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This paper presents an algorithm of cell balancing of LiFePO4 battery pack under the constraints of electric bicycle applications. The major purpose of cell balancing is to protect the battery from being overcharged and to equalize the state of charge of each battery cell. The nominal voltage and capacity of the considered battery pack for electric bicycle is 36V and 10Ah respectively. The conventional balancing method detects final voltage of each cell and consumes a long period of time to balance all cells, since the cell balancing will be active only at the end of charging process. This paper proposes an cell-balancing algorithm using the combination between Ah-balancing and delta voltage at the end of charging process in order to shorten the balancing time. A prototype of hardware will be constructed and tested. The functionality of the proposed cell balancing algorithm will be verified by the test results. [ABSTRACT FROM PUBLISHER]

Generally, brushless dc (BLDC) motor is widely used in electric bicycles. There are several advantages of this motor such as high efficiency, high dynamic response and low noise operation. However, an obvious disadvantage of BLDC motor is permanent magnets needed for the motor. At present, the cost of permanent magnets is sharply increasing due to their high demand. This circumstance might distract many people from the motor with permanent magnets to focus mainly on the motor without permanent magnets. Switched reluctance motor (SRM) is an interesting option to eliminate such problem. It does not require any permanent magnet and it has also a simple and robust construction. This paper presents a design process of SRM for an electric bicycle application using simulation software tools. The optimizing process of SRM model is simulated in PC-SRD program. The flux-linkage and torque as a function of rotor position and current can be obtained from the finite element method (FE method). Moreover, the dynamic simulation model of SRM model is generated in MATLAB/Simulink program. In this work, the outer rotor SRM for an electric bicycle is considered. Torque-speed and current density-speed characteristics of the designed SRM for electric bicycles are illustrated. [ABSTRACT FROM PUBLISHER]

In general, a brushless dc (BLDC) motor is modeled by using a trapezoidal waveform as a back electromotive force (E.M.F.). It is a simple model with moderate accuracy. However, when BLDC motor operates in a high speed range where the back E.M.F. plays an important role to the characteristic of the machine, the trapezoidal back E.M.F. could lead to erroneous results. Although the finite element (FE) analysis can be applied for modeling with high accuracy, it takes so much time to simulate one operating point. Moreover, it is complicated and time-consuming to run in the dynamic operations. Therefore, it needs to be optimized between accuracy and time consumption. This paper presents a dynamic simulation model of BLDC motor with more accuracy comparing to the conventional simulation model. It uses the back E.M.F. and inductance which are obtained from the finite element method (FE method). The model was implemented in MATLAB/Simulink and PLECS program. In this work, the outer rotor BLDC motor for electric bicycles was used. The results of simulation model were verified by experiment. [ABSTRACT FROM PUBLISHER]