Energy-supplementing battery equalization device and equalization method thereof

Abstract

The application discloses a kind of energy supplement type battery equalization device and equalization method thereof, including charging input port and processor, charging input port is electrically connected with non-isolated step-down circuit, non-isolated step-down circuit is connected with N isolated step-down circuits, N isolated step-down circuits are respectively connected with corresponding N constant-current limiting voltage equalization circuits, N constant-current limiting voltage equalization circuits are respectively connected with corresponding Nth battery cell, N constant-current limiting voltage equalization circuits are connected with processor;Through real-time detection of battery cell voltage by processor, once the maximum voltage difference of battery cell is detected to exceed equalization voltage difference threshold, start equalization circuit, until reach equalization time.The energy supplement type battery equalization device and equalization method thereof disclosed by the application can improve equalization efficiency, reduce energy loss, and thus improve charging efficiency, and at the same time, current detection circuit is added, to effectively guarantee circuit safety.

Description

Technical Field

[0001] The present invention relates to the technical field of battery management, and in particular to an energy supplement type battery balancing device and a balancing method thereof. Background Art

[0002] General battery balancing is divided into active balancing and passive balancing. Among them, passive balancing generally uses resistance heat release to release the "excess power" of high-capacity batteries to achieve the purpose of balancing. However, because the consumed energy is basically converted into heat energy, all such balancing generally has low power per unit time. Considering the heat dissipation and volume of the BMS board, the power of a single battery cell generally does not exceed 0.3W, so the balancing efficiency is also low and the energy loss is large. Active balancing transfers excess power to high-capacity batteries during charging and to low-capacity batteries during discharging, which can improve utilization efficiency. Active balancing includes capacitive balancing, inductive balancing, and transformer balancing, but all require frequent switching of the balancing circuit, which will accelerate the attenuation and aging of the battery cells.

[0003] Chinese patent document CN110165718A discloses a maintenance-free lithium battery management system with active and passive balancing. The system includes batteries, switches, balancing resistors, a switch control circuit, a constant current and voltage source, an isolated power supply, and an internal or external power supply. It combines passive and active balancing. When the voltage difference between cells is positive and greater than the balancing threshold voltage, the resistor releases energy. When the voltage difference between cells is negative and its absolute value is less than the balancing threshold voltage, the constant current and voltage source is used to boost the voltage. However, the passive balancing system still suffers from low balancing efficiency and high energy loss.

[0004] Patent document WO2018086459A1 discloses a method and circuit for balanced charging and discharging of a series battery pack, and a DC isolation step-down circuit. It is essentially an evolved version of capacitive active balancing. The balanced energy absorption stage comes from an external power supply, but this balancing method requires continuous absorption of energy and then release of energy, so it requires frequent switching of switches, and requires that some switches be opened synchronously, which greatly increases the complexity of the system and the complexity of control. Moreover, this balancing method is not a constant current and constant voltage method, which will cause an impact current to appear at the moment of releasing energy, accelerating the attenuation and aging of the battery cell.

[0005] Meanwhile, the existing balancing method can only balance one battery cell at a time, which is inefficient. Moreover, the existing balancing device does not have circuits and strategies to detect faults, and cannot guarantee circuit safety. Summary of the Invention

[0006] To solve the above technical problems, the present invention discloses an energy-supplementing battery balancing device and a balancing method thereof, which improves balancing efficiency, reduces energy loss, and thereby enhances charging efficiency, while also adding circuits and strategies for fault detection. The technical solutions adopted by the present invention are:

[0007] An energy-supplementing battery balancing device includes a charging input port and a processor, wherein the charging input port is electrically connected to a non-isolated buck circuit, the non-isolated buck circuit is connected to a current detection circuit, the current detection circuit is connected to N isolated buck circuits, the N isolated buck circuits are respectively connected to corresponding N constant current-limiting voltage balancing circuits, the N constant current-limiting voltage balancing circuits are respectively connected to corresponding N battery cells, and the N constant current-limiting voltage balancing circuits are all connected to the processor; wherein N is a natural number not less than 2;

[0008] The charging input port is used to supply power to the battery balancing device;

[0009] The non-isolated step-down circuit is used to reduce the system power supply voltage;

[0010] The current detection circuit is used to detect the total power of the isolated step-down circuit N, whether the self-detection circuit is faulty, whether the detection circuit is mistakenly opened, and balance control;

[0011] The isolation buck circuit is used to isolate the system power ground from the constant current energy replenishment ground, and to isolate the ground of each level of constant current energy replenishment. Its purpose is to ensure that the energy replenishment can only charge the battery cells with relatively low capacity, while ensuring that the overall voltage of the system remains unchanged;

[0012] The constant current and voltage limiting equalization circuit is used to ensure a constant charging current;

[0013] The processor is used to detect the cell voltage in real time and control the balancing process.

[0014] Furthermore, a voltage stabilizing circuit is connected between the non-isolated step-down circuit and the processor, and the current detection circuit is electrically connected to the voltage stabilizing circuit.

[0015] Furthermore, the non-isolated step-down circuit includes a first chip U1, and pin 1 of the first chip U1 is divided into two paths, the first path is connected to one end of the third capacitor C3, and the second path is connected to one end of the second resistor R2. Pin 2 of the first chip U1 is connected to one end of the first resistor R1, and pin 3 of the first chip U1 is divided into four paths, the first path is connected to one end of the sixth capacitor C6, the second path is connected to one end of the fifth resistor R5, the third path is grounded through the sixth resistor R6, and the fourth path is connected to the second capacitor group. Pin 4 of the first chip U1 is divided into three paths, the first path is connected to one end of the first capacitor group, the second path is connected to the charging input port, and the third path is grounded. Pin 5 of the first chip U1 is divided into two paths, the first path is connected to one end of the third resistor R3, and the second path is connected to the source of the second MOS tube Q2. Pin 6 of the first chip U1 is connected to the gate of the second MOS tube Q2, and pin 7 of the first chip U1 is connected to one end of the fourth capacitor C4. The other end of the fourth capacitor C4 is divided into two paths, the first path is connected to the first The other end of the three resistors R3 is connected, and the second path is connected to pin 8 of the first chip U1, the other end of the third capacitor C3, the other end of the second resistor R2, the other end of the first resistor R1, and the other end of the first capacitor group, and then connected to the charging input port; the first capacitor group includes a first capacitor C1 and a second capacitor C2 connected in parallel; the drain of the second MOS transistor Q2 is divided into three paths, the first path is connected to the cathode of the first diode D1, the second path is connected to one end of the fourth resistor C4, and the third path is connected to one end of the first inductor L1. The anode of the first diode D1 is grounded. One end of the fourth resistor C4 is divided into two paths, the first path is connected to the other end of the sixth capacitor C6, and the second path is connected to one end of the fifth capacitor C5. The other end of the first inductor L1, the other end of the fifth capacitor C5, and the other end of the fifth resistor R5 are connected to the other end of the second capacitor group. The second capacitor group includes a seventh capacitor C7 and an eighth capacitor C8 connected in parallel. The two ends of the second capacitor group are respectively connected to the power supply VBUS and ground.

[0016] Furthermore, the isolated step-down circuit includes a ninth chip U9, and pins 1 and 2 of the ninth chip U9 are connected to both ends of the twenty-sixth capacitor C26; pins 3 and 4 of the ninth chip U9 are connected to both ends of the thirtieth capacitor C30.

[0017] Furthermore, the constant current and voltage limiting balancing circuit includes a twenty-third resistor R23, one end of the twenty-third resistor R23 is divided into two paths, the first path is connected to the power supply V_BN, the second path is connected to the collector of the seventh transistor Q7, and the other end of the twenty-third resistor R23 is divided into three paths, the first path is connected to the Nth signal input port BLS_CTR_N, the second path is connected to the base of the seventh transistor Q7, and the third path is connected to the cathode of the twelfth voltage-stabilizing diode D12; the emitter of the seventh transistor Q7 is divided into five paths, the first path is connected to one end of the seventeenth resistor R17, the second path is connected to one end of the thirteenth resistor R13, the third path is connected to the emitter of the sixth transistor Q6, the fourth path is connected to one end of the fourteenth resistor R14, and the fifth path is connected to one end of the thirty-fifth capacitor C35; the seventeenth The other end of the resistor R17 is divided into two paths, the first path is grounded via the eighteenth resistor R18, and the second path is connected to the anode of the twelfth voltage-stabilizing diode D12; the other end of the thirteenth resistor R13 is divided into two paths, the first path is connected to the emitter of the fifth transistor Q5, and the second path is connected to the base of the sixth transistor Q6. The collector of the sixth transistor Q6, the other end of the fourteenth resistor R14, and the other end of the thirty-fifth capacitor C35 are combined and then divided into two paths, the first path is connected to the base of the fifth transistor Q5; the second path is connected to one end of the fifteenth resistor R15, the collector of the fifth transistor Q5 is connected to the anode of the tenth diode D10, and the cathode of the tenth diode D10 is connected to the Nth battery cell. The other end of the fifteenth resistor R15 is divided into two paths, the first path is grounded, and the second path is connected to the Nth battery cell.

[0018] Furthermore, the current detection circuit includes a fifth operational amplifier U5 and a sixth operational amplifier U6. Pin 1 of the fifth operational amplifier U5 is divided into two paths, one path is connected to pin 3 of the sixth operational amplifier U6 through the ninth resistor R9, and the other path is connected to one end of the eighth resistor R8. The other end of the eighth resistor R8 is divided into two paths, one path is connected to pin 2 of the sixth operational amplifier U6, and the other path is grounded; pin 2 of the fifth operational amplifier U5 is grounded, and pin 3 of the fifth operational amplifier U5 is connected to one end of the tenth resistor R10. The other end of the tenth resistor R10 is divided into two paths, one path is connected to the system power supply VBUS, and the other path is connected to one end of the seventh resistor R7. The fifth operational amplifier U5 is grounded, and pin 3 of the fifth operational amplifier U5 is connected to one end of the tenth resistor R10. The other end of the tenth resistor R10 is divided into two paths, one path is connected to the system power supply VBUS, and the other path is connected to one end of the seventh resistor R7. Pin 4 of the operational amplifier U5 is connected to one end of the eleventh resistor R11, and the other end of the eleventh resistor R11 is divided into two paths, one path is connected to the balancing power supply VBLS, and the other path is connected to the other end of the seventh resistor R7; pin 5 of the fifth operational amplifier U5 is divided into two paths, the first path is connected to the power supply, and the second path is grounded via the nineteenth capacitor C19; pin 1 of the sixth operational amplifier U6 is divided into two paths, one path is connected to the analog signal output terminal I_DET_ADC via the twelfth resistor R12, and the second path is connected to pin 4 of the sixth operational amplifier U6; pin 5 of the sixth operational amplifier U6 is divided into two paths, the first path is connected to the power supply, and the second path is grounded via the twenty-fifth capacitor C25.

[0019] Furthermore, the current detection circuit self-checks whether the circuit is faulty, including the following steps:

[0020] S2-1: Turn off all balancing drivers and detect the actual leakage current value in the current detection circuit;

[0021] S2-2: Determine the actual leakage current value in step S2-1: If the actual leakage current value is less than the leakage current threshold, the isolation step-down circuit is determined to be normal; if the actual leakage current value is greater than the leakage current threshold but less than the single-cell balancing current threshold, the isolation step-down circuit is determined to be abnormal; if the actual leakage current value is greater than the single-cell balancing current threshold, the isolation step-down circuit is determined to have a mis-conduction / short-circuit fault; wherein the leakage current threshold is the sum of the currents of the isolation circuits 1 to N in the no-load state, and the single-cell balancing current threshold is equal to the constant current value in the constant current and voltage-limiting balancing circuit;

[0022] S2-3: Turn on constant current and voltage limiting equalization circuits 1 to N in sequence, and after each turn on, check whether there is current in the current detection circuit. If there is current in the constant current and voltage limiting equalization circuit, subtract the actual leakage current value detected in step S2-1 from the current to obtain the current value;

[0023] S2-4: Judge the current value in step S2-3: if the current value is less than the single-cell balancing current range value, it is judged that the isolated buck circuit I is turned on and has a fault; if the current value is within the single-cell balancing current range value, it is judged that the isolated buck circuit I is normally detected; if the current value is greater than the single-cell balancing current range value, it is judged that the isolated buck circuit I has an overcurrent fault, wherein the isolated buck circuit I corresponds to the constant current and voltage limiting balancing circuit I, and the single-cell balancing current range value is equal to the single-cell balancing current threshold value.

[0024] The present invention also discloses a balancing method for an energy supplement type battery balancing device, which mainly includes the following steps:

[0025] S1-1: The processor detects the cell voltage in real time and enters S1-2 when it detects that the maximum cell voltage difference exceeds the balanced voltage difference threshold Vth;

[0026] S1-2: Obtain the voltage value VM of the highest voltage cell;

[0027] S1-3: According to the voltage value VM of the highest voltage cell, obtain the cell position that affects the equalization voltage difference threshold, that is, the nth cell, and its voltage value Vn;

[0028] S1-4: Calculate the capacity Cn corresponding to the nth cell by looking up the cell attribute table and using the following formula:

[0029] Cn=(Vn-Vi)×Ki+Vi

[0030] Where Vn is the voltage of the nth cell, Vi is the Vj corresponding to the smallest positive value obtained by subtracting Vn from Vj, Ki is the slope corresponding to Vi; Vj is the voltage of the jth cell in the cell attribute table;

[0031] S1-5: Calculate the capacity CM of the highest voltage cell by looking up the cell attribute table and using the following formula:

[0032] CM=(VM-Vk)×Kk+Vk

[0033] Where VM is the highest voltage cell, Vk is the Vj corresponding to the smallest positive value obtained by subtracting VM from Vj (j is a natural number in the range of 0-20), and Kk is the slope corresponding to Vk;

[0034] S1-6: Calculate the time T required for balancing according to the following formula:

[0035]

[0036] Wherein, Ib is the constant current value in the constant current and voltage limiting balancing circuit;

[0037] S1-7: Start the constant current and voltage limiting equalization circuit corresponding to the cell that affects the equalization voltage difference threshold;

[0038] S1-8: End the balancing process until the balancing time is reached.

[0039] Furthermore, the balanced voltage difference threshold Vth is 50mV.

[0040] The beneficial effects of the present invention are:

[0041] 1. Compared with the existing technology, the present invention replaces the original passive balancing analog front end with a processor for energy replenishment-type battery balancing solution; an isolation buck circuit is provided to isolate the system power ground from the constant current energy replenishment ground, and to isolate the ground of each level of constant current energy replenishment, ensuring that energy replenishment can only charge cells with relatively low capacity while ensuring that the overall system voltage remains unchanged, thereby improving the balancing power per unit time, improving balancing efficiency, and reducing energy loss.

[0042] 2. The energy-supplementing battery balancing device provided by the present invention adopts constant current and voltage limiting to avoid the surge current at the moment of releasing electric energy and slow down the attenuation and aging of the battery cell.

[0043] 3. The energy supplement type battery balancing device provided by the present invention is provided with a current detection circuit to perform self-test on the circuit to ensure circuit safety.

[0044] 4. The energy supplement type battery balancing device and balancing method provided by the present invention can balance multiple battery cells, with the number of balanced battery cells being N (i.e., the maximum number), thereby improving balancing efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Attachment Figure 1 FIG. 1 is a schematic diagram of a battery balancing device module according to an embodiment of the present invention.

[0046] Attachment Figure 2 Schematic diagram of a constant current and voltage limiting equalization circuit in an embodiment of the present invention.

[0047] Attachment Figure 3 Schematic diagram of a non-isolated buck circuit in an embodiment of the present invention.

[0048] Attachment Figure 4 2 is a circuit diagram of a current detection circuit in an embodiment of the present invention.

[0049] Attachment Figure 5 FIG. 4 is a circuit diagram of an isolated step-down circuit in an embodiment of the present invention.

[0050] Attachment Figure 6 Schematic diagram of a voltage stabilizing circuit in an embodiment of the present invention.

[0051] Attachment Figure 7 FIG. 4 is a schematic diagram of a processor in an embodiment of the present invention. DETAILED DESCRIPTION

[0052] The following further describes the embodiments of the present invention in conjunction with the accompanying drawings and examples. It should be noted that the examples do not limit the scope of protection claimed in the present invention.

[0053] Example 1

[0054] like Figure 1 As shown, an energy-supplementing battery balancing device includes a charging input port and a processor, the charging input port is electrically connected to a non-isolated buck circuit, the non-isolated buck circuit is connected to a current detection circuit, the current detection circuit is connected to N isolated buck circuits, the N isolated buck circuits are respectively connected to corresponding N constant current and voltage-limiting balancing circuits, the N constant current and voltage-limiting balancing circuits are respectively connected to corresponding N-th battery cells, and the N constant current and voltage-limiting balancing circuits are all connected to the processor; a voltage stabilizing circuit is connected between the non-isolated buck circuit and the processor, and the current detection circuit is electrically connected to the voltage stabilizing circuit.

[0055] The charging input port is connected to the charging input port of the BMS board, and the power of the charging input port is used to power the battery balancing device.

[0056] Because the object of the entire energy replenishment is the battery cell, for a battery pack composed of multiple battery cells connected in series and parallel, its voltage will be much greater than the battery cell voltage. Therefore, in order to further improve energy efficiency, a non-isolated buck circuit is set up to reduce the system power supply voltage.

[0057] like Figure 3As shown, the non-isolated step-down circuit includes a first chip U1, the 1 pin of the first chip U1 is divided into two paths, the first path is connected with one end of the third capacitor C3, and the second path is connected with one end of the second resistor R2, the 2 pin of the first chip U1 is connected with one end of the first resistor R1, the 3 pin of the first chip U1 is divided into four paths, the first path is connected with one end of the sixth capacitor C6, the second path is connected with one end of the fifth resistor R5, the third path is grounded through the sixth resistor R6, and the fourth path is connected with the second capacitor group, the 4 pin of the first chip U1 is divided into three paths, the first path is connected with one end of the first capacitor group, the second path is connected with the charging input port, and the third path is grounded, the 5 pin of the first chip U1 is divided into two paths, the first path is connected with one end of the third resistor R3, and the second path is connected with the source electrode of the second MOS tube Q2, the 6 pin of the first chip U1 is connected with the gate electrode of the second MOS tube Q2, the 7 pin of the first chip U1 is connected with one end of the fourth capacitor C4, the other end of the fourth capacitor C4 is divided into two paths, the first path is connected with the other end of the third resistor R3, and the second path is connected with the 8 pin of the first chip U1, the other end of the third capacitor C3, the other end of the second resistor R2, the other end of the first resistor R1 and the other end of the first capacitor group; the first capacitor group includes the first capacitor C1 and the second capacitor C2 in parallel; the drain electrode of the second MOS tube Q2 is divided into three paths, the first path is connected with the negative electrode of the first diode D1, the second path is connected with one end of the fourth resistor C4, and the third path is connected with one end of the first inductor L1, the positive electrode of the first diode D1 is grounded, one end of the fourth resistor C4 is divided into two paths, the first path is connected with the other end of the sixth capacitor C6, and the second path is connected with one end of the fifth capacitor C5, the other end of the first inductor L1, the other end of the fifth capacitor C5 and the other end of the fifth resistor R5 are connected with the other end of the second capacitor group, and the second capacitor group includes the seventh capacitor C7 and the eighth capacitor C8 in parallel, and the two ends of the second capacitor group are respectively connected with the power supply VBUS and the ground.

[0058] The current detection circuit is used for detecting the total power of the isolation step-down circuit N, facilitating self-checking whether the circuit is faulty, whether the detection circuit is mistakenly opened, and balance control.

[0059] As Figure 4As shown, the current detection circuit includes a fifth operational amplifier U5 and a sixth operational amplifier U6. Pin 1 of the fifth operational amplifier U5 is divided into two paths, one path is connected to pin 3 of the sixth operational amplifier U6 through the ninth resistor R9, and the other path is connected to one end of the eighth resistor R8. The other end of the eighth resistor R8 is divided into two paths, one path is connected to pin 2 of the sixth operational amplifier U6, and the other path is grounded; pin 2 of the fifth operational amplifier U5 is grounded, and pin 3 of the fifth operational amplifier U5 is connected to one end of the tenth resistor R10. The other end of the tenth resistor R10 is divided into two paths, one path is connected to the system power supply VBUS, and the other path is connected to one end of the seventh resistor R7. Pin 4 of the amplifier U5 is connected to one end of the eleventh resistor R11, and the other end of the eleventh resistor R11 is divided into two paths, one path is connected to the balancing power supply VBLS, and the other path is connected to the other end of the seventh resistor R7; pin 5 of the fifth operational amplifier U5 is divided into two paths, the first path is connected to the power supply, and the second path is grounded via the nineteenth capacitor C19; pin 1 of the sixth operational amplifier U6 is divided into two paths, one path is connected to the analog signal output terminal I_DET_ADC via the twelfth resistor R12, and the second path is connected to pin 4 of the sixth operational amplifier U6; pin 5 of the sixth operational amplifier U6 is divided into two paths, the first path is connected to the power supply, and the second path is grounded via the twenty-fifth capacitor C25.

[0060] The isolated buck circuit is used to isolate the system power ground from the constant current energy replenishment ground, and to isolate the ground of each level of constant current energy replenishment, so as to ensure that the energy replenishment can only charge the battery cells with relatively low capacity, while ensuring that the overall voltage of the system remains unchanged.

[0061] like Figure 5 As shown, the isolated step-down circuit includes a ninth chip U9, and pins 1 and 2 of the ninth chip U9 are connected to both ends of the twenty-sixth capacitor C26; pins 3 and 4 of the ninth chip U9 are connected to both ends of the thirtieth capacitor C30.

[0062] The constant current and voltage limiting equalization circuit is used to ensure a constant charging current and is also beneficial to the equalization control.

[0063] like Figure 2As shown, the constant current and voltage limiting balancing circuit includes a twenty-third resistor R23, one end of the twenty-third resistor R23 is divided into two paths, the first path is connected to the power supply V_BN, the second path is connected to the collector of the seventh transistor Q7, and the other end of the twenty-third resistor R23 is divided into three paths, the first path is connected to the Nth signal input port BLS_CTR_N, the second path is connected to the base of the seventh transistor Q7, and the third path is connected to the cathode of the twelfth voltage-stabilizing diode D12; the Nth signal input port BLS_CTR_N is pulled out from the pin of the processor; the emitter of the seventh transistor Q7 is divided into five paths, the first path is connected to one end of the seventeenth resistor R17, the second path is connected to one end of the thirteenth resistor R13, the third path is connected to the emitter of the sixth transistor Q6, the fourth path is connected to one end of the fourteenth resistor R14, and the fifth path is connected to the thirty-fifth One end of capacitor C35; the other end of the seventeenth resistor R17 is divided into two paths, the first path is grounded through the eighteenth resistor R18, and the second path is connected to the positive electrode of the twelfth voltage-stabilizing diode D12; the other end of the thirteenth resistor R13 is divided into two paths, the first path is connected to the emitter of the fifth transistor Q5, and the second path is connected to the base of the sixth transistor Q6. The collector of the sixth transistor Q6, the other end of the fourteenth resistor R14 and the other end of the thirty-fifth capacitor C35 are combined and then divided into two paths, the first path is connected to the base of the fifth transistor Q5; the second path is connected to one end of the fifteenth resistor R15, the collector of the fifth transistor Q5 is connected to the positive electrode of the tenth diode D10, the negative electrode of the tenth diode D10 is connected to the Nth battery cell, and the other end of the fifteenth resistor R15 is divided into two paths, the first path is grounded, and the second path is connected to the Nth battery cell.

[0064] A method for balancing an energy-supplementing battery balancing device mainly includes the following steps:

[0065] S1-1: The processor detects the cell voltage in real time and enters S1-2 when it detects that the maximum cell voltage difference exceeds the balanced voltage difference threshold Vth. The balanced voltage difference threshold Vth is generally 50mV.

[0066] S1-2: Obtain the voltage value VM of the highest voltage cell;

[0067] S1-3: By sampling the cell voltage in real time, the cell position that affects the equalization voltage difference threshold, that is, the nth cell, and its voltage value Vn are obtained;

[0068] S1-4: Calculate the capacity CN of the nth cell by looking up the cell attribute table and using the following formula:

[0069] CN=(Vn-Vi)×Ki+Vi

[0070] Where Vn is the voltage of the nth cell, Vi is the Vj corresponding to the smallest positive value obtained by subtracting Vn from Vj (j is 0, 1, 2..., 20), Ki is the slope corresponding to Vi; Vj is the voltage of the jth cell in the cell attribute table;

[0071] S1-5: Calculate the capacity CM of the highest voltage cell by looking up the cell attribute table and using the following formula:

[0072] CM=(VM-Vk)×Kk+Vk

[0073] Where VM is the highest voltage cell, Vk is the Vj corresponding to the smallest positive value obtained by subtracting VM from Vj (j is 0, 1, 2, ..., 20), Kk is the slope corresponding to Vk; Vj is the voltage of the jth cell in the cell attribute table;

[0074] S1-6: Calculate the time T required for balancing according to the following formula:

[0075]

[0076] Wherein, Ib is the constant current value in the constant current and voltage limiting balancing circuit;

[0077] S1-7: Start the constant current and voltage limiting equalization circuit corresponding to the cell that affects the equalization voltage difference threshold;

[0078] S1-8: End the balancing process until the balancing time is reached.

[0079] Among them, the battery cell attribute table is shown in Table 1:

[0080] Table 1 Battery cell properties

[0081]

[0082] The slope is calculated as follows:

[0083]

[0084] When the charger is connected or the entire battery pack starts charging, the BMS starts self-testing. The self-test process includes the following steps:

[0085] S2-1: Turn off all balancing drivers and detect the actual leakage current value in the current detection circuit;

[0086] S2-2: judging the actual leakage current value in step S2-1: if the actual leakage current value is less than the leakage current threshold value, it is judged that the isolation voltage reduction circuit is normal; if the actual leakage current value is greater than the leakage current threshold value and less than the single-section equalization current threshold value, it is judged that the isolation voltage reduction circuit has an abnormality; if the actual leakage current value is greater than the single-section equalization current threshold value, it is judged that the isolation voltage reduction circuit has a mis-conduction / short-circuit fault; wherein the leakage current threshold value is the sum of the currents of the isolation circuits 1-N in the no-load state, and the leakage current of one isolation circuit is generally not more than 10 mA, and the single-section equalization current threshold value is equal to the constant current value in the constant current voltage limiting equalization circuit, and the constant current value is generally greater than or equal to 400 mA;

[0087] S2-3: opening the constant current voltage limiting equalization circuits 1-N in turn, detecting whether there is a current in the current detection circuit after each opening, and if there is a current in the constant current voltage limiting equalization circuit I, the current is subtracted from the actual leakage current value detected in step S2-1 to obtain a current value;

[0088] S2-4: judging the current value in step S2-4: if the current value is less than the single-section equalization current range value, it is judged that the isolation voltage reduction circuit I has an opening fault; if the current value is within the single-section equalization current range value, it is judged that the isolation voltage reduction circuit I detection is normal; if the current value is greater than the single-section equalization current range value, it is judged that the isolation voltage reduction circuit I has an overcurrent fault, wherein the isolation voltage reduction circuit I corresponds to the constant current voltage limiting equalization circuit I, and the single-section equalization current range value is equal to the single-section equalization current threshold value.

[0089] Finally, it should be pointed out that the above embodiments are only used to illustrate the technical solutions of the present application and not to limit it, although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions of the present application, and they should be covered in the scope of the claims of the present application.

Claims

1. An energy supplement type battery balancing device, characterized in that: The device comprises a charging input port and a processor, wherein the charging input port is electrically connected to a non-isolated buck circuit, the non-isolated buck circuit is connected to a current detection circuit, the current detection circuit is connected to N isolated buck circuits, the N isolated buck circuits are respectively connected to corresponding N constant current limiting voltage balancing circuits, the N constant current limiting voltage balancing circuits are respectively connected to corresponding battery cells, and the N constant current limiting voltage balancing circuits are all connected to the processor; wherein N is a natural number not less than 2; The charging input port is used to supply power to the battery balancing device; The non-isolated step-down circuit is used to reduce the system power supply voltage; The current detection circuit is used to detect the total power of the isolated step-down circuit N, whether the self-detection circuit is faulty, whether the detection circuit is mistakenly opened, and balance control; The isolation buck circuit is used to isolate the system power ground from the constant current energy replenishment ground, and to isolate the ground of each level of constant current energy replenishment. Its purpose is to ensure that the energy replenishment can only charge the battery cells with relatively low capacity, while ensuring that the overall voltage of the system remains unchanged; The constant current and voltage limiting equalization circuit is used to ensure a constant charging current; The processor is used to detect the cell voltage in real time and control the balancing process; The constant current and voltage limiting equalization circuit includes a twenty-third resistor R23, one end of the twenty-third resistor R23 is divided into two paths, the first path is connected to the power supply V_BN, the second path is connected to the collector of the seventh transistor Q7, the other end of the twenty-third resistor R23 is divided into three paths, the first path is connected to the Nth signal input port BLS_CTR_N, the second path is connected to the base of the seventh transistor Q7, and the third path is connected to the cathode of the twelfth voltage-stabilizing diode D12; the emitter of the seventh transistor Q7 is divided into five paths, the first path is connected to one end of the seventeenth resistor R17, the second path is connected to one end of the thirteenth resistor R13, the third path is connected to the emitter of the sixth transistor Q6, the fourth path is connected to one end of the fourteenth resistor R14, and the fifth path is connected to one end of the thirty-fifth capacitor C35; the seventeenth resistor The other end of R17 is divided into two paths, the first path is grounded through the eighteenth resistor R18, and the second path is connected to the anode of the twelfth voltage-stabilizing diode D12; the other end of the thirteenth resistor R13 is divided into two paths, the first path is connected to the emitter of the fifth transistor Q5, and the second path is connected to the base of the sixth transistor Q6. The collector of the sixth transistor Q6, the other end of the fourteenth resistor R14, and the other end of the thirty-fifth capacitor C35 are combined and then divided into two paths, the first path is connected to the base of the fifth transistor Q5; the second path is connected to one end of the fifteenth resistor R15, the collector of the fifth transistor Q5 is connected to the anode of the tenth diode D10, and the cathode of the tenth diode D10 is connected to the Nth battery cell. The other end of the fifteenth resistor R15 is divided into two paths, the first path is grounded, and the second path is connected to the Nth battery cell.

2. The energy supplement type battery balancing device according to claim 1, wherein: A voltage stabilizing circuit is connected between the non-isolated step-down circuit and the processor, and the current detection circuit is electrically connected to the voltage stabilizing circuit.

3. The energy supplement type battery balancing device according to claim 1, wherein: The non-isolated step-down circuit includes a first chip U1, wherein pin 1 of the first chip U1 is divided into two paths, the first path is connected to one end of the third capacitor C3, the second path is connected to one end of the second resistor R2, the second path is connected to one end of the first resistor R1, the third path is connected to one end of the first resistor R1, the third path is connected to the ground via the sixth resistor R6, and the fourth path is connected to the second capacitor group, the fourth path is connected to the second capacitor group, the fourth path is connected to the second capacitor group, the first path is connected to the charging input port, and the third path is grounded, the fifth path is connected to the second MOS tube Q2, the sixth path is connected to the gate of the second MOS tube Q2, the seventh path is connected to one end of the fourth capacitor C4, and the fourth capacitor C4 is connected to the second MOS tube Q2. The other end of the transistor Q2 is divided into two paths, the first path is connected to the other end of the third resistor R3, and the second path is connected to pin 8 of the first chip U1, the other end of the third capacitor C3, the other end of the second resistor R2, the other end of the first resistor R1, and the other end of the first capacitor group, and then connected to the charging input port; the first capacitor group includes a first capacitor C1 and a second capacitor C2 connected in parallel; the drain of the second MOS transistor Q2 is divided into three paths, the first path is connected to the cathode of the first diode D1, the second path is connected to one end of the fourth capacitor C4, and the third path is connected to one end of the first inductor L1. The anode of the first diode D1 is grounded. One end of the fourth capacitor C4 is divided into two paths, the first path is connected to the other end of the sixth capacitor C6, and the second path is connected to one end of the fifth capacitor C5. The other end of the first inductor L1, the other end of the fifth capacitor C5, and the other end of the fifth resistor R5 are connected to the other end of the second capacitor group, which includes a seventh capacitor C7 and an eighth capacitor C8 connected in parallel. The two ends of the second capacitor group are respectively connected to the power supply VBUS and ground.

4. The energy supplement type battery balancing device according to claim 1, wherein: The isolated step-down circuit includes a ninth chip U9, wherein pins 1 and 2 of the ninth chip U9 are connected to both ends of the twenty-sixth capacitor C26; and pins 3 and 4 of the ninth chip U9 are connected to both ends of the thirtieth capacitor C30.

5. The energy supplement type battery balancing device according to claim 1, wherein: The current detection circuit includes a fifth operational amplifier U5 and a sixth operational amplifier U6. Pin 1 of the fifth operational amplifier U5 is divided into two paths, one path is connected to pin 3 of the sixth operational amplifier U6 via a ninth resistor R9, and the other path is connected to one end of the eighth resistor R8. The other end of the eighth resistor R8 is divided into two paths, one path is connected to pin 2 of the sixth operational amplifier U6, and the other path is grounded; pin 2 of the fifth operational amplifier U5 is grounded, and pin 3 of the fifth operational amplifier U5 is connected to one end of the tenth resistor R10. The other end of the tenth resistor R10 is divided into two paths, one path is connected to the system power supply VBUS, and the other path is connected to one end of the seventh resistor R7. Pin 4 of the amplifier U5 is connected to one end of the eleventh resistor R11, and the other end of the eleventh resistor R11 is divided into two paths, one path is connected to the balancing power supply VBLS, and the other path is connected to the other end of the seventh resistor R7; pin 5 of the fifth operational amplifier U5 is divided into two paths, the first path is connected to the power supply, and the second path is grounded via the nineteenth capacitor C19; pin 1 of the sixth operational amplifier U6 is divided into two paths, one path is connected to the analog signal output terminal I_DET_ADC via the twelfth resistor R12, and the second path is connected to pin 4 of the sixth operational amplifier U6; pin 5 of the sixth operational amplifier U6 is divided into two paths, the first path is connected to the power supply, and the second path is grounded via the twenty-fifth capacitor C25.

6. The energy supplement type battery balancing device according to claim 1, wherein: The current detection circuit self-checks whether the circuit is faulty and includes the following steps: S2-1: Turn off all balancing drivers and detect the actual leakage current value in the current detection circuit; S2-2: Determine the actual leakage current value in step S2-1: If the actual leakage current value is less than the leakage current threshold, the isolation step-down circuit is determined to be normal; if the actual leakage current value is greater than the leakage current threshold but less than the single-cell balancing current threshold, the isolation step-down circuit is determined to be abnormal; if the actual leakage current value is greater than the single-cell balancing current threshold, the isolation step-down circuit is determined to have a mis-conduction / short-circuit fault; wherein the leakage current threshold is the sum of the currents of the isolation circuits 1 to N in the no-load state, and the single-cell balancing current threshold is equal to the constant current value in the constant current and voltage-limiting balancing circuit; S2-3: Turn on constant current and voltage limiting equalization circuits 1 to N in sequence, and after each turn on, check whether there is current in the current detection circuit. If there is current in the constant current and voltage limiting equalization circuit, subtract the actual leakage current value detected in step S2-1 from the current to obtain the current value; S2-4: Judge the current value in step S2-3: If the current value is less than the single-section balancing current range value, it is judged that the isolation buck circuit I is turned on at a faulty state; if the current value is within the single-section balancing current range value, it is judged that the isolation buck circuit I is normally detected; if the current value is greater than the single-section balancing current range value, it is judged that the isolation buck circuit I is at an overcurrent fault, wherein the isolation buck circuit I corresponds to the constant current limiting balancing circuit I, and the single-section balancing current range value is equal to the single-section balancing current threshold value.

7. A balancing method for an energy supplement type battery balancing device, characterized in that: The energy supplement type battery balancing device according to any one of claims 1 to 6 mainly comprises the following steps: S1-1: The processor detects the cell voltage in real time and enters S1-2 when it detects that the maximum cell voltage difference exceeds the balanced voltage difference threshold Vth; S1-2: Obtain the voltage value VM of the highest voltage cell; S1-3: According to the voltage value VM of the highest voltage cell, obtain the cell position that affects the equalization voltage difference threshold, that is, the nth cell, and its voltage value Vn; S1-4: Calculate the capacity Cn corresponding to the nth cell by looking up the cell attribute table and using the following formula: ； Where Vn is the voltage of the nth cell, Vi is the Vj corresponding to the smallest positive value obtained by subtracting Vn from Vj, Ki is the slope corresponding to Vi; Vj is the voltage of the jth cell in the cell attribute table; S1-5: Calculate the capacity CM of the highest voltage cell by looking up the cell attribute table and using the following formula: ； Among them, VM is the highest voltage cell, Vk is the Vj corresponding to the smallest positive value obtained by subtracting VM from Vj, and Kk is the slope corresponding to Vk; S1-6: Calculate the time T required for balancing according to the following formula: ； Wherein, Ib is the constant current value in the constant current and voltage limiting balancing circuit; S1-7: Start the constant current and voltage limiting equalization circuit corresponding to the cell that affects the equalization voltage difference threshold; S1-8: End the balancing process until the balancing time is reached.

8. The balancing method of the energy supplement type battery balancing device according to claim 7, characterized in that: The equilibrium voltage difference threshold Vth is 50mV.

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