TWI693772B - 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 invention relates to a battery module, in particular to a battery module with a charge management function for each series-connected secondary battery cell.

At present, the charging method of the battery module is to use its positive and negative electrodes as charging input terminals, so-called co-charging points, to charge all the secondary battery cells in the battery module at once. However, because of the thermal gradient imbalance 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, the impedance of the assembled wire (nickel sheet, wire from the battery management system, etc.) Differences... and other factors, the battery module has a "battery imbalance" problem. Unbalanced battery will reduce battery module performance and shorten battery module (secondary battery cell) life.

Observe the source of the battery imbalance problem when the battery module is charged and discharged. During discharge, the secondary battery cells with low electricity content are quickly discharged. The secondary battery cells with high electricity content are still being discharged because they still have electricity, causing the secondary battery cells with low electricity content to be forced to continue to discharge, causing The secondary battery cell with low electricity content is damaged due to over-discharge. In addition to reducing the performance of the battery module, the entire battery module will eventually be damaged. During charging, the secondary battery cell with a high electrical content quickly fills up, and the secondary battery cell with a low electrical content is still being charged because it is not fully charged yet, causing the secondary battery cell with a high electrical content to be forced to continue charging. Including The secondary battery cell with high power is overcharged and damaged. It also leads to reduced battery module performance and eventual damage. Therefore, if the charging management of individual secondary battery cells is not performed during charging, in addition to failing to effectively achieve the purpose of charging, the damage of the battery module may be accelerated.

In order to solve the aforementioned problems, the Republic of China Invention Patent No. I632759 proposes a closed-loop charging voltage stabilizing device and system. The block diagram of this system is shown in FIG. 1. In short, the system belongs to a closed-loop charging voltage stabilizing system that uses common charging points. Since the amount of current flowing between the battery cells is the same at the common charge point, in order not to cause overcharging, the voltage stabilization unit uses the shunt enable unit and the shunt enhancement unit to guide the excessive current out so that each battery cell It can be maintained when the preset voltage value is reached during charging, and will not be overcharged. The system is designed with an independent battery management unit for each battery cell. However, its circuit design is complex, and bypass current is also likely to cause energy to dissipate and heat the battery module.

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

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

To solve the foregoing problems, the present invention provides a battery module having a charge management function for each series-connected secondary battery cell. This includes: a positive charge point; a negative charge point; a current detection switch, which is electrically connected to the positive charge point. When a current flows from the positive charge point to the current detection switch, the current detection The test switch is closed; a connecting circuit that electrically connects the positive co-charge point and the negative co-charge point; a plurality of secondary battery cells connected in series, the first and last secondary battery cells connected in series are connected to the The current detection switch is electrically connected to the negative charge point of the negative electrode; and a charging unit with the same number of secondary battery cells, each charging unit is electrically connected to the positive electrode and the negative electrode of a corresponding secondary battery cell The secondary battery cell is charged to a preset voltage value, wherein each charging unit is additionally electrically connected to the connection circuit for obtaining power to charge the secondary battery cell.

According to the present invention, the charging unit may further include: an input terminal circuit for electrically connecting the connection circuit; a transformer, electrically connected to the input terminal circuit, which will step down the DC power 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 DC current input to the transformer, thereby stabilizing the output voltage of the transformer; a certain current transfer to a voltage mode circuit , Electrically connected to the transformer, adjusting the DC current from the transformer to change from an initial low current amount to substantially maintain a fixed current amount within a first time and to maintain a fixed voltage value within a second time, to External output; and an output circuit, which 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 DC voltage adjusted by the voltage mode circuit to charge the secondary battery core.

Preferably, during the first time, the DC power adjustment may 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 DC power adjustment may be that the fixed current amount gradually decreases with time; after the second time, the corresponding secondary battery core is fully charged and the current amount drops to zero.

In addition, the battery module may further include a battery management module electrically connected to the current detection switch, the contacts of the adjacent two secondary battery cells, and the negative common charge point for detecting each secondary battery cell The voltage, current and temperature changes during charging and discharging, and active or passive balancing of the battery module during charging. A first switch may be provided on a line where the battery management module is electrically connected to the negative common charge point. When any secondary battery cell is detected as overdischarge or overheating during the discharge of the battery module, the The battery management module cuts off the first switch to stop the discharging operation of the battery module. Can also be used in the battery A second switch is provided on the line electrically connected to the negative common charge point of the management module. When any secondary battery cell of the battery module is detected to be overcharged or overheated during charging, 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-metal hydride 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 the secondary battery cells in the battery module are not fully charged, and some are overcharged. Damage caused by the module.

10‧‧‧ battery module

20‧‧‧Battery module

100‧‧‧current detection switch

110‧‧‧Composite component

120‧‧‧Transistor

200‧‧‧Connect circuit

310‧‧‧ First secondary battery cell

320‧‧‧Secondary secondary battery cell

330‧‧‧third secondary battery cell

410‧‧‧ First charging unit

411‧‧‧ input circuit

412‧‧‧Transformer

413‧‧‧Pulse width modulation circuit

414‧‧‧Constant current to constant voltage mode circuit

415‧‧‧ output circuit

420‧‧‧Second charging unit

430‧‧‧The third charging unit

500‧‧‧Battery management module

600‧‧‧External charging source

B+‧‧‧ Positive charge point

B-‧‧‧Negative charge point

S1‧‧‧ First switch

S2‧‧‧Second switch

R1‧‧‧ First resistance

R2‧‧‧Second resistance

R3‧‧‧ Third resistance

R4‧‧‧ Fourth resistance

1 is a block diagram of a conventional closed-loop charging regulator system, FIG. 2 is a block diagram of a battery module having a charge management function for each series-connected secondary battery cell according to an embodiment of the present invention, and FIG. 3 is a diagram A block diagram of a charging unit in a battery module. FIG. 4 is a block diagram of a current detection switch in the battery module. FIG. 5 is an external voltage of a secondary battery cell during charging in a constant current mode and a constant voltage mode. And the current change curve, Figure 6 is a comparison of the internal voltage change curve 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 described in further detail below with reference to the drawings.

Please refer to FIG. 1, which is a block diagram of battery modules 10 and 20 having a charge management function for each series-connected secondary battery cell according to the implementation of the present invention. The battery module 10 and the battery module 20 are presented according to the present invention, and their internal components and functions are the same, and different symbols are provided for the convenience of description only. Set. Take the battery module 10 as an example to illustrate its internal functional elements. The battery module 10 includes a positive common charge point B+, a negative common charge point B-, a current detection switch 100, a connection circuit 200, a first secondary battery cell 310, and a second secondary battery cell 320 3. 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 conventional technology in the technical field to which the present invention belongs, so they are not listed and explained one by one. In the following, according to the function of each element and the way of interaction with other elements, it will be explained separately with reference to FIGS. 2 to 6.

The positive charge point B+ and the negative charge point B- are the common charge 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 battery modules can be connected in series to charge more than two battery modules at a time. As shown in FIG. 2, the negative co-charging point B- of the battery module 10 is electrically connected to the positive co-charging point B+ of the battery module 20, and the positive co-charging point B+ of the battery module 10 is electrically connected to the negative pole of the external charging source 600 The negative 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 for two parallel battery modules.

When charging, the external charging source 600 will have a current flowing to the positive co-charging point B+, but according to the spirit of the present invention, the current will flow from the charging unit to the secondary battery cell instead of directly flowing from the positive co-charging point B+ to two. Secondary battery cell. In order to change the direction of the current, there is a design of the current detection switch 100. The current detection switch 100 is electrically connected to the positive common charge point B+. When current flows from the positive common charge point B+ into the current detection switch 100, the current detection switch 100 is turned off. In this way, the current can only flow to the negative charge point B- and other secondary battery cells. Generally, there are many types of the current detection switch 100, which is not limited in the present invention, but an implementation type is disclosed in the embodiments 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 virtual Surrounded by wireframe. The current detection switch 100 includes a composite device 110 having a P-type MOS and an inverted 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 charge point B+. The third resistor R3 is electrically connected to the second resistor R2 and is connected to the source of the transistor 120. The gate electrode of the transistor 120 is electrically connected to the first charging unit 410 through the fourth resistor R4, and the drain electrode thereof is grounded. In the composite element 110, the gate of the P-type MOS 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 charge point B+. The positive electrode of the electrode and the reverse diode is 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 the drain of the transistor 120 are turned on. At this time, in addition to passing the second resistor R2 and the third resistor R3 to the ground, the current also flows to the gate of the P-type MOS. Thus, the P-type MOS turns off the current conduction between its source and drain. Therefore, the current from the positive charge point B+ will not charge the first secondary battery cell 310 and the battery cell connected in series therewith.

The connection circuit 200 electrically connects the positive co-charging point B+ and the negative co-charging point B-, and serves as a source of DC power when each charging unit performs a charging operation. 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, with a minimum of two, and a maximum of no limit in theory. It should be noted that the first (first secondary battery cell 310) and the last (third secondary battery cell 330) secondary battery cells connected in series are electrically connected to the current detection switch 100 and the negative common charge point B-, respectively . In practice, the secondary battery cell can be any rechargeable battery cell, such as 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 Core or NiMH battery core.

The number of charging units is the same as the number of secondary battery cells, so that one-to-one charging can be performed. For example, the first charging unit 410 charges the first secondary battery cell 310, and the second charging unit 420 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 and negative electrodes of the corresponding secondary battery cell The secondary battery cell is charged to a preset voltage value. The preset voltage value is the calibrated voltage of the secondary battery cell. For an 18650 lithium-ion battery cell, the preset voltage value may be 3.7V. In other words, by charging the secondary battery cell through the charging unit, it can be ensured that the secondary battery cell's guaranteed charging voltage is at its nominal voltage, so that the overcharge state of excessive voltage or low voltage is not sufficient. status. In addition, each charging unit is electrically connected to the connecting 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 disclose the structure of the charging unit, this embodiment uses the first charging unit 410 as an example (the internal structure of each charging unit is the same). Please refer to FIG. 3, which is a block diagram of the first charging unit 410 in the battery module 10. The first charging unit 410 includes an input terminal circuit 411, a transformer 412, a pulse width modulation circuit 413, a constant current conversion voltage mode circuit 414, and an output terminal circuit 415. Each is explained 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 circuit 411, and the DC power input from the input circuit 411 is stepped down, for example, 5V is reduced to 3.7V. The type of 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, thereby stabilizing 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 the DC power from the transformer 412 is adjusted to change from an initial low current amount to maintain a fixed current amount for a first time and to maintain a fixed current amount for a second time Maintain a fixed voltage value, and output to the outside. In other words, the constant current transfer voltage mode circuit 414 performs constant current mode charging on the first secondary battery cell 310 in the first time, and the constant current transfer voltage mode circuit 414 charges the first secondary battery in the second time The core 310 implements constant voltage mode charging. In order to have a better understanding of this, please refer to FIG. 5, which is a graph of the change in external voltage and current of the secondary battery cell during charging in the constant current mode and the constant voltage mode. In FIG. 5, when charging is started just after the first time, the voltage of the first secondary battery cell 310 rises with time, but the current amount is still maintained at the initial low current amount of 0.5 A (I _min ). 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 when too much current amount will cause overheating. As the charging time is long, the DC power is adjusted from the lowest voltage value of 2.6V, and gradually increases to close to but does not exceed the fixed voltage value of 3.7V (close to _Vmax ) with time. At the same time, the amount of current increases steadily to 1.0A (I _cc , fixed amount of current). When the voltage of the first secondary battery cell 310 is substantially close to 3.7V, it enters the second time and starts the constant voltage mode. During this time, the direct current is adjusted to the fixed current amount, which gradually decreases with time; after the second time, the corresponding first secondary battery cell 310 completes charging, 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, the first secondary battery cell 310 is fully charged without overcharging or undercharging. The output circuit 415 is electrically connected to the positive electrode and the negative electrode of the corresponding first secondary battery cell 310, and is used to charge the first secondary battery cell 310 with the direct current adjusted by the constant current to the constant voltage mode circuit 414. The operations of the second charging unit 420 and the third charging unit 430 are also the same, and the difference only depends on different secondary battery cells, and has different first time and second time.

The battery management module 500 is electrically connected to the current detection switch 100, the contacts of two adjacent secondary battery cells, and the negative common charge point B- to detect the voltage during charging and discharging 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 charge point), and the first Two switches S2 to prevent damage to the battery module 10 due to abnormal secondary battery cells during discharging and charging. When any secondary battery cell of the battery module 10 is detected as over-discharge or overheating during the discharge 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 charging, the battery management module 500 can also turn 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.

The battery module 10 of the present invention is used for charging, which has better protection for the internal secondary battery core and can prolong the service life of the battery module 10. To this end, please refer to FIG. 6, the three secondary battery cells in this embodiment are placed in the conventional battery module and the battery module 10 of the present invention as an example to compare their charging process Difference. As shown in the upper part of Fig. 6, when three secondary battery cells are placed in a conventional battery module, each secondary battery cell is simultaneously charged. Because the structure or characteristics of each secondary battery cell are different, 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 not fully charged. However, when charging in the battery module 10, each secondary battery cell can be almost fully charged, but the time to reach full charge varies according to its own characteristics.

Although the present invention has been disclosed as above in the 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. The scope of protection of the present invention shall be subject to the scope defined in the attached patent application.

10‧‧‧ battery module

20‧‧‧Battery module

100‧‧‧current detection switch

200‧‧‧Connect circuit

310‧‧‧ First secondary battery cell

320‧‧‧Secondary secondary battery cell

330‧‧‧third secondary battery cell

410‧‧‧ First charging unit

420‧‧‧Second charging unit

430‧‧‧The third charging unit

500‧‧‧Battery management module

600‧‧‧External charging source

B+‧‧‧ Positive charge point

B-‧‧‧Negative charge point

S1‧‧‧ First switch

S2‧‧‧Second switch

R1‧‧‧ First resistance

Claims (7)

A battery module with charge management function for each secondary battery cell in series includes: a positive common charge point; a negative common charge point; and a current detection switch, which is electrically connected to the positive common charge point. When current flows into the current detection switch from the positive charge point of the positive electrode, the current detection switch is closed; a connecting circuit electrically connecting the positive charge point of the positive electrode and the negative charge point of the negative electrode; a plurality of secondary batteries connected in series Core, the first and last secondary battery cells connected in series are electrically connected to the current detection switch and the negative charge point respectively; a battery management module is electrically connected to the current detection switch and the adjacent two secondary batteries The contact of the core and the common charge point of the negative electrode are used to detect the voltage, current and temperature changes during the charging and discharging of each secondary battery core; and the charging unit with the same number of secondary battery cores, each charging The unit is electrically connected to the positive electrode and the negative electrode of a corresponding secondary battery cell to charge the corresponding secondary battery cell to a preset voltage value, wherein each charging unit is electrically connected to the connection circuit Obtain the power to charge the secondary battery cell. The battery module according to claim 1, wherein the charging unit further includes: an input circuit for electrically connecting the connection circuit; and a transformer electrically connected to the input circuit, which is 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 cycle of the DC power input to the transformer so that the transformer output voltage stable; A constant current transfer voltage mode circuit, electrically connected to the transformer, adjusts the DC current from the transformer to change from an initial low current amount to substantially maintain a fixed current amount within a first time and to maintain a fixed current amount during a second time Maintain a fixed voltage value and output to the outside; and an output terminal circuit, which is electrically connected to the positive and negative electrodes of the corresponding secondary battery cell, used to convert the constant current to the DC voltage adjusted by the voltage mode circuit, to the secondary The battery cell is charged. The battery module according to claim 2, wherein in the first time, the DC power is adjusted from a minimum voltage value to gradually increase over time to approach but not exceed the fixed voltage value. The battery module according to claim 2, wherein in the second time, the DC power is adjusted to decrease from the fixed current amount with time; after the second time, the corresponding secondary battery cell is fully charged, The amount of current drops to zero. According to the battery module of claim 1, a first switch is further provided on the line where the battery management module is electrically connected to the negative common charge point, when the battery module has any secondary battery during the discharge process When the core is detected as overdischarge or overheating, the battery management module cuts off the first switch to stop the discharge operation of the battery module. According to the battery module of claim 1, a second switch is further provided on the line where the battery management module is electrically connected to the negative common charge 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 cuts 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-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 nickel-metal hydride battery cells.

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