CN203126558U - Battery management system based on coprocessor and solid-state relay - Google Patents

Abstract

The utility model discloses a battery management system based on a coprocessor and a solid-state relay, which is a new type of battery management system with low self-consumption and high-precision SOC estimation. Based on an MC9S12XE single-chip microcomputer, the working state parameters of the battery can be monitored. , Carry out high-precision estimation of battery SOC, realize battery insulation monitoring, fault classification alarm and balance management. It includes a main control board and a current collection board and a voltage collection board respectively connected to it. The drive connector is connected to the relay; the current acquisition board uses a coprocessor combined with the main processor to realize the SOC estimation of the battery, and is connected to a current sensor through the current signal connector, and the current sensor is arranged between the relay and the high voltage general negative terminal; The voltage acquisition board collects voltage signals through an operational amplifier chip, and the power supply of the operational amplifier chip is controlled by a solid state relay.

Description

Battery Management System Based on Coprocessor and Solid State Relay

technical field

The utility model relates to a battery management system, in particular to a battery management system based on a coprocessor and a solid state relay. the

Background technique

As the main power source of electric vehicles, the performance of batteries will directly affect the promotion of electric vehicles. The battery management system not only needs to monitor the working status of the battery in real time, but also needs to balance the inconsistency of the cycled battery, so as to prevent the battery from overcharging and over-discharging, so as to improve the cycle life of the battery. the

At present, a lot of research has been done on the battery management system at home and abroad. For example, the intelligent management system of General Motors of the United States can realize the status monitoring of single batteries and has a balancing function. The products of domestic companies such as Yineng, Ligao, Guantuo and Mogong have also been widely used, but the current battery management system There are common problems such as large power consumption of the system and low accuracy of voltage acquisition in the non-working state, or the problem of low estimation accuracy of the remaining capacity of the battery (State of Charge, SOC). the

The collection of battery voltage by the battery management system is mostly based on the collection of the chip as a whole or the cyclic collection of analog switches or solid state relays. The former collection method will lead to an increase in the self-consumption power of the battery management system when it is not working, while the latter method It will reduce the accuracy of voltage acquisition, and also reduce the reliability of the battery management system; at present, the estimation of SOC in electric vehicles is mostly based on the open circuit voltage method and the ampere-hour integration method, so the estimation accuracy of the initial SOC and the current sampling speed are related to the The estimation rate of the SOC will affect the estimation accuracy of the overall SOC. the

Chinese patent CN 102975627A detects the type of the coupled USB device, and charges the USB device according to the type of the USB device. the

Chinese patent CN 101141076A connects the voltage detection unit to the auxiliary power supply or the battery unit through the contact relay to determine whether the circuit of the voltage detection unit is abnormal when starting or stopping; use the number of battery unit relays corresponding to the total number of battery units to perform battery For voltage acquisition, this acquisition method needs to cycle the battery unit relay on and off, which affects the life of the relay. In addition, due to the different voltage drop of the relay, the accuracy of the voltage acquisition corresponding to the battery will also decrease. the

Chinese patent CN 102064568A uses the LTC6802 coprocessor to collect battery voltage and output equalization control signals, and exchange data with the main controller through the SPI bus. However, this processing method cannot solve the problem of improving SOC accuracy. the

In summary, the battery management system has two major difficulties:

One is: high-precision estimation of SOC. The estimation of high-precision SOC includes high-precision estimation of initial SOC and high-precision estimation of SOC during system operation. Estimation, for the initial SOC estimation, the utility model adopts the relationship between the open circuit voltage and the SOC under different temperatures, different currents and charging and discharging states under different static times to carry out the initial SOC calibration; the SOC estimation in the system working process adopts the ampere-hour integral From the principle of the ampere-hour integral method, it can be seen that the reason that affects the estimation accuracy of SOC in the working process is the slow sampling speed of current and the slow calculation speed of SOC. the

The second is battery voltage acquisition with low power consumption and high precision. At present, the acquisition of battery voltage is mainly divided into two categories, one is chip-based voltage acquisition, and the other is the use of analog switches or solid state relays to cycle the voltage. Acquisition, the former acquisition method leads to a relatively large self-consumption power when the battery management system is in a non-working state, which affects the driving range of the electric vehicle battery. The latter method uses switches, and the voltage drop of each switch is different. , thus affecting the high-precision acquisition of the battery voltage, and reducing the reliability of the battery management system due to the switching back and forth of the switch. the

Contents of the invention

The purpose of this utility model is to overcome the deficiencies of the above-mentioned prior art and provide a low-power battery management system based on coprocessors and solid-state relays, which is a new type of battery management system with low self-consumption and high-precision SOC estimation , based on the MC9S12XE single-chip microcomputer, it can monitor the working state parameters of the battery, estimate the SOC of the battery with high precision, realize the insulation monitoring of the battery, fault classification alarm and balance management. the

In order to achieve the above object, the utility model adopts the following technical solutions:

A battery management system based on a coprocessor and a solid-state relay, which includes a main control board and a current acquisition board and a voltage acquisition board respectively connected to it, and the main control board is respectively connected to a high-voltage main positive circuit through a high-voltage electrical connector. terminal and the total negative terminal to realize high-voltage electrical insulation monitoring, and connect the relay through the power drive connector; the current acquisition board uses a coprocessor combined with the main processor to realize the SOC estimation of the battery, and connects the current sensor through the current signal connector, and the current The sensor is arranged between the relay and the general negative terminal of the high voltage electricity; the voltage acquisition board collects the voltage signal through the operational amplifier chip, and the power supply of the operational amplifier chip is controlled by the solid state relay. the

The system uses 12V/24V low-voltage batteries on electric vehicles to supply power to them through their respective DC/DC isolation modules; the system uses B0505 power chip to isolate communication power supply, and uses 6N137 high-speed optocoupler to monitor communication signals. Isolation to enhance the anti-interference ability of communication signals. the

The main control board includes a USB storage module for storing working state parameters. the

The main control board is connected with a display screen, and the display screen is a liquid crystal display to realize real-time display of working state parameters; the main control board also communicates with the electric vehicle instrument and the vehicle controller through the CAN bus. the

The main control board also includes a power supply module 1, a main controller module 1 and a communication module. the

The relay includes a main relay, a module relay and a charging relay, the main relay is connected to a load, and the load is connected to the high-voltage general positive terminal through a fuse, the module relay is a relay between battery packs, and the battery pack is the number of batteries controlled by each voltage acquisition board, and the charging relay is connected to the charger signal. the

The current collection board includes a power supply module II, a main controller module II and a current collection module. the

The current sensor is a bidirectional Hall current sensor. the

The voltage acquisition board is respectively connected to the temperature sensor installed on the positive and negative poles of the battery pack and the positive and negative terminals of the battery through the temperature signal connector and the voltage signal connector. There are several voltage acquisition boards, and each voltage acquisition board corresponds to at most 8 batteries. the

The voltage acquisition board is connected with the balance board through the balance board connector. the

The voltage acquisition board includes a power supply module III, a main controller module III, a voltage acquisition module and a temperature acquisition circuit. the

The voltage acquisition module includes a voltage signal connector, a diode, a solid-state relay, and an operational amplifier 1-8. The voltage of the high-voltage battery is connected to the anode of the diode D1-D6 through the voltage signal connector, and the cathode of the diode D1-D6 is connected to the pin of the solid-state relay 8. Pin 1 of the solid state relay is connected to the positive pole of the power supply, pin 2 is grounded through resistor R1, pin 7 supplies power to op amp chips 1-8 through capacitors C1, C2, and C3, and the positive pole of a single high-voltage battery is connected to resistor R3 The non-inverting input terminal of the operational amplifier chip 1-8, the negative pole is connected to the reverse input terminal of the operational amplifier chip 1-8 through the resistor R4, and the non-inverting input terminal is grounded through the resistor R2, and the reverse input terminal is connected to the output terminal of the operational amplifier through the resistor R5 , the output terminal of the operational amplifier is connected to the AD sampling port of the main chip through resistors R1 and C2. the

通过精确计算k-1至k时刻流经电池组的电流i(t)可计算电流积分值，加上充放电效率的修正，与电池组的初始状态相加就可获得当前的SOC，从上面分析可以看出，为了提高工作过程中SOC的估算精度，需要提高电流的采样速度及SOC的估算速率，本实用新型基于MC9S12XE单片机，采用协处理器与主处理器相结合的方式，主程序一直对电流信号进行采集，协处理器对SOC计算周期定时器中断进行处理，并通过双口RAM与主处理器交换电流数据， 从而实现SOC的估算。本实用新型另外还对电池容量的影响因素如电流、温度、老化状态、自放电进行研究，获得了上述参数与电池容量的关系曲线用于容量的修正。  The current acquisition module includes a current signal processing module, a current signal acquisition module and an SOC estimation module. The utility model adopts a bidirectional Hall sensor. Since the reference voltage of the AD sampling chip is 5V, in order to reduce the complexity of the circuit, -100mA- The 100mA current is first converted into a voltage of -2.5V-2.5V through a 25-ohm resistor, and then converted into an electrical signal of 0V-5V through a 2.5V reference voltage. A large number of previous results show that there is a certain relationship between the opening voltage and SOC. In order to improve the estimation accuracy of SOC, the utility model adopts the method of combining open circuit voltage and ampere-hour integration method. In order to improve the estimation accuracy of initial SOC, based on The relationship between the open-circuit voltage and SOC under different temperatures, different currents, and charging and discharging states obtained under different static times is used to calibrate the initial SOC value. Since the SOC is estimated during the system’s working process, the ampere-hour integral method is used for the calculation of the ampere-hour integral method. The formula is as follows,

By accurately calculating the current i(t) flowing through the battery pack at time k-1 to k, the current integral value can be calculated, plus the correction of the charging and discharging efficiency, and the current SOC can be obtained by adding it to the initial state of the battery pack. From the above It can be seen from the analysis that in order to improve the estimation accuracy of SOC in the working process, it is necessary to increase the sampling speed of current and the estimation speed of SOC. The current signal is collected, and the coprocessor processes the interrupt of the SOC calculation cycle timer, and exchanges current data with the main processor through the dual-port RAM, so as to realize the estimation of the SOC. In addition, the utility model also studies the influencing factors of battery capacity such as current, temperature, aging state and self-discharge, and obtains the relationship curve between the above parameters and battery capacity for capacity correction.

When the system is working, the main control board obtains the battery working status parameters through the 485 bus in the order of the current acquisition board and several voltage acquisition boards every 100ms. The main control board analyzes and judges the acquired data. When the voltage value of the single cell is too large, It is necessary to disconnect the charging relay. When the voltage of the single unit is too low and it is in the discharge state, it is necessary to disconnect the module relay and the main relay. When the current and temperature exceed a certain value, an alarm display is required. In addition, the main control board needs to monitor all voltages. Carry out comparison and judgment, find out the single battery whose voltage exceeds a certain set value of the minimum voltage, set this single battery needs to balance the flag bit, and notify the corresponding voltage acquisition board to perform equalization processing; Conduct an insulation monitoring and collect the total voltage value of the high-voltage electricity, and compare it with the voltage value obtained by the voltage acquisition board to judge the current energy consumption of the wire; The working state parameters of the system, combined with the real-time clock time, are saved in the USB storage device, so that the historical data can be analyzed in the future. the

When the whole system is running, it first performs system fault self-inspection. Fault self-inspection includes communication self-inspection, EEPROM storage data self-inspection, and alarm display for faults. When the self-inspection function passes, normal data collection, transmission, calculation, fault Judgment and parameter display process. the

The beneficial effects of the utility model:

The main control board of the battery management system of the utility model adopts the USB storage method, which enhances the readability of the stored data, and increases the storage capacity, which provides the possibility for monitoring the entire operating state of the battery from leaving the factory to being scrapped and establishing a corresponding database . the

In the utility model, the method of measuring and calculating the insulation resistance based on the terminal voltage is used to monitor the high-voltage electrical insulation, wherein the connection of the positive and negative terminals of the high-voltage electricity is controlled by a solid-state relay and passed through a fuse, which improves the safety of the system and integrates high-voltage electrical insulation. The overall voltage measurement function can be compared with the voltage obtained by the voltage acquisition board, which provides a method for calculating the energy consumption of the wire. the

The middle and high voltage voltage acquisition part of the utility model adopts the op-amp chip to collect directly, which reduces the cost of the whole system. At the same time, the power supply of the op-amp chip is controlled by the solid-state relay, which reduces the self-consumption power of the whole system in the non-working state, and at the same time improves The acquisition accuracy of the battery voltage is improved. the

The utility model stores the relationship between the open circuit voltage and the SOC under different currents, different temperatures and charging and discharging states under different resting times, and improves the accuracy of estimating the initial SOC by using the open circuit voltage. the

The SOC estimation in the current acquisition board adopts the combination of the coprocessor and the main processor. The coprocessor module is specially set up for processing interrupts and I/O. The time integration method estimates the timer interrupt in SOC to process and calculate the SOC at this time, thus improving the SOC estimation accuracy in the working process. the

Compared with the Chinese patent CN102975627A, the utility model proposes USB storage. The storage chip generally used in the storage of the battery management system is limited by the size of the storage space. For storage, electric vehicles are now in the development stage, and the database is not perfect. USB storage space is large and fast, which is of great significance to the establishment of electric vehicle battery database, and provides data support for the research of electric vehicles. the

Compared with the Chinese patent CN 101141076A, the utility model adopts a solid-state relay to control the power supply of the operational amplifier chip, and cuts off the power supply of the operational amplifier chip when the vehicle is in a parking state, thereby reducing the self-consumption of the entire battery management system in non-working state electricity. the

Compared with the Chinese patent CN 102064568A, the coprocessor proposed in this patent is an internal unit of the main processor, its speed is twice as fast as that of the main processor, and data exchange is performed with the main processor through bidirectional RAM, the two are not the same concept , The utility model utilizes the coprocessor to process the timer interrupt signal, which improves the estimation accuracy of the SOC in the system working process. the

In a word, the utility model provides SOC estimation in the working process of the coprocessor based on the chip core. In addition, the capacity of the battery also affects the high-precision estimation of SOC. The utility model studies the influencing factors of the battery capacity such as current, temperature, aging state, and self-discharge, and uses the relationship curve between the above parameters and the battery capacity to correct the capacity, thereby Improved overall SOC estimation accuracy. the

The utility model provides a battery voltage acquisition method using an improved operational amplifier chip. Compared with the traditional operational amplifier chip battery acquisition method, the utility model uses a solid state relay to control the power supply of the operational amplifier chip. When the vehicle is in a parking state , cut off the power supply of the operational amplifier chip, thereby reducing the self-consumption power of the entire battery management system in the non-working state. In addition, the utility model does not use any switch to control the voltage acquisition, which improves the accuracy of voltage acquisition and the reliability of the system. . the

Description of drawings

Figure 1 is a schematic diagram of the overall structure of the battery management system of the present invention;

Figure 2 is a schematic diagram of the power supply control of the operational amplifier chip;

Fig. 3 is a voltage signal processing circuit diagram;

1. Main control board, 2. Current acquisition board, 3. Voltage acquisition board, 4. Power module I, 5. High voltage electrical connector, 6. Power drive connector, 7. LCD display, 8. Power module II, 9. Current signal connector, 10. Power module II, 11. Voltage signal connector, 12. Temperature signal connector, 13. Balance board connector, 14. Balance board, 15. Current sensor, 16. Relay, 17. Fuse, 18. load. the

Detailed ways

The utility model will be further described below in conjunction with the accompanying drawings and embodiments. It should be noted that the following description is only for explaining the utility model, and does not limit its content. the

Figure 1 is a schematic diagram of the overall structure of the lithium battery management system. It can be seen from Figure 1 that the battery management system includes a main control board, a current acquisition board, a voltage acquisition board, an equalization board and a liquid crystal display. The main control board communicates with the current through the 485 bus The acquisition board is connected to the voltage acquisition board, exchanges data with the LCD screen through the 232 communication port, and communicates with external devices such as electric vehicle instruments and vehicle controllers through the CAN bus; the power drive connector of the main control board is connected to the relay, including Module relay, main relay, charging relay; the voltage signal connector of the voltage acquisition board is respectively connected to the positive and negative terminals of the battery, the temperature signal connector is connected to the temperature sensor, the temperature sensor is installed on the positive and negative poles of the battery pack, and the balance board connector is connected to the balance board; the current signal connector of the current acquisition board is connected to the Hall-type current sensor, and the current sensor is installed on the total negative terminal of the high-voltage power supply; the power supply of the whole system adopts the 12V/24V low-voltage battery on the electric vehicle through its own DC/DC The isolation module supplies power to it; in order to enhance the anti-interference ability of the communication signal, the B0505 power supply chip is used to isolate the communication power supply, and the 6N137 high-speed optocoupler is used to isolate the communication signal. When the whole system is running, it first performs system fault self-inspection. Fault self-inspection includes communication self-inspection, EEPROM storage data self-inspection, and alarm display for faults. When the self-inspection function passes, normal data collection, transmission, calculation, fault Judgment and parameter display process. the

Figure 2 is the schematic diagram of the power supply control of the operational amplifier chip. For the convenience of control, 8 batteries are used as a group for discussion. The 8 batteries have 9 different positive and negative terminals. They are connected to the voltage signal of the voltage acquisition board through high-temperature insulated wires. On the connectors, they are V1-, V1, V2, V3, V4, V5, V6, V7, and V8. In the actual process, the number of batteries in a group may be less than 8, but generally more than 2. In order to increase the system Practicability, the signal of the voltage signal connector part is respectively connected to the anode terminals of the diodes D1-D6, and the cathode terminals of the diodes are connected to obtain the voltage of an actual group of batteries, in order to reduce the self-consumption of the battery management system in the non-working state , Connect the obtained battery voltage to port 8 of the solid state relay U1. When the system starts, the low-voltage 12V/24V generates 5V voltage through the DC/DC isolation module, and the 1 port of the solid state relay will become a high level, and this high level is connected to the 2 port through the internal LED of the solid state relay and then grounded through the resistor R1 , so that the internal relay is turned on, pin 7 and pin 8 are connected, and the voltage of the battery supplies power to the operational amplifier chip 1-8 through the capacitors C1, C2, and C3, which can realize the work of the system; when the vehicle is in the parking state, When the low-voltage power is cut off, the whole system will be in a non-working state at this time, the DC/DC isolation module will not output 5V voltage, the 1 port of the solid state relay will become low level, and the internal relay will not be able to be turned on, pin 7 and pin 8 will be in the disconnected state, thereby reducing the self-consumption power when the system is not working. the

Figure 3 is a voltage signal processing circuit diagram. Since the number of a group of batteries is generally between 2 and 8, and all voltage processing principles are similar, the following describes the processing principle of a voltage signal. A general lithium battery The voltages are all lower than 10V. Since the reference voltage of the AD sampling chip adopted in the utility model is 5V, the voltage signal needs to be processed. terminal, the negative terminal of the single-cell battery is connected to the inverting input terminal of the operational amplifier through the resistor R4, and the non-inverting input terminal of the operational amplifier chip is grounded through the resistor R2, the inverting input terminal is connected to the output terminal through the resistor R5, and the signal output terminal is connected to the output terminal through the resistor R1 and capacitor C2 are connected to the acquisition port of the AD chip, and the positive and negative power supply terminals of 4 and 11 of the operational amplifier chip are connected to the battery voltage in Figure 2 after passing through capacitor C1, capacitor C2, and capacitor C3. In addition, the voltage of the positive power supply terminal is filtered by capacitor C1. When the circuit When the resistor R2=resistor R5, and the resistor R3=resistor R4, it is a typical operational amplifier differential amplifier circuit. Figure 3 combined with Figure 2 realizes the high-precision acquisition of voltage signals, and at the same time reduces the self-consumption power when the system is not working. the

Although the specific implementation of the utility model has been described above in conjunction with the accompanying drawings, it is not a limitation to the protection scope of the utility model. On the basis of the technical solution of the utility model, those skilled in the art can make Various modifications or deformations are still within the protection scope of the present utility model. the

Claims (10)

1. the battery management system based on coprocessor and solid-state relay, it comprises master control board and the connected current acquisition plate of difference and voltage acquisition plate, it is characterized in that, total anode and total negative terminal that described master control board connects respectively high-tension current by the high-tension current joint are realized the high-tension current insulating monitoring, by the power drive joint, succeed electrical equipment; The SOC that described current acquisition plate adopts coprocessor to be combined with primary processor and realizes battery estimates, connect current sensor by the current signal joint, described current sensor is arranged between relay and the total negative terminal of high-tension current; Described voltage acquisition plate gathers voltage signal by the amplifier chip, and the power supply of amplifier chip is controlled by solid-state relay.

2. battery management system according to claim 1, is characterized in that, described system adopts the low pressure storage battery of the 12V/24V on electronlmobil to power to it through DC/DC isolation module separately respectively; Described system adopts the B0505 power supply chip to be isolated the communication power supply, and adopts the 6N137 high speed photo coupling to be isolated communication signal.

3. battery management system according to claim 1, is characterized in that, described master control board comprises the USB memory module, for storing working status parameter.

4. battery management system according to claim 1, is characterized in that, described master control board is connected with read-out, and described read-out is LCDs, realizes the real-time demonstration to working status parameter; Described master control board is also by CAN bus and electric vehicle instrument and entire car controller communication.

5. battery management system according to claim 1, is characterized in that, described master control board also comprises power module I, main controller module I and communication module.

6. battery management system according to claim 1, it is characterized in that, described relay comprises total relay, module relay and charge relay, described total relay is connected to load, described load is connected to the total anode of high-tension current through wire fuse, described module relay is relay between battery pack, and described battery pack is the cell number that every block of voltage acquisition plate is controlled, and described charge relay connects the battery charger signal.

7. battery management system according to claim 1, is characterized in that, described current acquisition plate comprises power module II, main controller module II and current acquisition module.

8. battery management system according to claim 1, it is characterized in that, described voltage acquisition plate connects respectively the temperature sensor that is arranged on the battery pack positive and negative terminals and the positive and negative terminal of battery by temperature signal joint and voltage signal joint, described voltage acquisition plate has several, and each voltage acquisition plate corresponds to many 8 batteries.

9. battery management system according to claim 1, is characterized in that, described voltage acquisition plate is connected with balancing disk by the balancing disk joint.

10. battery management system according to claim 1, is characterized in that, described voltage acquisition plate comprises power module III, main controller module III, voltage acquisition module and temperature collection circuit.

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