In medium and small power applications

there are many problems such as large number of devices

large volume

low efficiency

low power density and complex control method in the two-stage LED drivers. By multiplexing a power MOSFET of a pre-stage bridgeless Sepic circuit and a post-stage DC-DC half-bridge LLC circuit

a single-stage resonant LED driver was proposed. In the proposed driver

the number of power MOSFETs used is reduced

the conduction loss is decreased

the control complexity and associated costs are reduced

the ZVS can be achieved by all power MOSFETs and the conversion efficiency is improved. The operating prin

ciple and operating process of the proposed driver were analyzed in detail

and the steady-state characteristics of the AC-DC PFC circuit unit and the LLC circuit unit were analyzed respectively. On this basis

the design of key circuit parameters was carried out. In order to limit the DC bus voltage variation range of the proposed single-stage driver

a digital hybrid control strategy was analyzed and optimally designed. The computer simulation analysis was carried out. A prototype was developed

and experimental research was conducted. The prototype was tested

with an AC input voltage range of 185-265 V

rms

an output current of 2 A

and a full-load power of 100 W

the variation range of the bus voltage can be limited to 377.8-399.8 V under full load

the PF can be obtained greater than 0.992

and the THD can be obtained less than 10%

and its efficiency can be achieved up to 93.89%. Computer simulation and experimental results have been obtained to verify effectiveness of the proposed driver and the optimized hybrid control strategy.