Research On The Interleaved BCM Boost PFC Converter

Due to the wide application of power electronic devices, power quality problems have caused more attention. To improve power quality effectively, the power factor correction (PFC) technology has being employed widespread in power and power supply system. At present, research of power factor correction technology focuses on improving the power density, increasing the efficiency and expanding the power level. By dividing power with multiple branch, interleaving parallel technology reduces input current ripple and EMI noise, and improve thermal management, improving the whole level, efficiency and the various performance.Paper firstly expounds the causes and harm of harmonic current, points out the significance of power factor correction, illustrates the classification of power factor correction circuit and related control method, and then introduces the hot spot of PFC technology research in recent years. On this basis, the principle of boundary conduction mode (BCM) Boost PFC and switch characteristic was analyzed, concluding several factors affecting the switch conduction time. Critical mode Boost PFC is controlled with frequency conversion, and switching frequency varies along with the change of the input voltage RMS and load.Then analyzed the interleaved BCM Boost PFC circuit operation. Compared with the single phase, analysis on the advantages of the interleaving parallel topology was made. The input current ripple, the size of the inductance and output current ripple were analyzed. In-depth analysis of the interleaving parallel control method was made. Paper respectively introduced open-loop master-slave method and based on phase-locked loop (PLL) closed-loop method, analyzed their principle and points out their respective problems. A novel interleaving parallel control method was put forward, with its working process and phase adjustment process analyzed. Considering the new control method, the simulation model was built and theoretical analysis is verified. The new control method was applied in four phase interleaved BCM PFC regulator.Main circuit parameters of power level in the interleaving parallel BCM Boost PFC were calculated, and experimental prototype of300W was made by using the chip of TI UCC28061.Under different input voltage and power levels, waveform of the input voltage, input current, inductance current and drive pulse were tested. The experiment shows that both branch work in BCM state; different input voltage and power levels make the different conduction time and different switching frequency. The experimental data of two phase interleaving parallel BCM Boost PFC and traditional CCM Boost PFC was analyzed, and the curve of PF efficiency and power factor was drew out. According to the graph, it was clear that the two phase interleaving parallel BCM Boost PFC has better overall efficiency and power factor.