Layered equalization circuit and equalization method for lithium battery pack

Abstract

The invention discloses a lithium battery pack layered equalization circuit and equalization method. The lithium battery pack layered equalization circuit comprises a plurality of lithium battery packs, a state equalization module and a Cuk circuit, the lithium battery packs are connected in series to form a second equalization circuit; the Cuk circuit forms a first equalization circuit, the discharging end of the first equalization circuit is connected with the charging end of each lithium battery pack in the second equalization circuit, and the charging end of the first equalization circuit is connected with the discharging end of each lithium battery pack in the second equalization circuit; a non-isolated Cuk circuit based on a switch selection circuit is arranged as a first equalization circuit, a reconfigurable circuit based on a switch bypass type is arranged as a second equalization circuit, and equalization is realized by adjusting the voltage difference between single batteries in a standing state of the battery pack; in the charging state of the battery pack, the battery monomers are further equalized to ensure that the battery pack can keep relatively consistent voltage and capacity in the charging process, so that the grading equalization of the lithium battery pack in the standing state and the charging state is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of battery energy storage, and in particular to a lithium battery component layer balancing circuit and balancing method. Background Art

[0002] Lithium-ion batteries are widely used in electric vehicles, energy storage power stations and mobile electronic devices due to their advantages such as high power density, high energy density and no memory effect.

[0003] Since the voltage of a single battery is not enough to meet the use requirements, multiple batteries are usually connected in series to form a battery pack. However, due to the differences in the internal characteristics of the single cells in the series battery pack, the working environment and the number of times used, the working characteristics of each single cell will be different, resulting in inconsistency between the cells in the battery pack. During the cycle use, the inconsistency will lead to low battery energy utilization, low capacity utilization and even serious safety accidents. Therefore, during the use of lithium batteries, balancing management is required to improve the consistency of the battery pack. Battery balancing technology is usually divided into passive balancing and active balancing. Passive balancing, also known as energy consumption balancing, refers to the consumption of all excess energy of battery cells in the form of heat. Passive balancing control is simple, but the energy utilization rate is low. Active balancing, as a non-energy consumption balancing, refers to transferring energy from high-energy single cells to low-energy single cells through a balancing circuit, thereby reducing the energy difference between single cells. Active balancing has high efficiency and low energy loss, but it is costly and the technology is relatively complex.

[0004] It can be seen that how to reasonably balance and control a lithium battery pack has become a technical problem that needs to be urgently solved by those skilled in the art. Summary of the invention

[0005] The present invention provides a lithium battery group layer balancing circuit and a balancing method to balance the energy between different batteries in a lithium battery group.

[0006] In order to solve the above technical problems, an embodiment of the present invention provides a lithium battery pack layer balancing circuit, including a plurality of lithium battery packs, a state balancing module and a Cuk circuit.

[0007] Each of the lithium battery packs comprises a first switch, a second switch and a single lithium battery. Each of the single lithium battery is connected in series with a first switch, and each of the single lithium battery is connected in parallel with a second switch.

[0008] The lithium battery packs are connected in series to form a second balancing circuit.

[0009] The Cuk circuit constitutes a first balancing circuit, a discharge end of the first balancing circuit is connected to a charge end of each of the lithium battery packs in the second balancing circuit, and a charge end of the first balancing circuit is connected to a discharge end of each of the lithium battery packs in the second balancing circuit.

[0010] The input end of the state balancing module is connected to the second balancing circuit, and the output end of the state balancing module is connected to the first balancing circuit.

[0011] Furthermore, the Cuk circuit includes a charging switch, a discharging switch, a first inductor, a second inductor, a first capacitor, a main control switch device, a first diode and a second diode.

[0012] The charging switch is connected to the charging end of each of the lithium battery packs in the second equalizing circuit, and the discharging switch is connected to the discharging end of each of the lithium battery packs in the second equalizing circuit.

[0013] Furthermore, the state balancing module includes a fuzzy logic controller, a drive signal generator, and a battery state collector.

[0014] The input end of the battery status collector is connected to each single lithium battery in the second balancing circuit.

[0015] The output end of the battery status collector is connected to the input end of the fuzzy logic controller.

[0016] The input end of the driving signal generator is connected to the output end of the fuzzy logic controller, and the output end of the driving signal generator is connected to the main control switch device of the first equalizing circuit.

[0017] Furthermore, the battery status collector includes at least one of the following:

[0018] Voltage detection device, current detection device, leakage detection device or temperature sensor.

[0019] Furthermore, the main control switch device is a MOSFET switch.

[0020] Another embodiment of the present invention provides a lithium battery component layer balancing method, which is implemented by the lithium battery component layer balancing circuit as described above, and includes:

[0021] The battery status data collected by the battery status collector disposed on the single lithium battery in each lithium battery pack is obtained.

[0022] According to the battery status data, it is determined whether the lithium battery pack is in a charging state.

[0023] If the lithium battery pack is in a charging state, a second balancing circuit is used to balance the lithium battery pack.

[0024] If the lithium battery pack is in a non-charging state, a first balancing circuit is used to balance the lithium battery pack.

[0025] Furthermore, if the lithium battery pack is in a non-charging state, the lithium battery pack is balanced using a first balancing circuit, including:

[0026] If it is determined according to the battery status data that the lithium battery pack is in a static state, the energy of each single lithium battery in the lithium battery pack is sorted according to the battery status data.

[0027] The energy in each of the lithium battery packs is balanced through a first balancing circuit according to the sorting result.

[0028] Furthermore, balancing the energy in each of the lithium battery packs through a first balancing circuit according to the sorting result includes:

[0029] A first lithium battery pack that needs to be charged and a second lithium battery pack that needs to be discharged are determined according to the sorting result.

[0030] The charging switch corresponding to the first lithium battery pack is controlled to be turned on, and the discharging switch of the second lithium battery pack is controlled to be closed.

[0031] The energy in the second lithium battery pack is transferred to the first lithium battery pack through the first balancing circuit.

[0032] Furthermore, the step of sorting the energy of the single lithium batteries in each of the lithium battery packs according to the battery status data includes:

[0033] The battery status data is analyzed using a fuzzy logic controller to obtain the SOC value of the corresponding lithium battery pack, and the energy difference between different lithium battery packs is calculated based on each SOC value.

[0034] Furthermore, the energy difference calculation process is:

[0035] ΔSOC=|SOC i -SOC j |

[0036] Among them, ΔSOC is the SOC difference between the two batteries, SOC i is the SOC value of battery pack i, SOC j is the SOC value of battery pack j.

[0037] Compared with the prior art, the embodiments of the present invention have the following advantages:

[0038] (1) a non-isolated Cuk circuit based on a switch selection circuit is provided as a first balancing circuit, and balancing is achieved by adjusting the voltage difference between battery cells when the battery pack is in a static state;

[0039] (2) A switch bypass-based reconfigurable circuit is provided as a second balancing circuit to further balance the battery cells when the battery pack is in a charging state, thereby ensuring that the voltage and capacity of the battery pack can be kept relatively consistent during the charging process, thereby achieving hierarchical balancing of the lithium battery pack in a static state and a charging state;

[0040] (3) Use fuzzy logic controller to deal with the ambiguity and uncertainty in the control circuit data, and achieve precise control of the balancing circuit through fuzzy reasoning and decision-making. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 A structural block diagram of a lithium battery component layer balancing circuit provided by an embodiment of the present invention;

[0042] Figure 2 A structural block diagram of a first balancing circuit of a lithium battery component layer balancing circuit provided in an embodiment of the present invention;

[0043] Figure 3 A working principle diagram of a first balancing circuit of a lithium battery component layer balancing circuit provided in an embodiment of the present invention in a static state;

[0044] Figure 4 A circuit state diagram of a first balancing circuit of a lithium battery component layer balancing circuit provided in an embodiment of the present invention when Q1 is closed;

[0045] Figure 5 A circuit state diagram of a lithium battery component layer balancing circuit provided by an embodiment of the present invention when Q1 is disconnected;

[0046] Figure 6 A circuit structure diagram of a second balancing circuit of a lithium battery component layer balancing circuit provided in an embodiment of the present invention;

[0047] Figure 7 A diagram of the balancing process of the second balancing circuit of the lithium battery component layer balancing circuit provided by an embodiment of the present invention;

[0048] Figure 8 A logic block diagram of a fuzzy logic controller for a lithium battery component layer balancing circuit provided by an embodiment of the present invention;

[0049] Fig. 9 A flow chart of overall battery balancing of a lithium battery component layer balancing circuit provided by an embodiment of the present invention;

[0050] Fig.10A simulation effect diagram of a lithium battery component layer balancing circuit in a static state provided by an embodiment of the present invention;

[0051] Fig.11 This is a simulation effect diagram of the lithium battery component layer balancing circuit under charging state provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0052] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0053] In the description of this application, the terms "first", "second", "third", etc. are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first", "second", "third", etc. may explicitly or implicitly include one or more of the feature. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0054] In the description of the present application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be a connection between the two elements. The terms "vertical", "horizontal", "left", "right", "upper", "lower" and similar expressions used herein are only for illustrative purposes, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0055] In the description of this application, it should be noted that, unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as those commonly understood by those skilled in the art. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood by specific circumstances.

[0056] An embodiment of the present invention provides a lithium battery component layer balancing circuit. For details, see Figure 1 and Figure 2 The circuit includes several lithium battery packs, a state balancing module, a Cuk circuit, a fuzzy logic controller, a drive signal generator and a battery state collector; wherein the battery state collector includes a voltage detection device, a current detection device, a leakage detection device or a temperature sensor, etc., for collecting battery state data.

[0057] Each lithium battery pack includes a first switch, a second switch and a single lithium battery. Each single lithium battery is connected in series with a first switch, and each single lithium battery is connected in parallel with a second switch.

[0058] The lithium battery packs are connected in series to form a second balancing circuit.

[0059] The Cuk circuit constitutes a first balancing circuit, a discharge end of the first balancing circuit is connected to a charge end of each lithium battery pack in the second balancing circuit, and a charge end of the first balancing circuit is connected to a discharge end of each lithium battery pack in the second balancing circuit.

[0060] The input end of the state balancing module is connected to the second balancing circuit, and the output end of the state balancing module is connected to the first balancing circuit.

[0061] The input end of the battery status collector is connected to each single lithium battery in the second balancing circuit.

[0062] The output end of the battery status collector is connected to the input end of the fuzzy logic controller.

[0063] The input end of the driving signal generator is connected to the output end of the fuzzy logic controller, and the output end of the driving signal generator is connected to the main control switch device of the first equalizing circuit.

[0064] The status of lithium batteries, such as voltage, current and temperature, is detected in real time by the single battery status acquisition module and transmitted to the controller. The controller estimates the SOC of the single battery according to the battery status. When the SOC of the single battery reaches the balanced start condition, the controller gives the corresponding metal-oxide semiconductor field effect transistor (MOSFET) and switch drive signals respectively, and balances the battery in the static state through the first balancing circuit, and balances the battery in the charging state through the second balancing circuit.

[0065] The first balancing circuit uses a non-isolated Cuk circuit based on a switch selection circuit as a balancing unit, which can effectively solve the problem that the traditional reconfigurable circuit topology cannot achieve battery balancing in a static state, and can also realize energy transfer between any battery cells. Its basic circuit structure is as follows Figure 2As shown. The switch selection circuit is composed of a charging switch S and a discharging switch K, which are respectively connected to the positive and negative electrodes of each single lithium battery and are used to select the single lithium battery to be balanced; the Cuk circuit is composed of a first inductor L1, a second inductor L2, a first capacitor C1, a main control switch device Q1, a first diode D1, and a second diode D2, and the main control switch device is a MOSFET switch.

[0066] The charging switch S is connected to the charging end of each lithium battery pack in the second balancing circuit, and the discharging switch K is connected to the discharging end of each lithium battery pack in the second balancing circuit.

[0067] The working principle of the first balancing circuit to balance the battery SOC in a static state is as follows Figure 3 As shown in FIG. 1 , it is stipulated that the upper switch S controls the low-energy single-cell side (also called the charging end B), and the lower switch K controls the high-energy single-cell side (also called the discharging end A). Assuming that the single-cell battery SOC B1 >SOC Bi , the balanced energy transfer process is as shown in the figure: energy is transferred from the high-energy single cell B1 to the low-energy single cell Bi, the upper selection switch Si on the low-energy side in the balanced circuit topology is closed, and the corresponding polarity of the battery Bi is connected to the charging terminal B of the Cuk circuit; at the same time, the corresponding lower selection switch K1 on the high-energy side is closed, and the corresponding polarity of the battery B1 is connected to the discharge terminal A of the Cuk circuit, thereby connecting the high-energy single cell B1 and the low-energy single cell Bi through the Cuk circuit for energy transfer.

[0068] Among them, the MOSFET switch in the Cuk balancing circuit is controlled by the PWM signal. In one signal cycle, the current loop has two states: when the switch tube Q1 is turned on, the diode D2 is reverse biased and cut off. Figure 4 As shown, battery B1 and inductor L1 form a loop, battery B1 charges inductor L1, and inductor L1 stores energy; capacitor C1 forms a loop with battery B2 and inductor L2, capacitor C1 stores energy in inductor L2 and charges battery B2. When switch tube Q1 is turned off, diode D2 is forward-conducted, and the current loop is as follows: Figure 5 As shown, the battery B1, the inductor L1 and the capacitor C1 form a closed loop, the battery B1 and the inductor L1 charge the capacitor C1, and the capacitor C1 stores energy; the inductor L2 and the battery B2 form a closed loop, and the inductor L2 charges the battery B2.

[0069] The inductor current of the Cuk balancing circuit should be in freewheeling mode during charge and discharge balancing to ensure a smooth flow of the balancing current, which is beneficial to improving the battery balancing rate and energy transfer efficiency. To ensure that the inductor current is in freewheeling mode, according to the design standard, the current fluctuation amplitude of the inductors L1 and L2 should be less than 30% of the average circuit current I:

[0070] Δi L1 <30% I

[0071] Δi L2 <30% I

[0072] Among them, Δi L1 is the current fluctuation amplitude of L1, Δi L2 is the current fluctuation amplitude of L2.

[0073] According to the on and off states of the switch tube Q1, the energy transfer relationship can be obtained:

[0074]

[0075] Among them, V in and V out are the input voltage and output voltage of the Cuk balanced main circuit, D is the duty cycle, T s is the switching period, L1 and L2 refer to the inductance values ​​of inductors L1 and L2 respectively.

[0076] The input-output relationship of the Cuk circuit can be obtained as follows:

[0077]

[0078] Take V in Limit voltage V for charging single battery B , from the above formula we can get:

[0079]

[0080] In order to reduce the ripple voltage of the capacitor, the voltage fluctuation amplitude should be less than 5% of the average value. During the off period of the switch tube Q1, that is, DT s <t<T s During this period, the inductor L1, B1 and C1 form a loop, and this loop charges the capacitor C1. According to the relationship between the electric quantities, we can get:

[0081]

[0082] Among them, V C1 is the capacitance C 1 voltage.

[0083] From this we can get C 1 Capacitance value:

[0084]

[0085] In actual application, the duty cycle D, the values ​​of inductors L1, L2 and capacitor C1 are calculated through the formula according to the balanced performance design requirements, and then the nominal inductance value and the nominal capacitance value are selected.

[0086] The average current I during the battery balancing energy transfer process L1 ,I L2 The calculation formula is as follows:

[0087]

[0088] Among them, V B1 With V Bi are the high energy side battery cell voltage and the low energy side battery cell voltage connected to the Cuk circuit respectively. And from the above formula, it can be seen that when the voltages of the two single cells involved in the balancing, the Cuk balancer parameters and the PWM signal period are known, the balancing current is only related to the duty cycle D of the PWM signal.

[0089] The second balancing circuit uses a switch bypass type reconfigurable circuit as a balancing unit, that is, each single battery is connected in parallel and in series with a switch, and the closing and opening of the switch is controlled according to the charge state of the battery cell to control the charging time of each battery cell, thereby achieving battery balancing. At the same time, the single battery that cannot work due to short circuit, open circuit or abnormal aging can be isolated from the circuit to improve the safety of the battery pack. Taking 4 series batteries as an example, the circuit structure is as follows Figure 6 shown.

[0090] Assume that the four batteries are numbered B1, B2, B3, and B4 in descending order according to SOC. The charging equalization process is as follows: Figure 7 Change the connection status of B1, B2 and B3, disconnect switches K2, K4 and K6, and close switches K1, K3 and K5, as shown. Figure 7 As shown in (a), at this time, B1, B2 and B3 are temporarily isolated from the circuit, and B4 is charged until the charge state of B3 and B4 is the same, and then B3 is reconnected to the battery pack, as shown in Figure 7 (b) shows that batteries B1 and B2 are still isolated. When the charge states of B2, B3, and B4 are the same, B2 is connected to the battery pack and B1 is isolated. Figure 7 Finally, when the charge states of B1 to B4 are the same, B1 is reconnected to the battery pack, as shown in Figure 7 (d) At this point, all batteries in the battery pack have the same state of charge and are charged simultaneously.

[0091] The first balancing circuit uses fuzzy control algorithm to dynamically adjust the balancing current. The fuzzy logic controller consists of a fuzzifier, a rule base, an inference engine and a defuzzifier, such as Figure 8 As shown, the fuzzified controller converts precise inputs into fuzzy variables. These fuzzy variables are then input into the inference engine and processed using a pre-constructed rule base consisting of practical experience and knowledge. The results of the inference engine are converted into precise outputs by the defuzzifier.

[0092] The input of fuzzy control is the absolute value of the difference between the average SOC value of the battery pack and the average SOC value of the two single cells in a balanced state, and the absolute value of the difference between the SOC values ​​of the two single cells in a balanced state. The relevant expressions are as follows:

[0093]

[0094] SOC dif =|SOC p -SOC e |

[0095] ΔSOC=|SOC i -SOC j |

[0096] Among them, SOC i and SOC j They are respectively represented as the SOC values ​​of the two single cells during charging and discharging in the balancing process, SOC p Refers to the average SOC value of the battery pack, SOC e is the average SOC value of the two cells in a balanced state, ΔSOC is the SOC difference between the two cells in a balanced state, and SOC dif Characterizes the difference between the balanced battery state of charge and the battery pack state of charge.

[0097] SOC dif The ranges of and ΔSOC are set to (0, 20%) and (0, 60%) respectively. The converted fuzzy variables are μ(x) and μ(y) corresponding to SOC respectively. dif and ΔSOC, which are divided into five fuzzy subsets: very small (VS), small (S), medium (M), large (L), and very large (VL). The output of the fuzzy logic controller I equ , whose range is set to (0,5) according to the maximum current allowed by the battery, and the fuzzy variable μ(z) corresponding to the interval is also divided into five sub-intervals: very small (VS), small (S), medium (M), large (L), and very large (VL). The present invention adopts a triangular fuzzy membership function with good control performance and simple calculation.

[0098] In the balancing process, the fuzzy rule table shown in Table 1 is established based on the following knowledge and experience:

[0099] 1) If SOC dif If ΔSOC is large and ΔSOC is also large, a large balancing current is required to reduce the balancing time.

[0100] 2) If ΔSOC is small, SOC dif If the voltage is also small, a small balancing current is required to ensure battery safety.

[0101] Table 1 Fuzzy rules table

[0102]

[0103] The fuzzy result obtained by the inference engine in the fuzzy controller cannot be directly used in the battery balancing solution, so it needs to be defuzzified and converted into a specific value. The present invention uses the centroid defuzzification method, and its expression is as follows:

[0104]

[0105] Where u(z) is the fuzzy result of the inference. Then the current obtained by the fuzzy logic controller is compared with the output current of the Cuk circuit collected, and then the pulse duty cycle D of the PWM signal is adjusted to balance the balancing circuit.

[0106] The overall battery balancing process based on the reconfigurable circuit is as follows Fig. 9 As shown, the specific process is:

[0107] Step 1: Perform fault detection on the battery pack. If a short circuit, open circuit or other fault is detected in a battery cell, bypass the battery to isolate it from the circuit, and then execute step 2; if no fault is detected in the battery cell, execute step 2.

[0108] Step 2: Measure the SOC of each battery in the battery pack.

[0109] Step 3: Determine whether the battery pack is in a charging state, that is, determine whether the battery pack is connected to an external power source. If the judgment is yes, go to step 4; if the judgment is no, go to step 5.

[0110] Step 4: Arrange the SOC of each single battery.

[0111] Step 5: Calculate the absolute value of the difference between the average SOC value of the battery pack and the average SOC value of the two cells in a balanced state. dif And the absolute value of the SOC difference between the two battery cells in a balanced state ΔSOC.

[0112] Step 6: Determine the battery SOC with the highest SOC max and the battery with the lowest SOC min Is the difference greater than the set SOC balance threshold SOC set If the answer is yes, execute step 7; if the answer is no, end the balancing process.

[0113] Step 7: Implement the SOC-based fuzzy control strategy to balance the battery cells in the static state.

[0114] Step 8: Determine the battery SOC with the highest SOC againmax and the battery with the lowest SOC min Is the difference greater than the set SOC balance threshold SOC set If the judgment is yes, then end the balancing; if the judgment is no, then return to step 7.

[0115] Step 9: Perform a balancing operation of the reconfigurable circuit on the cells in the charging state.

[0116] The present invention uses Matlab / Simulink for modeling and simulation, and takes a battery pack composed of 6 lithium-ion batteries as the object. The parameters of the lithium-ion batteries used are 3.7V / 2.2AH, and the SOC values ​​of each monomer in the battery pack are 76%, 72%, 70%, 65%, 62%, and 58% respectively. The SOC balancing threshold is set to 1%; the balancing simulation model includes a battery module, a double-layer selection switch, a reconfigurable module, a non-isolated Cuk equalizer, a switch control module, and a current control module based on a fuzzy controller. The switch control module is to open and close the double-layer selection switch according to the charge state of each monomer in the battery pack, and then select the battery that needs to be balanced. The current control module based on the fuzzy controller is composed of a Matlab function module, a Fuzzy module, and a PWM output module. The Matlab function module calculates the two input quantities of the Fuzzy module according to the corresponding formula. The Fuzzy module outputs the balanced current through the fuzzy control rule, while the PWM output module compares the actual current of the Cuk circuit collected with the balanced current output by the Fuzzy module, and then adjusts the pulse duty cycle D of the PWM switch of the Cuk circuit. The balanced simulation effect in the static state is shown in the figure below. Fig.10 As shown in Figure 2, the equalization simulation effect under charging state is as follows: Fig.11 shown.

[0117] The layered balancing of the lithium battery pack of the present invention can effectively isolate and bypass the faulty battery cells, improve the safety and service life of the battery pack, achieve the balancing of the battery cells in the static state and the charging state, effectively solve the problem of battery inconsistency, and improve the service life of the battery pack. At the same time, the balancing current of the battery in the static state can be dynamically adjusted according to the charge state of the battery cells, improve the balancing efficiency, and enhance the safety of the battery pack during the static balancing process.

[0118] The embodiment of the present invention further provides a lithium battery component layer balancing method, which is implemented by the lithium battery component layer balancing circuit as described above, and the method includes:

[0119] The battery status data collected by the battery status collector disposed on the single lithium battery in each lithium battery pack is obtained.

[0120] According to the battery status data, determine whether the lithium battery pack is in a charging state.

[0121] If the lithium battery pack is in a charging state, the second balancing circuit is used to balance the lithium battery pack.

[0122] If the lithium battery pack is in a non-charging state, the first balancing circuit is used to balance the lithium battery pack.

[0123] If the lithium battery pack is in a non-charging state, the first balancing circuit is used to balance the lithium battery pack, including:

[0124] If it is determined according to the battery status data that the lithium battery pack is in a static state, the energy of the single lithium batteries in each lithium battery pack is sorted according to the battery status data.

[0125] The energy in each lithium battery pack is balanced through the first balancing circuit according to the sorting result.

[0126] The energy in each lithium battery pack is balanced through a first balancing circuit according to the sorting result, including:

[0127] A first lithium battery pack that needs to be charged and a second lithium battery pack that needs to be discharged are determined according to the sorting result.

[0128] The charging switch corresponding to the first lithium battery pack is controlled to be turned on, and the discharging switch of the second lithium battery pack is controlled to be closed.

[0129] The energy in the second lithium battery pack is transferred to the first lithium battery pack through the first balancing circuit.

[0130] The energy of the single lithium batteries in each lithium battery pack is sorted according to the battery status data, including:

[0131] The battery status data is analyzed using a fuzzy logic controller to obtain the SOC value of the corresponding lithium battery pack, and the energy difference between different lithium battery packs is calculated based on each SOC value.

[0132] The energy difference calculation process is:

[0133] ΔSOC=|SOC i -SOC j |

[0134] Among them, ΔSOC is the SOC difference between the two batteries, SOC i is the SOC value of battery pack i, SOC j is the SOC value of battery pack j.

[0135] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A lithium battery component layer balancing circuit, characterized in that: It includes several lithium battery packs, state balancing modules and Cuk circuits; Each of the lithium battery packs comprises a first switch, a second switch and a single lithium battery, each of the single lithium battery is connected in series with a first switch, and each of the single lithium battery is connected in parallel with a second switch; The lithium battery packs are connected in series to form a second balancing circuit; The Cuk circuit constitutes a first balancing circuit, the discharge end of the first balancing circuit is connected to the charging end of each of the lithium battery packs in the second balancing circuit, and the charging end of the first balancing circuit is connected to the discharge end of each of the lithium battery packs in the second balancing circuit; The input end of the state balancing module is connected to the second balancing circuit, and the output end of the state balancing module is connected to the first balancing circuit.

2. The lithium battery component layer balancing circuit according to claim 1, characterized in that: The Cuk circuit includes a charging switch, a discharging switch, a first inductor, a second inductor, a first capacitor, a main control switch device, a first diode and a second diode; The charging switch is connected to the charging end of each of the lithium battery packs in the second equalizing circuit, and the discharging switch is connected to the discharging end of each of the lithium battery packs in the second equalizing circuit.

3. The lithium battery component layer balancing circuit as claimed in claim 1, characterized in that: The state balancing module includes a fuzzy logic controller, a drive signal generator, and a battery state collector; The input end of the battery status collector is connected to each single lithium battery in the second balancing circuit; The output end of the battery status collector is connected to the input end of the fuzzy logic controller; The input end of the driving signal generator is connected to the output end of the fuzzy logic controller, and the output end of the driving signal generator is connected to the main control switch device of the first equalizing circuit.

4. The lithium battery component layer balancing circuit as claimed in claim 3, characterized in that: The battery status collector includes at least one of the following: Voltage detection device, current detection device, leakage detection device or temperature sensor.

5. The lithium battery component layer balancing circuit as claimed in claim 1, characterized in that: The main control switch device is a MOSFET switch.

6. A lithium battery component layer balancing method, characterized in that: The method is implemented by the lithium battery component layer balancing circuit as described in claims 1 to 5, comprising: Acquiring battery status data collected by a battery status collector disposed on a single lithium battery in each lithium battery pack; According to the battery status data, determining whether the lithium battery pack is in a charging state; If the lithium battery pack is in a charging state, the second balancing circuit is used to balance the lithium battery pack; If the lithium battery pack is in a non-charging state, a first balancing circuit is used to balance the lithium battery pack.

7. The lithium battery component layer equalization method according to claim 6, characterized in that: If the lithium battery pack is in a non-charging state, the first balancing circuit is used to balance the lithium battery pack, including: If it is determined according to the battery status data that the lithium battery pack is in a static state, the energy of each single lithium battery in the lithium battery pack is sorted according to the battery status data; The energy in each of the lithium battery packs is balanced through a first balancing circuit according to the sorting result.

8. The lithium battery component layer equalization method according to claim 7, characterized in that: The step of balancing the energy in each of the lithium battery packs by using a first balancing circuit according to the sorting result includes: Determine a first lithium battery group that needs to be charged and a second lithium battery group that needs to be discharged according to the sorting result; Controlling the charging switch corresponding to the first lithium battery pack to be turned on, and controlling the discharging switch corresponding to the second lithium battery pack to be closed; The energy in the second lithium battery pack is transferred to the first lithium battery pack through the first balancing circuit.

9. The lithium battery component layer equalization method according to claim 7, characterized in that: The step of sorting the energy of the single lithium batteries in each of the lithium battery packs according to the battery status data comprises: The battery status data is analyzed using a fuzzy logic controller to obtain the SOC value of the corresponding lithium battery pack, and the energy difference between different lithium battery packs is calculated based on each SOC value.

10. The lithium battery component layer equalization method according to claim 9, characterized in that: The energy difference calculation process is: ΔSOC=|SOC i -SOC j | Among them, ΔSOC is the SOC difference between the two batteries, SOC i is the SOC value of battery pack i, SOC j is the SOC value of battery pack j.

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