Battery equalization system

Abstract

The utility model discloses a battery equalization system which is applied to a first battery unit and a second battery unit which are connected in series and adjacent to each other. The system is characterized in that a source electrode of a first MOSFET switch is respectively connected with a control chip and a positive electrode of a first battery unit, a drain electrode is respectively connected with the control chip and a negative electrode of the first battery unit, and a grid electrode is connected with the control chip; the source electrode of the second MOSFET switch is connected with the control chip and the positive electrode of the second battery unit, the drain electrode of the second MOSFET switch is connected with the control chip and the negative electrode of the second battery unit, and the grid electrode of the second MOSFET switch is connected with the control chip; one end of the inductor is connected with the drain electrode of the first MOSFET switch and the source electrode of the second MOSFET switch, and the other end of the inductor is connected with the negative electrode of the first battery unit and the positive electrode of the second battery unit. The battery equalization system can effectively improve the inductance energy transfer efficiency and the equalization speed.

Description

Technical Field

[0001] The utility model relates to the technical field of battery management, and more specifically, to a battery equalization system. Background Art

[0002] Traditional battery equalization technology mainly relies on the resistor dissipation scheme, which realizes voltage balance by consuming the energy of high-voltage battery cells in the form of heat. Such methods are inefficient, and the energy loss rate usually exceeds 30%, resulting in a decrease in the overall efficiency of the system. Summary of the Utility Model

[0003] In view of this, the purpose of the utility model is to provide a battery equalization system, which can solve the technical problem of low efficiency existing in traditional battery equalization technology.

[0004] In order to achieve the above purpose, the utility model provides the following technical solutions:

[0005] A battery equalization system is applied to adjacent series-connected battery cells. The adjacent series-connected battery cells include a first battery cell and a second battery cell. The battery equalization system includes a control chip, an inductor, a first MOSFET switch, and a second MOSFET switch. Among them:

[0006] The source of the first MOSFET switch is respectively connected to the control chip and the positive electrode of the first battery cell. The drain of the first MOSFET switch is respectively connected to the control chip and the negative electrode of the first battery cell. The gate of the first MOSFET switch is connected to the control chip. The source of the second MOSFET switch is respectively connected to the control chip and the positive electrode of the second battery cell. The drain of the second MOSFET switch is respectively connected to the control chip and the negative electrode of the second battery cell. The gate of the second MOSFET switch is connected to the control chip. One end of the inductor is respectively connected to the drain of the first MOSFET switch and the source of the second MOSFET switch. The other end of the inductor is respectively connected to the negative electrode of the first battery cell and the positive electrode of the second battery cell. The control chip is used to detect the voltage difference between the first battery cell and the second battery cell, generate corresponding switch switching signals and send them to the first MOSFET switch and the second MOSFET switch. The first MOSFET switch and the second MOSFET switch perform switching according to the switch switching signals.

[0007] Preferably, it further includes a first capacitor and a second capacitor; one end of the first capacitor is respectively connected to the source of the first MOSFET switch and the positive electrode of the first battery unit, and the other end of the first capacitor is respectively connected to the negative electrode of the first battery unit and the positive electrode of the second battery unit; one end of the second capacitor is respectively connected to the negative electrode of the first battery unit and the positive electrode of the second battery unit, and the other end of the second capacitor is respectively connected to the drain of the second MOSFET switch and the negative electrode of the second battery unit.

[0008] Preferably, the source of the first MOSFET switch is connected to the BATP pin of the control chip, the drain of the first MOSFET switch is connected to the BATC pin of the control chip, and the gate of the first MOSFET switch is connected to the HGATE pin of the control chip; the source of the second MOSFET switch is connected to the BATC pin of the control chip, the drain of the second MOSFET switch is connected to the BATN pin of the control chip, and the gate of the second MOSFET switch is connected to the LGATE pin of the control chip.

[0009] Preferably, it further includes a third capacitor; one end of the third capacitor is connected to the BST pin of the control chip, and the other end of the third capacitor is respectively connected to the drain of the first MOSFET switch, the source of the second MOSFET switch, and the SW pin of the control chip.

[0010] Preferably, it further includes a fourth capacitor; one end of the fourth capacitor is respectively connected to the negative electrode of the first battery unit and the positive electrode of the second battery unit, the other end of the fourth capacitor is connected to the BATP pin of the control chip, and the BATP pin of the control chip is further connected to the NC pin of the control chip.

[0011] Preferably, it further includes a fifth capacitor; the fifth capacitor is arranged between the fourth capacitor and the BATP pin of the control chip, one end of the fifth capacitor is connected to the fourth capacitor, and the other end of the fifth capacitor is connected to the BATP pin of the control chip.

[0012] Preferably, it further includes a resistor; one end of the resistor is connected to the negative electrode of the second battery unit, and the other end of the resistor is connected to the EN pin of the control chip.

[0013] Preferably, the drain of the first MOSFET switch and the source of the second MOSFET switch are further respectively connected to the ISET pin of the control chip.

[0014] When the control chip of the present utility model detects a large voltage difference between adjacent series-connected battery cells, it realizes the power transfer between adjacent battery cells by controlling the alternating conduction of the first MOSFET switch and the second MOSFET switch, thereby achieving battery energy balance. Compared with the traditional battery balancing technology, it not only has no heat dissipation problem and does not require additional heat dissipation design, but also can effectively save energy, improve the inductor energy transfer efficiency, and support a relatively high average current, thus effectively improving the balancing speed. Brief Description of the Drawings

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to the provided drawings.

[0016] Figure 1 It is a schematic structural diagram of the battery balancing system provided by the embodiment of the present utility model. Detailed Embodiments

[0017] The following will clearly and completely describe the technical solutions in the embodiments of the present utility model with reference to the drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all the embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present utility model.

[0018] Please refer to Figure 1 , which shows a schematic structural diagram of the battery balancing system provided by the embodiment of the present utility model; wherein, BAT1 represents the first battery cell, BAT2 represents the second battery cell, B-, B1, B2 represent the corresponding circuit connection points, Q1 represents the first MOSFET switch, Q2 represents the second MOSFET switch, L represents the inductor, R represents the resistor, C1 to C5 respectively represent the first capacitor to the fifth capacitor, U1 represents the control chip, and NC, BATP, EN, BATC, BATN, HGATE, ISET, SW, BST, LGATE respectively represent the corresponding pins in the control chip. The following is a specific description of a battery balancing system provided by the embodiment of the present utility model based on Figure 1 to make a specific description of a battery balancing system provided by the embodiment of the present utility model.

[0019] A battery equalization system provided by an embodiment of the present utility model is applied to adjacent battery cells connected in series. The adjacent battery cells connected in series include a first battery cell and a second battery cell; the battery equalization system includes a control chip, an inductor, a first MOSFET switch and a second MOSFET switch; wherein:

[0020] The source of the first MOSFET switch is respectively connected to the control chip and the positive electrode of the first battery cell, the drain is respectively connected to the control chip and the negative electrode of the first battery cell, and the gate is connected to the control chip; the source of the second MOSFET switch is respectively connected to the control chip and the positive electrode of the second battery cell, the drain is respectively connected to the control chip and the negative electrode of the second battery cell, and the gate is connected to the control chip; one end of the inductor is respectively connected to the drain of the first MOSFET switch and the source of the second MOSFET switch, and the other end is respectively connected to the negative electrode of the first battery cell and the positive electrode of the second battery cell; the control chip is used to detect the voltage difference between the first battery cell and the second battery cell, generate a corresponding switch switching signal and send it to the first MOSFET switch and the second MOSFET switch, and the first MOSFET switch and the second MOSFET switch perform switching according to the switch switching signal.

[0021] The battery equalization system of the embodiment of the present utility model belongs to an active battery equalization system based on inductive energy transfer, and can be applied to the voltage balance of multi-cell series battery packs, especially for the high-efficiency energy management requirements of lithium-ion battery packs in electric vehicles, electric motorcycles and energy storage systems.

[0022] The control chip can detect the voltage difference between the first battery cell and the second battery cell in real time; when the voltage difference exceeds a first threshold (i.e., a preset difference, which can be expressed as VKICK and can be set according to actual needs, such as 50 mV), the control chip starts the inductor energy transfer process, generates a switch switching signal and sends it to the high-frequency switches (the first MOSFET switch and the second MOSFET switch), controls the high-frequency switches to switch the charging and discharging direction of the inductor, and transfers the energy (i.e., electrical energy) from the high-voltage battery cell to the low-voltage battery cell; when the voltage difference is lower than a second threshold (VERROR, which can be set according to actual needs, such as 10 mV) and lasts for a preset time (TDONE, which can be set according to actual needs, such as 62 ms), the control chip determines that there is no need to perform inductor energy transfer but enters the sleep mode.

[0023] Specifically, for the process of inductive energy transfer, if the voltage of the first battery unit is higher than that of the second battery unit, the switch switching signal is used to control the opening of the first MOSFET switch and the turning off of the second MOSFET switch, so that the electrical energy of the first battery unit flows through the first MOSFET switch to the inductor, and then the first MOSFET switch is turned off and the second MOSFET switch is turned on, so that the electrical energy flows from the inductor through the second MOSFET switch to the second battery unit. If the voltage of the second battery unit is higher than that of the first battery unit, the switch switching signal is used to control the turning off of the first MOSFET switch and the opening of the second MOSFET switch, so that the electrical energy of the second battery unit flows through the second MOSFET switch to the inductor, and then the first MOSFET switch is turned on and the second MOSFET switch is turned off, so that the electrical energy flows from the inductor through the first MOSFET switch to the first battery unit. Among them, the switching frequency of the high-frequency switch can be 500 kHz, and the control chip issues a PWM signal (i.e., the switch switching signal) to drive the first MOSFET switch and the second MOSFET switch to conduct alternately.

[0024] It should be noted that the control chip and its functions (detecting the voltage difference, generating and sending a signal based on the voltage difference to control the relevant switch) are prior arts in this technical field. For example, Patent CN113992018A records that "the control chip is configured to: generate a valley sampling voltage based on the induced voltage on the first auxiliary winding, and the valley sampling voltage is used to characterize the voltage difference between the drain and the source of the main switch when the main switch connected to the primary winding changes from the off state to the on state; and generate a first control voltage based on the valley sampling voltage, and the first control voltage is used to control the main switch to change from the off state to the on state and is used to control the auxiliary switch connected to the second auxiliary winding to change from the on state to the off state". Among them, the control chip is configured to collect the voltage difference and generate a control voltage signal based on the voltage difference to control the relevant switch; Patent CN114530911B records that "the present invention provides a power supply protection method, device, power supply protection circuit, equipment and medium. The power supply protection method includes: obtaining the voltage difference between the two ends of the power supply control switch through a voltage detection circuit. Detecting the signal state of the first control signal, and the first control signal is a signal sent by a voltage regulation chip for turning on the power supply control switch. According to the voltage difference and the signal state, determining the circuit state of the power supply control switch. If the circuit state of the power supply control switch is short-circuited, then stop inputting the power supply voltage to the power supply control switch. Through the present invention, it is possible to determine whether the power supply control switch can effectively control the input of the power supply voltage according to the voltage difference between the two ends of the power supply control switch and the switch state of the power supply control switch. Furthermore, when the power supply control switch is in a short-circuit state, it is possible to timely stop the continuous input of the power supply voltage, thereby achieving the purpose of protecting the power supply circuit". Among them, after detecting the voltage difference between the two ends of the voltage control switch, the control of the circuit to which the power supply control switch belongs is realized based on this.

[0025] When the control chip of the present utility model detects that the voltage difference between adjacent series-connected battery cells is large, it realizes the power transfer between adjacent battery cells by controlling the alternating conduction of the first MOSFET switch and the second MOSFET switch, and then realizes the battery energy balance. Compared with the traditional battery balancing technology, it not only has no heat dissipation problem and does not require additional heat dissipation design, but also can effectively save energy, improve the inductive energy transfer efficiency, and support a relatively high average current, thereby effectively improving the balancing speed.

[0026] A battery balancing system provided by an embodiment of the present utility model may further include a resistor and capacitors from the first to the fifth. The control chip may include multiple pins such as NC, BATP, EN, BATC, BATN, HGATE, ISET, SW, BST, LGATE, etc.; among them:

[0027] One end of the first capacitor is respectively connected to the source of the first MOSFET switch and the positive electrode of the first battery unit, and the other end is respectively connected to the negative electrode of the first battery unit and the positive electrode of the second battery unit; One end of the second capacitor is respectively connected to the negative electrode of the first battery unit and the positive electrode of the second battery unit, and the other end is respectively connected to the drain of the second MOSFET switch and the negative electrode of the second battery unit;

[0028] The source of the first MOSFET switch is connected to the BATP pin of the control chip, the drain is connected to the BATC pin of the control chip, and the gate is connected to the HGATE pin of the control chip; The source of the second MOSFET switch is connected to the BATC pin of the control chip, the drain is connected to the BATN pin of the control chip, and the gate is connected to the LGATE pin of the control chip;

[0029] One end of the third capacitor is connected to the BST pin of the control chip, and the other end is respectively connected to the drain of the first MOSFET switch, the source of the second MOSFET switch and the SW pin of the control chip;

[0030] One end of the fourth capacitor is respectively connected to the negative electrode of the first battery unit and the positive electrode of the second battery unit, and the other end is connected to the BATP pin of the control chip, and the BATP pin of the control chip is also connected to the NC pin of the control chip;

[0031] The fifth capacitor is arranged between the fourth capacitor and the BATP pin of the control chip, with one end connected to the fourth capacitor and the other end connected to the BATP pin of the control chip;

[0032] One end of the resistor is connected to the negative electrode of the second battery unit, and the other end is connected to the EN pin of the control chip;

[0033] The drain of the first MOSFET switch and the source of the second MOSFET switch are also respectively connected to the ISET pin of the control chip.

[0034] In the embodiment of the present utility model, the first battery unit can be called the top unit, and the second battery unit can be called the bottom unit. The direction of energy transfer is dynamically selected by the voltage difference polarity, and can include the DOWN mode and the UP mode; The DOWN mode is that when the voltage of the top unit is high, the inductive energy is transferred from the top unit to the bottom unit; The UP mode is that when the voltage of the bottom unit is high, the inductive energy is transferred from the bottom unit to the top unit. Among them, the balancing current (Iavg) can be set through an external resistor (R_sense, and the value range can be from 5mΩ to 100mΩ), and satisfies the relationship:

[0035] Iavg = Rsense + 50mV.

[0036] It should be noted that the control chip can have a built-in state machine for managing the switching between different states such as sleep, detection, and balancing. Among them, the detection state means that the control chip can monitor the voltage difference between adjacent battery cells in real time, and trigger balancing when the difference exceeds a preset difference (such as 50 mV); the balancing state means that the control chip controls the inductor to charge and discharge through a high-frequency switch (such as 500 kHz) to achieve bidirectional energy transfer between adjacent battery cells; the sleep state means a state where no energy transfer is required, or a state where no detection or energy transfer is required, which can be set according to actual needs; thus, the three states of sleep, detection, and balancing can be dynamically switched according to the voltage difference between adjacent battery cells to optimize energy consumption. In addition, the functions of overvoltage, undervoltage, overcurrent, and temperature protection are also realized through other capacitors, resistors, and related circuits, so that the system integrates multi-level protection mechanisms such as overvoltage, undervoltage, overcurrent, and temperature to ensure the safe operation of the system.

[0037] In a specific implementation, the battery balancing system of the embodiment of the present invention can also implement a distributed cascade architecture, that is, it supports multiple control chips to work together, and thus can be extended to a multi-cell battery unit group, such as 16 channels, based on the same principle.

[0038] Taking two series-connected battery cells as an example, the implementation process of the present invention is described as follows:

[0039] Hardware configuration: The inductance value is selected as 2.2 μH, and the current withstand is ≥15 A; the MOSFET switch model is selected as a low-loss device with VDS = 30 V and RDS(on) = 5 mΩ; the control chip integrates a 500 kHz PWM generator and an ADC voltage detection module.

[0040] Working process: The initial state is that the chip is in the sleep state, and it wakes up every 100 ms to enter the detection state to detect the voltage difference; when the detected voltage difference > 50 mV, the balancing state is triggered; according to the polarity of the voltage difference, the DOWN or UP mode is selected, and the switching of two MOSFET switches is controlled through PWM signals to complete the inductor energy transfer; when the voltage difference < 10 mV lasts for 62 ms, it returns to the sleep state.

[0041] The embodiment of the present invention can achieve:

[0042] High-efficiency energy utilization: The inductor transfer efficiency ≥ 90%, and it saves more than 3 times the energy compared with the resistor scheme;

[0043] Fast balancing ability: It supports an average current of 10 A, and the balancing time is shortened to 1 / 5 of the traditional scheme;

[0044] Precise control: The voltage difference control accuracy is ±10 mV, and the battery life is extended by more than 20%;

[0045] Low-power operation: The power consumption in the sleep mode ≤ 2 μA, which is suitable for long-term standby devices.

[0046] In addition, the battery equalization system according to the embodiment of the present utility model can also add a protection mechanism:

[0047] 1. When the voltage of any battery cell is greater than a preset voltage value (such as 5V), all MOSFET switches are immediately turned off;

[0048] 2. When the temperature of the control chip is greater than a preset temperature value (such as 160°C), thermal shutdown is initiated and automatically restored after cooling.

[0049] In the above technical solutions provided by the embodiments of the present utility model, the parts that are the same as the implementation principles of the corresponding technical solutions in the prior art are not described in detail to avoid excessive elaboration.

[0050] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present utility model. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present utility model. Therefore, the present utility model will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A battery balancing system, characterized in that, Applied to adjacent battery cells in series, the adjacent battery cells in series include a first battery cell and a second battery cell; the battery equalization system includes a control chip, an inductor, a first MOSFET switch and a second MOSFET switch; wherein: The source of the first MOSFET switch is respectively connected to the control chip and the positive electrode of the first battery cell, the drain of the first MOSFET switch is respectively connected to the control chip and the negative electrode of the first battery cell, and the gate of the first MOSFET switch is connected to the control chip; the source of the second MOSFET switch is respectively connected to the control chip and the positive electrode of the second battery cell, the drain of the second MOSFET switch is respectively connected to the control chip and the negative electrode of the second battery cell, and the gate of the second MOSFET switch is connected to the control chip; one end of the inductor is respectively connected to the drain of the first MOSFET switch and the source of the second MOSFET switch, and the other end of the inductor is respectively connected to the negative electrode of the first battery cell and the positive electrode of the second battery cell; the control chip is used to detect the voltage difference between the first battery cell and the second battery cell, generate corresponding switch switching signals and send them to the first MOSFET switch and the second MOSFET switch, and the first MOSFET switch and the second MOSFET switch perform switching according to the switch switching signals.

2. The system according to claim 1, wherein It further includes a first capacitor and a second capacitor; one end of the first capacitor is respectively connected to the source of the first MOSFET switch and the positive electrode of the first battery cell, and the other end of the first capacitor is respectively connected to the negative electrode of the first battery cell and the positive electrode of the second battery cell; one end of the second capacitor is respectively connected to the negative electrode of the first battery cell and the positive electrode of the second battery cell, and the other end of the second capacitor is respectively connected to the drain of the second MOSFET switch and the negative electrode of the second battery cell.

3. The system according to claim 2, characterized in that, The source of the first MOSFET switch is connected to the BATP pin of the control chip, the drain of the first MOSFET switch is connected to the BATC pin of the control chip, and the gate of the first MOSFET switch is connected to the HGATE pin of the control chip; the source of the second MOSFET switch is connected to the BATC pin of the control chip, the drain of the second MOSFET switch is connected to the BATN pin of the control chip, and the gate of the second MOSFET switch is connected to the LGATE pin of the control chip.

4. The system according to claim 3, characterized in that It further includes a third capacitor; one end of the third capacitor is connected to the BST pin of the control chip, and the other end of the third capacitor is respectively connected to the drain of the first MOSFET switch, the source of the second MOSFET switch and the SW pin of the control chip.

5. The system according to claim 4, wherein It further includes a fourth capacitor; one end of the fourth capacitor is respectively connected to the negative electrode of the first battery unit and the positive electrode of the second battery unit, the other end of the fourth capacitor is connected to the BATP pin of the control chip, and the BATP pin of the control chip is further connected to the NC pin of the control chip.

6. The system according to claim 5, wherein It further includes a fifth capacitor; the fifth capacitor is disposed between the fourth capacitor and the BATP pin of the control chip, one end of the fifth capacitor is connected to the fourth capacitor, and the other end of the fifth capacitor is connected to the BATP pin of the control chip.

7. The system according to claim 6, characterized in that It further includes a resistor; one end of the resistor is connected to the negative electrode of the second battery unit, and the other end of the resistor is connected to the EN pin of the control chip.

8. The system according to claim 7, wherein The drain of the first MOSFET switch and the source of the second MOSFET switch are further respectively connected to the ISET pin of the control chip.

Images