Bridgeless high gain single-stage LED driver and its hybrid control strategy
The traditional two-stage LED driver is usually used in the small and medium power LED driv-ers,resulting in some problems such as large in size and high in cost,and a large conduction loss at low voltage input,etc.To solve the above problems,a bridgeless high gain single-stage LED driver integrated by a bridgeless quadratic Boost PFC circuit and DC-DC LLC circuit was proposed,in which high voltage gain and soft switching can be realized,a set of control circuit is needed and the circuit efficiency can be improved.Aiming at the problem that the DC bus voltage variation range of the proposed single-stage cir-cuit needs to be regulated,the APWM-PFM hybrid control strategy suitable for the proposed circuit was proposed and analyzed and the hybrid control principle and the control process were analyzed in detail.Finally,computer simulation was carried out and a 200 W experimental prototype was built up.In the range of input voltage80-120 Vrms,when the duty cycle is0.5,the maximum voltage gain is obtained to be 6.7,the power factor value of the prototype can be achieved to be higher than 0.990 in all line voltage ranges,the THD can be reduced to be lower than 15%and the DC bus voltage is regulated to be under 700 V to equilibrate the line characteristics and LLC performance.Under full load condition,the prototype efficiency can reach up to 93.20%when the input voltage is 110 Vrms.Compared with the traditional two-stage converter,the voltage gain is increased by 2.21 times,high voltage gain and soft switching are achieved,the efficiency under low-voltage input condition is effectively improved.The proposed circuit and control method have been proved to be effective by the simulation and experimental results.
LED driverspower factor correctionhigh gain Boost and LLC circuit integrationhybrid control strategysoft switch
万方数据
维普
