Yi-Hsiung Fang

Inductive power transmission technology for Li-ion battery charger

This paper proposes an inductive power transmission technology applied to Li-ion battery charger, and the feature of the system is no metal connections. The proposed system adopts the magnetic coupling structure for inductive charging to promote the safety and the convenience of charging systems. The EER ferrite cores are used to transfer power, and the capacitors are compensated to primary side and secondary sided for improving transform efficiency. The Li-ion battery charger uses CC-CV charging and has the temperature protection. Finally, the proposed system is implemented to verify the performance on a 3.7V/3000mAh Li-ion battery.

Design and implementation of power converters for wind generator with three phase power factor correction

The implementation of power converter for wind generator controlled by digital signal processor is presented in this paper. The proposed system is composed of a wind generator, lead-acid batteries, a three phase ac/dc full-bridge semi-controlled boost rectifier, a dc/dc single-ended primary inductance converter (SEPIC), a bi-directional converter and a full-bridge inverter. The wind generator is used as the main power source, and lead-acid batteries as the auxiliary power source. The proposed system adopts power factor correction to achieve unit power factor and maximum power point tracking (MPPT) to implement available maximum power, thus to improve the overall system performance. In addition, the bidirectional converter provides charging and discharging compensation to dc bus by controlling the duty cycle of switches. Finally, the full-bridge inverter produces a stable ac output with feedback.

A switched capacitor charge equalizer with cancellation mechanism of alternating current

A switched capacitor charge equalizer with cancellation mechanism of alternating current for electric vehicles (EVs) is proposed in this paper. In the studies of charge equalization, the switched capacitor type equalizer is popular due to its small volume and low cost. However, the cycle life of batteries may be reduced since the alternating current flows into batteries when the charge equalization current is delivered via them. Hence, the cancellation mechanism of alternating current is used to reduce the alternating current. The circuit topology and operation analysis of the proposed charge equalizer are described. Finally, the simulation is provided to verify the performance of the proposed equalizer.

Study of importance of charge equalization for LiFePO 4 battery pack

Series-connected battery pack is usually used in some applications, such as electric vehicles (EVs), uninterruptible power supplies (UPSs) and the compensation of distributed power generation, etc. When the batteries charged or discharged, the over-charging or over-discharging phenomenon usually occur without proper protection due to the difference in internal impedance and characteristics when batteries were manufactured. Therefore, the charging equalization of batteries is very important and needs to be implemented. In this paper, four LiFePO4 batteries in parallel are charged to 3.65V and pauses 30 minutes for rest. Afterwards, the LiFePO4 batteries are connected in series and discharged with different C-rates. The voltage of each battery is recorded and analyzed. Finally, the necessary conditions and limitations for designing the charging equalization circuit are presented.

Design and implementation of digital power converter for wind energy conversion system

This paper proposes the design and implementation of power converters for wind energy conversion system. The proposed system consists of a wind generator, a boost converter, and a full-bridge inverter. The wind generator is the main power source of the system, and a digital signal processor (TMS320F2812A) is used to be the system controller. The system controls the duty cycle of the boost converter to achieve the maximum power tracking. Finally, a unipolar switching full-bridge inverter is used to provide a stable output voltage. The experimental and simulation results on a 200-W wind generator are provided to verify the performance of the proposed system.