The theory is used to do a family or for factories, single-phase and three phase power exchange to exchange the relevant laws of the country's power supply voltage and frequency calculation rules the sundial standards, such as marine rules, the indirect exchange of user 220 V power supply single-phase three phase AC cord is 380 volts, a frequency of 50 Hz, other countries, the supply voltage and frequency, it may be a different voltage and frequency in the country, if there is a single-phase 100 V / 60 Hz, the button-type battery. 3-phase 200 to V / Hz, and so on, the the sundial standard voltage and power of testimonies frequency of transactions, the power of the industrial frequency of transactions. AC variable frequency power supply. 
 Typically, the voltage and frequency to consolidate the work of the same frequency exchange power conversion known as variable frequency power supply voltage or variable frequency AC power assembly. To the outbreak of the variable voltage and frequency, the decorative power of the first exchange of power is converted to direct current (DC), and the process of the rectification. Current (DC) is converted to the exchange of electric power (AC) General Assembly, the button. 
 Regulator (http://www.pandeng.org.cn)