Noncascading Structure for Electronic Ballast Design for Multiple LED Lamps With Independent Brightness Control

• Published in: IEEE transactions on power electronics Vol. 25; no. 2; pp. 331 - 340
• Main Authors: Xiaohui Qu, Siu-Chung Wong, Tse, C.K.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01-02-2010; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Applied sciences; Ballast; Brightness; Capacitors; Circuits; Current control; Design engineering; Electrical engineering. Electrical power engineering; Electrical machines; Electricity; Electronic ballasts; Electronics; Exact sciences and technology; Isolated power factor correction (PFC) regulator; Lamps; LED ballast; LED lamps; LED lighting; Light emitting diodes; Light sources; Miscellaneous; noncascading construction; Optoelectronic devices; Power factor correction; Real time; Regulation and control; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Switches; Transformers; Transformers and inductors; Various equipment and components; Electric transformer; Light source; Power converter; LED lamps; Brightness; Electric stress; noncascading construction; Ballast electricity; Low voltage; Isolated power factor correction (PFC) regulator; Power factor regulation; Selector switch; Power factor; Power factor correction; Durability; Compact design; Power electronics; Current control; LED lighting; Light bulbs; High power; High voltage; High efficiency; Power convertor; Reliability; Capacitor; LED ballast
• ISSN: 0885-8993; 1941-0107
• DOI: 10.1109/TPEL.2009.2028074

LED light sources, which are more compact, capable to change color in real time, less dissipative, and more durable are finding more applications than conventional light bulbs in domestic, commercial, and industrial environments. However, requirements such as high-power factor, long lifetime, accurate current control, and high-efficiency pose challenges to the design of LED ballast circuits. This paper proposes an LED ballast with a dual noncascading structure. The first-stage noncascading structure is an isolated current-fed power factor correction (PFC) preregulator. In the proposed design, the short-lifetime high-voltage storage capacitor at the primary is replaced by a long-lifetime low-voltage capacitor at the secondary, thus extending the overall system lifetime. The PFC is programmed by the conventional averaged current-mode control for high-power-factor applications. Furthermore, the high-voltage stress on the main switch, which is typical in current-fed converters, is reduced substantially by appropriately exploiting the transformer leakage inductance. The design uses two secondary transformer windings and an LED current driver to form a second noncascading structure to improve efficiency. Multiple noncascading structures can be used for LED lamps for instant independent brightness control. Analysis, design example, and prototype verification are given for the LED ballast.