In the new energy vehicle system, whether it is a hybrid (HEV) or an electric vehicle (EV), it is inseparable from the power battery as an energy storage medium. At present, lithium-ion batteries have occupied the leading position of automotive power batteries, in order to achieve longer battery life Mileage usually requires multiple batteries to be used in series/parallel to form a battery pack. Considering the energy, power and environmental requirements of the car, the safe and reliable use of large lithium-ion battery packs is definitely not a simple task. Therefore, it is necessary to adopt an appropriate battery management system to fully utilize the advantages of the new lithium battery.
1.1 The necessity of active balancing technology in electric vehicle battery management
1.1.1 Electric vehicle battery pack system architecture
Lithium batteries have strong energy storage capacity, but the Voltage and current of a single battery are too low to meet the needs of hybrid motors. To increase the current, multiple batteries must be connected in parallel, and to obtain a higher voltage, multiple batteries must be connected in series. The voltage of a single lithium battery is generally between 3.3V and 3.6V. For example, connecting up to 12 batteries in series to form a battery block has an output voltage between 30V and 45V, while a hybrid electric vehicle requires a DC power supply voltage of about 336V, so 8-10 battery blocks are usually required. ) Connecting in series means that the battery pack of an electric vehicle is composed of a large number of single cells (above 100 cells).
Design of electric vehicle battery management system based on active equalization technology and transformer IGBTM