Variable speed drives

The regenerative braking function is of great importance to the mechanical variable speed drives, which can effectively improve the efficiency of the system and realize the energy-saving purpose. Through the analysis and discussion of various regenerative circuits of variable speed drives, this paper provides a reference for practical application selection. The regenerative circuit based on the energy storage device and the common dc bus is suitable for certain applications. Based on the regeneration of the power electronic converter circuit, the current use very much, which USES the regeneration of the thyristor circuit, low cost, easy to achieve high power level, but because of thyristor is half controlled device, must consider the problem of the commutation of the need to take measures to ensure the reliable commutation, they inject a certain amount of harmonic current to the grid at the same time; Regeneration circuit type based on full controlled devices, although the cost is relatively high, but performance is good, can easily realize two-way flow of energy, and can significantly improve the power quality of grid side, therefore has good application prospect. Three - level dual PWM converter is also an optimal scheme for the application of regenerative circuits in multi-level topologies.