High voltage frequency converter is from high to low to high, low to high, high to high. The high-low high voltage inverter is to control the transformer of high-voltage power supply, control it with low voltage inverter, and use the step-up transformer to raise the voltage to the voltage we use to supply the high-voltage motor. Generally high and low methods are used in low power high voltage motor for frequency conversion and energy saving. Low high voltage inverter is controlled by low voltage inverter, and the voltage is raised to the use voltage of the motor directly with the boost transformer. The low high way is also used in low power high voltage motor for frequency conversion and energy saving. High high voltage inverter is directly used in series with multiple modules of frequency converter, directly using high voltage power supply, directly output high voltage for high voltage motor. The high and high method is mainly used in high-power high voltage motor for frequency conversion and energy saving.

VVVF technology is the strength of electric hybrid integrated technology, electromechanical integration, both to great power conversion (rectifier and inverter), collection, conversion and transmission and processing of information, so it must be divided into success rate and control two parts. The former is to solve the technical problems related to high voltage and large current, and the latter to solve the problem of hardware and software control. Therefore, the future high voltage variable frequency speed regulation technology will also be developed in these two aspects, which are mainly shown as follows:

① The high voltage inverter will develop towards the direction of high power, miniaturization and light.

② The high voltage inverter will develop in two directions, the high voltage and the multiple superposition of the direct device (the device series and the unit series).

③ A new type of power semiconductor device with higher voltage and larger current will be used in high voltage inverter.

④ At this stage, IGBT, IGCT and SGCT will still play the main role, and SCR and GTO will withdraw from the inverter market.

⑤ The application of vector control, magnetic flux control and direct torque control for speed sensorless will become mature.

⑥ To achieve the comprehensive digitization and automation: self setting parameters; optimization technology; fault diagnosis technology.

⑦ The application of 32 bits MCU, DSP and ASIC devices such as high precision, frequency converter, multi function.

⑧ The related industries are moving towards specialization, scale development, the social division of labor will be more obvious.