A new active Hybrid-Series-Parallel PWM dimming scheme for off-line integrated LED drivers with high efficiency and fast dynamics

Abstract

This Paper presents a double integrated converter used for light emitted diode (LED) lighting applications, with the additional feature of the pulse width modulation (PWM) as a dimming technique. The double integration is made by integrating a Buck converter at the output of the Integrated Buck-Flyback Converter (IBFC) to be the Integrated Buck-Flyback-Buck Converter (IBFBC). This additional converter role is to deliver the remaining of the dimming power back to the input, as the flyback could be considered as a power source, therefore in case of dimming in order to keep the power delivered by the flyback constant the additional Buck send the remaining power back to input. The new converter combines the improvements in the operational performance of the Hybrid-Series-Parallel (HSP) PWM dimming technic presented in a previous work, with insuring a higher level of efficiency. The work presents an average model as well as a mathematical model for the full IBFBC, in order to well explain the power flow of this double integrated converter, and decrease the switching devices complications. Finally, a prototype is made in order to confirm the results exported from the simulations with experimental results, these results are well analyzed so that the improvement gained from this converter is illustrated.