CN107819345A - A kind of battery management system provided with passive balance control function - Google Patents

Abstract

The invention relates to a battery management system with a passive balance control function. The system includes: a data collection module: collects operating parameters of the system, and uploads the parameters to a main control module; battery balance management module: the main control module The collected system working parameters manage the energy of individual batteries to balance the energy of each individual battery; temperature balance management module: collect the temperature when the system is working, and keep the temperature within a dynamic range through cooling measures; main control module: control the data The parameters of the acquisition module are analyzed and processed, and the working status of the battery balance management module and the temperature balance management module is controlled according to these parameters; the power supply module: provides a stable operating voltage for each module. The present invention detects the external characteristic parameters (such as voltage, current, temperature, etc.) of the battery and adopts an appropriate algorithm to realize the estimation and monitoring of the internal state of the battery (such as capacity and SOC, etc.), which is the basis and basis for the effective operation of the battery management system The essential.

Description

A battery management system with passive balance control function

technical field

The invention belongs to the technical field of mobile energy storage, and in particular relates to a battery management system provided with a passive balance control function.

Background technique

Energy storage technology is mainly used to stabilize the fluctuation of solar photovoltaic power generation/wind power generation, improve the grid's ability to absorb new energy, and at the same time, it also has a part of the peak power supply for the grid's valley power. Considering both distributed energy storage and large-scale grid-connected applications, the energy storage system should adopt a modular component construction method, which mainly includes a four-layer structure of battery modules, battery management systems, bidirectional energy storage converters, and monitoring and protection systems from bottom to top. . Among them, the battery management system is the charging and discharging control unit of the entire mobile energy storage system. It also takes into account the collection of system operating parameters and the safe operation of the control system. It is an indispensable part of the mobile energy storage power station. The equalization technology of the battery management system can change the charging and discharging current or the accumulated charge and discharge power of different batteries, which is the key technology to solve the difference in the consistency of battery groups. Continuous and effective current balance and correct balance control strategy can prevent battery consistency differences and play a decisive role in the service life of battery groups.

Contents of the invention

The present invention provides a battery management system equipped with a passive balance control function, which monitors the state of the battery in real time, collects operating parameters of the system, and performs heat management, battery balance management, and charge and discharge management of the battery after correctly obtaining the operating state of the battery. and fault alarms, etc.

The technical solution of the present invention is: a battery management system with a passive balance control function, the management system includes: a data acquisition module: collects the voltage and current information of the battery pack, and uploads the parameters to the main control module; the battery balance management module : The main control module manages the energy of a single battery according to the system working parameters collected by the data acquisition module, so that the energy of each single battery is balanced; the temperature balance management module: collects the temperature of the system when it is working, and keeps the temperature within a dynamic range through cooling measures Main control module: analyze and process the parameters of the data acquisition module, and control the working status of the battery balance management module and temperature balance management module according to these parameters; power supply module: provide stable operating voltage for each module. The data acquisition module includes a voltage detection unit, a current detection unit and an insulation detection unit, and the voltage detection unit, the current detection unit and the insulation detection unit transmit the collected data to the main control module. The current detection unit adopts a Hall current sensor. An optocoupler isolation module is also connected between the data acquisition module and the main control module, and the digital signal collected by the data acquisition module is input to the main control module after passing through the optocoupler isolation module. The battery management system also includes an isolated power module, and the power module obtains power supply for the voltage detection, current detection, and insulation detection units through the isolated power supply module. A diode is added to the input front end of the power module to complete reverse protection and enhance the anti-interference performance of the system. The battery management system also includes a display module connected to the main control module. The battery management system also includes an alarm module connected to the main control module.

The present invention has the following positive effects: 1) Real-time monitoring of battery status. By detecting the external characteristic parameters of the battery (such as voltage, current, temperature, etc.), and using appropriate algorithms, the estimation and monitoring of the internal state of the battery (such as capacity and SOC, etc.) are realized, which is the basis and key to the effective operation of the battery management system; (2) Perform thermal management, battery balance management, charge and discharge management, fault alarm, etc. after correctly obtaining the state of the battery.

Description of drawings

Fig. 1 is a system structure diagram of a specific embodiment of the present invention.

Fig. 2 is a circuit diagram of an equalization module according to a specific embodiment of the present invention.

Detailed ways

Referring to the accompanying drawings, through the description of the embodiments, the specific embodiments of the present invention include the shape, structure, mutual position and connection relationship of each part, the function and working principle of each part, and the manufacturing process of the various components involved. And the method of operation and use, etc., are described in further detail to help those skilled in the art have a more complete, accurate and in-depth understanding of the inventive concepts and technical solutions of the present invention.

The battery management system refers to the ability to monitor the parameter information of the power battery in real time, estimate the state of charge (SOC) of the battery, effectively manage and allocate the capacity of the battery pack, and have complete fault detection, alarm, data processing and transmission, etc. A complete system of functions.

The battery management system of the present invention includes a main control module, a data acquisition module, a display module, a battery balance management module, a temperature balance management module, a power supply module and a relay control module. The main control module is the core module of the entire battery management system and is used to control The data acquisition module collects the data of system operating parameters, analyzes and processes the returned data, and controls the working status of the battery balance management module and temperature balance management module according to the data processing results, so that the power balance of a single battery and the overall system Temperature, avoid excessive temperature, damage the instrument and reduce the service life. The main control module controls the pull-in and disconnection of the relay through the relay control module to control whether the battery pack supplies power to the outside, and the power supply module provides stable power for various electrical devices.

The data acquisition module includes a voltage detection unit, a current detection unit and an insulation detection unit. The voltage of a lithium-ion battery can best reflect the condition of the battery. It is the basis for overcharging and overdischarging of lithium-ion batteries, and can also preliminarily estimate the SOC of lithium-ion batteries by measuring the terminal voltage. In actual working conditions, with the charging and discharging of the battery pack, the voltage of the battery pack is constantly changing, and the consistency of the voltage between the single cells will also greatly affect the performance of the battery pack, so it is also necessary to detect the voltage of each single cell Voltage. After the analog-to-digital conversion of the single battery voltage is carried out by using a dedicated voltage acquisition chip, the digital signal is transmitted to the main control module through the optocoupler, and the detection accuracy of the single battery voltage is 10mV.

The working current and temperature of the battery pack are also important parameters of the battery pack. It can be judged whether there is over-discharge and over-current through the current, and the SOC of the battery can also be estimated by the ampere-hour method. In the actual working condition of the battery pack, the current range varies from -200A to +500A (accuracy: 1A). In order to ensure the accuracy of current collection, a shunt with high accuracy such as the full range is used to detect the total current of the battery pack. After the signal is conditioned, it is sent to the high-speed AD for digital-to-analog conversion and current integration calculation. After the digital signal is isolated by the optocoupler, it is input to the main control module for processing. The current detection generally uses a Hall current sensor.

The insulation detection unit is used to test and determine whether the insulation between the power battery pack and the vehicle body meets the standard. By measuring the voltage between the DC bus and the electric chassis, the insulation resistance value of the system is calculated.

The temperature balance management module is an important part of battery system management. A large amount of heat generated by the battery during operation is accumulated due to space constraints, resulting in uneven temperature everywhere and affecting the consistency of the battery cells. Therefore, it will reduce the battery charge and discharge cycle efficiency, affect the power and energy performance of the battery, and even lead to thermal runaway in severe cases, affecting the safety and reliability of the system. In order to maximize the performance and life of the battery pack, it is necessary to optimize the structure of the battery pack and perform thermal management on the battery pack.

On the one hand, the temperature of the battery pack is detected to prevent the battery pack from being overheated and the temperature difference is too large, and to prevent safety accidents; on the other hand, the working state of the battery is judged according to the temperature of the battery pack, which provides a basis for SOC correction. To detect the temperature, a plurality of temperature sensors are generally added to the battery pack to detect the temperature of each point in the battery pack. Due to the current of the power lithium-ion battery pack is often relatively large. After the temperature balance management module uploads the system temperature to the main control module, the main control module judges whether to take cooling measures according to the current temperature, so as to avoid the imbalance between batteries and reduce performance; eliminate the potential danger related to out-of-control temperature; through the use of air, liquid Direct or indirect contact with the battery to actively or passively heat/cool the battery pack; provide ventilation to ensure that the potentially harmful gases generated by the battery can be discharged in time, so as to ensure the safe operation of the battery.

The power supply module used in the battery management system of the present invention is converted from 24V to 5V, and the isolated power supply module is used to obtain power supply for voltage detection, current detection, insulation detection, and temperature detection. A diode is added to the front end of the power input to complete the reverse protection, and the two-stage filter circuit is conducive to the anti-interference of the system.

Accurate estimation of battery state of charge (State of Charge, SOC) is an important basis for power battery charge and discharge control and energy optimization management, which directly affects the service life of the battery. It can be seen that the accurate measurement of the remaining battery power is a very critical issue. However, battery SOC cannot be measured directly, and its size can only be estimated by parameters such as battery terminal voltage, charge and discharge current, and internal resistance. These parameters will also be affected by various uncertain factors such as battery aging, ambient temperature changes, and vehicle driving conditions. Therefore, accurate SOC estimation has become an urgent problem to be solved in the battery management system.

The battery charging and discharging current is selected as the system input, the battery SOC is the state variable, and the battery voltage is the system output. In the discrete system, the battery characteristic parameters are sampled at each sampling point as the system input, and the algorithm combines the input measured at the current moment and the state estimate at the previous moment to complete the update of the state variables and output. The present invention adopts the extended Kalman filter algorithm to calculate the SOC of the battery, and its iterative steps are as follows:

Step (1): First determine the parameters A _k-1 , C _k .

Step (2): Obtain an initial SOC value SOC ₀ and an initial value of the mean square estimation error P ₀ ⁺ .

Step (3): Obtain predicted SOC value x _k ⁻ and predicted voltage value y _k ⁻ .

Step (4): Obtain the predicted mean square estimation error P _k ⁻ , and calculate the Kalman gain L _k .

Step (5): Calculate the optimal estimate x _k ⁺ of the SOC and the optimal estimate of the mean square estimation error P _k ⁺ .

The present invention has been exemplarily described above in conjunction with the accompanying drawings. Obviously, the specific implementation of the present invention is not limited by the above methods, as long as various insubstantial improvements are adopted in the method concept and technical solutions of the present invention, or there is no improvement Directly applying the conception and technical solutions of the present invention to other occasions falls within the protection scope of the present invention.

Claims (8)

1. A kind of 1. battery management system provided with passive balance control function, it is characterised in that：The management system includes：Data Acquisition module：Battery voltage current information is gathered, and parameter is uploaded to main control module；

   Battery balanced management module：Main control module is according to the system operational parameters of data collecting module collected, to single battery Energy is managed, and makes each single battery balancing energy；

   Temperature equalization management module：Temperature when acquisition system works, makes temperature in a dynamic range by cooling measure；

   Main control module：The parameter of data acquisition module is analyzed and processed, and according to these state modulators and battery balanced pipe Manage the working condition of module and temperature equalization management module；

   Power module：Stable working voltage is provided for modules.
2. 2. the battery management system according to claim 1 provided with passive balance control function, it is characterised in that：The number Include voltage detection unit, current detecting unit and insulating properties detection unit, voltage detection unit, current detecting according to acquisition module The data of collection are sent to main control module by unit and insulating properties detection unit.
3. 3. the battery management system according to claim 2 provided with passive balance control function, it is characterised in that：The electricity Stream detection unit uses Hall current sensor.
4. 4. the battery management system according to claim 1 provided with passive balance control function, it is characterised in that：The number According to light-coupled isolation module is also associated between acquisition module and main control module, the data signal of data collecting module collected passes through light Main control module is inputted after coupling isolation module.
5. 5. the battery management system according to claim 1 provided with passive balance control function, it is characterised in that：The electricity Pond management system also includes insulating power supply module, and power module obtains voltage detecting, current detecting, insulation through insulating power supply module The power supply of property detection unit.
6. 6. the battery management system according to claim 5 provided with passive balance control function, it is characterised in that：The electricity Source module input front end adds diode and completes reverse protection, the anti-interference of strengthening system.
7. 7. the battery management system according to claim 1 provided with passive balance control function, it is characterised in that：The electricity Pond management system also includes display module, display module connection main control module.
8. 8. the battery management system according to claim 1 provided with passive balance control function, it is characterised in that：The electricity Pond management system also includes alarm module, alarm module connection main control module.