New Pfc Design And Its Applications In Frequency Conversion Air-conditioning Systems

The article analyzes the development status of both internal and international technology of frequency conversion air-condition. It is introduced in detail the fundamental of air-condition system. The control system of air-condition mainly includes control modules of frequency conversion, temperature, protection and anti-jamming. There have not only the analyses and researches for control fundamental but also the detail introduction of circuit of every control modules. In addition, the control system of air-condition can be divided into indoor and outdoor control parts according to its structure, and both parts and their communication are expounded in detail.There do many researches on Power Factor Correction (PFC) that applying to frequency conversion air-condition. By analyzing the history and development of PFC technology, associating the application characteristics of Active Power Factor Correction (APFC), the realization of APFC is studied with emphasis. First, there do researches, simulations and experiments about the traditional APFC technology of rising voltage type. The result indicates, with this type of APFC, that it can get higher Power Factor, restrain the pollution of harmonious waves effectively. Then, there do many researches about some type of chips for PFC control. It is analyzed that the design of circuit structure of APFC based on UC3854, and at the same time, it is introduced that the outline of design such as optimizing parameters, choosing components and planning PCB. It gets good experimental result by simulating with PSPICE9.1.With the PFC technology more and more mature, those simplifying the circuit structure, reducing the cost and enhancing the reliability become the new requirements increasingly. Withal, many researches, simulations and experiments are carried through with the new method of two-pulse brought by a Japanese company-Hitachi for the purpose of those reason. The main characteristic of it is that another pulse for the use of restraining noise would be sent a little while after having sent a pulse for power factor correction when the voltage is zero. The effect of correction should be different if the sending occasion different, and the mathematic model of this method was founded and then studied.Base on the methods of traditional APFC and two-pulse, a new method named PFC of chopping waves partly is brought forward that it would stop chopping when the instantaneous voltage value of sine wave are near zero or near the peak value. Importantly, there developed actual circuit and experiment with it. The result data of harmonious wave observed from FLUKE43 show that it can accord with the state standard. In this way, it can reduce the requirements of components and the power wastage when switching, can save the cost of product and enhance the reliability of system.