Bypass implementation method for battery module and degraded battery cell

Abstract

The invention relates to a battery module and a degraded battery cell bypass implementation method, and the battery module comprises a battery module which comprises a plurality of battery cell units connected in series; each battery cell unit comprises a battery cell monomer and a battery cell management circuit connected with the battery cell monomer in parallel; the cell management circuit comprises an equalization branch, a bypass part and a measurement and control module; the bypass part is used for short-circuiting the battery cell monomers by using thyristors when the battery cell monomers are degraded; and the measurement and control module is used for detecting the state of each battery cell monomer and controlling the bypass part and the equalization branch according to the state of the battery cell monomer. According to the invention, the degraded battery cell can be completely bypassed.

Description

Technical Field

[0001] The present invention relates to the technical field of electric energy storage, and in particular to a bypass implementation method for a battery module and a deteriorated battery cell. Background Art

[0002] As a core component of energy storage, battery modules are widely used in electric transportation, power storage, and new energy power generation. Battery modules are composed of multiple cells connected in series or in parallel. Although this structure improves energy density and flexibility to a certain extent, it also brings about the "short board effect", that is, the overall performance of a battery pack depends on the weakest battery cell, and the performance degradation of a degraded cell will cause the capacity and power output of the entire battery module to be restricted, which will eventually affect the output of the energy storage inverter. During the operation of the battery pack, the battery cell may degrade due to various factors (such as temperature, number of charge and discharge cycles, manufacturing defects, etc.), resulting in a decline in battery performance and even potential safety hazards. In order to minimize the negative impact of the "short board effect", the status of each cell in the battery pack can be monitored in real time, and automatically bypassed when degradation is detected to ensure the continuous use of the entire battery module.

[0003] The existing patent CN106992323A discloses a method of switching a faulty battery to a backup battery to maintain the normal operation of the battery pack. However, this method lacks the realization of the balancing function and is relatively costly, so it is not suitable for large-scale energy storage systems. The existing patent CN114726033A discloses a method of selectively connecting single cells and battery packs to the system according to demand and the status of each battery pack and single cell to solve the balancing problem between cells. However, the system structure in this method is complex, the number of power sources is large, and the cost is high. The existing patent CN117352865A discloses a battery module self-healing fault removal control method, in which the automatic bypass branch is a magnetic latching relay connected in parallel with the battery cell. This method may cause the relay to disconnect due to false triggering, and the degraded battery cell cannot be completely removed. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a battery module and a method for bypassing deteriorated battery cells, which can completely bypass the deteriorated battery cells.

[0005] The technical solution adopted by the present invention to solve the technical problem is: to provide a battery module, including:

[0006] A battery module includes a plurality of battery cell units connected in series; the battery cell units include battery cell monomers and battery cell management circuits connected in parallel with the battery cell monomers; the battery cell management circuit includes a bypass part and a measurement and control module; the bypass part is used to short-circuit the battery cell monomers using thyristors when the battery cell monomers deteriorate; the measurement and control module is used to detect the state of each of the battery cell monomers and control the bypass part according to the state of the battery cell monomers.

[0007] The bypass part includes a Boost converter and a bypass circuit; one input end of the Boost converter is connected to the positive electrode of the battery cell, and the other input end is connected to the negative electrode of the battery cell; one output end of the Boost converter is connected to one end of the second control switch, and the other output end is connected to the negative electrode of the battery cell; the bypass circuit is a thyristor, the thyristor is connected in parallel at both ends of the battery cell, and the gate of the thyristor is connected to the Boost converter through the other end of the second control switch; the Boost converter and the second control switch are controlled by the measurement and control module, when the battery cell is deteriorated, the Boost converter is started and the second control switch is closed, and when the battery cell is normal, the Boost converter stops working and the second control switch is disconnected.

[0008] The Boost converter includes an inductor, a diode, a switch tube and a capacitor, wherein one end of the inductor is connected to the positive electrode of the battery cell, the other end is connected to the positive electrode of the diode, and the negative electrode of the diode is connected to one end of the capacitor; one end of the switch tube is connected to the positive electrode of the diode, the other end is connected to the negative electrode of the battery cell, and the other end of the switch tube is also connected to the other end of the capacitor.

[0009] The cell management circuit further includes a balancing branch connected in parallel with the cell monomer, and the balancing branch is used to reduce the voltage across the cell monomer when the voltage across the cell monomer reaches a balancing voltage threshold.

[0010] The balancing branch includes a first control switch and a discharge resistor connected in series; the first control switch is controlled by the measurement and control module, closed when the voltage across the battery cell exceeds a threshold value, and disconnected when the difference between the voltage across the battery cell and the voltage across the battery cell of other battery cells is within a preset range.

[0011] The technical solution adopted by the present invention to solve the technical problem is: to provide a method for bypassing the deteriorated battery cells in the above-mentioned battery module, comprising the following steps:

[0012] The measurement and control module performs real-time detection on the status of each battery cell;

[0013] When the measurement and control module detects that the voltage across the battery cell reaches the bypass voltage threshold, a third control signal is sent to the Boost converter corresponding to the battery cell that reaches the bypass voltage threshold;

[0014] After receiving the third control signal, the Boost converter boosts the residual voltage in the battery cell and charges the capacitor;

[0015] When the measurement and control module detects that the voltage across the battery cell reaches the bypass stop threshold voltage, a second control signal is sent to the bypass circuit corresponding to the battery cell;

[0016] After receiving the second control signal, the bypass circuit controls the capacitor to release current to the gate of the thyristor, and causes the thyristor to be damaged and turned on, so that the battery cell is short-circuited.

[0017] The bypass implementation method of the deteriorated battery cells in the battery module also includes:

[0018] When the measurement and control module detects that the voltage at both ends of the battery cell reaches the equalization voltage threshold, a first control signal is sent to the equalization branch corresponding to the battery cell that reaches the equalization voltage threshold;

[0019] After receiving the first control signal, the balancing branch reduces the voltage across the battery cell;

[0020] When the measurement and control module detects that the difference between the voltage across the battery cell and the voltage across the battery cell of other battery cells is within a preset range, the measurement and control module stops sending the first control signal to the balancing branch;

[0021] After the balancing branch does not receive the first control signal, the voltage at both ends of the battery cell is stopped from being reduced.

[0022] Beneficial Effects

[0023] Due to the adoption of the above-mentioned technical scheme, the present invention has the following advantages and positive effects compared with the prior art: the present invention adds a bypass part in the battery cell unit, and the bypass part utilizes the irreversible damage direct-through characteristics of the thyristor under overcurrent in the main circuit or the drive circuit. When the battery cell deteriorates, it can be completely bypassed without stopping for replacement, thereby ensuring the continuous use of the battery module. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a structural diagram of a battery module according to an embodiment of the present invention. DETAILED DESCRIPTION

[0025] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0026] An embodiment of the present invention relates to a battery module, such as Figure 1 As shown, it includes a battery module and a measurement and control module.

[0027] The battery module includes a plurality of battery cells connected in series. Each battery cell includes a battery cell and a battery cell management circuit connected in parallel with the battery cell; the battery cell management circuit includes a bypass part and a measurement and control module, the bypass part is used to short-circuit the battery cell using a thyristor when the battery cell deteriorates; the measurement and control module is used to detect the state of each battery cell and control the bypass part according to the state of the battery cell. The battery cell can be various types of batteries, including lithium iron phosphate batteries, lead-acid batteries, supercapacitors, hybrid supercapacitors, etc.

[0028] The bypass part includes a Boost converter and a bypass circuit; one input end of the Boost converter is connected to the positive electrode of the battery cell V, the other input end is connected to the negative electrode of the battery cell V, one output end of the Boost converter is connected to one end of the second control switch K2, and the other output end is connected to the negative electrode of the battery cell V; the bypass circuit is a thyristor, the thyristor is connected in parallel at both ends of the battery cell V, and the gate G of the thyristor is connected to the Boost converter through the other end of the second control switch K2. The Boost converter and the second control switch K2 are controlled by the measurement and control module. When the battery cell is deteriorated, the Boost converter starts and the second control switch K2 is closed. When the battery cell is normal, the Boost converter stops working and the second control switch is disconnected.

[0029] The Boost converter in this embodiment includes an inductor L, a diode D, a switch tube S and a capacitor C, wherein one end of the inductor L is connected to the positive electrode of the battery cell V, and the other end is connected to the positive electrode of the diode D, and the negative electrode of the diode D is connected to one end of the capacitor C; one end of the switch tube S is connected to the positive electrode of the diode D, and the other end is connected to the negative electrode of the battery cell V, and the other end of the switch tube S is also connected to the other end of the capacitor C.

[0030] The battery cell management circuit of this embodiment may further include a balancing branch connected in parallel with the battery cell V, and the balancing branch is used to reduce the voltage across the battery cell when the voltage across the battery cell reaches a balancing voltage threshold.

[0031] The balancing branch includes a first control switch K1 and a discharge resistor R connected in series; the first control switch K1 is controlled by the measurement and control module, closed when the voltage across the battery cell V exceeds a threshold value, and disconnected when the difference between the voltage across the battery cell V and the voltage across the battery cell of other battery cells is within a preset range.

[0032] The measurement and control module in this embodiment is used to detect the state of each of the battery cells and control the bypass part according to the state of the battery cells. The measurement and control module in this embodiment can detect the data of the battery cells including the voltage, current, temperature, etc. at both ends of the battery cells, and can calculate the state of charge (SOC) and health (SOH) of the single battery cells.

[0033] When the measurement and control module detects that the battery cell is in a degraded state, it controls the bypass part to work, and the measurement and control module sends a trigger signal to the Boost converter. The residual power of the degraded battery cell V will be discharged to the capacitor C through the Boost converter until the voltage across the battery cell is zero; after the boost conversion, there is a higher voltage across the capacitor C. After the measurement and control module controls the second control switch K2 to close, the capacitor C sends a very large trigger current to the gate G of the thyristor to force the thyristor to be damaged and turned on, so that the degraded battery cell is bypassed.

[0034] When the measurement and control module detects that the voltage across a certain battery cell is higher than that across other battery cells, the measurement and control module controls the first control switch K1 on the balancing branch corresponding to the battery cell to close, and the battery cell is partially discharged through the discharge resistor R. After the voltage across the battery cell is balanced with the voltage across other battery cells, the first control switch K1 on the balancing branch is controlled to open.

[0035] Below Figure 1 Taking the cell V as an example, the bypass of the cell V by the battery module is described, which includes the following steps:

[0036] Step 1, the measurement and control module performs real-time detection on the status of each battery cell;

[0037] Step 2: The measurement and control module detects that the voltage across the battery cell V reaches the bypass voltage threshold, indicating that the battery cell V is in a degraded state. At this time, the measurement and control module sends a third control signal to the Boost converter corresponding to the battery cell V;

[0038] Step 3, after receiving the third control signal, the Boost converter triggers the switch tube S to control at a certain duty cycle, boosts the residual voltage in the battery cell V, and charges the capacitor C. At this time, the residual voltage in the battery cell V gradually decreases;

[0039] Step 4, when the measurement and control module detects that the voltage across the battery cell V reaches the bypass stop threshold voltage, it means that the power of the battery cell V has been completely released. At this time, the measurement and control module sends a second control signal to the bypass circuit corresponding to the battery cell V;

[0040] Step 5, after the bypass circuit receives the second control signal, the second control switch K2 is closed, so that the capacitor C releases current to the gate G of the thyristor, and the thyristor is damaged and turned on, so that the battery cell V is short-circuited. Since the damage of the thyristor is irreversible, the battery cell V is completely bypassed.

[0041] It is worth mentioning that the balancing process and bypass control of each battery cell can be performed simultaneously under the measurement and control of the measurement and control module. The following is an illustration of the balancing process of the battery cell V, which includes the following steps:

[0042] Step 6, when the measurement and control module detects that the voltage across the battery cell V reaches the balanced voltage threshold, it means that the voltage across the battery cell V exceeds the voltage across other battery cells V. At this time, the measurement and control module sends a first control signal to the balanced branch corresponding to the battery cell that reaches the balanced voltage threshold;

[0043] Step 7: After receiving the first control signal, the balancing branch controls the first control switch K1 to close, and reduces the voltage across the battery cell V through the discharge resistor R;

[0044] Step 8, when the measurement and control module detects that the difference between the voltage across the battery cell V and the voltage across the battery cell of other battery cells is within a preset range, the measurement and control module stops sending the first control signal to the balancing branch;

[0045] Step 9: After the balancing branch does not receive the first control signal, the first control switch K1 is controlled to be disconnected, and the battery module returns to a balanced state.

[0046] It is not difficult to find that in this embodiment, the battery module can automatically adjust and maintain the balanced state through the coordination of the balancing branch and the bypass circuit, and can bypass the degraded battery cells without an external power supply; the bypass circuit uses the irreversible damage direct-through characteristics of the thyristor under the overcurrent of the main circuit or the drive circuit, so as to completely bypass the degraded battery cells without stopping for replacement. This embodiment not only effectively utilizes the residual power of the degraded battery cells to damage and conduct the thyristor in the bypass circuit, preventing the degraded battery cells from short-circuiting and causing thermal runaway and other accidents, but also completely bypasses the degraded battery cells to maintain the normal operation of the battery module.

Claims

1. A battery module, characterized in that: include: A battery module comprises a plurality of battery cells connected in series; the battery cells comprise a battery cell and a battery cell management circuit connected in parallel with the battery cell; The cell management circuit includes a bypass part and a measurement and control module; The bypass part is used to short-circuit the battery cell using a thyristor when the battery cell is deteriorated; the measurement and control module is used to detect the state of each battery cell and control the bypass part according to the state of the battery cell.

2. The battery module according to claim 1, characterized in that: The bypass part includes a Boost converter and a bypass circuit; one input end of the Boost converter is connected to the positive electrode of the battery cell, and the other input end is connected to the negative electrode of the battery cell; one output end of the Boost converter is connected to one end of the second control switch, and the other output end is connected to the negative electrode of the battery cell; the bypass circuit is a thyristor, the thyristor is connected in parallel at both ends of the battery cell, and the gate of the thyristor is connected to the Boost converter through the other end of the second control switch; the Boost converter and the second control switch are controlled by the measurement and control module, when the battery cell is deteriorated, the Boost converter is started and the second control switch is closed, and when the battery cell is normal, the Boost converter stops working and the second control switch is disconnected.

3. The battery module according to claim 2, characterized in that: The Boost converter includes an inductor, a diode, a switch tube and a capacitor, wherein one end of the inductor is connected to the positive electrode of the battery cell, the other end is connected to the positive electrode of the diode, and the negative electrode of the diode is connected to one end of the capacitor; one end of the switch tube is connected to the positive electrode of the diode, the other end is connected to the negative electrode of the battery cell, and the other end of the switch tube is also connected to the other end of the capacitor.

4. The battery module according to claim 1, characterized in that: The cell management circuit further includes a balancing branch connected in parallel with the cell monomer, and the balancing branch is used to reduce the voltage across the cell monomer when the voltage across the cell monomer reaches a balancing voltage threshold.

5. The battery module according to claim 4, characterized in that: The balancing branch includes a first control switch and a discharge resistor connected in series; the first control switch is controlled by the measurement and control module, closed when the voltage across the battery cell exceeds a threshold value, and disconnected when the difference between the voltage across the battery cell and the voltage across the battery cell of other battery cells is within a preset range.

6. A method for bypassing deteriorated cells in a battery module as claimed in any one of claims 1 to 5, characterized in that: The following steps are involved: The measurement and control module performs real-time detection on the status of each battery cell; When the measurement and control module detects that the voltage across the battery cell reaches the bypass voltage threshold, a third control signal is sent to the Boost converter corresponding to the battery cell that reaches the bypass voltage threshold; After receiving the third control signal, the Boost converter boosts the residual voltage in the battery cell and charges the capacitor; When the measurement and control module detects that the voltage across the battery cell reaches the bypass stop threshold voltage, a second control signal is sent to the bypass circuit corresponding to the battery cell; After receiving the second control signal, the bypass circuit controls the capacitor to release current to the gate of the thyristor, and causes the thyristor to be damaged and turned on, so that the battery cell is short-circuited.

7. The bypass implementation method according to claim 6, characterized in that: Also includes: When the measurement and control module detects that the voltage at both ends of the battery cell reaches the equalization voltage threshold, a first control signal is sent to the equalization branch corresponding to the battery cell that reaches the equalization voltage threshold; After receiving the first control signal, the balancing branch reduces the voltage across the battery cell; When the measurement and control module detects that the difference between the voltage across the battery cell and the voltage across the battery cell of other battery cells is within a preset range, the measurement and control module stops sending the first control signal to the balancing branch; After the balancing branch does not receive the first control signal, the voltage at both ends of the battery cell is stopped from being reduced.

Images