No abstract

Summary This paper proposes a simple control scheme for single‐phase power factor correction (PFC) regulators, which provides the advantages of low current harmonic distortion and rapid transient response. Moreover, the proposed scheme needs only to add two sample‐and‐hold control circuits into the feed‐forward voltage loop and feedback‐voltage loop of PFC regulators. Accordingly, the system is not influenced by the 120‐Hz ripple voltage but improves the transient response time and input current harmonic distortion. The operating principles and control scheme are analyzed in detail. A 300‐W boost power factor corrector prototype is implemented to verify the feasibility of the proposed scheme. The experimental results are satisfactory. Copyright © 2014 John Wiley & Sons, Ltd.

No abstract

SUMMARY This paper presents a two‐transformer active‐clamping zero‐voltage‐switching (ZVS) isolated inverse‐SEPIC converter, which is mainly composed of two active‐clamping ZVS isolated inverse‐SEPIC converters. The proposed converter allows a low‐profile design for liquid crystal display TVs and servers. The presented two‐transformer active‐clamping ZVS isolated inverse‐SEPIC converter can equally share the total load current between two secondaries. Therefore, the output inductor copper loss and the output diode conduction loss can be decreased. Detailed analysis and design of this new two‐transformer active‐clamping ZVS isolated inverse‐SEPIC converter are described. Experimental results are recorded for a prototype converter with an AC input voltage ranging from 85 to 135 V, an output voltage of 12 V and a rated output current of 13.5A, operating at a switching frequency of 65 kHz. Copyright © 2012 John Wiley & Sons, Ltd.

SUMMARYThis study proposes a simple control scheme for using single-stage flyback (SSF) converters in lighting source applications for LEDs. Among the advantages of the average current mode is an I/O current ripple that is only one-half of the critical conduction mode (CRM). This condition helps extend the output capacitor lifetime while lowering the input EMI capacitance input EMI capacitance. The SSF converter proposed in this study operates in continuous conduction mode (CCM). In addition, two sample-and-hold (S/H) circuits are placed at the output voltage loop and feed-forward path, respectively. Since these S/H circuits access the average output current and average feed-forward voltage, the LED driver is unaffected by the 120-Hz ripple noise, the total harmonic distortion (THD) is reduced, and the transient response of the output current is improved. Finally, the operation principles and design considerations of the studied LED driver are analyzed and discussed. A laboratory prototype is also designed and tested to verify the feasibility.