Razširljiv nizkocenovni baterijski nadzorni sistem

Hrastovec, Luka (author), Pirc, Matija (mentor)

V diplomskem delu je predstavljen razvoj nizkocenovnega baterijskega nadzornega sistema (BMS - ang.: Battery Management System) in nekaj zanimivih uporabljenih rešitev. Zadnja leta je moč opaziti porast uporabe ultralahkih električnih vozil. Precej nov segment zahteva uporabo manjših baterijskih paketov za shrambo energije pri pogonu vozil. Za varno uporabo baterijskih paketov je BMS zelo pomemben. Na podočju kakovostnejših BMS, ki bi bili primerni za manjše baterijske pakete, je na trgu veliko pomanjkanje. Cene trenutnih komercialno dostopnih sistemov so previsoke. Cena za BMS lahko preseže ceno baterijskega paketa. Uporaba tovrstnih BMS ni smiselna. Najtežja naloga je bila izdelati čim cenejši sistem, ki bi bil primeren za uporabo z manjšimi baterijskimi paketi. Kljub nizki ceni mora BMS še vedno imeti vse potrebne varnostne mehanizme. S pomočjo kreativnega pristopa k reševanju problemov in uporabo inovativnih rešitev je bilo moč doseči zelo nizko ceno sistema. Analogno digitalni pretvornik (ADC) je uporabljen z zamenjanima vhodoma za referenčno in vhodno napetost. S tem je dosežena možnost meritve napajalne napetosti brez uporovnega delilnika in dodatne statične porabe energije. Negotovost tipa A napetostne meritve je manjša od 0,9 mV. Komunikacija uporablja vgrajeni analogni primerjalnik in dva zunanja upora. Kljub temu, da zaporedno vezani moduli delujejo na različnih referenčnih potencialih, to ne ovira prenosa sporočil. Testi z namensko dodanimi motnjami so potrdili zanesljivost prenosa sporočil na poljubno dolgi kaskadni vezavi. Proizvodnja cena za 1000 kosov je 1,37 EUR, kar bi omogočalo prodajno ceno med 6 in 10 EUR. To je vsaj trikrat boljše od trenutno najcenejše komercialne ponudbe. Projekt je odprtokoden, izdan pod imenom CarettaBMS. Namen projekta je, da bi lahko več ljudi imelo dostop do kakovostnejših BMS, ki so primerni tudi za manjše baterijske pakete.

• Language: Slovenian
• Keywords: Baterijski nadzorni sistem, BMS, baterijski paket, baterija, napetostna meritev, baterijska celica
• Work type: Bachelor thesis/paper
• Organization: FE - Faculty of Electrical Engineering
• Year: 2020
• PID: 20.500.12556/RUL-119080
• Publication date in RUL: 02.09.2020

Secondary language

• Language: English
• Title: Extensible cost effective battery management system

Abstract

The thesis presents the development of low-cost Battery Management System (BMS) and some interesting solutions used. In recent years, there has been an increase in the use of ultralight electric vehicles. A fairly new segment requires the use of smaller battery packs for energy storage to power vehicles. For safe use of battery packs, BMS is very important. There is a big shortage in the field of quality battery management systems, which would be suitable for smaller battery packs. Prices of the systems currently on the market are too high. The price of a BMS can exceed the price of a battery pack. The use of such BMS does not make sense. The most difficult task was to make the system as inexpensive as possible for use with smaller battery packs. Despite the low cost, BMS still has all the necessary safety mechanisms. By approaching the challenges in a creative way it was possible to find innovative solutions, which enabled a very low-cost implementation of the system. Analog to digital converter (ADC) is used with swapped inputs reference and ADC input. This makes it possible to measure the supply voltage without the use a of voltage divider and additional static energy consumption a voltage divider would entail. The type A standard uncertainty is 0.9 mV. The communication uses a built-in analog comparator and two external resistors. Despite the fact that series connected modules operate on different reference potentials, this does not affect the message transmission. Tests with artificially induced interfearence confirmed the communication reliability of an arbitrary number of modules connected in series. At the time of this writing the production price for 1000 pieces is estimated at 1,37 EUR per piece, which would allow the sell price between 6 and 10 EUR. This is at least three times better than the current cheapest commercial offer. The work was released as an open source project with the name CarettaBMS. The purpose is to allow access to better quality BMS suitable for smaller battery packs to a wider audience.

• Keywords: Battery management system, BMS, battery pack, battery, voltage measurement, battery cell