Ac variable frequency power speed regulation technology has been widely used in industrial developed countries. In the United States, 60%-65% of the power generation is used for motor drive, due to the effective use of frequency conversion speed regulation technology, only industrial transmission electricity saving 15%-20% of the electricity.

The use of variable frequency power supply speed regulation, one is according to the requirements of speed regulation, the second is energy saving. It is mainly based on the following factors:
    1) Frequency conversion speed regulation system has small loss and high working efficiency.
    2) The motor is always kept in a low slip operating state to reduce rotor loss.
    3) Soft starting and braking functions can be realized to reduce the impact of starting current.
    In the use of variable frequency power supply speed regulation, it is necessary to consider the process requirements, saving benefits, investment recovery period and other aspects. If only from the process requirements, saving benefits to consider, the following cases choose frequency control is more favorable:
    F According to the process requirements, the production line or a single equipment needs to adjust the motor speed according to the program or according to the requirements. Such as: packaging machine transmission system, according to different varieties of products, need to change the system transmission speed, the use of frequency control can make the speed control system simple structure, accurate control, and easy to achieve program control.
    F Variable frequency speed regulation instead of mechanical speed change. For example, the machine tool can not only save the complicated gear box, but also improve the accuracy and meet the program control requirements.
    F Variable frequency speed regulation is used instead of gate or baffle to adjust the flow rate for fans, pumps, compressors, etc. For example, the boiler pump, blower, and induced draft fan implement frequency control, which not only eliminates the need for servo amplifiers, electric operators, electric actuators and water supply valves (or windscreen), but also makes the entire boiler control system obtain rapid dynamic response, high control accuracy and stability.
    After the 1970s, the development of large-scale integrated circuit and computer control technology, as well as the application of modern control theory, make AC electric drive system gradually have a wide speed range, high speed stability range, high speed stability accuracy, fast dynamic response and reversible operation in the four quadrants and other good technical performance. In terms of speed regulation performance can be comparable with DC electric drive. In AC speed regulation technology, variable frequency speed regulation has an absolute advantage, and its speed regulation performance and reliability continue to improve, the price continues to reduce, especially the frequency conversion speed saving effect is obvious, and easy to achieve process automation, favored by the industrial industry.

1. Excellent characteristics of AC frequency conversion speed regulation
    1) Good smoothness and high efficiency during speed regulation. At low speed, the characteristic static closing rate is high and the relative stability is good.
    2) Large speed range, high precision.
    3) Low starting current, no impact on the system and power grid, power saving effect is obvious.
    4) The frequency conversion power supply is small, easy to install, debug and maintain.
    5) Easy to automate the process.
    6) There must be a dedicated frequency conversion power supply | voltage regulator, the current cost is high.
    7) In the constant torque speed regulation, the overload capacity of the low-speed motor is greatly reduced.

2. Comparison with other speed regulation methods
   There are three methods of AC motor speed regulation: pole change speed regulation, change slip rate speed regulation and frequency conversion speed regulation. Among them, frequency conversion speed regulation has the most advantage. Here only AC variable frequency speed control system and DC speed control system to do a comparison.
    Ac drive itself has the potential to save electricity that can be tapped. In the AC speed control system, there is often a certain margin when selecting the motor, and the motor does not always run under the maximum load; If the use of variable frequency power speed regulation technology, light load, through the motor speed control, can achieve the purpose of power saving. Industrial use of fans, pumps, compressors, etc., its electricity consumption accounts for about 50% of industrial electricity consumption; If the frequency conversion power supply speed regulation technology is used, its efficiency can be greatly improved, and the power consumption can be reduced by 10%.