AC variable frequency in recent decades to develop a new technology, with its superior speed performance, remarkable energy-saving effect and broad applicability in various fields of national economy, and is recognized as one of the most promising tone speed mode. AC frequency control technology is computer technology, comprehensive application of power electronics and motor drive technology, the basic principle is the on-off effect of power semiconductor devices, rectifier bridge by the frequency AC voltage into a DC voltage, and then by the inverter is converted to frequency, voltage adjustable AC voltage as the AC motor drive power, the motor to get the required voltage and current stepless, no one is an efficient way to speed differential loss of additional turn. Comprehensive strength of electric hybrid, mechanical and electrical integration on the basis of, for power electronics, micro technology and comprehensive application of the motor drive technology, which is AC frequency control technology. So you can slip as no additional loss of effective speed control, at the same time, so that the motor voltage and current stepless obtain needed. Frequency of technological development in the energy crisis, can effectively improve work efficiency greatly, because it automatically in accordance with the motor load and smooth growth, slow work. Thus, by changing the frequency of the motor power supply, as a high-efficiency, high-speed means of frequency control technology enables efficient regulation.