Voltage-sharing circuit of high-voltage battery management system BMS module and high-voltage management battery system

Abstract

The utility model discloses a voltage-sharing circuit of a high-voltage battery management system (BMS) module and a high-voltage management battery system, which are applied to a battery unit, and the battery unit comprises a positive voltage V + and a negative voltage V-. The voltage-sharing circuit comprises a discharge resistor R1, a switching tube Q1 and a switching tube driving circuit, wherein one end of the discharge resistor R1 is connected to a negative voltage V-. The source electrode of the switch tube Q1 is connected with a voltage V +, and the drain electrode is connected with the other end of the discharge resistor R1. And the grid electrode of the switch tube Q1 is connected with the switch tube driving circuit and is used for outputting a high level to the grid electrode of the switch tube Q1 after the voltage of the battery unit is higher than a threshold value, the switch tube Q1 is switched on, and the discharge resistor R1 discharges the battery unit to ensure that the voltage of the battery unit is kept balanced. According to the scheme, the voltage of the battery units is effectively balanced through the starting discharge resistor, and the circuit is low in cost, simple in structure and high in practical value.

Description

Technical Field

[0001] The utility model relates to the technical field of battery management, and in particular to a voltage equalizing circuit of a high-voltage battery management system BMS module and a high-voltage management battery system. Background Art

[0002] The development of lithium batteries has been integrated into all areas of our lives, including electric vehicles, photovoltaic energy storage, and uninterruptible backup power systems. However, a fatal disadvantage of lithium batteries is safety. In order to ensure that lithium batteries can work safely, a lithium battery management system (BMS) needs to be installed inside the lithium battery pack. BMS has the function of protecting the battery from various abnormalities. It performs related protection by turning off or on the MOS tube, such as short circuit protection, charging overcurrent protection, discharging overcurrent protection, charging overvoltage protection, battery cell overtemperature protection, low temperature protection, battery undervoltage protection, etc.

[0003] For some fields that require higher battery voltages, it is usually necessary to connect multiple groups of battery cells in series to increase the voltage. Because of the differences in the internal resistance of the battery, long-term operation will cause voltage differences between the battery cells, which will cause unbalanced module voltage. Unbalanced voltage will cause unbalanced heating of the battery cells, which will not only affect the safe operation of the battery cells, but also reduce their service life. Utility Model Content

[0004] In order to overcome the above shortcomings, the purpose of the present invention is to provide a voltage equalizing circuit for a high-voltage battery management system BMS module and a high-voltage management battery system to solve the problems raised in the above background technology.

[0005] In order to achieve the above purpose, the technical solution adopted by the utility model is a voltage equalization circuit of a high-voltage battery management system BMS module, which is applied to a battery cell, wherein the battery cell includes a positive voltage V+ and a negative voltage V-, and the voltage equalization circuit includes:

[0006] A discharge resistor R1, one end of the discharge resistor R1 is connected to the negative voltage V-.

[0007] The switch tube Q1 has a source connected to the voltage V+ and a drain connected to the other end of the discharge resistor R1.

[0008] The switch tube driving circuit, the gate of the switch tube Q1 is connected to the switch tube driving circuit, and is used to output a high level to the gate of the switch tube Q1 when the voltage of the battery cell is higher than the threshold, the switch tube Q1 is turned on, and the discharge resistor R1 discharges the battery cell to ensure that the battery cell voltage remains balanced.

[0009] Furthermore, the switch tube driving circuit includes a transistor Q2, a resistor R2 and a resistor R3. The emitter of the transistor Q2 is connected to the negative voltage V-, and the collector is connected in series with the resistor R2 and the resistor R3 to the voltage V+. The gate of the switch tube Q1 is connected to the node between the resistor R2 and the resistor R3.

[0010] Furthermore, the voltage balancing circuit also includes a voltage detection circuit. The voltage detection circuit includes a comparator U1, a resistor R4, a resistor R5, a resistor R6, a resistor R7 and a resistor R8. The resistor R5, the resistor R6 and the resistor R7 are connected in series between the voltage V+ and the negative voltage V- in sequence. The output end of the comparator U1 is connected to the base of the transistor Q2, the positive input end is connected to the node between the resistor R2 and the resistor R3, and the negative input end is connected in series with the resistor R8 to access the reference voltage Vref. The two ends of the resistor R4 are respectively connected to the pull-up power supply terminal VCC of the comparator U1 and the output end of the comparator U1.

[0011] Furthermore, the voltage balancing circuit also includes an isolation circuit. The isolation circuit includes a photocoupler U2, a resistor R9 and a capacitor C1. The input end of the photocoupler U2 is connected to one end of the resistor R9, and the output end is connected to the node between the negative input end and the resistor R8. One end of the capacitor C1 is connected to the negative input end, and the other end is connected to the negative input end.

[0012] Furthermore, the other end of the resistor R9 is used to connect to the main control MCU unit, and the main control MCU unit generates a PWM signal to set the duty cycle adjustment and give the reference voltage Vref.

[0013] Furthermore, the switch tube Q1 is a P-type switch tube.

[0014] The technical solution also adopted by the utility model is a high-voltage battery management system, characterized in that a voltage equalization circuit of a high-voltage battery management system BMS module is adopted, the high-voltage battery management system includes a main control MCU unit and multiple battery units, the multiple battery units are connected in series, and each of the battery units includes the voltage equalization circuit of the high-voltage battery management system BMS module. The main control MCU unit and the multiple battery units are connected in sequence in a daisy chain manner.

[0015] Preferably, the connection wires between the main control MCU unit and the multiple battery units are twisted pair wires and are sleeved with magnetic rings.

[0016] Compared with the prior art, the present application provides a high-voltage battery management system BMS module voltage equalization circuit and a high-voltage management battery system. In view of the difference in internal resistance of the battery cells themselves, long-term operation will cause voltage differences in the battery cells. Excessive voltage differences will not only cause uneven heat distribution, but also affect product safety and life. A module voltage equalization circuit is provided, which can detect that the voltage of the battery cell is higher than the threshold, and then set the threshold through the main control to set the PWM signal, and send the signal to each battery cell. The threshold value is mainly the duty cycle of the PWM signal. Start the switch tube to discharge the discharge resistor, so that the voltage of the battery cell is maintained at the set value, and the battery cell voltage is balanced. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a circuit schematic diagram of an embodiment of a voltage equalization circuit of a high-voltage battery management system BMS module of the utility model;

[0018] Figure 2 This is a structural block diagram of an embodiment of a high-voltage management battery system of the utility model. DETAILED DESCRIPTION

[0019] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present invention.

[0020] refer to Figure 1 , Figure 1 A circuit schematic diagram of a voltage equalizing circuit of a high-voltage battery management system BMS module provided by an embodiment of the utility model is shown.

[0021] like Figure 1 As shown, the technical solution provided by the present application is a voltage equalization circuit of a high-voltage battery management system BMS module, which is applied to a battery cell, and the battery cell includes a positive voltage V+ and a negative voltage V-. The voltage equalization circuit includes a discharge resistor R1, a switch tube Q1 and a switch tube drive circuit, wherein: one end of the discharge resistor R1 is connected to the negative voltage V-. The source of the switch tube Q1 is connected to the voltage V+, and the drain is connected to the other end of the discharge resistor R1. The gate of the switch tube Q1 is connected to the switch tube drive circuit, which is used to output a high level to the gate of the switch tube Q1 when the voltage of the battery cell is higher than the threshold, the switch tube Q1 is turned on, and the discharge resistor R1 discharges the battery cell to ensure that the battery cell voltage remains balanced.

[0022] The voltage equalization circuit of the high-voltage battery management system BMS module provided in this request has a P-type switch tube Q1, which ensures that the battery cell voltage remains balanced by turning on the switch tube Q1 to allow the discharge resistor R1 to discharge the battery cell.

[0023] In some embodiments, reference Figure 1 The switch tube driving circuit includes a transistor Q2, a resistor R2 and a resistor R3. The emitter of the transistor Q2 is connected to a negative voltage V-, and the collector is connected in series with the resistor R2 and the resistor R3 to a voltage V+. The gate of the switch tube Q1 is connected to the node between the resistor R2 and the resistor R3.

[0024] The voltage balancing circuit also includes a voltage detection circuit. The voltage detection circuit includes a comparator U1, a resistor R4, a resistor R5, a resistor R6, a resistor R7 and a resistor R8. The resistors R5, R6 and R7 are connected in series between the voltage V+ and the negative voltage V- in sequence. The output end of the comparator U1 is connected to the base of the transistor Q2, the positive input end is connected to the node between the resistor R2 and the resistor R3, and the negative input end is connected in series with the resistor R8 to the reference voltage Vref. The two ends of the resistor R4 are respectively connected to the pull-up power supply end VCC of the comparator U1 and the output end of the comparator U1.

[0025] Exemplarily, the output end of the comparator U1 is connected to the transistor Q2, the negative input end is used as the reference end, and the negative input end is used as the sampling end. When the output end of the comparator U1 is at a high level, the transistor Q2 is turned on, so that the gate A of the P-type switch tube Q1 is at a low level, and the voltage equalization circuit is started; when the output end of the comparator U1 is at a low level, the transistor Q2 is not turned on, and the gate A of the P-type switch tube Q1 is at a high level, and the voltage equalization circuit is not started.

[0026] In some embodiments, reference Figure 1 The voltage balancing circuit also includes an isolation circuit. The isolation circuit includes a photocoupler U2, a resistor R9, and a capacitor C1. The input end of the photocoupler U2 is connected to one end of the resistor R9, and the output end is connected to the node between the negative input end and the resistor R8. One end of the capacitor C1 is connected to the negative input end, and the other end is connected to the negative input end.

[0027] The other end of the resistor R9 is used to connect to the main control MCU unit, and the main control MCU unit generates a PWM signal to set the duty cycle adjustment and give a reference voltage Vref.

[0028] Exemplarily, an optocoupler U2 device is used to electrically isolate the battery cell, and the battery cell voltage is calculated by detecting the voltage of resistor R7. The negative input terminal of the comparator U1 is connected to a reference voltage Vref and the optocoupler U2. The duty cycle is controlled by a PWM signal to give an input voltage reference value, thereby setting the battery cell voltage for discharge.

[0029] refer to Figure 2 , Figure 2 A structural block diagram of a high-voltage management battery system provided by an embodiment of the utility model is shown.

[0030] In some embodiments, reference Figure 1 and Figure 2 The present application also provides a high-voltage battery management system, characterized in that the voltage balancing circuit of the high-voltage battery management system BMS module described in any one of the above embodiments is adopted, and the high-voltage battery management system includes a main control MCU unit and multiple battery cells, the multiple battery cells are connected in series, and each battery cell includes a high-voltage battery management system BMS module voltage balancing circuit. The main control MCU unit and the multiple battery cells are connected in sequence in a daisy chain manner.

[0031] Exemplarily, the high-voltage management battery system is a system in which multiple battery cells are connected in series. When a battery cell exceeds the set voltage during charging, the discharge resistor discharges the battery cell to suppress the voltage of the battery cell from being too high. Similarly, the module voltage is balanced by monitoring and starting the discharge resistor to achieve balanced operation of the battery system. The threshold is set by setting the PWM signal through the main control MCU unit, and the signal is sent to each battery cell. The threshold size is mainly the duty cycle of the PWM signal. When the voltage of the battery cell is too high, the discharge resistor is started to effectively suppress the voltage of the module and achieve balanced voltage of the battery cells.

[0032] Preferably, the connection wires between the main control MCU unit and the multiple battery units are twisted pair wires and are sleeved with magnetic rings.

[0033] For example, the radio waves radiated by each wire in the twisted pair during transmission will be offset by the radio waves emitted by the other wire, effectively reducing the degree of signal interference. The magnetic ring is further provided to prevent the line from being interfered by the outside world.

[0034] The specific working process of the voltage equalization circuit of the high-voltage battery management system BMS module provided in this request is as follows:

[0035] refer to Figure 1When the battery BMS system is running, it is necessary to charge multiple battery cells in series. Because the internal resistance of the battery cells is different, the long-term operating voltage is different. At this time, the voltage of the battery cell needs a set value. If the battery cell voltage is higher than the set value, the discharge resistor is started to release electricity to reduce the voltage to ensure that the voltage of each battery cell does not exceed the set value. First, the positive input terminal of the comparator U1 is connected to the resistor R7 / resistor R6 / resistor R5, and the battery cell voltage is detected by resistor voltage division. At this time, the voltage at the positive input terminal of the comparator U1 is V*R7 / (R7+R6+R5); the negative input terminal of the comparator U1 is connected to a reference voltage Vref and an optocoupler U2, and the duty cycle is controlled by a PWM signal to give the input voltage reference. At this time, the voltage at the negative input terminal of the comparator U1 is Vref * n%, where n% represents the duty cycle provided by the master control. The C1 capacitor filter converts the duty cycle pulsating voltage into a stable DC voltage, so that each battery cell is referenced to a fixed reference source. When the negative input terminal of the comparator U1 detects that the battery voltage exceeds the reference voltage Vref, the output terminal of the comparator U1 is at a high level, and the high level causes the transistor Q2 to turn on. At this time, the level of the gate (point A) of the P-type switch tube changes from a high level to a low level, and the P-type switch tube Q1 is turned on, so that the discharge resistor R1 discharges the battery cell. The discharge resistor R1 needs to use a high-power resistor and a heat sink due to heat generation until the battery voltage is lower than the reference limit. When other battery cells operate according to this working principle, battery cell balancing can be achieved.

[0036] Since the threshold setting is flexible, the discharge resistor can be started at different stages of the battery cell voltage, which is very practical for the expansion of battery cells. For example, if a customer uses three groups of battery cells, there will inevitably be a voltage difference if another group of batteries is added. If a voltage equalization circuit is added, this voltage difference problem will be solved. At the same time, the use of optocouplers in the circuit for electrical isolation can improve the safety of the product, while also allocating circuit independence, making assembly and use more convenient.

[0037] The above implementation modes are only for illustrating the technical concept and features of the utility model, and their purpose is to allow people familiar with this technology to understand the content of the utility model and implement it. It cannot be used to limit the protection scope of the utility model. Any equivalent changes or modifications made according to the spirit of the utility model should be included in the protection scope of the utility model.

Claims

1. A voltage equalization circuit of a high-voltage battery management system BMS module, applied to a battery cell, wherein the battery cell includes a positive voltage V+ and a negative voltage V-; characterized in that: The voltage balancing circuit comprises: A discharge resistor R1, one end of which is connected to the negative voltage V-; A switch tube Q1, wherein a source of the switch tube Q1 is connected to the voltage V+, and a drain of the switch tube Q1 is connected to the other end of the discharge resistor R1; The switch tube driving circuit, the gate of the switch tube Q1 is connected to the switch tube driving circuit, and is used to output a high level to the gate of the switch tube Q1 when the voltage of the battery cell is higher than the threshold, the switch tube Q1 is turned on, and the discharge resistor R1 discharges the battery cell to ensure that the battery cell voltage remains balanced.

2. The voltage balancing circuit according to claim 1, characterized in that: The switch tube driving circuit includes a transistor Q2, a resistor R2 and a resistor R3; the emitter of the transistor Q2 is connected to the negative voltage V-, and the collector is connected in series with the resistor R2 and the resistor R3 to be connected to the voltage V+; the gate of the switch tube Q1 is connected to the node between the resistor R2 and the resistor R3.

3. The voltage balancing circuit according to claim 2, characterized in that: It also includes a voltage detection circuit; the voltage detection circuit includes a comparator U1, a resistor R4, a resistor R5, a resistor R6, a resistor R7 and a resistor R8; the resistor R5, the resistor R6 and the resistor R7 are connected in series between the voltage V+ and the negative voltage V- in sequence; the output end of the comparator U1 is connected to the base of the transistor Q2, the positive input end is connected to the node between the resistor R2 and the resistor R3, and the negative input end is connected in series with the resistor R8 to access the reference voltage Vref; the two ends of the resistor R4 are respectively connected to the pull-up power supply end VCC of the comparator U1 and the output end of the comparator U1.

4. The voltage balancing circuit according to claim 3, characterized in that: It also includes an isolation circuit; the isolation circuit includes a photocoupler U2, a resistor R9 and a capacitor C1; the input end of the photocoupler U2 is connected to one end of the resistor R9, and the output end is connected to the node between the negative input end and the resistor R8; one end of the capacitor C1 is connected to the negative input end, and the other end is connected to the negative input end.

5. The voltage balancing circuit according to claim 3, characterized in that: The other end of the resistor R9 is used to connect to the main control MCU unit, and the main control MCU unit generates a PWM signal to set the duty cycle adjustment and give the reference voltage Vref.

6. The voltage balancing circuit according to claim 1, characterized in that: The switch tube Q1 is a P-type switch tube.

7. A high voltage management battery system, characterized in that: The voltage balancing circuit of the high-voltage battery management system BMS module as described in claims 1 to 6 is adopted, and the high-voltage management battery system includes a main control MCU unit and multiple battery cells, the multiple battery cells are connected in series, and each of the battery cells includes the voltage balancing circuit; the main control MCU unit and the multiple battery cells are connected in sequence in a daisy chain manner.

8. The high voltage management battery system according to claim 7, characterized in that: The connection wires between the main control MCU unit and the multiple battery units are twisted pair wires and are sleeved with magnetic rings.

Images