Active equalization control circuit of battery pack

Abstract

The utility model relates to the field of lithium battery charging and discharging protection, and discloses an active equalization control circuit of a battery pack, which comprises a control unit, an independent power supply, an optical coupler, an MOS (Metal Oxide Semiconductor) tube circuit and an equalization capacitor, each MOS tube circuit is electrically connected between the corresponding single battery and the balancing capacitor and is used for connecting or disconnecting a closed circuit of the single battery and the balancing capacitor; the positive electrode of the single independent power supply is electrically connected with the collector electrode of the single optical coupler, the negative electrode of the single independent power supply and the emitter electrode of the single optical coupler are correspondingly connected into the MOS tube circuit, the positive electrode of a diode in the optical coupler is electrically connected with the control unit, and the negative electrode of the diode in the optical coupler is grounded. The control circuit is used for controlling connection or disconnection of the independent power supply and the MOS tube circuit; the technical problem of electric energy waste of a battery charging and discharging protection circuit in the prior art is solved.

Description

Technical Field

[0001] The utility model relates to the field of lithium battery charging and discharging protection, and in particular to an active balancing control circuit of a battery pack. Background Art

[0002] At present, many devices on the market are powered by battery packs, which combine multiple single batteries in series or in parallel to obtain the final required voltage, current and capacity. When in use, multiple batteries are charged and discharged at the same time. However, in actual use, due to differences in materials, manufacturing processes, and usage environments, even if the capacity of new batteries is consistent when assembled, there will be various differences between the series-connected cells. The different state of charge of each battery affects the capacity of the battery pack, resulting in differences in capacity and voltage between single batteries in the battery pack, and the difference will gradually increase with continued use. If not handled, the battery's performance will deteriorate rapidly, resulting in premature overvoltage and undervoltage. Continuous deterioration will also accelerate battery damage and greatly reduce the battery's service life.

[0003] To address this problem, the existing solution is to connect a resistor in parallel between the positive and negative electrodes of a single battery cell to control the discharge of the resistor, thereby reducing the energy consumption of the single battery cell with excessively high voltage, reducing the voltage difference between the single battery cell and other single batteries, and ultimately achieving the purpose of balancing all batteries.

[0004] Although this method has a simple structure and is reliable to use, it releases electrical energy in the form of heat, resulting in energy waste. In addition, the heat generated by the balancing current is relatively large, causing the battery pack to heat up too high, posing a safety hazard. Utility Model Content

[0005] The utility model aims to provide an active balancing control circuit for a battery pack, so as to solve the technical problem of power waste in the battery charging and discharging protection circuit in the prior art.

[0006] In order to achieve the above-mentioned purpose, the utility model adopts the following technical scheme: an active balancing control circuit of a battery pack, including a control unit, an independent power supply, an optical coupler, a MOS tube circuit and a balancing capacitor;

[0007] The two electrodes of each battery are connected in series with a MOS tube circuit and then respectively connected to the two electrodes of the balancing capacitor, and the MOS tube circuit is used to connect the single battery and the balancing capacitor to form a closed loop;

[0008] The positive electrode of the independent power supply is connected to the collector of the optical coupler, the emitter of the optical coupler is connected to the gate of the MOS tube in the MOS tube circuit, the negative electrode of the independent power supply is connected to the MOS tube connection loop in the MOS tube circuit, the positive electrode of the diode in the optical coupler is electrically connected to the control unit, and the control unit is used to control the connection of the optical coupler so that the independent power supply allows the gate of the MOS tube to be powered, thereby controlling the connection or disconnection of the MOS tube circuit;

[0009] A detection circuit is connected to the power supply circuit of each battery, and the detection circuit includes a detection resistor connected to the power supply circuit of each battery, and the detection resistor is connected to the signal input end of the control unit. The control unit detects the voltage value of each battery and determines the voltage difference between any two batteries. If the voltage difference between any two batteries is greater than a threshold value, the control unit controls all the batteries to charge and discharge with the balancing capacitor in turn.

[0010] The principle and advantages of this solution are: in actual application, the control unit sets the threshold for controlling the start and end of balancing, the control unit obtains the voltage of each single battery, compares the voltage values, and if the voltage difference between two batteries is greater than the threshold, balancing starts, the control unit sends an electrical signal to the corresponding optical coupler, so that its diode light-emitting coupling circuit is connected, and the independent power supply supplies energy to the MOS tube circuit to connect each MOS tube, thereby connecting the single battery to the balancing capacitor, and the balancing capacitor is charged to be equal to the power supply of the battery;

[0011] The control unit cuts off the electrical signal to disconnect the balancing capacitor from the battery, and sends an electrical signal to the optical coupler corresponding to the other battery to connect the other battery to the balancing capacitor. If the voltage of the balancing capacitor is less than that of the other battery at this time, the balancing capacitor is charged and the other battery is discharged, and the connection between the balancing capacitor and the other battery is disconnected to connect the balancing capacitor to the battery again. The balancing capacitor is discharged and the battery is charged, which is equivalent to the balancing capacitor transferring the electric energy of the other battery to the battery, wherein only the electric energy transfer is generated, and the electric energy is not actively consumed, the efficiency is high and the loss is low, and the charging and discharging current can meet a large demand, the response speed is fast during the balancing process, the balancing time is short, the circuit operation is stable and reliable, and it can cope with the electric energy balancing between multiple batteries. If the number of batteries connected in series changes, it is only necessary to configure or delete the electrical components corresponding to the battery or the control unit to control the corresponding electrical signal port, which will not affect the use of the overall circuit, making the configuration of the circuit more flexible.

[0012] The circuit also uses an optical coupler to electrically isolate the independent power supply, so that each single battery can independently re-discharge the capacitor, making the circuit safer. The control unit is a programmable single-chip microcomputer, which can control the speed of balancing by programming the chip. In addition, the circuit has an automatic balancing detection function, which can control the automatic start and end of balancing, making the battery balancing intelligent, always keeping the battery in a balanced state, ensuring the performance of the battery pack, and extending the life of the battery pack.

[0013] In order to simplify the circuit and reduce the use of electrical components, another active balancing control circuit for a battery pack is provided. The circuit eliminates the use and connection of a detection resistor, and the control unit periodically controls the charge and discharge balancing between the single batteries.

[0014] The beneficial effect of this improvement is: the control unit automatically performs power balancing once every period of time. With multiple balancing, the electric energy is gradually transferred along with the balancing capacitor, so that the power of each single battery is balanced; when there are many single batteries connected in series, the single batteries will continuously have voltage differences, and the balancing capacitor will frequently start the balancing work. The corresponding timing duration is set according to the usage rules of battery performance, and the process of detecting voltage can be directly omitted, thereby eliminating electronic components such as detection resistors. Because the detection resistor corresponds to the single battery one by one, eliminating the setting of this component will greatly reduce costs and simplify the circuit.

[0015] As an improvement, the independent power supply is a packaged isolated power supply, and the isolated power supply provides 5V direct current.

[0016] The beneficial effects of this improvement are: preventing short circuits or overloads, reducing electrical interference, improving circuit operation stability, and more standardized circuit management when a large number of single-cell batteries are connected.

[0017] As an improvement, the independent power supply is a detachable dry cell battery, which provides 5V direct current.

[0018] The beneficial effect of this improvement is: further simplifying the circuit.

[0019] As an improvement, the MOS tube circuit includes a first MOS tube, a second MOS tube, a third MOS tube and a fourth MOS tube;

[0020] The drain of the first MOS tube is electrically connected to the negative electrode of the equalizing capacitor, and the drain of the third MOS tube is electrically connected to the positive electrode of the equalizing capacitor; the drain of the second MOS tube is electrically connected to the negative electrode of the single battery, and the drain of the fourth MOS tube is electrically connected to the positive electrode of the single battery;

[0021] The sources of the first MOS transistor and the second MOS transistor are interconnected and electrically connected to the negative electrode of one of the independent power supplies, and the gates of the first MOS transistor and the second MOS transistor are interconnected and electrically connected to the emitter of the optical coupler corresponding to the independent power supply;

[0022] The sources of the third MOS tube and the fourth MOS tube are interconnected and electrically connected to the negative electrode of another independent power supply, and the gates of the third MOS tube and the fourth MOS tube are interconnected and electrically connected to the emitter of the optical coupler corresponding to the independent power supply.

[0023] The beneficial effect of this improvement is: electrical isolation is performed, so that a single battery and a capacitor are charged and discharged independently, and the circuit is more stable.

[0024] As an improvement, a first stabilizing resistor is electrically connected between the control unit and the anode of the diode of the optocoupler; and a second stabilizing resistor is electrically connected between the anode of the independent power supply and the collector of the optocoupler.

[0025] The beneficial effect of this improvement is: further stabilizing the voltage and making the circuit run more stable

[0026] As an improvement, the first stabilizing resistor and the second stabilizing resistor are both 1 kΩ, and the equalizing capacitor is 100 μF.

[0027] As an improvement, the resistance of the detection resistor is 10 kΩ.

[0028] As an improvement, the first MOS tube, the second MOS tube, the third MOS tube and the fourth MOS tube are all N-channel MOS tubes with parasitic diodes.

[0029] The beneficial effect of this improvement is that it can protect the circuit, avoid short circuit of MOS tube caused by excessive voltage, and improve the stability of the circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic diagram of circuit connection of an embodiment of the utility model.

[0031] Figure 2 This is a schematic diagram of circuit connection of an embodiment of the utility model. DETAILED DESCRIPTION

[0032] The following is further described in detail through specific implementation methods:

[0033] The reference numerals in the drawings of the specification include: MOS tube circuit 1.

[0034] Example 1

[0035] Basically as attached Figure 1As shown, an active balancing control circuit of a battery pack includes a control unit, an independent power supply, an optical coupler, a MOS tube circuit 1 and a balancing capacitor;

[0036] If there are single battery V1 and single battery V2 connected in series in the main circuit, two MOS transistor circuits 1 are provided to correspond to the single battery V1 and the single battery V2 respectively; wherein MOS transistors Q1, Q2, Q3 and Q4 are provided to correspond to the single battery V1, and MOS transistors Q5, Q6, Q7 and Q8 are provided to correspond to the single battery V2;

[0037] An independent power supply u1 and an optical coupler P1 are set to correspond to MOS tubes Q1 and Q2; an independent power supply u2 and an optical coupler P2 are set to correspond to MOS tubes Q3 and Q4; an independent power supply u3 and an optical coupler P3 are set to correspond to MOS tubes Q5 and Q6; an independent power supply u4 and an optical coupler P4 are set to correspond to MOS tubes Q7 and Q8; and the balancing circuit is capacitor C1.

[0038] Among them, for the connection of a single battery V1, the drain of the MOS tube Q1 is electrically connected to the negative electrode of the capacitor C1, and the drain of the MOS tube Q3 is electrically connected to the positive electrode of the capacitor C1; the drain of the MOS tube Q2 is electrically connected to the negative electrode of the single battery V1, and the drain of the MOS tube Q4 is electrically connected to the positive electrode of the single battery V1;

[0039] The sources of the MOS transistors Q1 and Q2 are interconnected and electrically connected to the negative electrode of the independent power supply u1, and the gates of the MOS transistors Q1 and Q2 are interconnected and electrically connected to the emitter of the optical coupler P1; the sources of the MOS transistors Q3 and Q4 are interconnected and electrically connected to the negative electrode of the independent power supply u2, and the gates of the MOS transistors Q3 and Q4 are interconnected and electrically connected to the emitter of the optical coupler P2;

[0040] The connection between the single battery V2 and the MOS tubes Q5 to Q8, and the connection between the MOS tubes Q5 and Q6 and the independent power supply u3 and the optical coupler P3, and the MOS tubes Q7 and Q8 and the independent power supply u43 and the optical coupler P4 are the same as the connection method of the single battery V1; wherein the drain of the MOS tube Q5 is electrically connected to the negative electrode of the capacitor C1, and the drain of the MOS tube Q7 is electrically connected to the positive electrode of the capacitor C1.

[0041] The resistor R8 is set as the first stabilizing resistor of the optical coupler P1, and the resistor R7 is set as the second stabilizing resistor of the optical coupler P1, then the positive electrode of the independent power supply u1 is electrically connected to the collector of the optical coupler P1 through the resistor R7, and the control unit is electrically connected to the positive electrode of the diode of the optical coupler P1 through the resistor R8;

[0042] The connection method of optocouplers P2~P4 is similar. The positive electrode of independent power supply u2 is electrically connected to the collector of optocoupler P2 through resistor R5, and the control unit is electrically connected to the positive electrode of the diode of optocoupler P2 through resistor R6; the positive electrode of independent power supply u3 is electrically connected to the collector of optocoupler P3 through resistor R3, and the control unit is electrically connected to the positive electrode of the diode of optocoupler P3 through resistor R4; the positive electrode of independent power supply u4 is electrically connected to the collector of optocoupler P4 through resistor R1, and the control unit is electrically connected to the positive electrode of the diode of optocoupler P4 through resistor R2.

[0043] Among them, MOS tubes Q1~Q8 are N-channel MOS tubes with parasitic diodes, the resistance of resistors R1~R8 is 1kΩ, and the capacitance C1 is 100μF; the voltage of independent power supplies u1~u4 is 5V, and the independent power supply can be a detachable dry battery or a packaged isolated power supply; such as the isolated drive power chip model RM3390S. The control unit is an 8051 programmable single-chip microcomputer, which is electrically connected to a power supply with a voltage of 5V to supply energy to the control unit.

[0044] The control unit does not need to detect the voltage of the single battery V1 and the single battery V2, but only needs to pre-enter the program, such as making the equalizing capacitor charge and discharge equalized every two hours;

[0045] The specific balancing process is as follows:

[0046] First, the control unit sends an electrical signal to the optocoupler P1 and the optocoupler P2, so that the diodes of the optocoupler P1 and the optocoupler P2 emit light, so that the independent power supply u1 and the independent power supply u2 are connected with the MOS tubes Q1, Q2 and the MOS tubes Q3, Q4 respectively, and the MOS tubes Q1~Q4 are connected, so that the single battery V1 is connected with the capacitor C1, and the single battery V1 charges the capacitor C1.

[0047] After charging is completed, the voltage of the single battery V1 and the capacitor C1 are equal, the control unit cuts off the electrical signal to the optical coupler P1 and the optical coupler P2, the corresponding diodes are extinguished, the MOS tubes Q1~Q4 are disconnected, and the single battery V1 is disconnected from the capacitor C1; the control unit then sends an electrical signal to the optical coupler P3 and the optical coupler P4, so that the diodes of the optical coupler P3 and the optical coupler P4 emit light, and the MOS tubes Q5~Q8 are connected, so that the single battery V2 is connected with the capacitor C1;

[0048] (1) If the voltage of the single-cell battery V1 is greater than the voltage of the single-cell battery V2 at this time, the voltage of the capacitor C1 is greater than the single-cell battery V2, and the capacitor C1 discharges to the single-cell battery V2, and the voltage of the single-cell battery V2 increases to balance the voltage difference between the two. When the next active balancing occurs, the single-cell battery V1 transfers electrical energy to the capacitor C1 again, and this process repeats until balance is achieved; (2) If the voltage of the single-cell battery V1 is less than the voltage of the single-cell battery V2 at this time, the voltage of the capacitor C1 is less than the voltage of the single-cell battery V2, and the capacitor C1 charges to the single-cell battery V2, and the voltage of the single-cell battery V2 decreases to balance the voltage difference between the two. When the next active balancing occurs, the capacitor C1 transfers electrical energy to the single-cell battery V1, and this process repeats until balance is achieved; (3) If the voltage of the single-cell battery V1 is equal to the voltage of the single-cell battery V2 at this time, the voltage of the single-cell battery V2 remains unchanged, and the single-cell battery V1 and the single-cell battery V2 are in the balancing device.

[0049] Capacitor C1 performs active balancing once every two hours. With multiple balancing, the electric energy is transferred by capacitor C1, and the difference between single battery V1 and single battery V2 is balanced. In addition, the regular operation of capacitor C1 can also keep single battery V1 and single battery V2 in a balanced state at all times.

[0050] Example 2

[0051] Based on Example 1, as shown in the attached Figure 2 As shown, a detection resistor is provided, and the detection resistor corresponds to a single battery cell. Then, the detection resistor R9 is set to correspond to the single battery cell V2, and the detection resistor R10 corresponds to the single battery cell V1. The control unit is electrically connected to the positive electrode of the single battery cell V2 at the connection point VCC2 through the detection resistor R9, and the control unit is electrically connected to the positive electrode of the single battery cell V1 at the connection point VCC1 through the detection resistor R10, so that the control unit can actively monitor the voltage difference between the single battery cell V1 and the single battery cell V2. The control unit sets a threshold value for controlling the start and end of balancing, and the threshold value can be specifically set according to the actual situation. In this embodiment, the threshold value is set to 0.1V.

[0052] The specific balancing process is as follows:

[0053] The control circuit monitors the voltage of the single-cell battery V1 and the single-cell battery V2 in real time by the detection resistors R9 and R10. If the voltage of the single-cell battery V1 is 3.2V and the voltage of the single-cell battery V2 is 3.8V, and the difference between the two is 0.6V, which is greater than the threshold value of 0.1V, the control unit first controls the capacitor C1 to be connected to the single-cell battery V1, so that the capacitor C1 is fully charged to 3.2V voltage, and then controls the capacitor C1 to be disconnected from the single-cell battery V1 so that the capacitor C1 is connected to the single-cell battery V2, so that the capacitor C1 is fully charged to 3.35V voltage; disconnects the connection between the capacitor C1 and the single-cell battery V2, so that the capacitor C1 is connected to the single-cell battery V1, and the single-cell battery V1 is fully charged to 3.27V potential; repeatedly connects the capacitor C1 to the single-cell batteries V1 and V2 in turn to transfer electric energy, and finally makes the power supplies of the single-cell batteries V1 and V2 both 3.5V, so that the single-cell batteries V1 and the single-cell batteries V2 are always in a balanced state. Compared with Example 1, Example 2 can control the number of balancing times more flexibly, reduce unnecessary balancing times and thus reduce the energy consumption of the control unit and the independent power supply.

[0054] Since the voltage difference within a small range between single batteries has little impact on practical applications and can be ignored, in order to further save energy consumption, two thresholds can also be entered in the control unit, such as the first threshold controls the start of balancing and the second threshold controls the end of balancing; for example, the first threshold is set to 0.3V and the second threshold is set to 0.1V, then balancing starts when the voltage difference between single batteries V1 and V2 is greater than 0.3, and balancing ends when the voltage difference between single batteries V1 and V2 is less than or equal to 0.1V.

[0055] Embodiment 1 and Embodiment 2 are merely examples of the case where two single-cell batteries are connected in series. When there are multiple single-cell batteries connected in series, it is only necessary to add a corresponding number of independent power supplies, optical couplers, MOS tubes and other electronic component sets and connect them to the corresponding single-cell batteries to achieve balanced control between multiple batteries.

[0056] When there are multiple batteries connected in series, it is only necessary to compare the difference between the lowest voltage value and the highest voltage value to determine whether to start or end balancing.

[0057] The above is only an embodiment of the utility model, and the common knowledge such as the known specific technical solutions and / or characteristics in the solution is not described in detail here. It should be pointed out that for those skilled in the art, without departing from the technical solution of the utility model, several deformations and improvements can be made, which should also be regarded as the protection scope of the utility model, and these will not affect the effect of the implementation of the utility model and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. An active balancing control circuit for a battery pack, characterized in that: It includes a control unit, an independent power supply, an optical coupler, a MOS tube circuit and a balancing capacitor; The two electrodes of each battery are connected in series with a MOS tube circuit and then respectively connected to the two electrodes of the balancing capacitor, and the MOS tube circuit is used to connect the single battery and the balancing capacitor to form a closed loop; The positive electrode of the independent power supply is connected to the collector of the optical coupler, the emitter of the optical coupler is connected to the gate of the MOS tube in the MOS tube circuit, the negative electrode of the independent power supply is connected to the MOS tube connection loop in the MOS tube circuit, the positive electrode of the diode in the optical coupler is electrically connected to the control unit, and the control unit is used to control the connection of the optical coupler so that the independent power supply allows the gate of the MOS tube to be powered, thereby controlling the connection or disconnection of the MOS tube circuit; A detection circuit is connected to the power supply circuit of each battery, and the detection circuit includes a detection resistor connected to the power supply circuit of each battery, and the detection resistor is connected to the signal input end of the control unit. The control unit detects the voltage value of each battery and determines the voltage difference between any two batteries. If the voltage difference between any two batteries is greater than a threshold value, the control unit controls all the batteries to charge and discharge with the balancing capacitor in turn.

2. The active balancing control circuit of the battery pack according to claim 1, characterized in that: The resistance of the detection resistor is 10 kΩ.

3. An active balancing control circuit for a battery pack, characterized in that: It includes a control unit, an independent power supply, an optical coupler, a MOS tube circuit and a balancing capacitor; The two electrodes of each battery are connected in series with a MOS tube circuit and then respectively connected to the two electrodes of the balancing capacitor, and the MOS tube circuit is used to connect the single battery and the balancing capacitor to form a closed loop; The positive electrode of the independent power supply is connected to the collector of the optical coupler, the emitter of the optical coupler is connected to the gate of the MOS tube in the MOS tube circuit, the negative electrode of the independent power supply is connected to the MOS tube connection loop in the MOS tube circuit, the positive electrode of the diode in the optical coupler is electrically connected to the control unit, and the control unit is used to control the connection of the optical coupler so that the independent power supply allows the gate of the MOS tube to be powered, thereby controlling the connection or disconnection of the MOS tube circuit; The control unit controls the charging and discharging balance between the individual batteries at a regular time.

4. The active balancing control circuit of a battery pack according to claim 1 or 3, characterized in that: The independent power supply is a packaged isolated power supply, and the isolated power supply provides 5V direct current.

5. The active balancing control circuit of a battery pack according to claim 1 or 3, characterized in that: The independent power source is a detachable dry cell battery, which provides 5V direct current.

6. The active balancing control circuit of a battery pack according to claim 1 or 3, characterized in that: The MOS tube circuit includes a first MOS tube, a second MOS tube, a third MOS tube and a fourth MOS tube; The drain of the first MOS tube is electrically connected to the negative electrode of the equalizing capacitor, and the drain of the third MOS tube is electrically connected to the positive electrode of the equalizing capacitor; the drain of the second MOS tube is electrically connected to the negative electrode of the single battery, and the drain of the fourth MOS tube is electrically connected to the positive electrode of the single battery; The sources of the first MOS transistor and the second MOS transistor are interconnected and electrically connected to the negative electrode of one of the independent power supplies, and the gates of the first MOS transistor and the second MOS transistor are interconnected and electrically connected to the emitter of the optical coupler corresponding to the independent power supply; The sources of the third MOS tube and the fourth MOS tube are interconnected and electrically connected to the negative electrode of another independent power supply, and the gates of the third MOS tube and the fourth MOS tube are interconnected and electrically connected to the emitter of the optical coupler corresponding to the independent power supply.

7. The active balancing control circuit of the battery pack according to claim 6, characterized in that: A first stabilizing resistor is electrically connected between the control unit and the anode of the diode of the optical coupler; and a second stabilizing resistor is electrically connected between the anode of the independent power supply and the collector of the optical coupler.

8. The active balancing control circuit of the battery pack according to claim 7, characterized in that: The first stabilizing resistor and the second stabilizing resistor are both 1 kΩ, and the equalizing capacitor is 100 μF.

9. The active balancing control circuit of the battery pack according to claim 7, characterized in that: The first MOS tube, the second MOS tube, the third MOS tube and the fourth MOS tube are all N-channel MOS tubes with parasitic diodes.

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