Research On Reliability Of DC Inverter Multi-line System

Nowdays, multi-line system is one of the main development trend of middle and small air-conditioning system. Indoor multi-line machines are numerous and have quite a few external drives under the condition of modular multi-line. Therefore, a lot of parts and procedures are needed to ensure the normal operation of it. Those issuses must be addressed for research and development of multi-line system are: lubricant oil return problems of inverter compressor running in the low-frequency; how to get reliable operation of the DC inverter air conditioner; how tomake each allocation of the indoor unit get precise refrigerant flow as they needed; how to ensure the normal compressor lubricant oil return which can ensure that the compressor is not short of oil without affecting system performance; how to ensure the compressor refrigerant distribution among modules and among compressors inside modules.As the author was tracking a development project of DC inverter multi-line, he was supported by the Natural Science Foundation of Ningbo (2009A610097), post-doctoral funded supporting projects, Zhejiang Province (2009-bsh-19) and post-doctoral funded projects, Ningbo and he has done following research:Firstly, theoretic models of the various parts of DC inverter multi-line has been bulit. The compressor uses a DC inverter scroll compressor and considering the frequency change on the refrigerant flow in the modeling process can provide theoretic support for further experimental research.Secondly, the reliability of inverter compressor scroll (including oil return, hot start, cold start, force start) was conducted a systematic study. On this basis, it's proved that reliability proposed a important role for commercialization and reliability standards for commercialization of new products.Thirdly, related research on the PI algorithmhe of modular machine DC inverter multi-line refrigerant distribution, long-tube experiments, multi-line air-conditioning IPLV testing were conducted. Although modularity is the development trend of DC inverter air conditioner, in the process of modularing, blind spots and errors about this process should be avoided. The study pointed out that multiple modules performance relatively poorer than that of a single module, therefore, the machine modules outside should not be more than 3 sets.Fourthly, the reliability of the four-way valve has been tested which shown that refrigerant flow is the main factor t oaffect reliable exchange of four-way valve. Therefore, inverter compressor should use the four-way valve to control the compressor frequency and to ensure the normal four-way reversing valve exchange.