Synchronous Flyback Converter Coupled with Fuzzy Logic Control Efficiently Controls a Serially Connected VRLA Battery String

AbstractThis paper presents a high efficiency charge equalization system for balancing the energy in a serially connected, valveregulated, lead acid battery string using a synchronous flyback converter. Each flyback converter was coupled through a DC-link bus in order to increase the overall energy transfer efficiency of the system and to eliminate the problem of unbalanced charging of the batteries. To ensure that the charge equalization system operated smoothly and safely charged the batteries, a fuzzy logic controller was used in the control section of the system. The validity of this approach was confirmed by computer simulation and by experimentation. The efficiency of this synchronous flyback converter was 78.9 percent, better by approximately 1.07 percentthan the conventional flyback converter

Battery Management System for Future Electric Vehicles

The future of electric vehicles relies nearly entirely on the design, monitoring, and control of the vehicle battery and its associated systems. Along with an initial optimal design of the cell/pack-level structure, the runtime performance of the battery needs to be continuously monitored and optimized for a safe and reliable operation and prolonged life. Improved charging techniques need to be developed to protect and preserve the battery. The scope of this Special Issue is to address all the above issues by promoting innovative design concepts, modeling and state estimation techniques, charging/discharging management, and hybridization with other storage components

Modular multilevel converter with embedded battery cells for traction drives

This thesis proposes a new modular multilevel converter with embedded cell balancing for battery electric vehicles. In this topology, the battery cells are directly connected to the half-bridge choppers of the sub-modules, allowing the highest flexibility for the discharge and recharge of each individual cell. Tht: traditional battery management system is replaced by the control of the converter, which individually balances all the cells. A new balancing algorithm is presented and discussed in. the thesis, showing that the converter generates symmetric three-phase voltages with low harmonic distortion even for significantly unbalanced cells. The thesis also analyses stationary recharge of the battery cells from both three-phase and single-phase ac sources. The performance of the converter as a traction drive is assessed in terms of torque-speed characteristic and power losses for the full frequency range, including field weakening. A simplified model for estimating conduction and switching losses for the proposed modular multilevel converter is presented and the results for a typical driving cycle are compared with a traditional two-level converter. Simulation and experimental results on a kW-size prototype have confirmed the feasibility of the proposed traction modular converter in terms of effectiveness of the cell balancing control, validity of the proposed loss model, suitability of use for traction and effectiveness of recharging operations