A bidirectional active balancing method and apparatus for energy storage batteries

Abstract

This application discloses a bidirectional active balancing method and apparatus for energy storage batteries. The battery sampling circuit collects the voltage values ​​of all individual cells in the battery pack in real time. The battery sampling circuit transmits the signal to the main controller through an isolation circuit, and the DC switching power supply supplies power to the main controller. When the voltage value of an individual cell does not exceed the active balancing start threshold, the active balancing function is not activated. If the voltage value of the nth individual cell exceeds the active balancing start threshold, the main controller sends a control signal to drive the fully isolated sector control circuit to connect the bidirectional active balancing circuit to the nth individual cell, and performs active balancing on the nth individual cell. When the voltage value of the nth individual cell is lower than the active balancing start threshold, the main controller sends a control signal to disconnect the fully isolated sector control circuit and the bidirectional active balancing circuit, so that the battery pack is completely isolated from the bidirectional active balancing device circuit, the active balancing function is completed, and the active balancing ends.

Description

Technical Field

[0001] This application belongs to the field of energy storage battery technology, specifically relating to a bidirectional active balancing method and apparatus for energy storage batteries. Background Technology

[0002] In recent years, my country has been vigorously promoting the development of new energy, with energy storage being one of the key areas of focus. Currently, energy storage can be subdivided into large-scale storage, industrial and commercial storage, and residential storage, with lithium batteries and sodium batteries accounting for over 99% of the entire energy storage battery market. Due to the variability in battery manufacturing materials and processes, even batteries from the same manufacturer, model, and batch will not be identical in capacity and internal resistance parameters. Currently, battery packs used in energy storage projects are primarily composed of series-connected cells. If a single cell has a voltage of 3.6V, then 416 cells need to be connected in series to operate on a 1500V platform. If each battery pack consists of 52 cells, eight battery packs are required. During use, the temperature of cells in the middle of a battery pack will inevitably be higher than that of the surrounding cells. After a period of cycling, this difference will become apparent, resulting in varying voltages at the end of charging and discharging. This can cause the entire system to be incompletely charged or discharged, effectively reducing its capacity and leading to significant economic losses.

[0003] There are two types of energy storage battery balancing technologies: passive balancing and active balancing. Passive balancing can only solve the problem of excessively high voltage in a single battery cell, while active balancing can solve both excessively high and excessively low voltage in a single battery cell. Active balancing includes the following structure:

[0004] (1) Active balancing structure based on multi-winding transformer (bidirectional flyback type):

[0005] Transformers have many windings, complex designs, high costs, and large sizes.

[0006] Transformers have many windings and complex designs. If a planar transformer is designed under the constraints of existing PCB board installation and space, the cost will be very high. If a regular transformer is used, the volume will be very large with multiple windings, and installation and use will become difficult. This makes the design solution a dilemma.

[0007] like Figure 3As shown, the principle of energy storage in a transformer when the switching transistor is on and energy release when it is off is utilized to achieve bidirectional energy flow between the DC switching power supply and individual battery cells. The multi-winding transformer is the key component. The primary winding is connected to the DC switching power supply, and each secondary winding is connected to its corresponding individual battery cell. When the nth battery cell needs charging, the PWM0 signal controls the primary-side MOSFET to adjust the switching frequency, causing the primary winding of the transformer to store energy. The PWMn signal controls the MOSFET corresponding to the nth battery cell, causing the secondary winding connected to the nth battery cell to release energy, thus charging the nth battery cell. When the mth battery cell needs discharging, the PWMm signal controls the secondary-side MOSFET to adjust the switching frequency, causing the secondary winding of the transformer to store energy. The PWM0 signal controls the MOSFET corresponding to the DC switching power supply, causing the primary winding to release energy, thus discharging the mth battery cell.

[0008] (2) Based on the active equalization structure of the switching matrix:

[0009] A switch matrix is ​​a switching array composed of MOSFETs. The number of MOSFETs varies with the number of switching channels, calculated as 2 x (N + 1) + 4, where N is the number of channels. In other words, the more channels, the more MOSFETs are needed. For example, a typical front-end acquisition chip acquiring 16 voltage channels requires 38 MOSFETs. A 64-cell battery would require 152 MOSFETs, a very large number, increasing both the cost of the MOSFETs and the PCB area. Furthermore, MOSFETs are responsible for closing and opening the positive and negative terminals of individual cells, acting as a switch, but not in a traditional theoretical physical way. Instead, they open based on the characteristics of the PN junction. If the PN junction of the MOSFET breaks down, a serious short circuit will occur, with potentially disastrous consequences.

[0010] like Figure 4 As shown, a MOSFET switching matrix circuit is used to connect bidirectional DC-DC power supplies to individual cells requiring equalization according to logical relationships. The battery switching matrix control circuit includes a drive voltage and a matrix switch composed of MOSFETs Q1, Q2, Q3, and Q4. The output voltage of the corresponding individual cell's drive circuit controls the closing of MOSFETs Q1, Q2, Q3, and Q4, allowing the individual cell to be connected to the active equalization circuit for equalization. For example, when it is desired that cell #1 is closed, the output voltage of GA1 corresponding to the battery-side monitoring circuit controls the closing of MOSFETs Q1, Q2, Q3, and Q4, selecting cell #1 to be connected to the equalization loop. Similarly, cell #2 corresponds to GA2, and cell #12 corresponds to GA12.

[0011] Therefore, the active balancing products currently on the market are not yet perfect. Their complex technology, high cost, low safety, high failure rate, and large size make it difficult to apply them on a large scale in energy storage projects, which greatly restricts the development of my country's new energy industry. Summary of the Invention

[0012] The purpose of this application is to address the problems of the prior art by providing a bidirectional active balancing method and apparatus for energy storage batteries.

[0013] To solve the technical problem, the technical solution of this application is: a bidirectional active balancing device for energy storage batteries, comprising a DC switching power supply, a main controller, a bidirectional active balancing circuit, a battery sampling circuit, an isolation circuit, and a fully isolated sector control circuit. The battery sampling circuit receives signals from all individual cells in the battery pack, the isolation circuit receives signals from the battery sampling circuit, the main controller receives signals from the isolation circuit, the DC switching power supply is connected to the main controller to supply power, the main controller sends control signals to the bidirectional active balancing circuit and the fully isolated sector control circuit respectively, the DC switching power supply is bidirectionally electrically connected to the bidirectional active balancing circuit, the bidirectional active balancing circuit is bidirectionally electrically connected to the fully isolated sector control circuit, and the fully isolated sector control circuit is electrically connected to all individual cells in the battery pack respectively.

[0014] Preferably, the fully isolated sector control circuit includes multiple relay groups, each including relay S1, relay S2 and relay S3. Relay S1 is connected to a bidirectional active equalization circuit, and relay S1 is also connected to relay S2 and relay S3 respectively. Relay S2 is connected to the first single cell and the second single cell respectively, and relay S3 is connected to the third single cell and the fourth single cell respectively.

[0015] Preferably, the Ui+ and Ui- of the relay group are respectively connected to the output terminal of the bidirectional active equalization circuit, the Ui+ of the relay group is connected to the contact S1a of the relay S1, and the Ui- of the relay group is connected to the contact S1x of the relay S1.

[0016] Preferably, the contact S1b of relay S1 is connected to the contact S2a of relay S2, the contact S1c of relay S1 is connected to the contact S3a of relay S3, the contact S1y of relay S1 is connected to the contact S2x of relay S2, and the contact S1z of relay S1 is connected to the contact S3x of relay S3.

[0017] The contact S2b of the relay S2 is connected to the positive terminal of the first single cell, the negative terminal of the first single cell is connected to the contacts S2c and S2y of the relay S2, the contact S2y of the relay S2 is connected to the positive terminal of the second single cell, and the negative terminal of the second single cell is connected to the contacts S2z of the relay S2 and the contacts S3b of the relay S3.

[0018] The contact S3b of relay S3 is connected to the positive terminal of the third single cell, the negative terminal of the third single cell is connected to the contacts S3c and S3y of relay S3, the contact S3y of relay S3 is connected to the positive terminal of the fourth single cell, and the negative terminal of the fourth single cell is connected to the contact S3z of relay S3.

[0019] Preferably, the DC switching power supply is a DC-DC power supply.

[0020] Preferably, the main controller is an ARM core microprocessor and its resistor-capacitor network.

[0021] Preferably, the transformer of the bidirectional active balancing circuit has only one set of windings on the primary and secondary sides respectively.

[0022] Preferably, the battery sampling circuit is a battery voltage sampling chip AFE and its resistor-capacitor network.

[0023] Preferably, the isolation circuit is a serial or parallel communication isolation chip and its resistor-capacitor network.

[0024] Preferably, a bidirectional active balancing method for energy storage batteries is characterized by: including the aforementioned bidirectional active balancing device for energy storage batteries; the battery sampling circuit collects the voltage values ​​of all individual cells in the battery pack in real time; the battery sampling circuit transmits the signal to the main controller through an isolation circuit; and a DC switching power supply supplies power to the main controller; when the voltage value of an individual cell does not exceed the active balancing start threshold, the active balancing function is not activated; if the voltage value of the nth individual cell exceeds the active balancing start threshold, the main controller sends a control signal to drive the fully isolated sector control circuit to connect the bidirectional active balancing circuit to the nth individual cell, performing active balancing on the nth individual cell; when the voltage value of the nth individual cell is lower than the active balancing start threshold, the main controller sends a control signal to disconnect the fully isolated sector control circuit and the bidirectional active balancing circuit, completely isolating the battery pack from the bidirectional active balancing device circuit, completing the active balancing function, and ending the active balancing process.

[0025] Preferably, the drive signals of relays S1, S2 and S3 are signal G1, signal G2 and signal G3 respectively, and the three relays realize the bidirectional active equalization and matching function of four individual batteries.

[0026] When the first single cell needs to be balanced, signal G1 does not send a closing signal, relay S1 does not operate, and relay S1 is in a normally closed state. Signal G2 does not send a closing signal, relay S2 does not operate, and relay S2 is in a normally closed state. Signal G3 does not send a closing signal, relay S3 does not operate, and relay S3 is in a normally closed state. Current flows through contact S1a to contact S1b to contact S2a to contact S2b to the first single cell to contact S2y to contact S2x to contact S1y to contact S1x, completing the bidirectional active balancing and matching function of the first single cell.

[0027] When the second cell needs to be balanced, signal G1 does not send a closing signal, relay S1 does not operate and is in a normally closed state. Signal G2 sends a closing signal, relay S2 operates and is in a normally open state. Signal G3 does not send a closing signal, relay S3 does not operate and is in a normally closed state. Current flows through contact S1a to contact S1b to contact S2a to contact S2c to the second cell to contact S2z to contact S2x to contact S1y to contact S1x, completing the bidirectional active balancing and matching function of the second cell.

[0028] When the third cell needs to be balanced, signal G1 sends a closed signal, relay S1 operates, and relay S1 is in the normally open state. Signal G2 does not send a closed signal, relay S2 does not operate, and relay S2 is in the normally closed state. Signal G3 does not send a closed signal, relay S3 does not operate, and relay S3 is in the normally closed state. Current flows through contact S1a to contact S1c to contact S3a to contact S3b to the third cell to contact S3y to contact S3x to contact S1z to contact S1x, completing the bidirectional active balancing and matching function of the third cell.

[0029] When the fourth cell needs to be balanced, signal G1 sends a closed signal, relay S1 operates, and relay S1 is in the normally open state. Signal G2 does not send a closed signal, relay S2 does not operate, and relay S2 is in the normally closed state. Signal G3 sends a closed signal, relay S3 operates, and relay S3 is in the normally open state. Current flows through contact S1a to contact S1c to contact S3a to contact S3c to the fourth cell to contact S3z to contact S3x to contact S1z to contact S1x, completing the bidirectional active balancing function of the fourth cell.

[0030] Compared with the prior art, the advantages of this application are:

[0031] (1) This application proposes a bidirectional active balancing method and device for energy storage batteries. The battery sampling circuit collects the voltage values ​​of all individual cells in the current battery pack in real time. If the voltage value of an individual cell does not exceed the active balancing start threshold, the active balancing function is not activated. If the voltage value of the nth individual cell exceeds the active balancing start threshold, the main controller sends a control signal to drive the fully isolated fan-shaped control circuit to connect the bidirectional active balancing circuit to the nth individual cell and perform active balancing on the nth individual cell. When the voltage value of the individual cell is less than the active balancing start threshold, the main controller sends a control signal to disconnect the fully isolated fan-shaped control circuit and the bidirectional active balancing circuit, so that the battery pack is completely isolated from the bidirectional active balancing device circuit of this application, the active balancing function is completed, and the active balancing ends.

[0032] (2) This application controls the bidirectional active equalization circuit through a fully isolated sector control circuit, achieving low cost and small size, and especially significantly improving reliability. This application can ensure that even if the channel switching is wrong, it will not cause a short circuit accident in a single cell.

[0033] (3) The transformer of the bidirectional active balancing circuit used in this application has only one set of windings on the primary and secondary sides, which can reduce the volume by nearly 10 times and the price by 15 times, thus promoting the miniaturization of active balancing products and increasing the customer's acceptance of the cost of use.

[0034] (4) The fully isolated sector control circuit used in this application contains multiple relay groups, each relay group includes 3 relays, which can be selected to be 4 single cells. So, 16 single cells only require 12 relays, and one slave control of 4 16 single cells only requires 48 relays. This greatly reduces the number of components and the area occupied on the PCB board, and the cost can be reduced by more than 2 times.

[0035] (5) The relay in the fully isolated sector control circuit used in this application has a completely physical disconnection characteristic and there is no possibility of being short-circuited by breakdown. Furthermore, by incorporating the design concept of a binary tree, there is no possibility of the relay switching error causing a short circuit in a single battery. Therefore, this application has achieved great improvement in terms of size, cost, and safety. Attached Figure Description

[0036] Figure 1 This is a circuit diagram of a bidirectional active balancing method and device for energy storage batteries according to this application;

[0037] Figure 2 This is a circuit diagram of the fully isolated sector control circuit of this application;

[0038] Figure 3This is a schematic diagram of an existing active balancing structure based on a multi-winding transformer (bidirectional flyback type);

[0039] Figure 4 This is a schematic diagram of an existing circuit based on a switch matrix active equalization structure.

[0040] Explanation of reference numerals in the attached figures:

[0041] 1. DC switching power supply; 2. Main controller; 3. Bidirectional active balancing circuit; 4. Battery sampling circuit; 5. Isolation circuit; 6. Fully isolated sector control circuit; 7. Battery pack.

[0042] 7-1, First single cell; 7-2, Second single cell; 7-3, Third single cell; 7-4, Fourth single cell. Detailed Implementation

[0043] The present application is described in detail below with reference to the accompanying drawings and specific embodiments, but the present application is not limited to these embodiments. The present application covers any alternatives, modifications, equivalent methods, and solutions made within the spirit and scope of the present application. To provide the public with a thorough understanding of the present application, specific details are described in detail in the following embodiments, but those skilled in the art will fully understand the present application even without these detailed descriptions.

[0044] This application analyzes the active balancing of multi-winding transformers (bidirectional flyback type) and active balancing of switching matrix, identifies their main shortcomings, conducts in-depth research, solves their main shortcomings, and improves them.

[0045] Example 1

[0046] like Figure 1 As shown, this application discloses a bidirectional active balancing device for energy storage batteries, including a DC switching power supply 1, a main controller 2, a bidirectional active balancing circuit 3, a battery sampling circuit 4, an isolation circuit 5, and a fully isolated sector control circuit 6. The battery sampling circuit 4 receives signals from all individual cells in the battery pack 7, the isolation circuit 5 receives signals from the battery sampling circuit 4, and the main controller 2 receives signals from the isolation circuit 5. The DC switching power supply 1 is connected to the main controller 2 to supply power to the main controller 2. The main controller 2 sends control signals to the bidirectional active balancing circuit 3 and the fully isolated sector control circuit 6, respectively. The DC switching power supply 1 is bidirectionally electrically connected to the bidirectional active balancing circuit 3, and the bidirectional active balancing circuit 3 is bidirectionally electrically connected to the fully isolated sector control circuit 6. The fully isolated sector control circuit 6 is electrically connected to all individual cells in the battery pack 7.

[0047] Example 2

[0048] Preferred, such as Figure 2As shown, the fully isolated sector control circuit 6 includes multiple relay groups, each including relay S1, relay S2 and relay S3. Relay S1 is connected to the bidirectional active equalization circuit 3. Relay S1 is also connected to relay S2 and relay S3. Relay S2 is connected to the first single cell 7-1 and the second single cell 7-2. Relay S3 is connected to the third single cell 7-3 and the fourth single cell 7-4.

[0049] Preferred, such as Figure 2 As shown, Ui+ and Ui- of the relay group are respectively connected to the output terminal of the bidirectional active equalization circuit 3, Ui+ of the relay group is connected to the contact S1a of the relay S1, and Ui- of the relay group is connected to the contact S1x of the relay S1.

[0050] The contact S1b of relay S1 is connected to the contact S2a of relay S2, the contact S1c of relay S1 is connected to the contact S3a of relay S3, the contact S1y of relay S1 is connected to the contact S2x of relay S2, and the contact S1z of relay S1 is connected to the contact S3x of relay S3.

[0051] The contact S2b of relay S2 is connected to the positive terminal of the first single cell 7-1, the negative terminal of the first single cell 7-1 is connected to the contact S2c and contact S2y of relay S2, the contact S2y of relay S2 is connected to the positive terminal of the second single cell 7-2, and the negative terminal of the second single cell 7-2 is connected to the contact S2z of relay S2 and the contact S3b of relay S3.

[0052] The contact S3b of relay S3 is connected to the positive terminal of the third single cell 7-3. The negative terminal of the third single cell 7-3 is connected to the contacts S3c and S3y of relay S3. The contact S3y of relay S3 is connected to the positive terminal of the fourth single cell 7-4. The negative terminal of the fourth single cell 7-4 is connected to the contact S3z of relay S3.

[0053] Example 3

[0054] Preferably, the DC switching power supply 1 is a DC-DC power supply.

[0055] Preferably, the main controller 2 is an ARM core microprocessor and its resistor-capacitor network.

[0056] Preferably, the transformer of the bidirectional active balancing circuit 3 has only one set of windings on the primary and secondary sides respectively.

[0057] The bidirectional active balancing circuit is a power electronic device that enables bidirectional flow of electrical energy. It can act as a power source to supply power to the load or as a load to absorb electrical energy. It can dynamically adjust the voltage polarity or current direction according to needs to achieve flexible energy scheduling.

[0058] According to the existing technology, each secondary winding should be connected to one battery. If there are 16 individual batteries, then there would be 16 secondary windings. The problem solved by the fully isolated sector control circuit 6 is that one secondary winding is connected to 16 individual batteries in different time periods by means of relay switching. This reduces the number of windings required to one.

[0059] Preferably, the battery sampling circuit 4 is a battery voltage sampling chip AFE and its resistor-capacitor network.

[0060] Preferably, the isolation circuit 5 is a serial or parallel communication isolation chip and its resistor-capacitor network.

[0061] Example 4

[0062] Preferred, such as Figure 1 As shown, this application discloses a bidirectional active balancing method for energy storage batteries, including the aforementioned bidirectional active balancing device for energy storage batteries. The battery sampling circuit 4 collects the voltage values ​​of all individual cells in the battery pack 7 in real time. The battery sampling circuit 4 transmits the signal to the main controller 2 through the isolation circuit 5, and the DC switching power supply 1 supplies power to the main controller 2. When the voltage value of an individual cell does not exceed the active balancing start threshold, the active balancing function is not activated. If the voltage value of the nth individual cell exceeds the active balancing start threshold, the main controller 2 sends a control signal to drive the fully isolated sector control circuit 6 to connect the bidirectional active balancing circuit 3 to the nth individual cell, and performs active balancing on the nth individual cell. When the voltage value of the nth individual cell is lower than the active balancing start threshold, the main controller 2 sends a control signal to disconnect the fully isolated sector control circuit 6 and the bidirectional active balancing circuit 3, so that the battery pack 7 is completely isolated from the bidirectional active balancing device circuit, the active balancing function is completed, and the active balancing ends.

[0063] Preferred, such as Figure 2 As shown, the drive signals for relays S1, S2, and S3 are signals G1, G2, and G3, respectively. The three relays realize the bidirectional active balancing and matching function of four individual batteries.

[0064] When the first single cell 7-1 needs to be balanced, signal G1 does not send a closing signal, relay S1 does not operate, and relay S1 is in a normally closed state. Signal G2 does not send a closing signal, relay S2 does not operate, and relay S2 is in a normally closed state. Signal G3 does not send a closing signal, relay S3 does not operate, and relay S3 is in a normally closed state. Current flows through contact S1a to contact S1b to contact S2a to contact S2b to the first single cell 7-1 to contact S2y to contact S2x to contact S1y to contact S1x, completing the bidirectional active balancing and matching function of the first single cell 7-1.

[0065] When the second cell 7-2 needs to be balanced, signal G1 does not send a closing signal, relay S1 does not operate and is in a normally closed state. Signal G2 sends a closing signal, relay S2 operates and is in a normally open state. Signal G3 does not send a closing signal, relay S3 does not operate and is in a normally closed state. Current flows through contact S1a to contact S1b to contact S2a to contact S2c to the second cell 7-2 to contact S2z to contact S2x to contact S1y to contact S1x, completing the bidirectional active balancing and matching function of the second cell 7-2.

[0066] When the third cell 7-3 needs to be balanced, signal G1 sends a closing signal, relay S1 operates, and relay S1 is in the normally open state. Signal G2 does not send a closing signal, relay S2 does not operate, and relay S2 is in the normally closed state. Signal G3 does not send a closing signal, relay S3 does not operate, and relay S3 is in the normally closed state. Current flows through contact S1a to contact S1c to contact S3a to contact S3b to the third cell 7-3 to contact S3y to contact S3x to contact S1z to contact S1x, completing the bidirectional active balancing and matching function of the third cell 7-3.

[0067] When the fourth cell 7-4 needs to be balanced, signal G1 sends a closed signal, relay S1 operates, and relay S1 is in the normally open state. Signal G2 does not send a closed signal, relay S2 does not operate, and relay S2 is in the normally closed state. Signal G3 sends a closed signal, relay S3 operates, and relay S3 is in the normally open state. Current flows through contact S1a to contact S1c to contact S3a to contact S3c to the fourth cell 7-4 to contact S3z to contact S3x to contact S1z to contact S1x, completing the bidirectional active balancing function of the fourth cell 7-4.

[0068] The implementation method of the fully isolated sector control circuit is as follows:

[0069] like Figure 2As shown, the Ui+ and Ui- of the fully isolated sector control circuit 6 are connected to the output of the bidirectional active balancing circuit 3. Three relays S1, S2, and S3 implement the bidirectional active balancing function for four individual cells: cell1, cell2, cell3, and cell4. The drive signals for the three relays S1, S2, and S3 are signals G1, G2, and G3, respectively. For example, when cell1 needs balancing, signal G1 does not send a closing signal, so relay S1 does not operate and remains normally closed. Similarly, signal G2 does not send a closing signal, so relay S2 does not operate and remains normally closed. And when signal G3 does not send a closing signal, relay S3 does not operate and remains normally closed. Current flows through S1a to S1b to S2a to S2b to cell1 to S2y to S2x to S1y to S1x, completing the balancing function for cell1. For example, when cell 2 requires equalization, signal G1 does not send a closing signal, relay S1 does not operate, and relay S1 remains normally closed. Signal G2 sends a closing signal, relay S2 operates, and relay S2 remains normally open. Signal G3 does not send a closing signal, relay S3 does not operate, and relay S3 remains normally closed. Current flows through S1a to S1b to S2a to S2c to cell 2 to S2z to S2x to S1y to S1x, completing the equalization function for cell 2. Other cell equalization methods follow the same logic.

[0070] The fully isolated sector control circuit 6 is developed based on a binary tree data structure. Each node has at most two child nodes, called the left child node and the right child node, respectively. Therefore, no matter if the relay malfunctions, is damaged, or has a logic error, it will never cause a short circuit fault in a single battery. Moreover, only 3 small relays are needed for every 4 single batteries, which greatly reduces the PCB area and greatly promotes the mass application of active balancing in the market.

[0071] Application Example 1:

[0072] Existing technology uses multi-winding transformers to achieve active balancing. The disadvantages are that there are many windings, large size, high price, and large space occupation, which cannot make the product miniaturized and thus the price is high.

[0073] The transformer of the bidirectional active balancing circuit 3 used in this application has only one set of windings on the primary and secondary sides, which can reduce the size by nearly 10 times and the price by 15 times, thus promoting the miniaturization of active balancing products and increasing customers' acceptance of usage costs.

[0074] Application Example 2:

[0075] Existing matrix switch circuit solutions are based on a switch matrix composed of a large number of MOSFETs. The formula for calculating the number of MOSFETs is 2 x (N + 1) + 4. Based on 16 individual cells, this requires 38 MOSFETs. Since one slave switch consists of four 16-cell cells, the total number of MOSFETs is 152. This results in high MOSFET costs, and 152 MOSFETs occupy a significant amount of PCB board space, becoming a burden in terms of both cost and product size. Furthermore, the MOSFET matrix switch is directly connected to the individual cells, lacking true physical isolation. Therefore, if a MOSFET fails, it can cause a short circuit in the battery.

[0076] The fully isolated sector control circuit 6 used in this application controls the bidirectional active balancing circuit 3, which includes relays. Three relays can be selected to control up to four individual batteries, so only 12 relays are needed for 16 individual batteries. One slave control of four 16 individual batteries requires only 48 relays, which greatly reduces the number of components and the area occupied on the PCB board, reducing the cost by more than 2 times. The relays in this application have a completely physical disconnection characteristic, so there is no possibility of being short-circuited by breakdown. In addition, the design concept of binary tree makes it impossible for the relay to cause a short circuit in an individual battery due to switching error. Therefore, the design of this application has achieved great improvement in terms of size, cost, and safety.

[0077] The principle behind this application is as follows:

[0078] This application includes a DC switching power supply 1, a main controller 2, a bidirectional active balancing circuit 3, a battery sampling circuit 4, an isolation circuit 5, and a fully isolated sector control circuit 6. The battery sampling circuit 4 collects the voltage values ​​of all individual cells in the current battery pack 7 in real time. If the voltage value of an individual cell does not exceed the active balancing start threshold, the active balancing function is not activated. If the voltage value of the nth individual cell exceeds the active balancing start threshold, the main controller 2 sends a control signal to drive the fully isolated sector control circuit 6 to connect the bidirectional active balancing circuit 3 to the nth individual cell, and performs active balancing on the nth individual cell. When the voltage of the individual cell is less than the active balancing start threshold, the main controller 2 sends a control signal to disconnect the fully isolated sector control circuit 6 and the bidirectional active balancing circuit 3, so that the battery pack 7 is completely isolated from the bidirectional active balancing device circuit of this application, the active balancing function is completed, and the active balancing ends.

[0079] The preferred embodiments of this application have been described in detail above. However, this application is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of this application.

[0080] Many other changes and modifications can be made without departing from the concept and scope of this application. It should be understood that this application is not limited to the specific embodiments, and the scope of this application is defined by the appended claims.

Claims

1. A bidirectional active equalization device for energy storage batteries, characterized by: The application relates to a battery pack control system, which comprises a direct-current switching power supply (1), a main controller (2), a bidirectional active equalization circuit (3), a battery sampling circuit (4), an isolation circuit (5) and a completely isolated sector control circuit (6), wherein the battery sampling circuit (4) receives signals of all single batteries in a battery pack (7), the isolation circuit (5) receives signals of the battery sampling circuit (4), the main controller (2) receives signals of the isolation circuit (5), the direct-current switching power supply (1) is connected with the main controller (2) to supply power for the main controller (2), the main controller (2) sends control signals to the bidirectional active equalization circuit (3) and the completely isolated sector control circuit (6) respectively, the direct-current switching power supply (1) is bidirectionally connected with the bidirectional active equalization circuit (3), the bidirectional active equalization circuit (3) is bidirectionally connected with the completely isolated sector control circuit (6), and the completely isolated sector control circuit (6) is connected with all single batteries in the battery pack (7) respectively. The bidirectional active equalization circuit (3) is a power electronic device for realizing bidirectional flow of electric energy, dynamically adjusting voltage polarity or current direction according to requirements, and realizing flexible scheduling of energy, and only one set of windings is arranged on the primary side and the secondary side of the transformer of the bidirectional active equalization circuit (3). The isolation circuit (5) is a serial or parallel communication isolation chip and a resistance-capacitance network thereof. The completely isolated sector control circuit (6) comprises a plurality of relay groups, the relay group comprises a relay S1, a relay S2 and a relay S3, the relay S1 is connected with the bidirectional active equalization circuit (3), the relay S1 is further connected with the relay S2 and the relay S3 respectively, the relay S2 is connected with a first single battery (7-1) and a second single battery (7-2) respectively, and the relay S3 is connected with a third single battery (7-3) and a fourth single battery (7-4) respectively. Ui+ and Ui- of the relay group are connected to output ends of the bidirectional active equalization circuit (3), Ui+ of the relay group is connected with a contact S1a of the relay S1, and Ui- of the relay group is connected with a contact S1x of the relay S1. A contact S1b of the relay S1 is connected with a contact S2a of the relay S2, a contact S1c of the relay S1 is connected with a contact S3a of the relay S3, a contact S1y of the relay S1 is connected with a contact S2x of the relay S2, and a contact S1z of the relay S1 is connected with a contact S3x of the relay S3. A contact S2b of the relay S2 is connected with a positive electrode of the first single battery (7-1), a negative electrode of the first single battery (7-1) is connected with a contact S2c and a contact S2y of the relay S2, a contact S2y of the relay S2 is connected with a positive electrode of the second single battery (7-2), a negative electrode of the second single battery (7-2) is connected with a contact S2z of the relay S2 and a contact S3b of the relay S3. The contact S3b of the relay S3 is connected to the positive pole of the third monomer battery (7-3), the negative pole of the third monomer battery (7-3) is connected to the contact S3c and the contact S3y of the relay S3, the contact S3y of the relay S3 is connected to the positive pole of the fourth monomer battery (7-4), and the negative pole of the fourth monomer battery (7-4) is connected to the contact S3z of the relay S3.

2. The bidirectional active balancing device for energy storage batteries of claim 1, wherein: The direct-current switching power supply (1) is a DC-DC power supply.

3. The bidirectional active balancing device for energy storage batteries of claim 1, wherein: The main controller (2) is an ARM core microprocessor and its resistance-capacitance network.

4. The bidirectional active balancing device for energy storage batteries of claim 1, wherein: The battery sampling circuit (4) is a battery voltage sampling chip AFE and its resistance-capacitance network.

5. A bidirectional active balancing method for energy storage batteries, characterized in that: The battery sampling circuit (4) collects the voltage values of all monomer batteries in the battery pack (7) in real time, transmits the signal to the main controller (2) through the isolation circuit (5), and the direct-current switching power supply (1) supplies power to the main controller (2); if the voltage value of the nth monomer battery does not exceed the active balancing starting threshold, the active balancing function is not started; if the voltage value of the nth monomer battery exceeds the active balancing starting threshold, the main controller (2) sends a control signal to drive the completely isolated sector control circuit (6) to connect the bidirectional active balancing circuit (3) to the nth monomer battery, and the nth monomer battery is actively balanced; when the voltage value of the nth monomer battery is lower than the active balancing starting threshold, the main controller (2) sends a control signal to disconnect the completely isolated sector control circuit (6) and the bidirectional active balancing circuit (3), so that the battery pack (7) is completely isolated from the bidirectional active balancing device circuit, the active balancing function is completed, and the active balancing is ended.

6. The bidirectional active balancing method for energy storage batteries of claim 5, wherein: The driving signals of the relays S1, S2 and S3 are signals G1, G2 and G3 respectively, and the three relays realize the bidirectional active balancing selection function of the four monomer batteries; When the first monomer battery (7-1) needs to be balanced, the signal G1 does not send a closing signal, the relay S1 does not act, the relay S1 is in a normally closed state, the signal G2 does not send a closing signal, the relay S2 does not act, the relay S2 is in a normally closed state, the signal G3 does not send a closing signal, the relay S3 does not act, the relay S3 is in a normally closed state, and the current passes through the contacts S1a to S1b to S2a to S2b to the first monomer battery (7-1) to the contacts S2y to S2x to S1y to S1x, thereby completing the bidirectional active balancing selection function of the first monomer battery (7-1). When the second monomer battery (7-2) needs to be balanced, the signal G1 does not send a closing signal, the relay S1 does not act, the relay S1 is in the normally closed state, the signal G2 sends a closing signal, the relay S2 acts, the relay S2 is in the normally open state, the signal G3 does not send a closing signal, the relay S3 does not act, the relay S3 is in the normally closed state, the current passes through the contact S1a to the contact S1b to the contact S2a to the contact S2c to the second monomer battery (7-2) to the contact S2z to the contact S2x to the contact S1y to the contact S1x, complete the bidirectional active balancing option function for the second monomer battery (7-2); When the third monomer battery (7-3) needs to be balanced, the signal G1 sends a closing signal, the relay S1 acts, the relay S1 is in the normally open state, the signal G2 does not send a closing signal, the relay S2 does not act, the relay S2 is in the normally closed state, the signal G3 does not send a closing signal, the relay S3 does not act, the relay S3 is in the normally closed state, the current passes through the contact S1a to the contact S1c to the contact S3a to the contact S3b to the third monomer battery (7-3) to the contact S3y to the contact S3x to the contact S1z to the contact S1x, complete the bidirectional active balancing option function for the third monomer battery (7-3); When the fourth monomer battery (7-4) needs to be balanced, the signal G1 sends a closing signal, the relay S1 acts, the relay S1 is in the normally open state, the signal G2 does not send a closing signal, the relay S2 does not act, the relay S2 is in the normally closed state, the signal G3 sends a closing signal, the relay S3 acts, the relay S3 is in the normally open state, the current passes through the contact S1a to the contact S1c to the contact S3a to the contact S3c to the fourth monomer battery (7-4) to the contact S3z to the contact S3x to the contact S1z to the contact S1x, complete the bidirectional active balancing option function for the fourth monomer battery (7-4).

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