A battery active equalization device suitable for lithium battery pack

Abstract

The application provides a battery active equalization device suitable for a lithium battery pack. The device comprises a lithium ion power battery module and a charge-discharge equalization circuit, wherein the lithium ion power battery module can be composed of a single battery monomer or a plurality of battery monomers connected in series or in series-parallel; the charge-discharge equalization circuit is composed of IGBT (containing an anti-parallel continuous current diode) and corresponding wires, the equalization device can realize energy equalization in the charge-discharge process, energy equalization in the idle state and other functions, and has the advantages of low equalization loss, small heat generation, fast equalization speed, flexible equalization mode and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electric vehicles, in particular to a power battery energy balancing system. BACKGROUND

[0002] With the continuous development of science and technology, people's demand for energy is also increasing, and the large-scale use of traditional fuel vehicles has accelerated the consumption speed of fossil energy such as oil, and the burning of fossil energy not only produces a large amount of greenhouse gases, causing global warming, but also produces a large amount of fine particulate matter, nitrogen oxides, ozone, carbon monoxide and other substances harmful to human health. China aims to reach the peak of carbon dioxide emissions by 2030, and strive to achieve carbon neutrality by 2060.

[0003] An electric vehicle refers to a vehicle that uses an on-board power source as power and uses an electric motor to drive wheels to travel, and meets the requirements of road traffic and safety regulations. With the continuous progress of electric vehicle technology and the continuous decline in cost, from the beginning of relying on government subsidies for development to now improving core competitiveness, it still has certain competitiveness under the policy of gradually reducing subsidies, and the market has huge room for growth.

[0004] New energy vehicles represented by electric vehicles are one of the most important means of carbon emission reduction in the transportation field. Since they do not emit harmful gases during driving, they have relatively less impact on the environment than traditional vehicles. Therefore, developing electric vehicles to replace traditional fuel vehicles is an effective way to solve the problem of fossil energy shortage and environmental pollution.

[0005] Due to the energy density and voltage level of the power battery at the present stage, the current battery part of the electric vehicle needs to be composed of many battery monomers, and the battery has consistency differences, so in order to maximize the use of battery power to improve the endurance level of the electric vehicle, an energy balancing circuit needs to be used.

[0006] The common balancing circuit currently mainly includes passive balancing and active balancing:

[0007] Passive balancing, also known as battery energy consumption balancing, mainly connects the battery in parallel with a voltage stabilizing tube or through a switch with a resistor in parallel. Generally, it is a voltage stabilizing tube method and a resistor method. Passive balancing generally has problems such as heating and low balancing efficiency, which limits large-scale use; active balancing mainly includes switch capacitor type, energy storage inductor type, DC-DC type, and balancing circuit based on transformer, but these balancing methods under the existing technology have problems such as insufficient balancing efficiency and insufficient balancing power, so it is necessary to develop a high-efficiency battery energy balancing circuit. SUMMARY

[0008] In order to overcome the above prior art deficiencies, the present application provides a high-power, high-efficiency energy balancing circuit, which solves the problems of low balancing efficiency and large heat generation in the prior art.

[0009] The specific configuration of the present application is as follows.

[0010] A battery active balancing device suitable for lithium battery pack, comprising a lithium ion power battery module and a charge-discharge balancing circuit, wherein the lithium ion power battery module can be composed of one battery monomer or a plurality of series or series-parallel connected battery monomers; the charge-discharge balancing circuit is composed of IGBT and corresponding wires.

[0011] The modular charge-discharge balancing circuit connects each battery module together, when the total number of battery modules is n, for battery module i, when i=1: two IGBTs in the same direction connected in series are connected between the positive and negative electrodes of the battery, wherein the anode of the diode in the IGBT close to the negative electrode of the battery module is connected to the negative electrode of the battery module, the cathode of the diode in the IGBT close to the positive electrode of the battery module is connected to the positive electrode of the battery module, and the connection between the two IGBTs leads to the positive total output terminal of the battery pack; in addition, the positive electrode of the battery module is connected to the positive electrode of the adjacent battery module through another independent IGBT, and the direction of the IGBT is: the cathode of the diode is connected to the positive electrode of the battery module i.

[0012] When the battery module i is between 2 and n-1, two IGBTs in the same direction connected in series are connected between the positive and negative electrodes of each battery module, wherein the anode of the diode in the IGBT close to the negative electrode of the battery module is connected to the negative electrode of the battery module, the cathode of the diode in the IGBT close to the positive electrode of the battery module is connected to the positive electrode of the battery module, and the connection between the two IGBTs leads to the negative electrode of the i-1th battery module through a wire; in addition, the positive electrode of the battery module is connected to the positive electrodes of the adjacent two battery modules through independent IGBTs, wherein when connected to the i-1th battery module, the direction of the IGBT is: the anode of the diode is connected to the positive electrode of the battery module i; when connected to the i+1th battery module, the direction of the IGBT is: the cathode of the diode is connected to the positive electrode of the battery module i.

[0013] When the battery module i=n, two IGBTs in the same direction connected in series are connected between the positive and negative electrodes of the battery module, wherein the anode of the diode in the IGBT close to the negative electrode of the battery module is connected to the negative electrode of the battery module, the cathode of the diode in the IGBT close to the positive electrode of the battery module is connected to the positive electrode of the battery module, and the connection between the two IGBTs leads to the negative electrode of the i-1th battery module through a wire; in addition, the positive electrode of the battery module is connected to the positive electrode of the adjacent i-1th battery module through an independent IGBT, and the direction of the IGBT is: the anode of the diode is connected to the positive electrode of the battery module i.

[0014] In the charging process, when the battery module i (i = 1, 2, …, n-1) needs to be bypassed, the control logic of the IGBT is as follows: T 3i-1 trigger on, T 3i and T 3i-2 latch off; in the discharging process, when the battery module i (i = 1, 2, …, n-1) needs to be bypassed, the control logic of the IGBT is as follows: T 3i-1 trigger on, T 3i and T 3i-2 latch off; for the battery module i (i = 1, 2, …, n-1), turn off T 3i-2 , turn on T 3i-1 , T 3i , and the energy balance between the battery modules can be achieved. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 is an IGBT-based lithium battery pack active balancing device;

[0016] Figure 2 is a mechanical switch-based lithium battery pack active balancing device, which can reduce the cost by replacing the IGBT with a mechanical switch; DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application.

[0018] Reference Figure 1 , Figure 1 is an IGBT-based lithium battery pack active balancing device, which can independently perform energy balancing operations between any adjacent battery modules. Taking battery module 2 and battery module 3 as an example, the on and off logic between other adjacent modules is similar to that of these two IGBTs, turn on IGBT: T6 and T8, turn off IGBT: T7, at this time IGBT: T4 and T5 are complementary on and off, and T9 can be in any state. At this time, the energy balancing process between battery module 2 and battery module 3 will be carried out, and in this process, no high-frequency switching action is needed, so the energy loss can be effectively reduced.

[0019] If the battery module i is filled with electricity first due to the imbalance between the battery modules, at this time, if the entire battery pack continues to be charged, it will cause the battery module i to be overvoltage, at this time, the battery module can be bypassed through the topology, when i = 1, 2, …, n-1, the control logic of the IGBT is as follows: T 3i-1 trigger on, T 3i and T 3i-2 latch off; when i = n, T 3i-1Turn on, T 3i-2 Latched.

[0020] If the battery module i is the first to complete discharging, at this time if the discharging operation is continued to the whole battery pack, over-discharge of the battery module will be caused, at this time the battery module can be bypassed through the topology, when i = 1, 2, …, n-1, the control logic of IGBT is as follows: T 3i-1 Turn on, T 3i and T 3i-2 Latched; when i = n, T 3i-1 Turn on, T 3i-2 Latched.

[0021] If at this time all the battery modules are not in the charging or discharging state, and energy balancing operation is needed between the battery modules, turn on IGBT: T 3i-1 and T 3i (when i = the maximum value n of the battery module, only T 3i-1 needs to be turned on), turn off IGBT: T 3i-2 .

[0022] For the mechanical switch-based lithium battery pack active balancing device shown in Figure 2 , the control mode is similar to that of the IGBT-based lithium battery pack active balancing device, since the corresponding positions are replaced by mechanical switches, at the time of control, the mechanical switches at the corresponding positions are switched to be operated.

[0023] Finally, it should be noted that: the described embodiments are only some of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

Claims

1. A battery active balancing device suitable for lithium battery packs, characterized in that: Each lithium-ion power battery module has an equalization circuit consisting of IGBTs and corresponding wires connected to its positive and negative terminals. Except for the equalization circuit of the battery module that is directly connected to the negative terminal of the battery pack, which contains 2 IGBTs, the equalization circuit of each other battery module contains 3 IGBTs. When the total number of battery modules is n, for battery module i, when i=1: two IGBTs connected in series in the same direction are connected between the positive and negative terminals of the battery. The anode of the diode in IGBT T2, which is closer to the negative terminal of the battery module, is connected to the negative terminal of the battery module. The cathode of the diode in IGBT T1, which is closer to the positive terminal of the battery module, is connected to the positive terminal of the battery module. The connection between these two IGBTs leads to the positive output terminal of the battery pack. In addition, the positive terminal of this battery module is connected to the positive terminal of the adjacent battery module through another independent IGBT T3. The direction of the IGBT is: the cathode of the diode is connected to the positive terminal of battery module i. When the number of battery modules i is between 2 and n-1, two IGBTs connected in series in the same direction are connected between the positive and negative terminals of each battery module, wherein the IGBT closest to the negative terminal of the battery module is: T 3i-1 The anode of the diode is connected to the cathode of the battery module, and the IGBT near the anode of the battery module is T. 3i-2 The cathode of the diode is connected to the positive terminal of the battery module, and the lead wire between these two IGBTs is connected to the negative terminal of the (i-1)th battery module. Furthermore, the positive terminal of this battery module is connected to the positive terminals of two adjacent battery modules via independent IGBTs. When connected to battery module i-1, the IGBT is: T 3(i-1) The direction is as follows: the anode of the diode is connected to the positive terminal of battery module i; when connected to battery module i+1, the IGBT: T 3i The direction is: the cathode of the diode is connected to the positive terminal of battery module i; When battery module i=n, ​​two IGBTs connected in series in the same direction are connected between the positive and negative terminals of the battery module, wherein the IGBT closer to the negative terminal of the battery module is: T 3n-1 The anode of the diode is connected to the cathode of the battery module, and the IGBT near the anode of the battery module is T. 3n-2 The cathode of the diode is connected to the positive terminal of the battery module. IGBT: T 3n-1 With IGBT:T 3n-2 The connecting wire between them is led out and connected to the negative terminal of the (n-1)th battery module; in addition, the positive terminal of this battery module is connected through an independent IGBT: T 3(n-1) The diode is connected to the positive terminal of the adjacent battery module n-1. The direction of the IGBT is such that the anode of the diode is connected to the positive terminal of battery module n. During charging, when battery module i, i=1, 2, ..., n-1 needs to be bypassed, the control logic for the IGBT is as follows: T 3i-1 Trigger conduction, T 3i-2 Lockout, T 3i It can be in an active state or an active state; During the discharge process, when battery module i, i=1, 2, ..., n-1 needs to be bypassed, the control logic for the IGBT is as follows: T 3i-1 Trigger conduction, T 3i-2 Lockout, T 3i It can be in an on or off state; for any battery module i, i=1,2,…,n-1, the off state is T. 3i-2 Activate T 3i-1 T 3i This allows for energy balance between battery modules.

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