Modified zero-voltage-switching single-stage LED driver based on Class E converter with constant frequency control method

This study presents an integrated-stage AC-DC lighting-emitting diode (LED) driver based on flyback and Class-E converter with high power factor (PF) with a wide range of the duty cycle. The flyback circuit works in discontinuous conduction mode to realise the PF correction function, and the Class-E circuit is used as DC-DC converter to transfer the energy to the LED load. By sharing the common switch of the two circuits, the cost of system can be decreased distinctly. In addition, the Class-E converter provides soft-switching operation in a resonant mode, which can improve the converter efficiency. By integrating the flyback and Class-E converters, the soft-switching characteristic is still kept. In addition, the LED driver can be operated with wide duty cycle range to achieve a design degree of freedom to regulate the output current at a constant working frequency which makes the design of EMI filter easier. The operational principles, detailed analysis and design considerations of the LED driver are presented. A 100 W prototype is presented in an experimental condition to certifying the validity of the proposed integrated-stage LED driver.