The 400Hz power supply or variable frequency power supply converts AC power from the grid into AC→DC→AC, outputting a pure sine wave. The output frequency and voltage can be adjusted within a certain range. It differs from the variable frequency speed control used for motor tuning and from the standard AC voltage stabilizer.
Variable frequency power supplies mainly consist of two types: linear amplifiers and SPWM switching types.
What is a VFD?
The variable frequency drive is primarily composed of rectification (AC to DC), filtering, inversion (DC to AC), braking unit, driving unit, detection unit, and microprocessing unit. The variable frequency drive adjusts the output voltage and frequency by switching the internal IGBTs, providing the required power voltage according to the actual needs of the motor to achieve energy-saving and speed regulation. Additionally, variable frequency drives offer numerous protection functions, such as overcurrent, overvoltage, and overload protection, among others. With the continuous increase in industrial automation, variable frequency drives have found extensive applications.
The Difference Between Variable Frequency Power Supplies and Inverters
The 400Hz power supply or frequency converter is a variable frequency device consisting of an entire circuit that converts AC to DC, then back to AC with filtering. It has found extensive application. The frequency converter not only simulates various grid parameters for output but also provides a pure, reliable, low harmonic distortion, and high-stable sine wave power supply for voltage and frequency in the design, development, production, and testing applications of export electrical manufacturers. The frequency converter is very close to an ideal AC power supply and can output any grid voltage and frequency. The inverter is composed of circuits such as AC to DC to AC (modulated wave). The standard name for the inverter should be a variable frequency speed controller. Its output voltage waveform is a pulse square wave, with a high harmonic content, where voltage and frequency change proportionally and cannot be adjusted separately, which does not meet the requirements of AC power supplies. In principle, it is not suitable for use as a power supply and is generally only used for the speed control of three-phase asynchronous motors.
