Browsing by Author "Lai, Wang-Wei"

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Dual Modulation Technique for High Efficiency in High Switching Buck Converters Over a Wide Load Range
(2010)
Tsai, Jen-Chieh
;
Huang, Tsung-Ying
;
Lai, Wang-Wei
;
Chen, Ke-Horng
;
電控工程研究所
The design of a compact size switching converter under high switching operation causes a drastically decreasing in power conversion efficiency. This paper presents a dual modulation technique to improve the power conversion efficiency with a little increase in output ripple. Especially, the trade-off between the output ripple and the efficiency can meet the requirement of the portable devices. Simulation results show that the converter can operate at 5 MHz with a supply voltage from 3V to 4.5V. The output voltage ripple can be kept smaller than 30mV when load current varies from 20mA to 800mA. Besides, the power efficiency is higher than 85% over a wide load current range.
Dual Modulation Technique for High Efficiency in High-Switching Buck Converters Over a Wide Load Range
(2011-07-01)
Tsai, Jen-Chieh
;
Huang, Tsung-Ying
;
Lai, Wang-Wei
;
Chen, Ke-Horng
;
電控工程研究所
A dual modulation technique to improve power conversion efficiency with minimal increase in output voltage ripple is presented. The worsening switching noise caused by parasitic resistance and inductance due to high-switching operation can also be alleviated by the proposed ac ripple detector. Furthermore, the dual modulation method can speed up the load transient response since the switching frequency can increase to 5 MHz during the transient period. At very light loads, the switching frequency is always kept higher than the acoustic frequency to avoid noisy sound. Experiment results show that the converter operates at 5 MHz using a small inductor of 1 mu H. The load transient response time is shorter than 3 mu s when load current changes from 150 to 450 mA or vice versa. Power efficiency is kept higher than 85% over a wide load current range. Specifically, light efficiency can be raised to about 45% above that of the conventional design.
Reduction of Equivalent Series Inductor Effect in Constant On-Time Control DC-DC Converter without ESR Compensation
(2011)
Lee, Yu-Huei
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Lai, Wang-Wei
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Pai, Wan-Yu
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Chen, Ke-Horng
;
Du, Ming-Jhe
The proposed constant on-time control DC-DC converter removes the need of conventional equivalent series resistor (ESR) compensation and simultaneously aims to eliminate equivalent series inductor (ESL) effect of the output capacitor. Since the on-time period is set simply by input and output voltages, the switching frequency in continuous conduction mode (CCM) operation is relatively constant over a wide input voltage range. In addition, fast transient response and small transient dip voltage can be achieved. Simulation results show that the output ripple and the recovery time keep smaller than 5 mV and 10 mu s, respectively, when load current step is 500 mA and ESR is smaller than 5 m Omega.