the balance determining units detecting battery voltages of the battery units during the detecting timing to determine whether to start a battery voltage balance process; and
a battery voltage balance unit coupled to the battery units, the balance determining unit, and the timing control unit, when the battery voltage balance process starts, the battery voltage balance unit controlling at least one of a charging rate and a discharging rate of the battery unit having a highest battery voltage and at least one of a charging rate and a discharging rate of the battery unit having a lowest battery voltage to have a difference, such that battery voltage difference between any two of the battery units is deceased to within a first predetermined value or a first predetermined percentage.
2. The battery voltage balance apparatus as claimed in claim 1 , wherein the timing control unit comprises at least one capacitor determining periods of the detecting timing and the balance timing.
3. The battery voltage balance apparatus as claimed in claim 1 , wherein the timing control unit determines the period of the balance timing according to a value of a current flowing through the battery voltage balance unit.
4. The battery voltage balance apparatus as claimed in claim 1 , wherein the balance determining unit comprises an energy storage circuit coupled to the plurality of battery units, and when the battery voltage balance process starts, the energy storage circuit stores energy and selectively charges at least one of the plurality of battery units by the stored energy.
5. The battery voltage balance apparatus as claimed in claim 1 , wherein the balance determining unit starts the battery voltage balance process when the battery voltage difference between any two of the plurality of battery units is higher than a second predetermined value or a second predetermined percentage.
6. The battery voltage balance apparatus as claimed in claim 5 , wherein the timing control unit comprises at least one capacitor determining periods of the detecting timing and the balance timing.
7. The battery voltage balance apparatus as claimed in claim 5 , wherein the timing control unit determines the period of the balance timing according to a value of a current flowing through the battery voltage balance unit.
8. The battery voltage balance apparatus as claimed in claim 5 , wherein the balance determining unit comprises an energy storage circuit coupled to the plurality of battery units, and when the battery voltage balance process starts, the energy storage circuit stores energy and selectively charges at least one of the battery units by the stored energy.
9. The battery voltage balance apparatus as claimed in claim 1 , wherein the balance determining unit starts the battery voltage balance process when the battery voltage difference between any two of the plurality of battery units is higher than a second predetermined value or a second predetermined percentage and when the battery voltages of the plurality of battery units are within a predetermined battery voltage range or higher than a third predetermined value.
10. The battery voltage balance apparatus as claimed in claim 9 , wherein the timing control unit comprises at least one capacitor determining periods of the detecting timing and the balance timing.
11. The battery voltage balance apparatus as claimed in claim 9 , wherein the timing control unit determines the period of the balance timing according to a value of a current flowing through the battery voltage balance unit.
12. The battery voltage balance apparatus as claimed in claim 9 , wherein the balance determining unit comprises an energy storage circuit coupled to the plurality of battery units, and when the battery voltage balance process starts, the energy storage circuit stores energy and selectively charges at least one of the plurality of battery units by the stored energy.
13. The battery voltage balance apparatus as claimed in claim 12 , the balance determining unit further comprises a converting unit bucking or boosting a voltage of at least one of the plurality of battery units and storing the bucked or boosted voltage to the energy storage circuit.
14. A battery charge apparatus, adapted to charge a battery module, wherein the battery module comprises a plurality of battery units coupled in series, the battery charge apparatus comprising:
a charge control unit coupled to a power supply and the battery module and controlling the power supply to provide a charge current to charge the battery module;
a timing control unit alternately determining a detecting timing and a balance timing, wherein the detecting timing and the balance timing do not overlap with each other;
a balance determining unit coupled to the plurality of battery units and the timing control unit and detecting battery voltages of the plurality of battery units during the detecting timing to determine whether to start a battery voltage balance process; and
a battery voltage balance unit coupled to the plurality of battery units, the balance determining unit, and the timing control unit, when the battery voltage balance process starts, the battery voltage balance unit controlling a charging rate of the battery unit having a highest battery voltage and a charging rate of the battery unit having a lowest battery voltage to have a difference, such that battery voltage difference between any two of the plurality of battery units is decreased to within a first predetermined value or a first predetermined percentage.
15. The battery charge apparatus as claimed in claim 14 , wherein the balance determining unit comprises an energy storage circuit coupled to the battery units, and when the battery voltage balance process starts, the energy storage circuit stores energy and selectively charges at least one of the plurality of battery units by the stored energy.
16. The battery charge apparatus as claimed in claim 14 , wherein the balance determining unit starts the battery voltage balance process when the battery voltage difference between any two of the plurality of battery units is higher than a second predetermined value or a second predetermined percentage.
17. The battery charge apparatus as claimed in claim 16 , wherein the balance determining unit comprises an energy storage circuit coupled to the plurality of battery units, and when the battery voltage balance process starts, the energy storage circuit stores energy and selectively charges at least one of the plurality of battery units by the stored energy.
18. The battery charge apparatus as claimed in claim 16 , wherein the balance determining unit starts the battery voltage balance process when the battery voltage difference between any two of the plurality of battery units is higher than a second predetermined value or a second predetermined percentage and when the plurality of battery voltages of the battery units are within a predetermined battery voltage range or higher than a third predetermined value.
19. The battery charge apparatus as claimed in claim 18 , wherein the balance determining unit comprises an energy storage circuit coupled to the plurality of battery units, and when the battery voltage balance process starts, the energy storage circuit stores energy and selectively charges at least one of the plurality of battery units by the stored energy.
20. The battery charge apparatus as claimed in claim 14 , the balance determining unit further comprises a converting unit bucking or boosting a voltage of at least one of the plurality of battery units and storing the bucked or boosted voltage to the energy storage circuit.