CN102064568A - Active equalizing and protecting system of stackable series-connected lithium battery - Google Patents

Abstract

A stackable series lithium battery active balance and protection system: the coprocessor is connected to the processor through the SPI bus; each of the balance units includes a single battery and a balance circuit; wherein, each adjacent two balance units Connect in series in the following manner: the first equalizing circuit is connected in parallel with the first single cell, the first equalizing circuit includes a first P-channel MOSFET and a first N-channel MOSFET, and the drains of the two MOSFETs are connected to the gate connected, and connected to the coprocessor through the first signal input terminal; the sources of the first and second MOSFETs are respectively connected in parallel to the positive and negative ends of the first single battery; the positive pole of the second single battery It is connected to the negative pole of the first unit battery; the second equalization circuit connected in parallel to both ends of the second unit battery has the same structure as the first equalization circuit; the drains of the first and second equalization units are connected through supercapacitors.

Description

Active balancing and protection system for stackable series lithium batteries

technical field

The invention relates to a dynamic and active equalization and protection method for a lithium battery pack, in particular to a dynamic and active equalization technology and method for a lithium battery pack that can be stacked and flexibly configured.

Background technique

The application of lithium-ion batteries is becoming more and more extensive. In some applications, multiple single batteries are required to be connected in series or in parallel to meet the energy requirements of the system. Lithium-ion batteries have high requirements for charging and discharging. When overcharge, overdischarge, overcurrent and short circuit occur, the internal pressure and heat of lithium-ion batteries will increase greatly, which will easily generate sparks, burn and even explode. Therefore, lithium-ion batteries Group overcharge, discharge protection is necessary. In lithium-ion, the inconsistency of each single battery requires that necessary balancing measures be taken to ensure its safety and stability during use.

Now commonly used lithium battery equalization techniques include: bypass resistance method, multi-output winding auxiliary charging method, distributed equalization method based on DC/DC conversion, and switched capacitor method. Among them, the bypass resistance method is a dissipative equalization method, and the energy utilization rate is very low during the equalization process; the multi-output winding auxiliary charging method is bulky, the transformer winding is complicated, and the structure is not conducive to expansion; the distributed DC/DC converter based The equalization method requires a lot of switching elements and inductance-capacitor devices, the cost is relatively high, and the energy transmission efficiency is low; the traditional switched capacitor method is a more common equalization method, which requires more switches, and its equalization current is small and the equalization time is long. In recent years, with the commercialization of double-layer large-capacity capacitors and the reduction of costs, double-layer large-capacity capacitors have been widely used in energy storage and other aspects. As energy storage units, double-layer large-capacity capacitors are used in charging It has great advantages in terms of discharge and energy density; Power MOSFET (Power MOSFET) is a unipolar voltage control device, which not only has self-shutoff capability, but also has low driving power, high switching speed, and no secondary Breakdown, wide safe working area and other characteristics, its excellent performance is especially suitable as a switching device.

From the perspective of the new energy industry chain, whether it is lithium-ion batteries for energy storage or power lithium-ion batteries for electric vehicles, there is a bottleneck problem of the battery management system, and battery balancing and protection technology is the core technology of the battery management system. A breakthrough is expected to form a guiding dominant position in the industry. In the past 20 years, scientists and application engineers from all over the world have done a lot of work on this issue, and domestic research is also in the ascendant. In this regard, domestic and foreign patents mainly include: US5886502, US6114835, US6278604, US6356055, US6844703, US7279867, US7609031, US20040032236, US20050077875 , US20050269989, US20080018299, US20090167243, CN2814766, CN101183798, CN2899130, CN101262138, CN1449085, etc.

Stacking design is a new concept that has emerged in recent years. It emphasizes the modularization and scalability of product design to meet the needs of systems of different scales. The modular design concept can effectively use existing technologies and products, and reduce the complexity of product development. In addition, it can provide technology reuse measures to unify the product line and process flow and reduce management and industrialization costs. Power batteries are widely used, from conventional electric bicycles, electric motorcycles, to electric vehicles, electric buses, etc. The scale requirements of batteries in these applications are different, but they all have a general commonality: reasonable equalization circuits and algorithms are required Perform high current fast equalization. The traditional solution to such problems is to design a product development process for each specific application and set up a professional R&D team, so that different R&D personnel are actually doing many common tasks without interacting with each other. Communication makes every job cost a lot of manpower and material resources. However, the stacking design modularizes common objects and adopts menu customization for non-common parts, which effectively avoids the above problems. At present, most of the companies involved in the electric vehicle industry are many of the previous manufacturers of electric bicycles and electric motorcycles. They may be familiar with the original car body, drive and power system, and the stacked dynamic balance and protection settings and technologies can be realized. Inheriting the original product lines of these enterprises and being compatible with new product lines can effectively reduce the capital investment of these enterprises and increase their competitiveness.

There are few reports on dynamic equalization and protection settings and technologies of stackable series lithium battery packs. The realization of this technology has high application value and technical content, and can meet the different balance and protection requirements of the existing electric bicycles, electric motorcycles, hybrid electric vehicles, electric vehicle multi-level power sources and energy storage battery stacks.

Contents of the invention

In order to solve the current application requirements of power battery packs and energy storage battery packs of different grades, the purpose of the present invention is to provide a dynamic balance and protection system for stackable series lithium battery packs. In order to achieve the above purpose, the technical solution adopted by the present invention is: a stackable series lithium battery active equalization and protection system, the system includes a main processor, a co-processor and more than two equalization units, wherein:

The coprocessor is connected with the processor through the SPI bus;

Each of the balancing units includes a single battery and a balancing circuit; wherein, every two adjacent balancing units are connected in series in the following manner:

The first balancing circuit is connected in parallel with the first single cell, the first balancing circuit includes a first P-channel MOSFET _Q1 and a first N-channel MOSFET _Q2 , and the drains of the two MOSFETs are connected; The gates of the two MOSFETs are connected, and are connected to the coprocessor through the first signal input terminal _Sn to receive the switch control signal input by the coprocessor; the sources of the first and second MOSFETs are respectively connected in parallel to the _positive and negative ends of the first single battery; the positive and negative ends of the first single battery are also connected to _the a coprocessor, configured to output a differential signal to the coprocessor, where the differential signal is an actual voltage signal of the first single battery;

The positive pole of the second single battery is connected to the negative pole of the first single battery; the second equalizing circuit connected in parallel at both ends of the second single battery is the same structure as the first equalizing circuit, wherein, with the second single battery The source of the second P-channel MOSFET connected to the positive pole of the battery is connected to the source of the first N-channel MOSFET connected to the negative pole of the first single battery through a common node, and the second single battery is connected to the negative pole of the first single battery. The first single battery shares a voltage signal output terminal;

The drains of the first and second equalization units are connected through supercapacitors.

The main processor is connected to no more than 15 expansion modules through the SPI bus, and each expansion module includes a coprocessor connected to more than two equalization units.

Each co-processing is connected with 4 to 12 equalization units.

The main processor and the expansion modules form a star topology.

The main processor is connected with the expansion module through a magnetic coupling circuit.

The active balance and protection system of the stackable serial lithium battery provided by the invention can realize the dynamic balance and protection of the high voltage and high current battery pack. It adopts a modular design, which is convenient for expanding applications. You can choose to add different numbers of extended equalization modules to meet the different equalization and protection requirements of multi-level power supplies for electric bicycles, electric motorcycles, hybrid vehicles, and electric vehicles.

Description of drawings

Fig. 1 is the structural block diagram of stackable serial lithium battery active equalization and protection system provided by the present invention;

Fig. 2 is a schematic diagram of coprocessor pins in the stackable series lithium battery active equalization and protection system provided by the present invention;

Fig. 3 is a schematic diagram of the basic equalization unit of the active equalization and protection system of the stackable series lithium battery provided by the present invention;

Fig. 4 is a schematic diagram of an equalization circuit in which 6 single cells are connected in series to form a battery pack in the active equalization and protection system of a stackable series lithium battery provided by the present invention;

Fig. 5 is a schematic diagram of a stackable series lithium battery active equalization and protection system provided by the present invention for circuit isolation through a magnetic coupling device;

6 is a schematic diagram of the driving waveform output by the main processor driving circuit of the stackable series lithium battery active equalization and protection system provided by the present invention;

Fig. 7 is an effect diagram of equalization of 2 serially connected batteries of the present invention;

Fig. 8 is an effect diagram of equalizing 12 series-connected batteries of the present invention;

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings.

As shown in FIG. 1 , it is a structural block diagram of a stackable serial lithium battery active equalization and protection system provided by the present invention. The system includes a main control module and several expandable modules.

1. Main control module:

The main control module includes a main processor, a co-processor, and a balance unit corresponding to the co-processor with up to 12 series-connected single batteries, including 12 switch units connected to 12 energy transfer units.

The main processor is an ordinary single-chip microcomputer, DSP processor, ARM processor and FPGA controller, etc., responsible for signal collection and arrangement, adjustment of equalization strategy, and sending measurement and control instructions to the coprocessor. The main processor communicates with the coprocessor through the serial peripheral interface (Serial Peripheral Interface, SPI) bus, and returns the various voltage signals measured by the coprocessor to the main processor, so as to flexibly realize the dynamic and active battery packs of various specifications. balanced. The main processor can control up to 16 coprocessors, one of which is the coprocessor on the main module, and the other 15 coprocessors are located on the expansion module. According to the system scale, the expansion module can be selected reasonably.

As shown in FIG. 2 , it is a schematic diagram of coprocessor pins used in the stackable series lithium battery active balancing and protection system provided by the present invention.

In this embodiment, the coprocessor adopts Linear Technology's LTC6802-2 (hereinafter referred to as LTC6802) integrated chip (Integrated Circuit, IC). LTC6802-2 is a complete battery monitoring IC with a built-in 12-bit ADC , a precision voltage reference, a high-voltage input multiplexer, and a serial interface. Each LTC6802-2 is capable of measuring the voltage of 12 series-connected cells with a total input voltage up to 60V. Multiple LTC6802-2 devices can be connected in series to monitor the voltage of each cell in a long string of series connected cells. Each LTC6802-2 has an individually addressable serial interface, and each battery input has an associated MOSFET switch for discharging any overcharged cells.

The LTC6802 pins are shown in Figure 2: V+ is the positive wiring pin of the battery pack; V- is the negative wiring pin of the battery pack; A ₀ ~ A ₃ are address selection lines; SCKI, SDI, SDO, and CSBI form an SPI interface, The coprocessor communicates with the main processor through the SPI interface; C ₁ ~ C ₁₂ are the voltage input terminals of 12 single cells, C ₁₂ is connected to the highest potential terminal in the string of batteries, C ₁ is connected to the lowest potential terminal in the string of batteries, In the case of multi-chip connections, C ₁ is connected to C ₁₂ of the next LTC6802. S ₁ ~ S ₁₂ are the discharge terminals driven by the on-chip N-MOSFET tube, which can discharge with a small current; VTEMP1, VTEMP2 are 2-way temperature signal input terminals, which can be connected to negative temperature coefficient (Negative Temperature Coefficient, NTC) thermistors; VREF It is the reference point output terminal; VREG is the high end of the logic level of the chip; TOS is the SPI mode setting terminal; MMB is the working mode setting terminal; WDTB is the watchdog clock output terminal; GPIO1, GPIO2 (General Purpose Input/Output, GPIO) is a general-purpose input and output interface.

2. Balance principle

As shown in FIG. 3 , two batteries are taken as an example to illustrate the balancing unit of the active balancing method provided by the present invention. The basic equalization circuit of the present invention is based on the equalization of the switched capacitor method, and utilizes the capacitance to transfer the battery energy from the high-voltage single battery to the low-voltage single battery. Using power metal-oxide-semiconductor field-effect transistors (Metal-Oxide-Semiconductor Field-Effect Transistor, MOSFET) tubes to form a bidirectional switch array, the main processor controls the balance module to operate the switch array to realize the transfer of charges between batteries to achieve the purpose of battery balance .

In Fig. 3, C _A and C _B are 2 energy saving devices connected in series, the negative pole of C _A is connected to the positive pole of C _B ; Q ₁ and Q ₃ are power type P-MOSTFET tubes, Q ₂ and Q ₄ are power type N- MOSTFET tube; each equalization unit adopts P-MOSFET and N-MOSFET switching devices, and the P-channel MOSFET tube is connected to the gate of the N-channel MOSFET tube to form an interlock switch. D ₁ , D ₂ , D ₃ , D ₄ are zener diodes; R ₁ ~ R ₅ are resistors; C _n , C _n-1 , C _n-2 are voltage measurement signal output ports; S _n , S _n-1 It is the control signal output terminal of the coprocessor.

The positive and negative ends of each single battery C _A , C _B are connected in parallel with equalizing circuits. In the balanced circuit, the gate of a P-channel MOSFET _Q1 is connected to the gate of an N-channel MOSFET _Q2 . Similarly, _Q3 is connected to the gate of _Q4 to form an interlock switch and form two bidirectional switch pair. The sources of Q1 and _Q2 are respectively connected in parallel to the positive and negative terminals of the single battery C _A ; similarly, the sources of _Q3 and _Q4 are respectively connected in parallel to the positive and negative terminals of the single battery C _B ; Q ₂ It is connected with the source of _Q3 at the positive end of the single cell _CB through a common node. C ₁ is a supercapacitor as an energy transfer unit. One end of C ₁ is connected to the drains of Q ₁ and Q ₂ , and the other end is connected to the drains of Q ₃ and Q ₄ .

The positive and negative terminals of the battery output differential signals to the coprocessor through the output terminals C _n , C _n-1 , and C _n-2 respectively. The differential signal is the voltage signal of the single battery, and the single battery C The positive and negative voltage values of _A and the positive and negative voltage values of the single battery C _B , that is, the differential signals between C _n and C _n-1 , C _n-1 and C _n-2 are output to the external circuit, where , the negative pole of C _A is the same as the positive pole voltage value of C _B. S _n , S _n-1 are two independent control signal output terminals in the coprocessor, which output synchronous pulse signals as the switching signals of the two bidirectional switch pairs to control the two bidirectional switch pairs, and the high and low levels of the control logic The differential levels corresponding to the voltage levels of terminals C _n-1 and C _n-2 are respectively connected to the gates of the two MOSFETs in turn, and output control signals to them to control the _{conduction ,} closure.

The coprocessor collects the voltage signals of each single battery through the C _n , C _n-1 , C _n-2 ... port, and transmits these single battery voltage signals to the main control module through the SPI bus. The main processor, the main processor decides to adopt a certain control strategy by comparing the voltage signals of various channels, and transmits these control strategies to the corresponding coprocessor through the SPI bus, through which the coprocessor controls the related switches S _n , S _{n- 1} ......Output pulse switch signal.

For example, in Figure 3, the voltage measurement signal output ports C _n , C _n-1 , C _n-2 output voltage signals to the coprocessor, if the voltage difference between C _n , C _n-1 is smaller than C _n-1 , The voltage difference between C _n-2 , that is, the voltage of C _A is less than the voltage of C _B , first output a high-level control signal through the S _n and S _n-1 ports, so that Q ₂ and Q ₄ are turned on, and Q ₁ , Q ₃ is cut off, at this time C ₁ is connected across the two ends of C _B , and capacitor C ₁ is charged by battery C _B ; after a period of charging, S _n , S _n-1 ports output low-level control signals, so that Q ₂ , Q ₄ is turned off, Q ₁ and Q ₃ are turned on, at this time C ₁ is connected across the two ends of _CA , and capacitor C ₁ discharges to _CA. The charging period mentioned here refers to the time for the circuit to reach a steady state again, which can be calculated according to circuit analysis theory. For example, if the on-resistance of _Q2 is 50mΩ and C is 1F, this period of time should be greater than 5* 50mΩ*1F=250ms. vice versa. In this way, using the supercapacitor as the energy transfer carrier, after repeated operations of S _n and S _n-1 for several times, the transfer of charge from the high-voltage single cell to the low-voltage single cell can be realized, so as to achieve the effect of the supercapacitor on the battery pack. energy balance.

Zener diodes D ₁ and D ₂ are respectively connected in parallel with single cells C _A and C _B in the equalizing unit circuit. And similar to the series connection of the single cells _CA and _CB , the anode of the Zener diode _D1 is connected in series with the cathode of _D2 . Zener diodes D ₃ and D ₄ are respectively connected between the positive poles of batteries C _A and C _B and the control signal input terminals S _n and S _n-1 , and a resistor R ₂ is connected in series between their negative poles and the control signal input terminals And R ₄ , D ₁ -D ₄ , R ₂ and R ₄ provide protection for the equalization unit circuit.

C ₂ and C ₃ are ordinary filter capacitors, which are respectively connected between the differential voltage signal input terminals C _n and C _n-1 and between C _n-1 and C _n-2 of the external circuit. C ₂ , R ₁ and C ₃ , R ₃ have an anti-aliasing effect on the differential voltage signal and increase measurement accuracy.

As shown in Figure 4, the schematic diagram of the equalization circuit takes 6 single cells connected in series to form a battery pack as an example. When multiple batteries are connected in series, according to the basic equalization unit in Figure 2, the MOSFET tube pair with the above-mentioned common gate is used to form a bidirectional controllable switch, and the S _i (i∈1～n) signal corresponding to the battery controls the gate pole, and the drain connection of the MOSFET pair is connected to one pole of the double-layer bulk capacitor.

3. Expansion module

The expansion module does not have a main processor part, but only a coprocessor and a balance unit corresponding to 12 series-connected single batteries, including 12 switch units connected to 12 energy transfer units. The structure of the coprocessor also adopts the above-mentioned LTC6802-2 coprocessor. These expansion modules communicate with the main module through an electrically isolated SPI bus.

Each coprocessor LTC6802 can manage 4-12 batteries and measure their monomer voltage, and provide control signals to the operation switch of the balancing unit at the same time. The coprocessor is responsible for the voltage collection of each unit, the on-site temperature detection, and returns the signal to the main processor. The main processor gives the control algorithm to control the coprocessor to perform switching actions according to the instructions and perform dynamic balance.

4. Stacking measures

The expandability of the present invention is that the coprocessor manages a plurality of lithium batteries in groups, and then transmits to the main processor through the SPI serial communication mode. Usually each coprocessor group manages 4-12 lithium batteries. SPI adopts a star topology structure, the main processor is the SPI communication initiator, and each coprocessor is the slave SPI communication end, forming a master-slave communication network.

In the case of no expansion unit, the main control module can independently complete the complete balance control function of up to 12 lithium batteries. At this time, the coprocessor is connected to 12 lithium batteries, and the series connection voltage is 30VDC to 60VDC. For the balance control of higher-voltage battery packs with a series voltage of 60VDC to 1000VDC, it can be flexibly expanded according to the scale of battery pack series connection, up to 15 modules can be expanded, and each module is connected to 12 series batteries, plus the main control module. According to the number of connected batteries, a total of up to 192 batteries can be realized, and dynamic active balancing with a series voltage of 300VDC to 1000VDC can be realized.

5. Electrical isolation measures

As shown in Figure 5, it is an example of circuit isolation through magnetic coupling devices. In this embodiment, ADUM1411 magnetic coupling IC of ADI Company is used to realize electrical isolation. The main processor of the present invention communicates with each equalizing module through magnetic coupling technology or photoelectric coupling, and is strictly electrically isolated from the co-processor. Except for communication, there is no direct electrical connection between the main processor and the co-processor. Electrical safety isolation between the main circuit of the battery pack and the control circuit without electrical coupling. In order to achieve the purpose of SPI communication electrical isolation, technologies such as transformer isolation, photoelectric isolation, and magnetic coupling isolation can be used to achieve SPI communication isolation.

6. Equilibrium strategy (algorithm)

The balance algorithm of the present invention is completed by the main processor. According to different charging and discharging states, according to the battery information obtained from the co-processor, compare the battery voltage, and decide to realize various flexible functions such as uplink equalization, downlink equalization, and maximum difference monomer equalization. The equalization control strategy, and output the corresponding driving level signal through the maximum 12 Si ports of the communication control coprocessor to control each equalization unit circuit. The balance switch control based on complex logic algorithm can also be realized by calculation algorithm. The control strategy is written in C language, and written into the main controller program memory or on-chip FLASH by the JTAG interface.

The uplink equalization method starts from the battery with the highest cell voltage, and always balances the battery with the highest cell voltage with adjacent batteries, which is often used for equalization during charging; the downlink equalization is always performed between the battery with the lowest cell voltage and adjacent batteries Equalization, often used for equalization during discharge; maximum difference cell equalization is to always search and compare the two batteries with the largest voltage difference between adjacent cells in the battery pack, and is often used for equalization under discharge or idle state; In the case of adopting the above algorithm, the global synchronous pulse equalization method can be adopted, that is, without comparing the voltages of each cell, the main processor controls the Si port of all coprocessors to output synchronous sequence pulses through SPI communication, and the battery pack will be activated after a series of cycles. achieve balance.

The switching frequency of the equalizing system provided by the invention is faster than that of the prior art. In the above embodiments, the calculation is based on the maximum charging time of 250 milliseconds, and according to the characteristics of the computing device, the balanced switching frequency is generally 0.4 Hz to 40 Hz, the maximum current that the switch can provide can reach more than 60 A, and the normal use range is 4 to 20 A . The voltage difference of each single battery can be controlled within 50mV, the maximum instantaneous equalization current can reach more than 34A, and the average equalization current can be between 4 and 10A. The equalization switching frequency of the traditional Buck-Boost technology is generally above 5kHz, and the equalization switching frequency of the equalization system provided by the present invention is much lower than that of the traditional Buck-Boost technology, so that a perfect equalization effect can be achieved.

The main processor can control and operate the driving circuit of the coprocessor through SPI communication. Figure 6 is a schematic diagram of the driving waveform output by the coprocessor after receiving the command from the main processor. The waveform is a 1Hz square wave with an amplitude of 5V and a duty cycle of 50 %. Taking the balance circuit of 2 cells in series as shown in Figure 3 as an example, _Sn and Sn _-1 are loaded with the synchronization pulse, and the equalization effect is shown in Figure 7. The voltage difference of two cells with a voltage difference of 1V reaches the voltage balance quickly after several equalization actions within 4000 milliseconds. The voltage of the battery drops, thereby realizing the balance between the 2 series connected batteries.

Figure 8 is a 12-cell battery balancing effect diagram. The initial cell voltages are 3.1V, 3.2V, 3.3V, 3.4V, 3.5V, 3.6V, 3.7, 3.8, 3.9V, 4.0V, 4.1V, 4.2V , adopting the pulse sequence in Figure 6 and adopting the synchronous pulse equalization strategy, the 12-cell battery pack with an initial maximum cell voltage difference of 1.1V quickly reaches equilibrium within 60 seconds, and the maximum cell voltage difference at equilibrium is less than 30mV. The enlarged part in the figure shows some details of the equalization process. The fine ripple curve reflects the capacitor charge and discharge curve process of the equalization process, and its ripple fluctuation is less than 40mV.

7. Protection measures

In the main control module, the onboard Allegro MicroSystems ACS758 current sensor chip or optional 4-20mA, single 5V power supply, Hall effect current transformer is used to collect the main circuit current signal of the battery pack, and the signal is directly transmitted to the main control module The analog input port of the main processor on the computer; the voltage acquisition of each single battery is completed by the coprocessor and communicated to the main processor. Each voltage acquisition unit of the coprocessor adopts an anti-aliasing design to ensure that the accuracy of the voltage acquisition data reaches 14-bit precision. The analog-to-digital converter (Analog to Digital Converter, ADC) of the coprocessor adopts the improved successive approximation (Successive Approximation Register, SAR) analog-to-digital conversion algorithm, which improves the speed of voltage acquisition, and all voltage acquisition can be completed within 13ms.

The PCB circuit design of the equalization unit can achieve high current balance, the trace width of the high current route is not less than 3mm (120mil), and tin plating is added. In order to ensure the signal quality, the general control signal and communication signal line width is not less than 0.5mm (20mil). The main control circuit board adopts a 4-layer wiring method, and the middle two layers are the GND layer (negative version) and the power layer (negative version). The power layer is divided into +24V and +5V by the internal electrical layer segmentation technology.

The present invention adopts a resettable fuse and a positive temperature coefficient (Positire Temperature Coefficient, PTC) thermistor to realize the automatic protection of the overcurrent and short circuit of the main circuit of the battery, and sets a circuit breaker or a protective relay in the main circuit of the battery to protect the main circuit.

In the present invention, each coprocessor is also responsible for local temperature detection and alarm output of the battery pack, and each coprocessor (LTC6802-2) can provide 2-way temperature detection loops and 2-way fan output drive loops to realize the cooling function of the battery pack . As shown in FIG. 2 , the GPIO1 and GPIO2 of the coprocessor output 2 channels of fan driving level signals. Two negative temperature coefficient thermistors NTC1 and NTC2 are respectively connected to the VTEMP1 and V-terminals and VTEMP2 and V-terminals of the coprocessor LTC6802 to form two battery pack temperature detection circuits. The LTC6802 collects these temperature signals and transmits them by communication. to the main processor, and then the main processor sends a control command communication back to the LTC6802, and the LTC6802 outputs the fan switch signal to achieve the purpose of cooling.

The peripheral functional unit of the main controller of the present invention also includes a watchdog circuit using MAX706; a clock circuit using an 8M active clock oscillator; a CAN communication interface, an asynchronous serial communication (UART) interface, a power supply voltage stabilizing circuit, and the like.

The invention can realize the dynamic balance and protection of the battery pack with high voltage and high current. The battery equalization effect ensures that the voltage difference between the single cells is less than 50mV, and the total voltage of the balanced battery pack can reach 1000V. It adopts a modular design, which is convenient for expanding applications. You can choose to add different numbers of extended equalization modules to meet the different equalization and protection requirements of multi-level power supplies for electric bicycles, electric motorcycles, hybrid vehicles, and electric vehicles.

The above content is a detailed description of the present invention in conjunction with specific preferred embodiments, which are all examples for easy understanding, and the specific implementation of the present invention should not be considered to be limited to these descriptions. For those skilled in the art, various possible equivalent changes or substitutions made without departing from the concept of the present invention shall fall within the protection scope of the present invention.

Claims (5)

1. A stackable series lithium battery active equalization and protection system, characterized in that the system includes a main processor, a coprocessor and more than two equalization units, wherein: The coprocessor is connected with the processor through the SPI bus; Each of the balancing units includes a single battery and a balancing circuit; wherein, every two adjacent balancing units are connected in series in the following manner: The first equalizing circuit is connected in parallel with the first single cell, and the first equalizing circuit includes a first P-channel MOSFET (Q ₁ ) and a first N-channel MOSFET (Q ₂ ), and the drains of the two MOSFETs are poles are connected; the gates of the two MOSFETs are connected, and are connected to the coprocessor through the first signal input terminal (S _n ) to receive the switch control signal input by the coprocessor; the first and second The sources of the MOSFET tubes are respectively connected _in parallel to the positive and negative ends of the first single cell; , C _n-1 ) are connected to the coprocessor to output a differential signal to the coprocessor, and the differential signal is the actual voltage signal of the first single battery; The positive pole of the second single battery is connected to the negative pole of the first single battery; the second equalizing circuit connected in parallel at both ends of the second single battery is the same structure as the first equalizing circuit, wherein, with the second single battery The source of the second P-channel MOSFET connected to the positive pole of the battery is connected to the source of the first N-channel MOSFET connected to the negative pole of the first single battery through a common node, and the second single battery is connected to the negative pole of the first single battery. The first single battery shares a voltage signal output terminal; The drains of the first and second equalization units are connected through supercapacitors. 2. The stackable series lithium battery active balancing and protection system according to claim 1, wherein the main processor is connected to no more than 15 expansion modules through the SPI bus, and each expansion module includes a The coprocessor is connected to more than two equalization units. 3. The stackable active equalization and protection system for series-connected lithium batteries according to claim 1 or 2, wherein each co-processing unit is connected to 4 to 12 equalization units. 4. The stackable active balancing and protection system for series-connected lithium batteries according to claim 2, wherein the main processor and the expansion modules form a star topology. 5. The active balance and protection system for stackable series-connected lithium batteries according to claim 2, wherein the main processor is connected to the expansion module through a magnetic coupling circuit.

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