TW202038527A - Battery module having charging management function for each secondary battery cell connected in series - Google Patents

Abstract

A battery module having charging management function for each secondary battery cell connected in series is disclosed. The battery module includes a positive common charge point, a negative common charge point, a current detecting switch, a connecting circuit, several secondary battery cells, and charging units which have the same number as the secondary battery cells. For the battery module in the present invention, since each secondary battery cell has a charging unit for charging according to its characteristics, thereby eliminating the secondary battery cells in the battery module from being full and overcharging, causing damage to the battery module.

Description

Battery module with charge management function for each secondary battery cell connected in series

The present invention relates to a battery module, in particular to a battery module with a charging management function for each secondary battery cell connected in series.

The current charging method of the battery module uses its positive and negative electrodes as charging input terminals, which is the so-called common charging point, to charge all the secondary battery cells in the battery module at a time. However, because of the unbalanced thermal gradient in the battery module, the difference in the capacity of the secondary battery cell, the difference in the self-discharge rate, the internal resistance of the secondary battery cell, and the resistance of the assembly wire (from the nickel sheet, the wire from the battery management system, etc.) Difference...and other factors, the battery module has caused the problem of "battery imbalance". Unbalanced battery will reduce the performance of the battery module and shorten the life of the battery module (secondary battery cell).

Investigate the source of the battery imbalance and observe it when the battery module is charged and discharged. During discharging, the secondary battery cells with low power content are quickly discharged, and the secondary battery cells with high power content are still discharging because they are still charged. As a result, the secondary battery cells with low power content are forced to continue to discharge. The secondary battery cell with low charge is over-discharged and damaged. In addition to reducing the performance of the battery module, the entire battery module is eventually damaged. During charging, the secondary battery cell with high power content is quickly fully charged, and the secondary battery cell with low power content is still being charged because it is not fully charged. As a result, the secondary battery cell with high power content is forced to continue charging, causing With The secondary battery cell with high power is overcharged and damaged. It also leads to reduced performance of the battery module and eventually damage. Therefore, if charging is not performed for individual secondary battery cells during charging, in addition to failing to effectively achieve the charging purpose, it may also accelerate the damage of the battery module.

In order to solve the aforementioned problems, the Republic of China Invention Patent No. I632759 proposes a closed-loop charging and stabilizing device and system. The block diagram of the system is shown in Figure 1. In short, the system belongs to a closed-loop charging and stabilizing system that uses a common charging point for charging. Since the amount of current flowing between the battery cells is equal when charging at the common charging point, in order not to cause overcharging, the voltage stabilization unit uses the shunt enabling unit and the shunt enhancement unit to guide the excessive current out, so that each battery cell It can be maintained when it reaches the preset voltage value during charging, and it will not overcharge. The system is an independent battery management unit designed for each battery cell. However, its circuit design is complicated, and the bypass current can easily cause energy dissipation and heat the battery module.

Therefore, based on the above remaining charging problems, the present invention provides a battery module with a charging management function for each secondary battery cell connected in series, in order to solve the above problems at once.

This paragraph of text extracts and compiles certain features of the present invention, and other features will be disclosed in subsequent paragraphs. Its purpose is to cover the spirit and scope of the additional patent application, various modifications and similar arrangements.

To solve the aforementioned problems, the present invention proposes a battery module with a charge management function for each secondary battery cell connected in series. This includes: a positive common charging point; a negative common charging point; a current detection switch, which is electrically connected to the positive common charging point. When current flows from the positive common charging point into the current detection switch, the current detection switch The test switch is closed; a connecting circuit electrically connects the positive common charging point and the negative common charging point; a plurality of secondary battery cells in series, the first and last secondary battery cells in series are respectively connected to the The current detection switch is electrically connected to the negative common charging point; and charging units with the same number of secondary battery cores, each charging unit is electrically connected to the positive and negative electrodes of a corresponding secondary battery core for the corresponding The secondary battery cell is charged to a preset voltage value, and each charging unit is electrically connected to the connection circuit to obtain power for charging the secondary battery cell.

According to the present invention, the charging unit may further include: an input terminal circuit for electrically connecting to the connection circuit; a transformer electrically connected to the input terminal circuit to step down the direct current input from the input terminal circuit; The pulse width modulation circuit forms a loop with the transformer to monitor the voltage output of the transformer to adjust the duty cycle of the direct current input to the transformer, so as to stabilize the output voltage of the transformer; a certain current is converted to a constant voltage mode circuit , Is electrically connected to the transformer, and adjusts the direct current from the transformer to change from an initial low current amount to substantially maintaining a constant current amount within a first period of time and substantially maintaining a constant voltage value within a second period of time. External output; and an output circuit, electrically connected to the positive and negative poles of the corresponding secondary battery core, used to convert the constant current to the DC adjusted by the constant voltage mode circuit to charge the secondary battery core.

Preferably, in the first time, the direct current adjustment can be from a minimum voltage value gradually increasing with time to close to but not exceeding the fixed voltage value. During the second time, the direct current adjustment may be the fixed current amount, which gradually decreases with time; after the second time, the corresponding secondary battery cell is fully charged and the current amount drops to zero.

In addition, the battery module may further include a battery management module, which is electrically connected to the current detection switch, the contact point of the two adjacent secondary battery cells, and the negative common charging point for detecting each secondary battery cell The voltage, current and temperature changes during charging and discharging, and the battery module is actively or passively balanced during charging. A first switch can be provided on the line connecting the battery management module to the negative common charging point. When any secondary battery cell is detected overdischarge or overheating during the discharge process of the battery module, the The battery management module turns off the first switch to stop the discharging operation of the battery module. Can also be used in this battery A second switch is provided on the line of the management module electrically connected to the negative common charging point. When any secondary battery cell of the battery module is detected to be overcharged or overheated during the charging process, the battery management module Turn off the second switch to stop the charging operation of the battery module.

Preferably, the secondary battery cell may be a nickel-metal hydride battery cell, a nickel-cadmium battery cell, a lithium ion battery cell, a lithium polymer battery cell, a lead-acid battery cell, a lithium iron battery cell, or a nickel hydrogen battery cell.

In the battery module of the present invention, because each secondary battery cell has a charging unit to charge its characteristics, it can avoid that some secondary battery cells in the battery module are not fully charged, some are overcharged, and cause damage to the battery. Damage caused by the module.

10‧‧‧Battery Module

20‧‧‧Battery Module

100‧‧‧Current detection switch

110‧‧‧Composite components

120‧‧‧Transistor

200‧‧‧Connecting circuit

310‧‧‧The first secondary battery cell

320‧‧‧Second secondary battery cell

330‧‧‧The third secondary battery cell

410‧‧‧First charging unit

411‧‧‧Input terminal circuit

412‧‧‧Transformer

413‧‧‧Pulse width modulation circuit

414‧‧‧Constant current to constant voltage mode circuit

415‧‧‧Output circuit

420‧‧‧Second charging unit

430‧‧‧third charging unit

500‧‧‧Battery Management Module

600‧‧‧External charging source

B+‧‧‧Anode common charging point

B-‧‧‧Negative charge point

S1‧‧‧First switch

S2‧‧‧Second switch

R1‧‧‧First resistor

R2‧‧‧Second resistor

R3‧‧‧Third resistor

R4‧‧‧Fourth resistor

Fig. 1 is a block diagram of a conventional closed-loop charging and stabilizing system. Fig. 2 is a block diagram of a battery module with a charging management function for each secondary battery cell connected in series according to an embodiment of the present invention. Fig. 3 is the A block diagram of a charging unit in a battery module. Figure 4 is a block diagram of a current detection switch in the battery module. Figure 5 shows the external voltage of the secondary battery cell in constant current mode and constant voltage mode. And the change curve of the current, Figure 6 is a graph comparing the internal voltage change of the battery cell under different charging systems.

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the drawings.

Please refer to Fig. 1, which is a block diagram of battery modules 10 and 20 with a charge management function for each secondary battery cell connected in series according to the implementation of the present invention. Both the battery module 10 and the battery module 20 are presented in accordance with the present invention, and their internal components and functions are the same. The different symbols are only provided for convenience of explanation Set. Take the battery module 10 as an example to illustrate its internal functional components. The battery module 10 includes a positive common charging point B+, a negative common charging point B-, a current detection switch 100, a connection circuit 200, a first secondary battery cell 310, and a second secondary battery cell 320 , A third secondary battery cell 330, a first charging unit 410, a second charging unit 420, a third charging unit 430, a battery management module 500, a first switch S1 and a second switch S2. In addition, the battery module 10 may also include other active and passive components and/or circuit boards to assist the operation of the aforementioned components. However, these auxiliary elements belong to the prior art in the technical field of the present invention, so they will not be listed one by one. Hereinafter, according to the function of each element and the way of interaction with other elements, respectively, it will be described in conjunction with Figs. 2-6.

The positive common charging point B+ and the negative common charging point B- are common charging points exposed outside the battery module 10. The positive common charging point B+ can be electrically connected to the negative electrode of an external charging source 600, and the negative common charging point B- can be electrically connected to the positive electrode of the external charging source 600, so that the external charging source 600 can charge the battery module 10. However, the battery module of the present invention has a feature that the battery modules can be connected in series to charge more than two battery modules at a time. As shown in Figure 2, the negative common charging point B- of the battery module 10 is electrically connected to the positive common charging point B+ of the battery module 20, and the positive common charging point B+ of the battery module 10 is electrically connected to the negative electrode of the external charging source 600 , The negative common charging point B of the battery module 20 is electrically connected to the positive electrode of the external charging source 600. This is a standard charging method of two parallel battery modules.

When charging, the external charging source 600 will have current flowing to the positive common charging point B+, but according to the spirit of the present invention, the current will then flow from the charging unit to the secondary battery cell instead of directly flowing from the positive common charging point B+ to the second battery cell. Secondary battery cell. In order to change the direction of the current, the current detection switch 100 is designed. The current detection switch 100 is electrically connected to the positive common charging point B+. When a current flows into the current detection switch 100 from the positive common charging point B+, the current detection switch 100 is turned off. In this way, the current can only flow to the negative electrode common charging point B- and other secondary battery cells. Generally speaking, the current detection switch 100 has many types, which are not limited in the present invention, but one implementation type is disclosed in the embodiment of the present invention. In this regard, please refer to FIG. 4, which is a block diagram of the current detection switch 100 in the battery module 10. The current detection switch 100 is a phantom Surrounded by wireframe. The current detection switch 100 includes a composite element 110 having a P-type MOS and a reverse diode, a transistor 120, a second resistor R2, a third resistor R3, and a fourth resistor R4. The second resistor R2 is electrically connected to the positive common charging point B+. The third resistor R3 is electrically connected to the second resistor R2 and connected to the source of the transistor 120. The gate of the transistor 120 is electrically connected to the first charging unit 410 through the fourth resistor R4, and its drain is grounded. The gate of the P-type MOS in the composite element 110 is electrically connected to the third resistor R3 and the second resistor R2, the source of the P-type MOS and the negative electrode of the reverse diode are electrically connected to the positive common charging point B+, and the drain of the P-type MOS The anode and the anode of the reverse diode are electrically connected to the first secondary battery cell 310. When charging, current flows into the composite element 110 and the first charging unit 410 from the positive common charging point B+. When the current of the first charging unit 410 further flows to the gate of the transistor 120 through the fourth resistor R4, the source and drain of the transistor 120 are turned on. At this time, the current can not only pass through the second resistor R2 and the third resistor R3 to the ground terminal, but also flow to the gate of the P-MOS. Thus, the P-type MOS turns off the current conduction between its source and drain. Therefore, the current from the positive common charging point B+ will not charge the first secondary battery cell 310 and the battery cells connected in series therewith.

The connecting circuit 200 is electrically connected to the positive common charging point B+ and the negative common charging point B-, as a DC power source for each charging unit during charging operations. The secondary battery cells 310, 320, and 330 are electrically connected in series. According to the present invention, the number of secondary battery cells is not limited to the three proposed in this embodiment, but can be designed according to actual needs, at least two, and at most theoretically unlimited. It should be noted that the first (first secondary battery cell 310) and the last (third secondary battery cell 330) connected in series are electrically connected to the current detection switch 110 and the negative common charging point B- . In practice, the secondary battery cell can be any battery cell that can be recharged and reused, such as nickel-metal hydride battery cells, nickel-cadmium battery cells, lithium-ion battery cells, lithium polymer battery cells, lead-acid battery cells, and lithium iron batteries. Core or Ni-MH battery core.

The number of charging units is the same as the number of secondary battery cells to enable one-to-one charging operations. For example, the first charging unit 410 charges the first secondary battery cell 310, and the second charging unit 420 charges the second battery cell. The secondary battery cell 320 is charged, and the third charging unit 430 charges the third secondary battery cell 330. Each charging unit is electrically connected to the positive electrode and the negative electrode of the corresponding secondary battery core for the corresponding The secondary battery cell is charged to a preset voltage value. The preset voltage value is the calibration voltage of the secondary battery cell. For an 18650 lithium ion battery cell, the preset voltage value can be 3.7V. In other words, by charging the secondary battery cell through the charging unit, it can be ensured that the maintaining charge voltage of the secondary battery cell is its rated voltage, and it will not cause an overcharge state with too high voltage or insufficient charging with too low voltage. status. In addition, each charging unit is electrically connected to the connection circuit 200 to obtain power for charging the secondary battery cell.

The charging unit is another core element of the present invention. In order to clearly reveal the structure of the charging unit, this embodiment takes the charging unit 410 as an example for description (the internal structure of each charging unit is the same). Please refer to FIG. 3, which is a block diagram of the charging unit 410 in the battery module 10. The charging unit 410 includes an input circuit 411, a transformer 412, a pulse width modulation circuit 413, a constant current-to-voltage mode circuit 414, and an output circuit 415. They are explained separately below.

The function of the input circuit 411 is to electrically connect the connection circuit 200. The transformer 412 is electrically connected to the input terminal circuit 411, and will step down the direct current input from the input terminal circuit 411, for example, to reduce 5V to 3.7V. The type of the transformer 412 is not limited by the present invention. The pulse width modulation circuit 413 and the transformer 412 form a loop for monitoring the voltage output of the transformer 412 to adjust the duty ratio of the direct current input to the transformer 412, so as to stabilize the output voltage of the transformer 412. The combination of the pulse width modulation circuit 413 and the transformer 412 is widely used in the technical field, and the relevant details will not be repeated here.

The constant current to constant voltage mode circuit 414 is electrically connected to the transformer 412, and adjusts the direct current from the transformer 412 to change from an initial low current amount to substantially maintaining a constant current amount within a second time period. Essentially maintain a fixed voltage value and output to the outside. In other words, during the first time, the constant current to constant voltage mode circuit 414 charges the first secondary battery cell 310 in constant current mode, and during the second time, the constant current to constant voltage mode circuit 414 charges the first secondary battery. The core 310 implements constant voltage mode charging. In order to have a better understanding of this, please refer to Figure 5, which is a graph showing the change of external voltage and current of the secondary battery cell in constant current mode and constant voltage mode during charging. In FIG. 5, when the first time starts and charging is proceeding, the voltage of the first secondary battery cell 310 rises with time, but the current amount is still maintained at 0.5 A (I _min ) of the initial low current amount. The initial low current amount at this time is called a trigger charge, and the purpose is to prevent the first secondary battery cell 310 from being charged at a low voltage, and a too large amount of current may cause overheating. As the charging time is longer, the direct current is adjusted from the lowest voltage value of 2.6V, gradually increasing over time to close to but not exceeding the fixed voltage value, 3.7V (close to V _max ). At the same time, the amount of current steadily increased to 1.0A (I _cc , a fixed amount of current). When the voltage of the first secondary battery cell 310 is substantially close to 3.7V, the second time is entered and the constant voltage mode is activated. During this time, the direct current is adjusted to the fixed current amount and gradually decreases with time; after the second time, the corresponding first secondary battery cell 310 is fully charged, and the current amount drops to zero. At the same time, the charging voltage is maintained at around 3.7V. After the second time, the voltage value drops slightly. After the second time has passed, the first secondary battery cell 310 is fully charged, and there is no overcharge or undercharge phenomenon. The output circuit 415 is electrically connected to the positive electrode and the negative electrode of the corresponding first secondary battery cell 310 to convert the constant current to the DC power adjusted by the constant voltage mode circuit 414 to charge the first secondary battery cell 310. The operations of the second charging unit 420 and the third charging unit 430 are also the same, the difference is only depending on the different secondary battery cells, and the first time and the second time are different.

The battery management module 500 is electrically connected to the current detection switch 100, the contact point of two adjacent secondary battery cells, and the negative common charging point B+ to detect the charging and discharging voltage of each secondary battery cell, Current and temperature changes. However, the battery management module 500 controls the first switch S1 electrically connected to the third secondary battery cell 330 through a first resistor R1 (on the line where the battery management module 500 is electrically connected to the negative common charging point), and the second The second switch S2 further prevents damage to the battery module 10 due to abnormal secondary battery cells during the discharge and charging process. When any secondary battery cell of the battery module 10 is detected to be over-discharged or over-heated during the discharging process, the battery management module 500 turns off the first switch S1 to stop the discharge operation of the battery module 10. Similarly, when any secondary battery cell of the battery module 10 is detected to be overcharged or overheated during the charging process, the battery management module 500 can also cut off the second switch S2 to stop the charging of the battery module 10 operation. The battery management module 500 is a further guarantee for the operation of the charging unit.

Using the battery module 10 of the present invention for charging has a better protective effect on the internal secondary battery cells and can prolong the service life of the battery module 10. For this reason, please refer to Fig. 6, which is an example of placing the three secondary battery cells in this embodiment in a conventional battery module and in the battery module 10 of the present invention to compare their charging processes. The difference. As shown in the upper part of Figure 6, when three secondary battery cells are placed in a conventional battery module, each secondary battery cell is simultaneously charged. Because each secondary battery cell has a different structure or characteristic, the first secondary battery cell 310 is overcharged, the second secondary battery cell 320 is normally charged, and the third secondary battery cell 330 is undercharged. However, when charging in the battery module 10, each secondary battery cell can be almost fully charged, but the time to full charge varies according to its own characteristics.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention. Anyone with ordinary knowledge in the technical field can make some changes and modifications without departing from the spirit and scope of the present invention. Therefore, The scope of protection of the present invention shall be subject to those defined by the attached patent scope.

10‧‧‧Battery Module

20‧‧‧Battery Module

100‧‧‧Current detection switch

200‧‧‧Connecting circuit

310‧‧‧The first secondary battery cell

320‧‧‧Second secondary battery cell

330‧‧‧The third secondary battery cell

410‧‧‧First charging unit

420‧‧‧Second charging unit

430‧‧‧third charging unit

500‧‧‧Battery Management Module

600‧‧‧External charging source

B+‧‧‧Anode common charging point

B-‧‧‧Negative charge point

S1‧‧‧First switch

S2‧‧‧Second switch

R1‧‧‧First resistor

Claims (8)

A battery module with a charge management function for each secondary battery cell in series, including: a positive electrode common charging point; a negative electrode common charging point; a current detection switch, which is electrically connected to the positive electrode common charging point. When current flows into the current detection switch from the positive common charging point, the current detection switch is closed; a connection circuit electrically connecting the positive common charging point and the negative common charging point; a plurality of secondary batteries connected in series The first and last secondary battery cores connected in series are respectively electrically connected to the current detection switch and the negative common charging point; and charging units with the same number of secondary battery cores, and each charging unit corresponds to one The positive pole and the negative pole of the secondary battery cell are electrically connected to charge the corresponding secondary battery cell to a preset voltage value, wherein each charging unit is electrically connected to the connection circuit to obtain the secondary battery The power to charge the core. The battery module according to claim 1, wherein the charging unit further includes: an input terminal circuit for electrically connecting to the connection circuit; a transformer, electrically connected to the input terminal circuit, to be connected to the input terminal The DC power input by the circuit is stepped down; a pulse width modulation circuit forms a loop with the transformer to monitor the voltage output of the transformer to adjust the duty ratio of the DC power input to the transformer, so that the transformer output voltage Stable; a constant current to constant voltage mode circuit, electrically connected to the transformer, adjusts the direct current from the transformer to change from an initial low current amount to substantially maintaining a constant current amount in a first time and a second time The inner substance maintains a fixed voltage value and outputs it to the outside; and An output terminal circuit is electrically connected to the positive and negative electrodes of the corresponding secondary battery core, and is used to convert the constant current to the direct current adjusted by the constant voltage mode circuit to charge the secondary battery core. The battery module according to claim 2, wherein in the first time, the direct current is adjusted to a minimum voltage value and gradually increases over time to close to but not exceeding the fixed voltage value. The battery module according to claim 2, wherein during the second time, the direct current is adjusted to the fixed current amount and gradually decreases with time; after the second time, the corresponding secondary battery cell is fully charged, The amount of current drops to zero. The battery module according to claim 1, further comprising a battery management module, electrically connected to the current detection switch, the contact point of two adjacent secondary battery cells, and the negative common charging point for detecting Measure the voltage, current and temperature changes of each secondary battery cell during charging and discharging. For the battery module described in claim 5, a first switch is further provided on the line connecting the battery management module to the negative common charging point, when the battery module has any secondary battery during the discharge process When the core is detected to be over-discharged or over-heated, the battery management module turns off the first switch to stop the discharge operation of the battery module. For the battery module described in claim 5, a second switch is further provided on the line connecting the battery management module to the negative common charging point, when the battery module has any secondary battery during the charging process When the core is detected to be overcharged or overheated, the battery management module turns off the second switch to stop the charging operation of the battery module. The battery module according to claim 1, wherein the secondary battery cell is a nickel-hydrogen battery cell, a nickel-cadmium battery cell, a lithium ion battery cell, a lithium polymer battery cell, a lead-acid battery cell, and a lithium iron battery cell Or Ni-MH battery cell.

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