TWI443933B - Power balanced circuit for series battery set - Google Patents

Description

Battery series energy balance circuit

The invention relates to a battery series energy balance circuit, in particular to a series connection of a plurality of battery cells, and the balance module of the transformer winding is mainly used to achieve the energy balance of each battery cell.

At present, in order to increase the use voltage, battery applications are often used in series connection. In order to increase the service life and reduce the difference of battery cells, the selection of batteries is very important, usually based on battery voltage, internal resistance and capacity. Classify the battery to search for a battery with a high performance matching (Cell). As the number of times the battery is charged and discharged and the degree of aging, the voltage difference of each battery cell will become larger and larger. When the battery pack is charging, it will reach the overcharge protection point early, and the over-discharge protection point will be activated early when discharging, which will greatly reduce the usable capacity of the battery pack. The following example can explain this phenomenon.

Please refer to FIG. 1 . In this example, the battery pack is composed of three battery cells 11 , 12 , 13 implemented as lithium batteries connected in series, and here, the three battery cells 11 , 12 , 13 have not been charged yet. Before the discharge test, as shown in Fig. 2, the voltage of each of the battery cells 11, 12, and 13 is the same.

Furthermore, after the discharge phase, the voltage of each of the battery cells 11, 12, 13 is as shown in Fig. 3 (the oblique line region is the change in energy of each battery after discharge), wherein the battery cell 12 is aged. It is faster than the battery cell 11 and the battery cell 13, and the difference in unbalance after the multiple use is significantly increased, and since the current battery protection IC is a voltage measurement method, as long as there is any battery cell (such as the third The voltage of the battery cell 12) in the figure is lower than the low voltage protection point (such as 2.6V in Figure 3), the protection IC will stop all the battery cells 11, 12, 13 to perform the discharge action, so there is only one battery list Early aging of the body will cause the entire battery pack to inform the powerless message early, and will also make the user feel that the battery pack will soon be out of power.

Furthermore, please refer to FIG. 4, in the charging phase, since the battery cell 11 actually has more energy remaining than the other two battery cells 12, 13, the charging protection point will be reached as early as possible (such as In Fig. 4, 4.2V), when the battery protection IC is activated, all the battery cells 11, 12, 13 stop charging, so the user feels that the battery pack is fully charged.

Therefore, in the case of repeatedly charging and discharging the battery pack, the problem caused by the energy imbalance between the battery cells will only become more and more serious. Under the action of the protection IC, the utilization rate of the battery pack is very low.

In order to solve the above problems, there is a discharge circuit arrangement as shown in FIG. 5, wherein the battery cells 11 are connected in parallel with a set of discharge circuits 14, which include a resistor 141 and a switch 142, the battery pack. Each of the battery cells 11, 12, and 13 can be connected in parallel to the discharge circuit 14. By controlling the resistor 141 and the switch 142, the voltage after the energy release of each of the battery cells 11, 12, and 13 can be uniformized. Operationally, as shown in FIG. 6, the lowest energy battery cell 12 is used as a reference point (such as 3.7 V in FIG. 6), and then the battery cells 11 and the battery cells 13 are slanted to the battery cells. 12 equal, and can achieve the purpose of battery voltage balance. This type of passive voltage balancing technology is based on energy release. When charging, when the charging speed is greater than the circuit balancing capability, the charging current must be reduced, so the charging time will be lengthened. When discharging, the battery energy is not much left. It is even more impossible to start the balancing circuit and discharge the battery with energy. Therefore, such technology is inefficient, and there are still some defects such as heat generation and waste of energy.

In view of the above problems, an object of the present invention is to provide a battery series energy balance circuit, in particular, each battery module transmits and senses a transformer winding, and can achieve high energy transfer from low to low in the discharge mode to obtain the battery power. Balance and recharge the power in the transformer winding to charge the battery in charging mode.

Therefore, in order to achieve the above objective, the battery series energy balance circuit of the present invention comprises a first battery module, a second battery module and a transformer winding, wherein the first battery module has a first battery unit and a a first discharge circuit and a first charging circuit, the first discharge circuit has a first coil connected in series with the first battery unit, and the first charging circuit includes a second coil and a first diode for the first The battery cells are connected in series. Further, the second battery module has a second battery cell, a second discharge circuit and a second charging circuit. The second discharge circuit is composed of a second coil and a second battery cell. The second charging circuit includes a third coil and a second diode to be connected in series with the second battery unit. In addition, the transformer winding couples the first coil, the second coil, and the third coil. The battery series energy balance circuit of the present invention, in the discharge mode, the first discharge circuit and the second discharge circuit balance the energy of the first coil and the second coil by the transformer winding, and discharge balance the first battery cell and the second battery cell In the charging mode, the energy of the second coil is recharged to the first battery cell, and the energy of the third coil is recharged to the second battery cell.

In summary, the present invention is compared with the prior art, and the battery series energy balance circuit of the present invention can be applied to different types of batteries by the above-mentioned circuit, that is, it is not necessary to monitor each battery voltage during the balancing process. Moreover, the number of coils can be adjusted according to the number of batteries connected in series, so that the effect of the battery module can be expanded indefinitely. Furthermore, since the invention is an energy transfer architecture and non-energy consumption, the balance loss can be reduced, the efficiency is high, and the balance time can be achieved. Short-term effects, which in turn improve battery utilization and extend service life, while reducing battery waste.

Hereinafter, a battery series energy balance circuit according to various preferred embodiments of the present invention will be described with reference to the related drawings.

Please refer to FIG. 7, which is a circuit diagram of a battery series energy balance circuit according to a preferred embodiment of the present invention. The battery-series energy balance circuit of the present invention includes a first battery module 20, a second battery module 30, and a transformer winding 40. The first battery module 20 has a first battery unit 21, a first discharge circuit having a first coil 22 connected in series with the first battery cell 21, and a first charging circuit including a second coil 32 and a first diode 23 is connected in series with the first battery unit 21, and the second battery module 30 has a second battery unit 31, a second discharge circuit and a second charging circuit, and the second discharge circuit has a second coil 32 and a second The second battery unit 31 is connected in series, and the second charging circuit includes a third coil 34 and a second diode 33 connected in series with the second battery unit 31, and the transformer winding 40 is coupled to the first coil 22 and the second coil. 32 and the third coil 34, in a discharge mode, the first discharge circuit and the second discharge circuit balance the energy of the first coil 22 and the second coil 32 by the transformer winding 40, and discharge balance the first battery cell 21 With the second battery cell 31, and in a charging mode In the formula, the energy of the second coil 32 is recharged to the first battery cell 21 and the energy of the third coil 34 is recharged to the second battery cell 31.

Furthermore, in FIG. 7, it is further disclosed that the first battery module 20 has a first switch 25, and the first switch 25 is connected in series with the first battery unit 21 and the first coil 22, and the second battery module The second switch 35 also has a second switch 35. The first switch 25 and the second switch 35 are in a discharge mode when the communication is closed. The first battery unit 21, the first coil 22 and the first switch 25 form a closed loop. The second battery cell 31, the second coil 32, and the second switch 35 form a closed loop. At this time, the battery currents of the first battery cell 21 and the second battery cell 31 enter the first coil 22 and the second coil, respectively. 32 to generate the excitation current, and by the balance characteristic of the core of the transformer winding 40, the energy is transferred from high to low, so that the battery cells with higher voltages of the two battery cells 21, 31 release the battery with lower voltage. Up to balance.

Furthermore, when the first switch 25 and the second switch 35 are in the charging mode when the disconnection is not connected, the first battery cell 21, the first diode 23 and the second coil 32 form a closed loop, and The second battery cell 31, the second diode 33, and the third coil 34 also form a closed loop, and the energy remaining in the second coil 32 and the third coil 34 passes through the first diode 23 and the second, respectively. The diode 33 is charged to the first battery cell 21 and the second battery cell 31.

Please refer to Figure 8 for the battery balance timing diagram from the above discharge mode to the charging mode. As shown, when the first switch 25 and the second switch 35 are in closed communication (discharge mode), the excitation currents of the first coil 22 and the second coil 32 are due to the first battery cell 21 and the second battery cell 31. The battery current is injected and increased with time, this stage may be referred to as an energy balance area; and when the first switch 25 and the second switch 35 are disconnected (charging mode), the second coil 32 and the third coil 34 are The exciting current will gradually flow to the first battery cell 21 and the second battery cell 31, and thus will gradually decrease over time, and this stage may be referred to as an energy recovery zone.

Here, the ratio of the energy balance zone to the energy recovery zone depends on the performance of the transformer winding 40. The energy transfer is related to the transformer technology, and the residual energy of the transformer can reduce the time.

Furthermore, it should be noted that, in addition to the above embodiments, the battery series energy balance circuit of the present invention can extend a plurality of battery modules in series, as shown in FIG. 9, which is connected to the first battery module. A battery module 50 is further disposed between the battery module 50 and the second battery module 30. The battery module 50 also has a battery unit, a discharge circuit and a charging circuit. The functions of the battery module 50 in the charging and discharging mode are as described above. The same, here is no further description.

In summary, the battery series energy balance circuit of the present invention does not need to detect the battery voltage when the balance mechanism operates. When the switch is closed and turned on, the battery and the transformer winding form a loop, and the battery current enters the transformer winding to generate an exciting current. The energy enters the transformer core from the transformer winding, the energy will shift from high to low, and the higher voltage battery charges the lower voltage battery; when the switch is disconnected and not conducting, the energy left in the transformer will pass the energy through the diode Recycling and charging the battery, thereby achieving the following advantages:

1. No need to detect battery voltage: At present, different types of batteries have different terminal voltages, and each battery voltage needs to be monitored during the balancing process. Therefore, the existing balancing method cannot be applied to different types of batteries (such as lead-acid batteries, nickel-metal hydride). Battery and lithium battery). However, the circuit embodiment of the present invention can be applied to series balancing of different types of batteries.

2. Charge and discharge parallel: The circuit embodiment of the present invention is not affected by the charge and discharge path, and can be applied to balance between charging and battery discharge.

3. Stackable type: According to the number of batteries connected in series, with the number of adjustment coils, it can be expanded indefinitely without being affected by the number of batteries.

4. High efficiency: The circuit implementation method of the invention is an energy transfer architecture, which is non-energy consumption, so that the balance loss is small, the efficiency is high, and the balance time is short, the battery utilization rate is increased, the service life is prolonged, and the battery waste is reduced.

The above is intended to be illustrative only and not limiting. Any equivalent modifications or alterations to the spirit and scope of the invention are intended to be included in the scope of the appended claims.

11. . . Battery cell

12. . . Battery cell

13. . . Battery cell

14. . . Discharge circuit

141. . . resistance

142. . . switch

20. . . First battery module

twenty one. . . First battery cell

twenty two. . . First coil

twenty three. . . First diode

25. . . First switch

30. . . Second battery module

31. . . Second battery cell

32. . . Second coil

33. . . Second diode

34. . . Third coil

35. . . Second switch

40. . . Transformer winding

50. . . Battery module

Figure 1 is a schematic circuit diagram of a series battery pack;

Figure 2 is a schematic diagram of the amount of electricity before the batteries of the series battery pack are tested without charge and discharge;

Figure 3 is a schematic diagram of the amount of electricity after discharge of each battery in Figure 2;

Figure 4 is a schematic diagram of the amount of electricity after charging each battery in Figure 3;

Figure 5 is a circuit diagram of a conventional battery discharge circuit;

Figure 6 is a schematic diagram showing the electric charge balance of each battery by the circuit of Figure 5;

Figure 7 is a circuit diagram of a battery series energy balance circuit according to a preferred embodiment of the present invention;

8 is a timing diagram of a cell balance of a battery series energy balance circuit according to a preferred embodiment of the present invention;

Figure 9 is a circuit diagram of a battery series energy balance circuit according to another preferred embodiment of the present invention.

20. . . First battery module

twenty one. . . First battery cell

twenty two. . . First coil

twenty three. . . First diode

25. . . First switch

30. . . Second battery module

31. . . Second battery cell

32. . . Second coil

33. . . Second diode

34. . . Third coil

35. . . Second switch

Claims (4)

A battery series energy balance circuit includes: a first battery module including a first battery unit, a first discharge circuit, and a first charging circuit, the first discharge circuit including a first coil and the The first battery cell is connected in series, the first charging circuit includes a second coil and a first diode to be connected in series with the first battery cell; and a second battery module includes a second battery cell, a second discharge circuit including a second coil in series with the second battery unit, the second charging circuit including a third coil and a second diode In series with the second battery cell; and a transformer winding coupled to the first coil, the second coil, and the third coil, in a discharge mode, the first discharge loop and the second discharge loop Recharging the first battery cell and the second battery cell by balancing the energy of the first coil and the second coil by the transformer winding, and in a charging mode, returning the energy of the second coil Charge to the first Cell, and back-filled with the energy of the third coil to the second cell. The battery series energy balance circuit of claim 1, wherein the first battery module further includes a first switch, and the first open relationship is connected in series with the first battery unit and the first coil. The discharge mode is the closed mode, and the charging mode is when the disconnection is not connected. The battery series energy balance circuit of claim 1, wherein the second battery module further includes a second switch, the second open relationship is connected in series with the second battery unit and the second coil, The discharge mode is the closed mode, and the charging mode is when the disconnection is not connected. The battery series energy balance circuit of claim 1, further comprising a plurality of battery modules, each battery module comprising a battery unit, a discharge circuit and a charging circuit, the discharge circuit having A coil is coupled in series with the battery cell, the charging circuit having another coil and a diode in series with the battery cell, and the coil systems are coupled to the transformer winding.