Series battery pack active equalization circuit, system and method

Abstract

The invention provides a series battery pack active equalization circuit, system and method. Comprising a series battery pack module, a switch connection module and a bidirectional forward converter module, the series battery pack module comprises a first battery and a second battery which are connected in series; the bidirectional forward converter module comprises a primary side part and a secondary side part, and the primary side part comprises a first equalization loop and a second equalization loop which are respectively used for energy transmission and energy recovery; the first equalization loop comprises a first bidirectional series switch network and a switch resonance unit which are respectively used for enabling the first equalization loop to be bidirectionally communicated and preventing the two sides of the first bidirectional series switch network from generating current abrupt change; the switch connection module comprises a first single-pole double-throw switch module and a second single-pole double-throw switch module which are respectively used for connecting the first battery to the first equalization loop or the second equalization loop and connecting the second battery to the secondary side part. According to the active equalization circuit of the series battery pack, the battery energy equalization efficiency is improved.

Description

Technical Field

[0001] The embodiments of the present application relate to the technical field of switching power supplies, and particularly to an active equalization circuit, system and method for a series battery pack. Background Art

[0002] An active equalization circuit for a series battery pack is a circuit that balances the voltage differences between battery cells by transferring energy, and is used to manage and optimize the voltage and capacity consistency of each battery cell in the series battery pack.

[0003] In the prior art, the voltage differences between battery cells can be balanced through a forward converter topology. When it is detected that the energy of a single battery in the series battery pack is higher or lower than the average value, the corresponding switch is controlled by a controller so that the energy is transferred to the secondary side through the mutual inductance of the converter, and then the energy is transferred from the secondary side to the single battery with energy lower than the average value through a parallel diode to quickly achieve energy equalization between the batteries. However, there is magnetic leakage in the coil of the forward converter topology, resulting in low energy equalization efficiency.

[0004] Based on this, in the prior art, there is a problem of low energy equalization efficiency between battery packs. Summary of the Invention

[0005] The embodiments of the present application provide an active equalization circuit, system and method for a series battery pack to achieve the effect of improving the energy equalization efficiency of the battery pack.

[0006] In a first aspect, the embodiments of the present application provide an active equalization circuit for a series battery pack, connected to an equalization control circuit; comprising:

[0007] The active equalization circuit for a series battery pack includes a series battery pack module, a switch connection module and a bidirectional forward converter module;

[0008] The series battery pack module includes n batteries connected in series, where n is any positive integer greater than 1;

[0009] The bidirectional forward converter module includes a primary side part and a secondary side part. The primary side part includes a first equalization loop and a second equalization loop. The first equalization loop is used to transmit energy to the secondary side part, and the second equalization loop is used for energy recovery; the first equalization loop includes a first bidirectional series switch network and a switch resonance unit. The first bidirectional series switch network is used to make the first equalization loop bidirectionally connected, and the switch resonance unit is used to prevent current mutations on both sides of the first bidirectional series switch network.

[0010] The switch connection module includes a first single-pole double-throw switch module and a second single-pole double-throw switch module. The first single-pole double-throw switch module is used to connect the first battery in the series battery pack module to the first equalization circuit or the second equalization circuit, and the second single-pole double-throw switch module is used to connect the second battery in the series battery pack module to the secondary side part.

[0011] In a possible implementation, the switch resonant unit includes a switch resonant capacitor and a switch resonant inductor. The switch resonant capacitor is connected in parallel with the first bidirectional series switch network, and the switch resonant inductor is connected in series with the first bidirectional series switch network.

[0012] In a possible implementation, the first bidirectional series switch network is a metal oxide semiconductor field effect transistor in bidirectional series.

[0013] In a possible implementation, the series battery pack active equalization circuit further includes a first connection line, a second connection line, a third connection line, and a fourth connection line. The primary side part includes a first connection end and a second connection end, and the secondary side part includes a third connection end and a fourth connection end;

[0014] The first connection line is used to connect the first battery to the first connection end or the second connection end;

[0015] The second connection line is used to connect the first battery to the first connection end or the second connection end;

[0016] The third connection line is used to connect the second battery to the third connection end or the fourth connection end;

[0017] The fourth connection line is used to connect the second battery to the third connection end or the fourth connection end.

[0018] In a possible implementation, the first single-pole double-throw switch module includes a first single-pole double-throw switch and a second single-pole double-throw switch, and the second single-pole double-throw switch module includes a third single-pole double-throw switch and a fourth single-pole double-throw switch;

[0019] The moving end of the first single-pole double-throw switch is connected to the first connection end, the first fixed end of the first single-pole double-throw switch is connected to the first connection line, and the second fixed end of the first single-pole double-throw switch is connected to the second connection line;

[0020] The moving end of the second single-pole double-throw switch is connected to the second connection end, the first fixed end of the second single-pole double-throw switch is connected to the first connection line, and the second fixed end of the second single-pole double-throw switch is connected to the second connection line;

[0021] The moving end of the third single-pole double-throw switch is connected to the third connection end, the first fixed end of the third single-pole double-throw switch is connected to the third connection line, and the second fixed end of the third single-pole double-throw switch is connected to the fourth connection line;

[0022] The moving end of the fourth single-pole double-throw switch is connected to the fourth connection end, the first fixed end of the fourth single-pole double-throw switch is connected to the third connection line, and the second fixed end of the fourth single-pole double-throw switch is connected to the fourth connection line.

[0023] In a possible implementation, the switch connection module further includes a plurality of connection switches;

[0024] The plurality of connection switches are used to connect the first battery to the first connection line and the second connection line, and are also used to connect the second battery to the third connection line and the fourth connection line.

[0025] In a possible implementation, the switch connection module further includes a plurality of connection switches;

[0026] The plurality of connection switches are used to connect the first battery to the first connection line and the second connection line, and are also used to connect the second battery to the third connection line and the fourth connection line.

[0027] In a possible implementation, the connection switch is a metal-oxide semiconductor field-effect transistor connected in bidirectional series.

[0028] In a possible implementation, the first balancing circuit includes a first primary winding group, the second balancing circuit includes a second primary winding group, and the secondary side portion includes a secondary winding group.

[0029] In a second aspect, the present application provides a series battery pack active balancing system, including a series battery pack active balancing circuit and a balancing control circuit, and the series battery pack active balancing circuit and the balancing control circuit are connected.

[0030] In a possible implementation, the balancing control circuit includes a controller and a collection module, and the collection module and the controller are respectively connected to the series battery pack active balancing circuit;

[0031] The collection module is used to collect the state of charge of each battery in the series battery pack module;

[0032] The controller is used to obtain the state of charge of each battery in the series battery pack module collected by the collection module, determine the first battery and the second battery according to the state of charge of each battery; and control the switch states of the first single-pole double-throw switch module and the second single-pole double-throw switch module to connect the first battery to the first balancing circuit or the second balancing circuit, and connect the second battery to the secondary side portion.

[0033] In a third aspect, the present application provides a series battery pack active balancing method, which is applied to the controller of the balancing control circuit, and the method includes:

[0034] Obtain the state of charge of each battery in the series battery pack module collected by the collection module;

[0035] Determine the first battery and the second battery according to the state of charge of each battery;

[0036] Control the switch states of the first single-pole double-throw switch module and the second single-pole double-throw switch module to connect the first battery to the first equalization circuit or the second equalization circuit and connect the second battery to the secondary side part.

[0037] The active equalization circuit, system and method for a series battery pack provided by the embodiments of the present application. It includes a series battery pack module, a switch connection module and a bi-directional forward converter module; wherein, the series battery pack module includes a plurality of serially connected batteries, the bi-directional forward converter module includes a primary side part and a secondary side part, the primary side part includes a first equalization circuit and a second equalization circuit, and the first equalization circuit includes a first bi-directional series switch network and a switch resonance unit; the switch connection module includes a first single-pole double-throw switch module and a second single-pole double-throw switch module. Through the switch connection module, the first battery in the series battery pack module is connected to the first equalization circuit or the second equalization circuit, and the second battery in the series battery pack module is connected to the secondary side part to achieve energy transfer and energy recovery. Among them, compared with the energy equalization realized by the forward converter topology structure in the prior art, in the present application, the first bi-directional series switch network bidirectionally connects the first equalization circuit, avoiding overcurrent or short-circuit situations during the energy equalization process. The switch resonance unit eliminates the energy loss caused by excessive current, and due to the high-resistance characteristic of the first bi-directional series switch network, when the single-pole double-throw switch is switched, it can prevent current mutation during the energy equalization process and eliminate the impact of current spikes on the battery, thereby improving the efficiency of energy equalization. Description of the Drawings

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0039] Figure 1 It is a schematic structural diagram of the forward converter topology structure provided by the prior art;

[0040] Figure 2 It is a schematic structural diagram of the active equalization circuit for a series battery pack provided by the embodiments of the present application Figure 1 ;

[0041] Figure 3 It is a schematic structural diagram of the active equalization circuit for a series battery pack provided by the embodiments of the present application Figure 2 ;

[0042] Figure 4 Schematic diagram of the application scenario of an active balancing circuit for a series battery pack provided by an embodiment of the present application Figure 1 ;

[0043] Figure 5 Schematic diagram of the application scenario of an active balancing circuit for a series battery pack provided by an embodiment of the present application Figure 2 ;

[0044] Figure 6 Schematic diagram of energy balancing in an active balancing circuit for a series battery pack provided by an embodiment of the present application;

[0045] Figure 7 Schematic diagram of voltage and current waveforms in an active balancing circuit for a series battery pack provided by an embodiment of the present application;

[0046] Figure 8 Schematic diagram of the structure of an active balancing system for a series battery pack provided by an embodiment of the present application;

[0047] Figure 9 Schematic diagram of the flow of an active balancing method for a series battery pack provided by an embodiment of the present application;

[0048] Figure 10 SOC (State of Charge) waveform diagram of an active balancing circuit for a series battery pack provided by an embodiment of the present application;

[0049] Figure 11 SOC waveform diagram of a forward converter topology provided by an embodiment of the present application;

[0050] Figure 12 Voltage waveform diagram of an active balancing circuit for a series battery pack provided by an embodiment of the present application;

[0051] Figure 13 Voltage waveform diagram of a forward converter topology provided by an embodiment of the present application.

[0052] Reference numerals:

[0053] T n : Coil;

[0054] T: Secondary side coil;

[0055] 1: Series battery pack module;

[0056] B n : Battery;

[0057] B 2n-1 : First battery;

[0058] B 2n: Second battery;

[0059] 2: Switch connection module;

[0060] S n : The switch corresponding to battery B n ;

[0061] DPDTa: First double-pole double-throw switch module;

[0062] 201: First double-pole double-throw switch;

[0063] 202: Second double-pole double-throw switch;

[0064] DPDTb: Second double-pole double-throw switch module;

[0065] 211: Third double-pole double-throw switch;

[0066] 212: Fourth double-pole double-throw switch;

[0067] S an : Connection switch connecting to the first battery;

[0068] S bn : Connection switch connecting to the second battery;

[0069] 3: Bidirectional forward converter module;

[0070] 30: Primary side part;

[0071] L1: First inductor;

[0072] C1: First capacitor;

[0073] 301: First equalization circuit;

[0074] S a : First bidirectional series switch network;

[0075] 3010: Switch resonance unit;

[0076] N pa : First primary winding group;

[0077] N sb : Second primary winding group;

[0078] N sa : Secondary winding group;

[0079] a1: First connection line;

[0080] a2: Second connection line;

[0081] a3: First connection end;

[0082] a4: The second connection terminal;

[0083] C r : The switching resonant capacitor;

[0084] L r : The switching resonant inductor;

[0085] 302: The second balancing circuit;

[0086] 31: The secondary side part;

[0087] b1: The third connection line;

[0088] b2: The fourth connection line;

[0089] b3: The third connection terminal;

[0090] b4: The fourth connection terminal;

[0091] D a : The first diode;

[0092] D b : The second diode;

[0093] D2: The third diode;

[0094] 303: The third balancing circuit;

[0095] 304: The fourth balancing circuit;

[0096] 4: The controller;

[0097] 5: The acquisition module;

[0098] VCC: The positive pole;

[0099] GND: Grounding. Specific embodiments

[0100] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the following will clearly and completely describe the technical solutions in the embodiments of this application with reference to the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are some, but not all, of the embodiments of this application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in this application without creative efforts shall fall within the protection scope of this application.

[0101] Battery energy balancing refers to the process of making the voltage or capacity of each battery cell consistent when multiple batteries are connected in series or parallel to form a battery pack. By balancing the energy of each battery cell in the battery pack, overcharging or over-discharging of the battery cells can be avoided, the risk of thermal runaway can be reduced, thereby extending the battery service life, improving safety, and optimizing the battery performance.

[0102] In the prior art, it is possible to use Figure 1 the forward converter topology shown to balance the voltage differences between battery cells.

[0103] The forward converter topology includes a first series battery pack, a first switch connection module, a first converter, and a first controller. The first series battery pack includes n batteries B connected in series n , where n is any positive integer greater than 1; the first switch connection module includes switches S corresponding to the batteries B n ; the first converter includes coils T corresponding to the batteries B n and a secondary side coil T. n n and the secondary side coil T.

[0104] In the specific working process of the forward converter topology, when it is detected that the energy of the battery B in the first series battery pack n is lower than or higher than the energy average value, the first controller controls the corresponding switch in the first switch connection module to connect the circuit, so that the battery with energy higher than the average value transfers energy to the secondary side coil T through the corresponding coil T in the first converter n , and then transfers the energy to the battery with energy lower than the average value through the secondary side coil T, thereby achieving the energy balance of the battery pack.

[0105] However, in the above specific working process, when transferring battery energy through the mutual inductance of the first converter, there is a magnetic leakage phenomenon, resulting in an increase in battery energy loss and a reduction in the efficiency of energy balance between batteries.

[0106] To solve the above technical problems, the inventors of the present application have found that when transferring battery energy through mutual inductance, adding a bidirectional series switch network makes the first balancing loop bidirectionally connected, avoiding overcurrent or short - circuit conditions during the energy balance process, adding a switch resonance unit to eliminate energy loss caused by excessive current, and avoiding current mutation when a single - pole double - throw switch is switched, thereby eliminating the impact of current spikes on the battery and achieving an improvement in energy balance efficiency.

[0107] Based on this, the embodiments of the present application propose a series battery pack active balancing circuit, system and method to improve the energy balance efficiency between batteries.

[0108] Figure 2 The structural schematic diagram of the series battery pack active balancing circuit provided by the embodiments of the present application Figure 1 . As Figure 2 shown, the series battery pack active balancing circuit includes: a series battery pack module 1, a switch connection module 2, and a bidirectional forward converter module 3.

[0109] ​Optionally, the switch connection module 2 is respectively connected to the series battery pack module 1 and the bidirectional forward converter module 3.

[0110] In some possible implementation manners, through the opening and closing states of the switches in the switch connection module 2, the batteries in the series battery pack module 1 can be connected to the devices in the bidirectional forward converter module 3.

[0111] The series battery pack module 1 includes n batteries connected in series, where n is any positive integer greater than 1.

[0112] In this embodiment, for example, the batteries are numbered B1, B2, B3, B4 to B n , and by numbering the series battery pack module 1, the connection manner of each battery in the series battery pack module 1 can be determined.

[0113] The bidirectional forward converter module 3 includes a primary side part 30 and a secondary side part 31. The primary side part 30 includes a first balancing circuit 301 and a second balancing circuit 302. The first balancing circuit 301 is used to transfer energy to the secondary side part 31, and the second balancing circuit 302 is used for energy recovery; the first balancing circuit 301 includes a first bidirectional series switch network S a and a switch resonant unit 3010. The first bidirectional series switch network S a is used to make the first balancing circuit 301 bidirectionally connected, and the switch resonant unit 3010 is used to prevent current mutations from occurring on both sides of the first bidirectional series switch network S a .

[0114] In this embodiment, the bidirectional forward converter module 3 is used to convert a fixed DC voltage into a variable DC voltage, enabling high-efficiency energy transfer between different voltage levels and meeting the stability requirements under different load conditions.

[0115] Optionally, the first bidirectional series switch network S a is a bidirectional series metal-oxide-semiconductor field-effect transistor.

[0116] In this embodiment, the first bidirectional series switch network S a is composed of two metal-oxide-semiconductor field-effect transistors connected in series in opposite directions; wherein, the metal-oxide-semiconductor field-effect transistor includes a gate, a source, and a drain. By applying a voltage to the gate, the current flows out from the two drains respectively and then enters the two sources, thereby realizing bidirectional current flow and avoiding overcurrent or short-circuit conditions during the energy balancing process.

[0117] In the first bidirectional series switch network S aDuring the disconnection period, the switch resonance unit 3010 makes the circuit in a resonant state, reducing the voltage to 0V, thereby eliminating the overlap of voltage and current during the circuit connection process and avoiding energy loss during circuit connection.

[0118] The switch connection module 2 includes a first double-pole double-throw switch module DPDTa and a second double-pole double-throw switch module DPDTb. The first double-pole double-throw switch module DPDTa is used to connect the first battery B in the series battery pack module 1 2n-1 to the first equalization circuit 301 or the second equalization circuit 302. The second double-pole double-throw switch module DPDTb is used to connect the second battery B in the series battery pack module 1 2n to the secondary side part 31.

[0119] Optionally, the first double-pole double-throw switch module DPDTa is connected to the primary side part and is used to connect the battery with a larger SOC in the series battery pack module 1 to the primary side part for energy equalization.

[0120] Optionally, the second double-pole double-throw switch module DPDTb is connected to the secondary side part and is used to connect the battery with a smaller SOC in the series battery pack module 1 to the secondary side part for energy equalization.

[0121] Optionally, the switch connection module 2 may further include other switches to realize the flexible connection between the battery, the primary side part, and the secondary side part, so as to adapt to different equalization working conditions.

[0122] In this embodiment, the first double-pole double-throw switch module DPDTa is used to connect the first battery B in the series battery pack module 1 2n-1 to the first equalization circuit 301 or the second equalization circuit 302, thereby making the first equalization circuit 301 and the second equalization circuit 302 connected, realizing the discharge and energy recovery of the first battery B 2n-1 The second double-pole double-throw switch module DPDTb is used to connect the second battery B in the series battery pack module 1 2n to the secondary side part 31, realizing the charging and energy recovery of the second battery B 2n of the second battery B.

[0123] In this embodiment, energy equalization is realized through the series battery pack module 1, the switch connection module 2, and the bidirectional forward converter module 3. Among them, the bidirectional forward converter module 3 enables high-efficiency energy transfer between different voltage levels and meets the stability requirements under different load conditions. The first bidirectional series switch network S in the bidirectional forward converter module 3 a realizes the bidirectional flow of current, avoids overcurrent or short-circuit conditions during the energy equalization process, and in the first bidirectional series switch network S aDuring the disconnection period, the switch resonance unit 3010 eliminates the overlap of voltage and current during the circuit connection process, avoids energy loss during circuit connection, and effectively improves the energy balance efficiency of the battery.

[0124] Figure 3 Structural schematic of the active equalization circuit for series battery packs provided by the embodiments of the present application Figure 2 , on the basis of the embodiment shown in Figure 2 , as shown in Figure 3 , the switch resonance unit 3010 includes a switch resonance capacitor C r and a switch resonance inductor L r , the switch resonance capacitor C r is connected in parallel with the first bidirectional series switch network S a , and the switch resonance inductor L r is connected in series with the first bidirectional series switch network S a .

[0125] In this embodiment, the resonance capacitor C r is a capacitor used to store and release electrical energy. By applying voltage to the first bidirectional series switch network S through the resonance capacitor C r , the voltage and current stresses of the switching devices in the first bidirectional series switch network S are reduced, and switching losses are reduced. a a a

[0126] The switch resonance inductor L r is an inductor used to store magnetic energy, and converts magnetic energy into electrical energy in the circuit to make the current change smoother, thereby eliminating current spikes.

[0127] Further, as shown in Figure 3 , the active equalization circuit for series battery packs further includes a first connection line a1, a second connection line a2, a third connection line b1, and a fourth connection line b2.

[0128] The primary side portion 30 includes a first connection end a3 and a second connection end a4, and the secondary side portion 31 includes a third connection end b3 and a fourth connection end b4.

[0129] The first single-pole double-throw switch module DPDTa includes a first single-pole double-throw switch 201 and a second single-pole double-throw switch 202, and the second single-pole double-throw switch module DPDTb includes a third single-pole double-throw switch 211 and a fourth single-pole double-throw switch 212.

[0130] The switch connection module 2 further includes a plurality of connection switches S an and S bn .

[0131] Optionally, the connection switches S an and Sbn They are all bidirectionally connected in series metal-oxide-semiconductor field-effect transistors, which avoid overcurrent or short circuit during the energy balancing process.

[0132] The first balancing circuit 301 includes a first primary winding group N pa , and the second balancing circuit 302 includes a second primary winding group N sb , and the secondary side part includes a secondary winding group N sa .

[0133] In this embodiment, through the energy transfer between the first primary winding group N pa and the secondary winding group N sa , the energy balance between batteries is achieved; through the mutual conversion between electric energy and magnetic energy in the second primary winding group N sb , energy recovery is achieved.

[0134] In this embodiment, the connection modes of the batteries and the circuits include:

[0135] The first connecting wire a1 is used to connect the first battery B 2n-1 to the first connection end a3 or the second connection end a4.

[0136] The second connecting wire a2 is used to connect the first battery B 2n-1 to the first connection end a3 or the second connection end a4.

[0137] The third connecting wire b1 is used to connect the second battery B 2n to the third connection end b3 or the fourth connection end b4.

[0138] The fourth connecting wire b2 is used to connect the second battery B 2n to the third connection end b3 or the fourth connection end b4.

[0139] Among them, the first battery B 2n-1 refers to the battery with battery energy higher than the preset energy threshold, and the second battery B 2n refers to the battery with battery energy lower than the preset energy threshold. For example, the preset energy threshold can be the average energy of all batteries in the series battery pack module 1.

[0140] In this embodiment, the connection modes of each switch in the switch connection module 2 and the circuit include:

[0141] The moving end of the first single-pole double-throw switch 201 is connected to the first connection end a3, the first fixed end of the first single-pole double-throw switch 201 is connected to the first connecting wire a1, and the second fixed end of the first single-pole double-throw switch 201 is connected to the second connecting wire a2.

[0142] The moving terminal of the second single-pole double-throw switch 202 is connected to the second connection terminal a4, the first fixed terminal of the second single-pole double-throw switch 202 is connected to the first connection line a1, and the second fixed terminal of the second single-pole double-throw switch 202 is connected to the second connection line a2.

[0143] The moving terminal of the third single-pole double-throw switch 211 is connected to the third connection terminal b3, the first fixed terminal of the third single-pole double-throw switch 211 is connected to the third connection line b1, and the second fixed terminal of the third single-pole double-throw switch 211 is connected to the fourth connection line b2.

[0144] The moving terminal of the fourth single-pole double-throw switch 212 is connected to the fourth connection terminal b4, the first fixed terminal of the fourth single-pole double-throw switch 212 is connected to the third connection line b1, and the second fixed terminal of the fourth single-pole double-throw switch 212 is connected to the fourth connection line b2.

[0145] Multiple connection switches S an For connecting the first battery B 2n-1 to the first connection line a1 and the second connection line a2, S bn For connecting the second battery B 2n to the third connection line b1 and the fourth connection line b2.

[0146] In this embodiment, through the above connection method, each module in the series battery pack active equalization circuit is connected, while achieving energy equalization between batteries, reducing energy loss, and thus improving the energy equalization efficiency.

[0147] Exemplarily, Figures 4 to 5 is a schematic diagram of an application scenario of a series battery pack active equalization circuit provided by an embodiment of the present application. On the basis of the Figure 3 shown embodiment, as Figure 4 shown:

[0148] For example, if the energy in the first battery B1 is higher than that in the second battery B2, or the first battery B1 is higher than a preset energy threshold and the second battery B2 is lower than the preset energy threshold, this time period is recorded as from t0 to t1.

[0149] During the time period from t0 to t1, close the connection switches S a1 、S a2 , close the first bidirectional series switch network S a , and close the first single-pole double-throw switch module DPDTa. At this time, the energy in the first battery B1 is transmitted to the first primary winding group N pa through the first connection line a1 and the second connection line a2, and through the energy conversion between electric energy and magnetic energy, the energy is transferred from the first primary winding group N pa to the secondary winding group N saAmong them, the first balancing circuit 301 is as shown by the dashed line on the left as Figure 4 shown.

[0150] At the same time, the first battery B1 inputs energy into the first inductor L1 and the first capacitor C1. Among them, U c1 (0) represents the voltage of the first capacitor C1 at the moment t0. Then, according to Kirchhoff's voltage law, the voltages U c1 and currents I c1 are calculated as follows:

[0151]

[0152]

[0153]

[0154]

[0155]

[0156] Among them, is the resonance frequency, n1 is the battery number, is the resonance frequency of the lower characteristic impedance, is the total resistivity after the parallel connection of the first inductor L1 and the first capacitor C1, is a constant, is the voltage of the first battery B1.

[0157] When the energy is transferred from the first primary winding group N pa to the secondary winding group N sa , close the second single-pole double-throw switch module DPDTb, close the connection switches S b2 、S b3 , turn on the second diode D b . At this time, the energy is transmitted to the second battery B2 through the second diode D b , the third connection line b1, and the fourth connection line b2 to achieve energy balance between the first battery B1 and the second battery B2. Among them, the third balancing circuit 303 is as shown by the dashed line on the right as Figure 4 shown. The third balancing circuit 303 is used to transfer energy from the secondary winding group N sa to the second battery B2.

[0158] When the energy in the first battery B1 is equal to that in the second battery B2, or when the first battery B1 is greater than or equal to a preset energy threshold and the second battery B2 is greater than or equal to the preset energy threshold, this time period is recorded as from t1 to t2, where t1 is the moment when the energy in the first battery B1 is equal to that in the second battery B2, or the moment when the first battery B1 is greater than or equal to the preset energy threshold and the second battery B2 is greater than or equal to the preset energy threshold.

[0159] At this time, as Figure 5 shown, disconnect the first bidirectional series switch network S a , and continue to close the connection switches S a1 , S a2 , S b2 , S b3 , turn on the first diode D a , then the current of the first primary winding group N pa is interrupted. According to the principle of electromagnetic induction, the second primary winding group N sb generates an induced voltage with the polarity of "negative on the upper side and positive on the lower side", as well as the corresponding induced current, and transmits the energy back to the first battery B1 through the first inductor L1 to achieve energy recovery. Among them, the second equalization circuit 302 is as Figure 5 shown by the left dotted line.

[0160] At the same time, the second diode D b is no longer conducting. At this time, since the current of the second inductor L2 cannot change suddenly, the second inductor L2 will generate an induced voltage of "negative on the left and positive on the right", making the third diode D2 conduct. At this time, the energy stored in the second inductor L2 and the second capacitor C2 is transmitted to the second battery B2 through the fourth equalization circuit 304, then the fourth equalization circuit 304 is as Figure 5 shown by the right dotted line.

[0161] Among them, U c2 (1) represents the voltage of the second capacitor C2 at the moment t1. Then, according to Kirchhoff's voltage law, the voltage U c2 and current I c2 of the second inductor L2 and the second capacitor C2 are calculated as follows:

[0162]

[0163]

[0164]

[0165]

[0166]

[0167] Among them, is the resonant frequency, n2 is the battery number, is the lower characteristic impedance of the resonant frequency, is the total resistivity after the parallel connection of the second inductor L2 and the second capacitor C2, is a constant, is the voltage of the second battery B2.

[0168] At this time, as Figure 6 shown, the SOC between the first battery B1 and the second battery B2 starts to equalize as time t increases.

[0169] The voltage V of the first bidirectional series switch network S a , the current i of the first primary winding group N Sa , the current i of the second primary winding group N pa , the current i of the secondary winding group N Npa , the current i of the secondary winding group N sb , the current i of the secondary winding group N Nsb , the current i of the secondary winding group N sa , the current i of the secondary winding group N Nsa The waveform changes with time t as Figure 7 shown.

[0170] In this embodiment, the first battery can also be a battery with an even battery number, and the second battery can also be a battery with an odd battery number. Then, by closing the corresponding connection switches S an and S bn , the energy balance between the first battery and the second battery can be achieved, and this embodiment does not limit this.

[0171] Figure 8 This is an active equalization system for a series battery pack provided by an embodiment of the present application. As Figure 8 shown, the active equalization system for a series battery pack includes an active equalization circuit for a series battery pack and an equalization control circuit, and the active equalization circuit for a series battery pack is connected to the equalization control circuit.

[0172] The equalization control circuit includes a controller 4 and a collection module 5. The collection module 5 and the controller 4 are respectively connected to the active equalization circuit for a series battery pack.

[0173] The collection module 5 is used to collect the state of charge of each battery B in the series battery pack module 1 n .

[0174] In this embodiment, the state of charge of the battery B n refers to the proportion of the remaining battery power of the battery B n (SOC, State of Charge).

[0175] The controller 4 is used to obtain the state of charge of each battery B in the series battery pack module 1 collected by the collection module 5 nThe state of charge, according to each battery B n The state of charge, determine the first battery B 2n-1 And the second battery B 2n ; And control the switching states of the first double-pole double-throw switch module DPDTa and the second double-pole double-throw switch module DPDTb, so as to connect the first battery B 2n-1 To the first balancing circuit 301 or the second balancing circuit 302, and connect the second battery B 2n To the secondary side portion 31.

[0176] In this embodiment, for example, the controller 4 obtains the state of charge of each battery B in the series battery pack module collected by the acquisition module 5 n After the state of charge, by comparing the state of charge of each battery B in the series battery pack module 1 n Of the state of charge, the highest value of the state of charge of battery B n Of the state of charge of battery B n Is used as the first battery B 2n-1 , And the lowest value of the state of charge of battery B n Of the state of charge of battery B n Is used as the second battery B 2n ; Calculate the difference between the first battery B 2n-1 And the second battery B 2n . If the difference between the first battery B 2n-1 And the second battery B 2n Reaches a preset energy threshold, then generate two sets of complementary pulse width adjustment signals, and send the two sets of complementary pulse width adjustment signals to the first double-pole double-throw switch module DPDTa and the second double-pole double-throw switch module DPDTb respectively, so as to control the switching states of the first double-pole double-throw switch module DPDTa and the second double-pole double-throw switch module DPDTb, so as to connect the first battery B 2n-1 To the first balancing circuit 301 or the second balancing circuit 302, and connect the second battery B 2n To the secondary side portion 31.

[0177] In this embodiment, the closing of each switch in the series battery pack active balancing circuit is controlled in real time through the balancing control circuit, so as to connect the corresponding circuit in time, realize battery energy balancing, and thus improve the battery energy balancing efficiency.

[0178] Figure 9 Is a schematic flowchart of a series battery pack active balancing method provided by an embodiment of the present application, which is applied to the controller of the balancing control circuit, as Figure 9 Shown, this method includes:

[0179] S901. Obtain the state of charge of each battery in the series battery pack module collected by the acquisition module.

[0180] In this embodiment, by obtaining the state of charge of each battery in the series battery pack module collected by the acquisition module, the state of charge of each battery can be judged in real time, thereby improving the real-time performance of battery energy balancing.

[0181] S902. Determine a first battery and a second battery according to the state of charge of each battery.

[0182] In this embodiment, the states of charge of each battery are compared, the highest value among the states of charge of the batteries is used as the first battery, and the lowest value among the states of charge of the batteries is used as the second battery.

[0183] S903. Control the switching states of the first single-pole double-throw switch module and the second single-pole double-throw switch module to connect the first battery to the first balancing circuit or the second balancing circuit, and connect the second battery to the secondary side part.

[0184] In this embodiment, in this embodiment, if the difference between the first battery and the second battery reaches a preset energy threshold, the switching states of the first single-pole double-throw switch module and the second single-pole double-throw switch module are controlled according to the generated pulse width adjustment signal to connect the first battery to the first balancing circuit or the second balancing circuit, and connect the second battery to the secondary side part.

[0185] In this embodiment, by monitoring the state of charge of each battery through the controller, the timeliness of battery energy balancing is effectively improved, thereby improving the efficiency of battery energy balancing.

[0186] Exemplarily, Figure 10 is a SOC waveform diagram of a series battery pack active balancing circuit provided by an embodiment of the present application, Figure 11 is a SOC waveform diagram of a forward converter topology structure provided by an embodiment of the present application; wherein, Figure 10 and Figure 11 the abscissa in is time, with the unit of second (s), Figure 10 and Figure 11 the ordinate in is SOC. Figure 12 is a voltage waveform diagram of a series battery pack active balancing circuit provided by an embodiment of the present application, Figure 13 is a voltage waveform diagram of a forward converter topology structure provided by an embodiment of the present application; wherein, Figure 12 and Figure 13 the abscissa is time, with the unit of second (s), Figure 12 and Figure 13 the ordinate in is voltage, with the unit of volt (V).

[0187] As Figures 10 to 13As shown, there are two sets of identical batteries B1, B2, B3, B4, B5, and B6, and energy balancing is performed through a series battery pack active balancing circuit and a forward converter topology respectively.

[0188] As Figure 10 shown, the SOCs of batteries B1, B2, B3, B4, B5, and B6 tend to be consistent at 750S, and the error value of the SOC is 0.5%.

[0189] As Figure 11 shown, the SOCs of batteries B1, B2, B3, B4, B5, and B6 tend to be consistent at 750S, and the error value of the SOC is 2%.

[0190] In this embodiment, through Figures 10 to 11 comparison, it is known that the series battery pack active balancing circuit has a lower error value of the SOC than the forward converter topology.

[0191] As Figure 12 shown, the maximum voltage difference of batteries B1, B2, B3, B4, B5, and B6 before the start of balancing is 0.16V, and the maximum difference of batteries B1, B2, B3, B4, B5, and B6 at 750S is 0.06V.

[0192] As Figure 13 shown, the maximum voltage difference of batteries B1, B2, B3, B4, B5, and B6 before the start of balancing is 0.16V, and the maximum difference of batteries B1, B2, B3, B4, B5, and B6 at 750S is 0.025V.

[0193] In this embodiment, through Figures 12 to 13 comparison, it is known that the series battery pack active balancing circuit has a lower voltage error value than the forward converter topology.

[0194] Among them, the energy balancing efficiency is calculated as follows:

[0195]

[0196] Among them, n is the number of batteries, i is the battery number, is the proportion of the remaining battery charge of the i-th single battery after balancing, is the capacity of the single battery, is the proportion of the remaining battery charge of the i-th single battery before balancing, is the energy obtained by charging.

[0197] In this embodiment, the energy equalization efficiency of the series battery pack active equalization circuit and the forward converter topology is calculated through Formula 11. The energy equalization efficiency of the series battery pack active equalization circuit is obtained as 96.78%, and the energy equalization efficiency of the forward converter topology is 94.52%. Based on this, the series battery pack active equalization circuit effectively improves the energy equalization efficiency.

[0198] This embodiment also provides a series battery pack active equalization device, including:

[0199] An acquisition module, configured to acquire the state of charge of each battery in the series battery pack module collected by the acquisition module.

[0200] A determination module, configured to determine a first battery and a second battery according to the state of charge of each battery.

[0201] A control module, configured to control the switching states of the first single-pole double-throw switch module and the second single-pole double-throw switch module, so as to connect the first battery to the first equalization circuit or the second equalization circuit, and connect the second battery to the secondary side part.

[0202] This embodiment also provides a series battery pack active equalization device, which includes at least one processor and a memory. Optionally, the device further includes a communication component. Among them, the processor, the memory, and the communication component are connected through a bus.

[0203] In the specific implementation process, at least one processor executes the computer execution instructions stored in the memory, so that at least one processor executes the above method.

[0204] For the specific implementation process of the processor, reference can be made to the above method embodiment. The implementation principle and technical effect are similar, and will not be elaborated here in this embodiment.

[0205] In the above embodiment, it should be understood that the processor may be a central processing unit (English: Central Processing Unit, abbreviated as: CPU), or may also be other general-purpose processors, digital signal processors (English: Digital Signal Processor, abbreviated as: DSP), application specific integrated circuits (English: Application Specific Integrated Circuit, abbreviated as: ASIC), etc. The general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc. The steps of the method disclosed in combination with the invention can be directly embodied as being executed and completed by a hardware processor, or executed and completed by a combination of hardware and software modules in the processor.

[0206] The memory may include a random access memory (RAM), and may also include non-volatile memory (NVM), such as at least one disk memory.

[0207] The bus may be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, an Extended Industry Standard Architecture (EISA) bus, or the like. The bus may be divided into an address bus, a data bus, a control bus, etc. For ease of representation, the buses in the drawings of this application are not limited to only one bus or one type of bus.

[0208] This application also provides a computer program product, including a computer program, which implements the above method when executed by a processor.

[0209] This application also provides a computer-readable storage medium, in which computer-executable instructions are stored, and when the processor executes the computer-executable instructions, the above method is implemented.

[0210] The above-readable storage medium may be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as a static random access memory (SRAM), an electrically erasable programmable read-only memory (EEPROM), an erasable programmable read-only memory (EPROM), a programmable read-only memory (PROM), a read-only memory (ROM), a magnetic memory, a flash memory, a magnetic disk, or an optical disk. The readable storage medium may be any available medium accessible by a general-purpose or special-purpose computer.

[0211] An exemplary readable storage medium is coupled to the processor, so that the processor can read information from the readable storage medium and write information to the readable storage medium. Of course, the readable storage medium may also be a component of the processor. The processor and the readable storage medium may be located in an application-specific integrated circuit. Of course, the processor and the readable storage medium may also exist as discrete components in a device.

[0212] The division of units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Another point is that the displayed or discussed couplings or direct couplings or communication connections to each other may be indirect couplings or communication connections through some interfaces, devices or units, and may be electrical, mechanical or other forms.

[0213] The unit described as a separate component may or may not be physically separated. The component shown as a unit may or may not be a physical unit, that is, it may be located in one place or distributed across multiple network units. Some or all of these units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0214] In addition, each functional unit in various embodiments of the present invention can be integrated in a processing unit, or each unit can exist physically alone, or two or more units can be integrated in one unit.

[0215] If the function is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or a part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods in various embodiments of the present invention. The aforementioned storage medium includes: removable hard disks, read-only memories (ROMs), random access memories (RAMs), magnetic disks, or optical discs and other various media that can store program codes.

[0216] Those of ordinary skill in the art can understand that all or part of the steps to implement the above method embodiments can be completed by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When this program is executed, it executes the steps including the above method embodiments; and the aforementioned storage medium includes: ROMs, RAMs, magnetic disks, or optical discs and other various media that can store program codes.

[0217] Finally, it should be noted that: After considering the specification and practicing the invention disclosed here, those skilled in the art will easily think of other implementation schemes of the present invention. The present invention aims to cover any variations, uses, or adaptive changes of the present invention. These variations, uses, or adaptive changes follow the general principles of the present invention and include common general knowledge or conventional technical means in the technical field not disclosed in the present invention. It is not limited to the exact structure described above and shown in the drawings, and various modifications and changes can be made without departing from its scope. The scope of the present invention is only limited by the appended claims.

Claims

1. An active equalization circuit for a series battery pack, characterized in that Connected to the equalization control circuit; The series battery pack active equalization circuit includes a series battery pack module, a switch connection module, and a bi-directional forward converter module; The series battery pack module includes n batteries connected in series, where n is any positive integer greater than 1; The bi-directional forward converter module includes a primary side part and a secondary side part. The primary side part includes a first equalization circuit and a second equalization circuit. The first equalization circuit is used to transfer energy to the secondary side part, and the second equalization circuit is used for energy recovery. The first equalization circuit includes a first bi-directional series switch network and a switch resonance unit. The first bi-directional series switch network is used to make the first equalization circuit bi-directionally connected, and the switch resonance unit is used to prevent current mutation on both sides of the first bi-directional series switch network; The switch connection module includes a first single-pole double-throw switch module and a second single-pole double-throw switch module. The first single-pole double-throw switch module is used to connect the first battery in the series battery pack module to the first equalization circuit or the second equalization circuit, and the second single-pole double-throw switch module is used to connect the second battery in the series battery pack module to the secondary side part.

2. The active equalization circuit for a series battery pack according to claim 1, wherein The switch resonance unit includes a switch resonance capacitor and a switch resonance inductor. The switch resonance capacitor is connected in parallel with the first bi-directional series switch network, and the switch resonance inductor is connected in series with the first bi-directional series switch network.

3. The active equalization circuit for series battery packs according to claim 1, wherein The first bi-directional series switch network is a bi-directional series of metal oxide semiconductor field effect transistors.

4. The active equalization circuit for the series battery pack according to any one of claims 1 to 3, characterized in that The series battery pack active equalization circuit further includes a first connection wire, a second connection wire, a third connection wire, and a fourth connection wire. The primary side part includes a first connection end and a second connection end, and the secondary side part includes a third connection end and a fourth connection end; The first connection wire is used to connect the first battery to the first connection end or the second connection end; The second connection wire is used to connect the first battery to the first connection end or the second connection end; The third connection wire is used to connect the second battery to the third connection end or the fourth connection end; The fourth connection wire is used to connect the second battery to the third connection end or the fourth connection end.

5. The active balancing circuit for the series battery pack according to claim 4, wherein The first single-pole double-throw switch module includes a first single-pole double-throw switch and a second single-pole double-throw switch module. The second single-pole double-throw switch module includes a third single-pole double-throw switch and a fourth single-pole double-throw switch module; The moving end of the first single-pole double-throw switch is connected to the first connection end. The first fixed end of the first single-pole double-throw switch is connected to the first connection wire, and the second fixed end of the first single-pole double-throw switch is connected to the second connection wire; The moving end of the second single-pole double-throw switch is connected to the second connection end. The first fixed end of the second single-pole double-throw switch is connected to the first connection wire, and the second fixed end of the second single-pole double-throw switch is connected to the second connection wire; The moving end of the third single-pole double-throw switch is connected to the third connection end, the first fixed end of the third single-pole double-throw switch is connected to the third connection line, and the second fixed end of the third single-pole double-throw switch is connected to the fourth connection line; The moving end of the fourth single-pole double-throw switch is connected to the fourth connection end, the first fixed end of the fourth single-pole double-throw switch is connected to the third connection line, and the second fixed end of the fourth single-pole double-throw switch is connected to the fourth connection line.

6. The active balancing circuit for series battery packs according to claim 4, wherein The switch connection module further includes a plurality of connection switches; The plurality of connection switches are used to connect the first battery to the first connection line and the second connection line, and are also used to connect the second battery to the third connection line and the fourth connection line.

7. The active equalization circuit for series battery packs according to claim 6, characterized in that The connection switch is a bidirectional series metal oxide semiconductor field effect transistor.

8. The active balancing circuit for series battery packs according to any one of claims 1 to 3, characterized in that, The first equalization circuit includes a first primary winding group, the second equalization circuit includes a second primary winding group, and the secondary side portion includes a secondary winding group.

9. An active equalization system for a series battery pack, characterized in that, It includes the series battery pack active equalization circuit and the equalization control circuit according to any one of claims 1 to 7, and the series battery pack active equalization circuit and the equalization control circuit are connected.

10. The active balancing system for series battery packs according to claim 9, wherein, The equalization control circuit includes a controller and a collection module, and the collection module and the controller are respectively connected to the series battery pack active equalization circuit; The collection module is used to collect the state of charge of each battery in the series battery pack module; The controller is used to obtain the state of charge of each battery in the series battery pack module collected by the collection module, determine the first battery and the second battery according to the state of charge of each battery; and control the switch states of the first single-pole double-throw switch module and the second single-pole double-throw switch module to connect the first battery to the first equalization circuit or the second equalization circuit, and connect the second battery to the secondary side portion.

11. An active equalization method for a series battery pack, characterized in that, For the controller applied to the equalization control circuit according to claim 9, the method includes: Obtain the state of charge of each battery in the series battery pack module collected by the collection module; Determine the first battery and the second battery according to the state of charge of each battery; Control the switch states of the first single-pole double-throw switch module and the second single-pole double-throw switch module to connect the first battery to the first equalization circuit or the second equalization circuit, and connect the second battery to the secondary side portion.

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