A lead-acid battery active balancing device

Abstract

The utility model discloses a kind of lead-acid battery active equalization device, comprising: control module, switch module, flyback transformer and sampling module;Control module is connected with switch module, flyback transformer, sampling module, flyback transformer is connected with switch module, sampling module;To be controlled battery pack includes multiple series lead-acid batteries, lead-acid battery is connected with switch module, flyback transformer;Sampling module generates feedback signal, control module generates control signal according to feedback signal, switch module closes or shuts off the connection between lead-acid battery and flyback transformer according to control signal, and flyback transformer switches charge-discharge state according to feedback signal.Flyback transformer is used as electric quantity transfer medium, and the voltage of each lead-acid battery is balanced.

Description

Technical Field

[0001] This utility model relates to the field of battery balancing technology, and in particular to an active balancing device for lead-acid batteries. Background Technology

[0002] Currently, due to the advantages of lead-acid batteries such as high safety and low cost, the vast majority of two-wheeled electric vehicles in China use lead-acid battery packs as their power source. As users' demands for overall vehicle performance gradually increase, the number of batteries connected in series in these power lead-acid battery packs is also increasing. At the time of manufacture, the internal resistance, voltage, and other characteristics of each power lead-acid battery cannot be exactly the same; if the voltage differences between individual lead-acid batteries are not controlled, these differences will increase with each use. This means that the more lead-acid batteries connected in series, the faster the rate of voltage difference will occur, and the shorter the battery pack's lifespan will be.

[0003] However, due to their low energy density and large size, and the limited space in two-wheeled electric vehicles, lead-acid battery packs cannot be assembled into a closed battery pack like lithium batteries, and a BMS (Battery Management System) cannot be added inside the battery pack to monitor and protect each lead-acid battery, such as through active or passive balancing measures, to ensure that the voltage of each lead-acid battery remains consistent.

[0004] Therefore, there is an urgent need for a lead-acid battery equalization device to ensure that the voltage of each lead-acid battery in the battery pack is the same. Utility Model Content

[0005] In order to overcome the shortcomings of the existing technology, the purpose of this utility model is to provide an active balancing device for lead-acid batteries, which uses a flyback transformer as the power transfer medium to achieve voltage balancing of each lead-acid battery, avoid large differences between lead-acid batteries, and extend the life of the battery pack.

[0006] To solve the above problems, this utility model is implemented according to the following solution:

[0007] An active balancing device for lead-acid batteries is provided, comprising: a control module, a switching module, a flyback transformer, and a sampling module; the control module is connected to the switching module, the flyback transformer, and the sampling module, and the flyback transformer is connected to the switching module and the sampling module.

[0008] The battery pack to be controlled includes multiple lead-acid batteries connected in series, and the lead-acid batteries are connected to the switching module and the flyback transformer;

[0009] The sampling module generates a feedback signal, the control module generates a control signal based on the feedback signal, the switching module closes or closes the connection between the lead-acid battery and the flyback transformer based on the control signal, and the flyback transformer switches the charging and discharging states based on the control signal.

[0010] Compared with the prior art, the beneficial effects of the active balancing device for lead-acid batteries of this utility model are as follows: the control module generates a control signal based on the feedback signal, drives the switching module to connect the lead-acid battery with high charge to the flyback transformer, and uses the energy storage characteristics of the flyback transformer to store excess energy and then releases the stored charge to the lead-acid battery with lower charge, thereby avoiding the difference between lead-acid batteries becoming larger and extending the battery pack's lifespan.

[0011] Optionally, the flyback transformer includes a primary coil and a secondary coil in the same number as the lead-acid battery; the primary coil is connected to the lead-acid battery, the sampling module, and the control module; the first input terminal of the secondary coil is connected to the switching module; and the second input terminal of the secondary coil is connected to the lead-acid battery.

[0012] Optionally, the switching module includes multiple switching units with identical structures, the number of which is the same as the number of lead-acid batteries; the switching units are connected to the control module and the first input terminal of the secondary coil.

[0013] Optionally, the switching unit includes a switching transistor and a signal output circuit. The switching transistor is connected to the signal output circuit and the control module, and the signal output circuit is connected to the first input terminal of the secondary coil.

[0014] Optionally, the switching transistor is a MOSFET.

[0015] Optionally, the control module includes a control chip, a signal amplification circuit, and a transformer control unit; the control chip is connected to the signal amplification circuit, the transformer control unit, and the sampling module; the signal amplification circuit is connected to the switching transistor and the lead-acid battery; and the transformer control unit is connected to the primary coil.

[0016] Optionally, the control chip is an STM32F103C8T6. Attached Figure Description

[0017] Figure 1 This is a structural block diagram of the active balancing device of this utility model;

[0018] Figure 2 This is a schematic diagram of the signal amplification circuit of this utility model;

[0019] Figure 3This is a partial circuit diagram of the active equalization device of this utility model;

[0020] Figure 4 This is a schematic diagram of the control chip of this utility model;

[0021] The attached diagram shows the following labels: 1. Control module; 101. Control chip; 102. Signal amplification circuit; 103. Transformer control unit; 2. Switching module; 201. Switching transistor; 202. Signal output circuit; 3. Flyback transformer; 4. Sampling module; 5. Battery pack to be controlled; Detailed Implementation

[0022] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0023] In the following description, when referring to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims. In the description of this application, it should be understood that the terms "first," "second," "third," etc., are used only to distinguish similar objects and are not necessarily used to describe a specific order or sequence, nor should they be construed as indicating or implying relative importance. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0024] See Figure 1 As shown, the present invention discloses an active balancing device for lead-acid batteries, comprising: a control module 1, a switch module 2, a flyback transformer 3, and a sampling module 4; the control module 1 is connected to the switch module 2, the flyback transformer 3, and the sampling module 4, and the flyback transformer 3 is connected to the switch module 2 and the sampling module 4; the battery pack to be controlled 5 comprises multiple lead-acid batteries connected in series, and the lead-acid batteries are connected to the switch module 2 and the flyback transformer 3.

[0025] The sampling module 4 generates a feedback signal, the control module 1 generates a control signal based on the feedback signal, the switching module 2 closes or closes the connection between the lead-acid battery and the flyback transformer 3 based on the control signal, and the flyback transformer 3 switches the charging and discharging state based on the feedback signal.

[0026] In one embodiment of this utility model, the flyback transformer 3 includes a primary coil and a secondary coil of the same number as the lead-acid batteries. Taking a commonly available resistor consisting of six lead-acid batteries connected in series as an example, there are six secondary coils and two primary coils. The turns ratio of the primary coil to the secondary coil is 3:1. The primary coil is connected to the lead-acid batteries, the sampling module 4, and the control module 1. The first input terminal of the secondary coil is connected to the switch module 2, and the second input terminal of the secondary coil is connected to the lead-acid batteries.

[0027] In one embodiment of this utility model, the switch module 2 includes multiple switch units with the same structure, the number of switch units being the same as the number of lead-acid batteries; each switch unit is connected to a lead-acid battery, the control module 1, and the first input terminal of the secondary coil; wherein, the switch unit includes a switch transistor 201 (which is a MOS transistor) and a signal output circuit 202, the switch transistor 201 being connected to the control module 1 and the signal output circuit 202, and the signal output circuit 202 being connected to the first input terminal of the secondary coil.

[0028] The control module 1 includes a control chip 101 (STM32F103C8T6), a signal amplification circuit 102, and a transformer control unit 103. The control chip 101 is connected to the signal amplification circuit 102, the transformer control unit 103, and the sampling module 4. The signal amplification circuit 102 is connected to the switching transistor 201, and the transformer control unit 103 is connected to the primary coil. The equalization device of this invention will now be described using a battery pack 5 consisting of six series-connected lead-acid batteries as an example.

[0029] See Figure 2-4 As shown, the negative terminal of the lead-acid battery is connected to the signal amplification circuit 102 to form a current loop from the positive terminal of the lead-acid battery to the second input terminal of the secondary coil, the first input terminal of the secondary coil, the switching unit, the signal amplification circuit 102, and the negative terminal of the lead-acid battery. The initial signal output by the control chip 101 is amplified by the signal amplification circuit 102 to obtain six control signals, S1, S2, ..., S6. These control signals are used to control the switching state of the switching transistor 201. When the signal amplification circuit 102 has no output, the lead-acid battery will not self-discharge or recharge, thus avoiding self-discharge of the lead-acid battery when it is idle and extending the life of the lead-acid battery.

[0030] When the switch 201 is turned on, the connection between the switch 201 and the first input terminal of the secondary coil is closed. At this time, the current loop between the switch 201, the first input terminal of the secondary coil, the second input terminal of the secondary coil, and the lead-acid battery is closed. That is, the connection (current loop) between the lead-acid battery and the secondary coil of the flyback transformer 3 is closed. At this time, the lead-acid battery releases electricity to the secondary coil. When the switch 201 is turned off, the flyback transformer uses the mutual inductance principle to store the electricity released by the lead-acid battery in the primary coil.

[0031] The sampling module 4 feeds back the voltage of each lead-acid battery through the feedback signal Umux, thereby enabling the sampling of the voltage of 6 lead-acid batteries with only one I / O port of the control chip 101. The transformer control unit 103 includes a MOSFET T7. The control signal Prim_L generated by the control chip 101 is used to switch the charging and discharging state of the primary coil of the flyback transformer 3. Specifically, it controls the switching state of the MOSFET T7. When the MOSFET T7 is on, the flyback transformer 3 is in the discharging state, and the primary coil releases electricity to the lead-acid battery pack. When the MOSFET T7 is off, the flyback transformer 3 is in the charging state. Specifically, when the MOSFET T7 is kept off, any switch 201 changes from off to on, and the primary coil transfers electricity to the secondary coil connected to the switch 201. The secondary coil charges the single lead-acid battery connected in parallel with it.

[0032] Assuming the voltage of lead-acid battery B1 is higher than that of the other lead-acid batteries, the balancing device operates as follows: Control chip 101 generates control signal S1 to control switch T8 to turn on, causing lead-acid battery B1 to release power to its parallel secondary coil. When the power release time is equal to a preset time, control signal S1 to turn off switch T8 is generated. Flyback transformer 3 uses mutual inductance to transfer the electrical energy of the secondary coil to the primary coil, that is, the primary coil stores the power released by lead-acid battery B1 to the secondary coil. Then, control chip 101 generates control signal Prim_L to turn on MOSFET T7 (transformer control unit 103), controlling flyback transformer 3 to be in a discharging state. The primary coil uses its stored power to charge the battery pack to be controlled (lead-acid batteries B1-B6). Sampling module 4 collects the battery voltage of all lead-acid batteries again, determines the voltage difference between lead-acid battery B1 and the average voltage of all lead-acid batteries, and repeats the above process of power transfer and average voltage determination until the voltage difference between lead-acid battery B1 and the average voltage of all lead-acid batteries is no greater than 0.1V. At this point, the equalization device stops working, thus transferring the excess power of lead-acid battery B1 to all lead-acid batteries in the battery pack, thereby achieving power equalization of multiple lead-acid batteries in the battery pack.

[0033] Assuming the voltage of lead-acid battery B1 is lower than that of the other lead-acid batteries, the balancing device operates as follows: Control chip 101 generates control signals S1-S6 to control switches T1, T2, T3, T5, T6, and T8 to open, causing lead-acid batteries B1-B6 to release power to their parallel secondary coils. When the power release time equals a preset time, control signals S1-S6 are generated to close switches T1, T2, T3, T5, T6, and T8. The flyback transformer 3 uses mutual inductance to transfer the energy of the secondary coil to the primary coil, i.e., the primary coil stores the power released by lead-acid batteries B1-B6 to the secondary coil. The control signal S1 for opening switch T8 controls the flyback transformer 3 to be in a discharging state. The primary coil transfers the stored power to the secondary coil connected in parallel with lead-acid battery B1 through mutual inductance with the secondary coil, and the secondary coil charges lead-acid battery B1. The acquisition module 4 acquires the battery voltage of all lead-acid batteries again, determines the voltage difference between lead-acid batteries B1-B6 and the average voltage of all lead-acid batteries, and repeats the above process of power transfer and average voltage determination until the voltage difference between any one of the six lead-acid batteries and the average voltage of all lead-acid batteries is no greater than 0.1V. At this point, the equalization device stops working, realizing the transfer of excess power in the battery pack to the lead-acid battery B1 with low power, thereby achieving power balance among the multiple lead-acid batteries in the battery pack.

[0034] This invention utilizes the energy storage characteristics of the flyback transformer 3 to store excess energy from lead-acid batteries and releases the stored energy to lead-acid batteries with lower energy levels, thereby preventing the voltage difference between multiple lead-acid batteries in the battery pack from increasing and extending the battery pack's lifespan.

[0035] The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. An active balancing device for lead-acid batteries, characterized in that, include: The system includes a control module, a switching module, a flyback transformer, and a sampling module; the control module is connected to the switching module, the flyback transformer, and the sampling module, and the flyback transformer is connected to the switching module and the sampling module. The battery pack to be controlled includes multiple lead-acid batteries connected in series, and the lead-acid batteries are connected to the switching module and the flyback transformer; The sampling module generates a feedback signal, the control module generates a control signal based on the feedback signal, the switching module closes or closes the connection between the lead-acid battery and the flyback transformer based on the control signal, and the flyback transformer switches the charging and discharging state based on the feedback signal.

2. The active balancing device for lead-acid batteries according to claim 1, characterized in that, The flyback transformer includes a primary coil and a secondary coil in the same number as the lead-acid battery. The primary coil is connected to the lead-acid battery, the sampling module, and the control module. The first input terminal of the secondary coil is connected to the switching module, and the second input terminal of the secondary coil is connected to the lead-acid battery.

3. The active balancing device for a lead-acid battery according to claim 2, characterized in that, The switching module includes multiple identical switching units, the number of which is the same as the number of lead-acid batteries; the switching units are connected to the control module and the first input terminal of the secondary coil.

4. The active balancing device for a lead-acid battery according to claim 3, characterized in that, The switching unit includes a switching transistor and a signal output circuit. The switching transistor is connected to the signal output circuit and the control module. The signal output circuit is connected to the first input terminal of the secondary coil.

5. The active balancing device for a lead-acid battery according to claim 4, characterized in that, The switching transistor is a MOSFET.

6. The active balancing device for a lead-acid battery according to claim 4, characterized in that, The control module includes a control chip, a signal amplification circuit, and a transformer control unit; the control chip is connected to the signal amplification circuit, the transformer control unit, and the sampling module; the signal amplification circuit is connected to the switching transistor and the lead-acid battery; and the transformer control unit is connected to the primary coil.

7. The active balancing device for a lead-acid battery according to claim 6, characterized in that, The control chip is an STM32F103C8T6.

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