| Abstract [eng] |
Electric vehicle battery pack is one of the most expensive and important components of the car, for its reliable functionality additional attention must be given. Battery control modules at the market lacks functionality and connecting compatibility with other electric car modules. In this thesis battery pack control circuitry will be designed, which ensures safe and reliable battery pack working. Additional safety features will be also realized. After analyzing other electric vehicle manufacturers used battery pack control solutions, the most suitable system structure was chosen. Central control unit with remote battery voltage and temperature measurement and balancing units was chosen. To ensure battery pack longevity, battery cell manufacturer claimed battery working conditions must be ensured: working voltage, temperature and current. Batteries for its inner chemical process tends to discharge differently, to avoid voltage variation between cells additional balancing circuitry must be used. Additional heater for battery is necessary if pack is used in negative temperature. LiFePO4 batteries can be charged in 0 ℃ ～ 45 ℃ temperature and discharged -20 ℃ ～ 55 ℃ temperature. Battery pack insulation must be measured to ensure user safety and it must be higher than 500 Ω/volt. Battery pack control system was implemented, which is capable to measure cell temperature from -50 °C to 150 °C, measure every single cell voltage from 1 V to 5 V, balance all batteries in the pack. Measure battery pack current from <±0.1 A to ±500 A. After carrying out experimental studies system operation was tested. System is capable to indicate battery pack insulation fault. System soft start function was implemented for charging up system’s high-power capacitors. Additional circuitry was made to ensure battery pack assisting personal safety, service disconnector, high voltage cable disconnector. Efficient system working algorithm was created. Experimental studies confirmed smooth system performance. |
