Project
| # | Title | Team Members | TA | Documents | Sponsor |
|---|---|---|---|---|---|
| 6 | Low-cost Active Cell Balancing BMS Honorable Mention |
Dmitry Ilchenko Drew Zoghby Vijay Gopalakrishnan |
Bonhyun Ku | final_paper1.pdf proposal1.pdf |
|
| # Problem In an era of growing popularity of electric and hybrid vehicles, more efficient and safe battery systems are critical. The best battery management topologies which provide longer range of the vehicles and extend the life of the battery cells themselves are active balancing battery management systems. They redistribute the charge between the batteries to make their state of charge the same instead of burning the excessive energy the way passive cell balancers do. However due to the global silicon shortage caused by covid-19 pandemic a lot of companies like TI, ST, Analog Devices and others who produce battery management ICs are not able to stock enough chips for the public use. Our RSO, Illini EV Concept, faced this problem last semester when we were not able to produce new BMS boards because the ICs we used were out of stock. # Solution Overview Our solution is to work around the silicone shortage, by avoiding the need for specialized chips. We will design a novel active balancing BMS using low cost and highly available ICs. By choosing simple, low cost, high volume chips, the necessary components of our system are less likely to be out of stock. This allows high performance, safe BMS systems to continue to be built despite the shortage of speciality ICs. We are proposing to build a BMS for 13s battery pack, which is 48V industry standard, with active pack-to-cell balancing. The BMS will keep track of the voltages of each cell, and when there is a cell whose voltage is smaller than every other cell, we will start charging that cell with constant current until the cell reaches the average voltage across all the other cells. Our BMS system will be capable of measuring voltages of each cell of the battery pack, find the least charged one, and use the whole pack to charge the individual cell back to the average cell voltage. # Solution Components: ## -Switch Matrix The switch matrix will be used to connect an arbitrary battery cell to the charge circuit. It will consist of an array of FETs used to connect between the desired cell and the isolated power supply that will charge the cell ## -Cell ADC Adc will get proper readings of each cell. It should communicate with a microcontroller to track the values of each cell. ## -Cell Charge Circuit The cell charge circuit will receive power from the battery pack. It will be connected to an individual cell through the switch matrix. The charge circuit will use a standard lithium battery charge cycle to bring the connected cell voltage back in line with every other cell in the pack. ## -Power Convertors Isolated output DC-DC converter to power microcontroller and other ICs on the board for safety ## -Microcontroller STM32 (or alternative low-cost) microcontroller to get the voltage readings from ADCs, send signals to the switch matrix, measure temperature of the pack, detect fault conditions. # Criterion for Success Our project will be successful if it supports active balancing (as defined above) on a 13s4p battery pack, throughout the charge and discharge cycle. It also must rely on high-availability ICs, that are less likely to be affected by product shortages. This means the switch matrix and adc will not use a speciality ic, even if they are currently available. For the cell charge circuit, we may attempt to design our own. However, as single cell lithium charge ICs are highly available, if this proves to be too time consuming, we would consider using an off the shelf IC. An additional goal is to have a scalable design that can be easily adapted to different battery pack configurations. ## Team members: -Dmitry Ilchenko dmitryi2 \ -Vijay Gopalakrishnan vijayg2 \ -Andrew Zoghby azoghby2 |
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