Domestic variable frequency air conditioners started late in China. By the end of 1997, domestic variable frequency air conditioners were all assembled with imported emblem parts. In Japan, variable condensation control has become the standard technology of air conditioners and refrigerators, and variable frequency air conditioners account for 80% of the whole ten air conditioner markets. Since 1998, it has attracted the attention of home appliance industry and consumers in China. Changhong, Haier, Hisense, Chunlan and other air-conditioning manufacturers have accelerated the pace of technology introduction or research and development. For example, Changhong has introduced the technology of Japan TOSHIBA Company, Hisense has introduced the technology of Japan SANYO Company and PHILIPS Company of the Netherlands, and Haier has jointly developed domestic inverter air-conditioning technology with intellectual property rights based on China and Tsinghua University.