Study On The Single-Phase Active Power Factor Correction Circuit

Power factor correction technology is an effective method of restraining harmonic currents and increasing power factor, which has been attended more and more in recent years. Main circuit topologies and control methods are analyzed and compared on the basis of the principle of Active Power Factor Correction (APFC), which characteristics are summarized. Passive Power factor correction circuit, two-stage and single-stage APFC circuits are researched, which applications are given by comparison of their performance.Boost converter and UC3854 are used in designing a 500W APFC circuit. The circuit parameters are calculated. The main circuit and compensating network of the control circuit are respectively optimized using nonlinear optimum methods.The objective of design optimization for the main circuit is to minimize the total size and the results indicate the total size is reduced by 0.5%. The objective of design optimization for the current loop is to maximize the cross-over frequency. The results show the stability is improved and the capability of suppressing the switching noise is far better than the original. The objective of design optimization for the voltage loop is to minimize the gain of the line ripple voltage.As a result the bandwidth minishes obviously and optimization design excelles in restraining the ripple.The validity of the optimum results is proved by the simulation.DC voltage sensorless single-phase APFC circuit is studied. Neither DC voltage nor AC current sensors used in the conventional PFC circuit are required to construct the control circuit. DC voltage and ac line current are regulated by detecting an AC line voltage waveform. The constant DC voltage and the sinusoidal current waveform in phase with the AC line voltage can be obtained. The proposed circuit is very simple and the implementation is also easy. It is of advantage to reduce size and cost. The principle of the DC sensorless PFC circuit is analytically investigated. Then the feasibility is verified by some simulation.