Research On Multi-output Sharing LED Driver Based On CLCL-T Resonant Network

As a new generation of green light source,LED is highly appreciated for it's major advantages,such as,long life,high light efficiency,saving energy and protecting environment.Therefore,LED has been already widely used in various lighting situation,especially in high-power lighting,such as,street lighting,tunnel lighting.The performance of the LED driver directly affects the reliability of the entire lighting system,so it's essential for the development of LED lighting to research on the high-power LED driver.Firstly,the paper introduces the research status of the LED driver,including the LED driver circuit topology,multi-output sharing schemes,as well as dimming technologies,and analyzes the different power levels of LED driver topology,which leading to the half-bridge resonant converter,a ideal circuit topology suitable for high-power LED driver.Then,on the basis of analyzing the constant current characteristic of the half-bridge resonant network,proposing a LED driver circuit topology based on the CLCL-T resonant network,which can keep the output current constant under different lamp voltage without closed-loop control.Besides,establishing the FHA model of CLCL-T resonant converter by First Harmonic Approximation method,deducing the expression of output current with the working frequency and the resonant parameters,and analyzing in detail the working principle characteristic of constant current and the influence on the precision of constant current by resonant parameters.Also,the circuit parameters have been designed according to the current sensitivity,constant current and ZVS conditions.Secondly,a multi-output sharing scheme combining with parallel transformer and jumper capacitance is proposed on the basis of the CLCL-T resonant network,adding a PDM dimming strategy suitable for it,which realizes 2n-output current balancing and dimming control.The principle of the multi-output current sharing as well as the dimming control has been analyzed in detail.Then,the design process of the hardware and software system is given,and the feasibility is verified by Saber simulation software.Besides,proposing a LED driver topology with any way current sharing,analyzing the principle and conditions of current sharing,and verifying the circuit by simulation and experiment.Finally,a 108W LED driver principle prototype has been established and the experimental tests have been done.The waveform test and experimental data analysis verify that the scheme proposed is feasible.