Knee Voltage Detection Technique for Primary-Side Regulator

• Main Authors: Yu-Sheng Gan, 甘昱昇
• Other Authors: Chorng-Sii Hwang
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/369sx7

碩士 === 國立雲林科技大學 === 電機工程系 === 102 === Nowadays, high-tech products are an essential part of our lives. Portable electronic devices greatly enhance the quality and convenience of life. One of the critical elements in portable electronic devices is the rechargeable battery. Therefore, how to transfer energy to the battery in a fast and efficient way under the best and the safest condition is an important issue. Universal Serial Bus (USB) is a frequently-used interface protocol in personal computer. And it’s also widely applied in the portable electronic devices. The most common charging method of portable electronic devices is to transform alternating current (AC) into direct current (DC) with the aid of the USB interface. Primary-Side Regulator (PSR) can be adopted in a low-cost and high-efficiency charger. And it is also a charger that can accept high input voltages of supply mains. Since there is no direct feedback path for Primary-Side Regulator (PSR) to obtain the accurate information of the output voltage, how to obtain the correct output information of charging system in order to maintain switching stability of constant current and constant voltage becomes a critical design issue. The knee voltage is defined as the output voltage without the voltage drop of the diode at the secondary-side. In order to acquire the correct output information, this thesis is dedicated on the knee voltage detection (KVD) technique that can track the secondary output voltage via the auxiliary-side winding with the diode being cutoff. And a dynamic self-calibrator circuit is also realized to prevent detection errors against incorrect output information. Therefore, the PSR can switch between the constant current (CC) mode and constant voltage (CV) mode accurately and stably during charging.