Battery large-voltage-difference active rapid equalization circuit and method

Abstract

The invention provides a battery large-voltage-difference active fast equalization circuit, which comprises N energy storage batteries connected in series, 2N switch tubes and N pairs of inductance coils, each energy storage battery is in one-to-one correspondence with each pair of inductance coils, a secondary winding of each inductance coil is connected in parallel with the corresponding energy storage battery after being connected in series with one switch tube, and a secondary winding of each inductance coil is connected in parallel with the corresponding energy storage battery after being connected in series with the corresponding switch tube. The primary windings of the inductance coils are sequentially connected in series and then integrally connected with the N energy storage batteries connected in series in parallel, and meanwhile, the primary windings are further connected to one ends of the corresponding energy storage batteries through switching tubes; and the switch tube is controlled to be conducted according to the maximum voltage difference between the energy storage batteries. The circuit has the advantages of a flyback fixed power equalization circuit under the condition of high voltage difference and a push-pull automatic rapid equalization circuit under the condition of low voltage difference, an ideal equalization mode can be realized at low cost, the equalization control mode is very simple, only 50% duty ratio driving is needed, frequent measurement and checking of battery voltage are not needed, and the circuit is simple in structure and convenient to operate. The balanced battery voltage difference is lt; the voltage is 10 millivolts.

Description

Technical Field

[0001] The present invention relates to the field of battery balancing, and in particular to a battery large voltage difference active fast balancing circuit and method. Background Art

[0002] In practical applications, batteries are always used in series / parallel. When the battery power is insufficient, they are charged uniformly. Due to differences in battery characteristics or the increase in differences between batteries after a period of use, there will be large differences in the capacity of each battery after multiple charges and discharges. For series battery packs, the overall discharge capacity of the battery is limited by the battery with the smallest capacity. This is the short board effect of the wooden barrel. An effective way to solve the short board effect is to balance the battery pack. In practice, voltage balancing is generally used instead of capacity balancing. That is, when the voltage of each battery is charged to the same voltage, the battery power is considered to be the same, that is, the battery power is balanced.

[0003] There are many balancing solutions at present, including active balancing, passive balancing, etc. In the current active balancing solution, only the small voltage difference between batteries <0.8v can be balanced. For the large voltage difference (>0.8v), the balancing current is too large and cannot be supported. Summary of the invention

[0004] In view of the problems existing in the prior art, a battery large voltage difference active fast equalization circuit and method are provided, which realizes equalization under the condition of large battery voltage difference (>0.8v) by limiting the output power. When the battery voltage difference is reduced to the required range, it can perform fast and automatic equalization according to the voltage difference, that is, it can achieve constant power equalization of large voltage difference and automatic and fast equalization of small voltage difference according to the voltage difference.

[0005] The first aspect of the present invention proposes a battery large voltage difference active fast equalization circuit, comprising N series-connected energy storage batteries, 2N switching tubes and N pairs of inductors, each energy storage battery corresponds to each pair of inductors one by one, wherein the secondary winding of the inductor is connected in series with a switching tube and then connected in parallel with the corresponding energy storage battery, the primary winding of the inductor is sequentially connected in series with the N series-connected energy storage batteries as a whole and, at the same time, the primary winding is also connected to one end of the corresponding energy storage battery through a switching tube; the switching tube is controlled to be turned on according to the maximum voltage difference between each energy storage battery.

[0006] As a preferred solution, the switch tube connected in series with the primary winding and the switch tube connected in series with the secondary winding are turned on alternately and the received control signals have opposite phases.

[0007] As a preferred solution, the turns ratio of the primary winding to the secondary winding of each pair of inductor coils is 1:1.

[0008] As a preferred solution, when the maximum voltage difference between the energy storage batteries is between 0.1 and 0.5, the switch tube connected in series with the primary winding and the switch tube connected in series with the secondary winding are alternately turned on.

[0009] As a preferred solution, when the maximum voltage difference between each energy storage battery is greater than or equal to 0.5V, the 1st to N-1th switch tubes connected to the primary winding are turned off, and the Nth switch tube connected to the primary winding and the switch tube connected to the secondary winding are alternately turned on.

[0010] As a preferred solution, the switch tube receives a square wave pulse signal with a duty cycle of 50%.

[0011] As a preferred solution, the switch tube is a MOS tube.

[0012] As a preferred solution, each energy storage battery is connected to a BMS for providing voltage information of each energy storage battery.

[0013] The second aspect of the present invention provides a method for active fast equalization of a battery with a large voltage difference, which is implemented based on the active fast equalization circuit for a battery with a large voltage difference described in the first aspect, and includes:

[0014] Detect the maximum voltage difference between each energy storage battery;

[0015] When the maximum voltage difference is greater than or equal to 0.5, the 1st to N-1st switch tubes connected to the primary winding are controlled to be turned off, and the Nth switch tube connected to the primary winding and the switch tube connected to the secondary winding are alternately turned on to charge the energy storage battery with the lowest voltage;

[0016] When the maximum voltage difference is less than 0.5, the switch tube connected in series with the primary winding and the switch tube connected in series with the secondary winding are controlled to be turned on alternately until the balancing of each energy storage battery is completed.

[0017] Compared with the prior art, the beneficial effects of the above technical solution are as follows: the present invention combines the advantages of the flyback fixed power balance under high voltage difference and the push-pull automatic fast balance under low voltage difference, which can achieve the ideal balance mode at low cost. The control mode of balance is also very simple, only 50% duty cycle drive is required, and there is no need to frequently measure and check the battery voltage. The balance effect can also be achieved by using timed long balance. After balance, the battery voltage difference is <10 millivolts. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of a battery large voltage difference active fast equalization circuit proposed in an embodiment of the present invention.

[0019] Figure 2 A schematic diagram of large voltage difference equalization of a battery large voltage difference active fast equalization circuit proposed in an embodiment of the present invention.

[0020] Figure 3 A schematic diagram of small voltage difference equalization of a battery large voltage difference active fast equalization circuit proposed in an embodiment of the present invention. DETAILED DESCRIPTION

[0021] Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar modules or modules with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be construed as limitations on the present application. On the contrary, the embodiments of the present application include all changes, modifications and equivalents that fall within the spirit and connotation of the appended claims.

[0022] Since the current active balancing solutions can generally only balance the battery when the voltage difference is smaller than 0.8v, they cannot support larger voltage difference (>0.8v) due to the excessive balancing current. Based on this, the embodiment of the present invention proposes a battery large voltage difference active fast balancing circuit, which can achieve balancing under the condition of large battery voltage difference (>0.8v) by limiting the output power, and can perform fast and automatic balancing according to the voltage difference when the battery voltage difference is reduced to the required range. That is, it can balance the large voltage difference with constant power, and balance the small voltage difference automatically and quickly according to the voltage difference.

[0023] Please refer to Figure 1 The battery large voltage difference active fast equalization circuit includes N series-connected energy storage batteries, 2N switch tubes and N pairs of inductor coils, each energy storage battery corresponds to each pair of inductor coils one by one, wherein the secondary winding of the inductor coil is connected in series with a switch tube and then connected in parallel with the corresponding energy storage battery, the primary winding of the inductor coil is connected in series in sequence and then connected in parallel with the N series-connected energy storage batteries as a whole, and at the same time, the primary winding is also connected to one end of the corresponding energy storage battery through a switch tube; the switch tube is controlled to be turned on according to the maximum voltage difference between each energy storage battery.

[0024] In practical applications, the switch connected in series with the primary winding and the switch connected in series with the secondary winding are turned on alternately and receive control signals with opposite phases. In one embodiment, the control signal received by the switch is a square wave pulse signal with a duty cycle of 50%.

[0025] In this embodiment, the turns ratio of the primary winding to the secondary winding of each pair of inductor coils is 1: 1. In other embodiments, the turns ratio of the primary winding to the secondary winding of the inductor coils can also be adjusted according to requirements.

[0026] Through the balancing circuit proposed in this embodiment, it is only necessary to detect the maximum voltage difference between each energy storage battery in real time, and then control the on and off of the switch tube to achieve rapid balancing of the energy storage battery. Specifically, when the maximum voltage difference between each energy storage battery is between 0.1 and 0.5, the switch tube connected in series with the primary winding and the switch tube connected in series with the secondary winding are alternately turned on. When the maximum voltage difference between each energy storage battery is greater than or equal to 0.5v, the 1st to N-1st switch tubes connected to the primary winding are turned off, and the Nth switch tube connected to the primary winding and the switch tube connected to the secondary winding are alternately turned on.

[0027] In practical applications, energy storage batteries are generally equipped with BMS, and the maximum voltage difference between energy storage batteries can be obtained through the energy storage battery voltage information provided by BMS.

[0028] The switch tube is a controllable switch device, and any suitable semiconductor switch device can be selected, such as a metal oxide semiconductor field effect tube (Metal Oxide Semiconductor Field Effect Transistor, MOSFET) or a bipolar junction transistor (Bipolar Junction Transistor, BJT) or a junction field effect transistor (Junction Field Effect Transistor, JFET), etc. In this embodiment, an NMOS tube is used as a switch tube for illustration. In other embodiments, other types of switch tubes can also be adjusted.

[0029] In order to better understand the present embodiment, a battery large voltage difference active fast equalization circuit is proposed. The following takes 4 energy storage batteries connected in series as an example to illustrate the equalization circuit and its working method. Correspondingly, the equalization circuit includes 8 MOS switches and 4 pairs of inductors. It should be noted that in actual applications, the number of energy storage batteries and the number of switches and inductors can be adjusted accordingly as needed.

[0030] Please refer to Figure 1, the energy storage batteries D1, D2, D3, and D4 are connected in series in sequence, the first end of the energy storage battery D1 is respectively connected to the first ends of the primary winding Ns and the secondary winding Nf of the inductor T1, the second end of the energy storage battery D1 is connected to the second end of the secondary winding Nf of the inductor T1 through the MOS switch tube Q8, and is connected to the second end of the primary winding Ns of the inductor T1 through the MOS switch tube Q7. The first end of the energy storage battery D2 is connected to the first end of the secondary winding Nf of the inductor T2, the second end of the energy storage battery D2 is connected to the second end of the secondary winding Nf of the inductor T2 through the MOS switch tube Q6, and is connected to the second end of the primary winding Ns of the inductor T2 through the MOS switch tube Q5. The first end of the energy storage battery D3 is connected to the first end of the secondary winding Nf of the inductor T3, and the second end of the energy storage battery D3 is connected to the second end of the secondary winding Nf of the inductor T3 through the MOS switch tube Q4, and is connected to the second end of the primary winding Ns of the inductor T3 through the MOS switch tube Q3. The first end of the energy storage battery D4 is connected to the first end of the secondary winding Nf of the inductor T4, and the second end of the energy storage battery D4 is connected to the second end of the secondary winding Nf of the inductor T4 through the MOS switch tube Q2, and is connected to the second end of the primary winding Ns of the inductor T4 through the MOS switch tube Q1. Finally, the primary windings of the inductors T1, T2, T3, and T4 are connected in series in sequence, and the second end of the energy storage battery D4 is connected to the outside. Each energy storage battery is connected to a BMS (not shown in the figure).

[0031] In this balancing circuit, Q1, Q3, Q5, Q7 are a group of MOS switches, and the gate input is the same group of square wave pulse signals with a duty cycle of 50%. Q2, Q4, Q6, Q8 are another group of MOS switches, and the gate input is another group of square wave pulse signals with a duty cycle of 50%. The signal phases of the two groups of MOS switch tubes are exactly opposite, that is, when Q1, Q3, Q5, Q7 is turned on, Q2, Q4, Q6, Q8 is turned off, and vice versa. The number of turns of the primary winding and the secondary winding in the inductor coils T1, T2, T3, T4 is the same, and the turn ratio is Ns:Nf=1:1.

[0032] It should be noted that Figure 1 What is shown is only a connection diagram of using an NMOS tube as a switch. When a PMOS tube is used as a switch tube, its setting position is adjusted, but the principle is the same.

[0033] The following is for Figure 1 The working process of the equalization circuit shown is explained.

[0034] Please refer to Figure 2, which shows the working mode 1 of the balancing circuit under small voltage difference. When the BMS balancing system is working, the BMS system will measure the voltage of the four energy storage batteries. When the maximum voltage difference of the four energy storage batteries is 0.1< and <0.5V (assuming that the voltage of the energy storage battery D3 is low), the two groups of MOS tubes (Q1, Q3, Q5, Q7 and Q2, Q4, Q6, Q8) are turned on and off alternately. At this time, the circuit is a push-pull circuit. The battery with high voltage charges the battery with low voltage (and it may be three batteries charging one battery), and the charging current increases with the increase of the voltage difference, that is, the greater the voltage difference, the greater the balancing current. In this case, voltage balancing can be achieved quickly.

[0035] Please refer to Figure 3 , which shows the working mode 2 of the balancing circuit under large voltage difference. When the BMS measures the battery voltage difference>=0.5v, the driving pulses of Q3, Q5, and Q7 are stopped, that is, Q3, Q5, and Q7 are in the off state, and only the two groups of MOS tubes Q1 and Q2, Q4, Q6, and Q8 are switched alternately. At this time, the circuit works in the flyback balancing state, that is, when Q1 is turned on, the battery pack charges the primary winding Ns in the four inductors T1, T2, T3, and T4. When Q1 is turned off and Q2, Q4, Q6, and Q8 are turned on, the electric energy stored in the primary winding Ns in the four inductors T1, T2, T3, and T4 charges the battery with low voltage through the secondary winding Nf. Because 4Ns:Nf=4:1, the switch duty cycle is 50%, so the flyback voltage on the secondary winding Nf is (V D1 +V D2 +V D3 +V D4 ) / 4, if the voltage of D3 is the lowest (V D3 It must be <(V D1 +V D2 +V D3 +V D4 ) / 4), so the secondary winding Nf charges D3, and the cycle continues until D3 reaches the average voltage.

[0036] Although it can eventually reach overall balance when working in working mode 2, it takes longer time when the battery voltage difference is small. If in working mode 2, the BMS finds that the battery voltage difference is <0.5v by measuring the battery voltage, it can switch to working mode 1 for balancing, so that all battery power balance can be achieved faster.

[0037] Furthermore, this embodiment also provides a balancing method based on a battery large voltage difference active fast balancing circuit, which specifically includes:

[0038] (1) Real-time detection of the maximum voltage difference between each energy storage battery;

[0039] (2) When the maximum voltage difference is greater than or equal to 0.5, the 1st to N-1st switch tubes connected to the primary winding are controlled to be turned off, and the Nth switch tube connected to the primary winding and the switch tube connected to the secondary winding are alternately turned on to charge the energy storage battery with the lowest voltage;

[0040] (3) When the maximum voltage difference is less than 0.5, the switch tube connected in series with the primary winding and the switch tube connected in series with the secondary winding are controlled to be turned on alternately until the balancing of each energy storage battery is completed.

[0041] This embodiment also proposes a distributed energy storage rod, which includes N series-connected energy storage batteries, and the energy storage battery uses the aforementioned battery large voltage difference active fast equalization circuit to complete the voltage difference equalization. Since the voltage of the battery is uneven after leaving the factory, the maximum voltage difference between the batteries can be as large as 2-3v. The factory will not perform equalization charging before assembly, nor will it perform measurement of similar voltages and assembly after sorting (reducing assembly procedures). Therefore, it is required that the equalization circuit can safely equalize the situation where the initial state of the battery pack is a large voltage difference, and it cannot cause dangerous situations such as overheating due to the large equalization current caused by the large voltage difference. When this equalization circuit is applied to the distributed energy storage rod, it solves the large voltage difference of the initial assembly of the battery. After being used on site and after an automatic equalization, the energy storage rod automatically performs equalization under the condition of a small voltage difference.

[0042] The present invention combines the advantages of two circuits: flyback fixed power balancing under high voltage difference and push-pull automatic fast balancing under low voltage difference, which can realize the ideal balancing method at low cost. The control method of balancing is also very simple, only 50% duty cycle driving is required, and there is no need to frequently measure and check the battery voltage. The balancing effect can also be achieved by using timed long balancing. After balancing, the battery voltage difference is <10 millivolts.

[0043] Example 1

[0044] This embodiment proposes a battery large voltage difference active fast equalization circuit, including N series-connected energy storage batteries, 2N switching tubes and N pairs of inductors, each energy storage battery corresponds to each pair of inductors one by one, wherein the secondary winding of the inductor is connected in series with a switching tube and then connected in parallel with the corresponding energy storage battery, the primary winding of the inductor is sequentially connected in series with the N series-connected energy storage batteries as a whole and connected in parallel, and at the same time, the primary winding is also connected to one end of the corresponding energy storage battery through a switching tube; the switching tube is controlled to be turned on according to the maximum voltage difference between each energy storage battery.

[0045] Example 2

[0046] On the basis of Embodiment 1, in this embodiment, the switch tube connected in series with the primary winding and the switch tube connected in series with the secondary winding are turned on alternately and the received control signals have opposite phases.

[0047] Example 3

[0048] On the basis of Example 2, in this embodiment, the turns ratio of the primary winding to the secondary winding of each pair of inductor coils is 1:1.

[0049] Example 4

[0050] On the basis of Embodiment 3, in this embodiment, when the maximum voltage difference between the energy storage batteries is between 0.1 and 0.5, the switch tube connected in series with the primary winding and the switch tube connected in series with the secondary winding are alternately turned on.

[0051] Example 5

[0052] Based on Example 4, in this embodiment, when the maximum voltage difference between each energy storage battery is greater than or equal to 0.5V, the 1st to N-1th switch tubes connected to the primary winding are turned off, and the Nth switch tube connected to the primary winding and the switch tube connected to the secondary winding are alternately turned on.

[0053] Example 6

[0054] On the basis of Embodiment 1, in this embodiment, the switch tube receives a square wave pulse signal with a duty cycle of 50%.

[0055] Example 7

[0056] On the basis of Embodiment 1, in this embodiment, the switch tube is a MOS tube.

[0057] Example 8

[0058] On the basis of Example 1, in this embodiment, each energy storage battery is connected to a BMS for providing voltage information of each energy storage battery.

[0059] Example 9

[0060] This embodiment proposes a method for active fast equalization of a battery with a large voltage difference, which is implemented based on the active fast equalization circuit for a battery with a large voltage difference described in Embodiment 1, and includes:

[0061] Detect the maximum voltage difference between each energy storage battery;

[0062] When the maximum voltage difference is greater than or equal to 0.5, the 1st to N-1st switch tubes connected to the primary winding are controlled to be turned off, and the Nth switch tube connected to the primary winding and the switch tube connected to the secondary winding are alternately turned on to charge the energy storage battery with the lowest voltage;

[0063] When the maximum voltage difference is less than 0.5, the switch tube connected in series with the primary winding and the switch tube connected in series with the secondary winding are controlled to be turned on alternately until the balancing of each energy storage battery is completed.

[0064] Example 10

[0065] This embodiment proposes a distributed energy storage rod, which includes N series-connected energy storage batteries. The energy storage batteries use the battery large voltage difference active fast equalization circuit described in Embodiment 1 to achieve voltage difference equalization.

[0066] The present invention can be better implemented through Examples 1 to 10.

[0067] For those skilled in the art, the specific meanings of the above terms in the present invention can be understood in specific situations; the drawings in the embodiments are used to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0068] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A battery large voltage difference active fast equalization circuit, characterized in that: It includes N series-connected energy storage batteries, 2N switching tubes and N pairs of inductors, each energy storage battery corresponds to each pair of inductors one by one, wherein the secondary winding of the inductor is connected in series with a switching tube and then connected in parallel with the corresponding energy storage battery, the primary winding of the inductor is sequentially connected in series with the N series-connected energy storage batteries as a whole and at the same time, the primary winding is also connected to one end of the corresponding energy storage battery through a switching tube; the switching tube is controlled to be turned on according to the maximum voltage difference between each energy storage battery.

2. The battery large voltage difference active fast equalization circuit according to claim 1, characterized in that: The switch tube connected in series with the primary winding and the switch tube connected in series with the secondary winding are turned on alternately and receive control signals with opposite phases.

3. The battery large voltage difference active fast equalization circuit according to claim 1, characterized in that: The turns ratio of the primary winding to the secondary winding of each pair of inductor coils is 1:

1.

4. The battery large voltage difference active fast equalization circuit according to claim 1, characterized in that: When the maximum voltage difference between the energy storage batteries is between 0.1 and 0.5, the switch tube connected in series with the primary winding and the switch tube connected in series with the secondary winding are alternately turned on.

5. The battery large voltage difference active fast equalization circuit according to claim 1, characterized in that: When the maximum voltage difference between the energy storage batteries is greater than or equal to 0.5V, the 1st to N-1st switch tubes connected to the primary winding are turned off, and the Nth switch tube connected to the primary winding and the switch tube connected to the secondary winding are alternately turned on.

6. The battery large voltage difference active fast equalization circuit according to claim 2, characterized in that: The switch tube receives a square wave pulse signal with a duty cycle of 50%.

7. The battery large voltage difference active fast equalization circuit according to claim 1, characterized in that: The switch tube is a MOS tube.

8. The battery large voltage difference active fast equalization circuit according to claim 1, characterized in that: Each energy storage battery is connected to the BMS to provide voltage information of each energy storage battery.

9. A method for active and rapid equalization of large voltage differences in batteries, characterized in that: The battery large voltage difference active fast equalization circuit according to any one of claims 1 to 8 is implemented, comprising: Detect the maximum voltage difference between each energy storage battery; When the maximum voltage difference is greater than or equal to 0.5, the 1st to N-1st switch tubes connected to the primary winding are controlled to be turned off, and the Nth switch tube connected to the primary winding and the switch tube connected to the secondary winding are alternately turned on to charge the energy storage battery with the lowest voltage; When the maximum voltage difference is less than 0.5, the switch tube connected in series with the primary winding and the switch tube connected in series with the secondary winding are controlled to be turned on alternately until the balancing of each energy storage battery is completed.

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