Semi-T-shaped three-step metallized safety film capacitor

Abstract

A semi-T-shaped three-step metallized safety film capacitor comprises an insulating core rod, a first metallized safety film and a second metallized safety film. The first metallized safety film includes a base film, a metal plating layer, and a T-shaped insulator. The metal coating comprises a thickened region, a low sheet resistance region, a middle sheet resistance region, a high sheet resistance region and a margin region according to the thickness. The thickness of the metal coating is correspondingly adjusted, it can be guaranteed that the current densities of all the parts of the metalcoating are basically consistent in the current magnitude changing process, the current bearing capacity of the metallized safety film is greatly improved, and then the loss of the first metallized safety film and the loss of the second metallized safety film are reduced. The T-shaped insulating part is only arranged on the middle sheet resistance area and the high sheet resistance area, so that insulating substances on the metallized safety film are greatly reduced, the area of each film coating area divided by the T-shaped insulating part is correspondingly reduced, and therefore, when a certain film coating area is cut off, the lost capacitance is correspondingly reduced, and the capacitor is more durable.

Description

technical field [0001] The invention relates to the technical field of power electronic capacitors such as DC support capacitors for flexible engineering and rail locomotives, and in particular to a half-T-shaped three-step metallized safety film capacitor. Background technique [0002] At present, metallized film capacitors are becoming more and more popular due to their good self-healing properties and pressure resistance, and metallized film capacitors are the most important raw materials for their production. The thinner the coating thickness of the metallized film, the higher its square resistance, and the film with high square resistance has better self-healing performance but poor flow capacity. On the contrary, the thicker the coating, the smaller the square resistance, the lower the self-healing ability but the better the flow ability. When self-healing is excessive, a large amount of self-healing energy accumulated in a short period of time will also cause the bas...

AI Technical Summary

Problems solved by technology

[0004] 1. Due to the existence of a large number of insulation gaps, the loss of components made of safety films is much greater than that of ordinary metallized films of the same specification. The capacitor heats up more seriously during operation, and the high temperature will lead to poor voltage resistance of the base film.

[0005] 2. The safety film designed in the industry usually adopts a coating structure with constant square resistance, but the current on the coating plate is not constant, which leads to insufficient current flow capacity at the coating position with high current density, and poor ability to withstand overcurrent. Difficult to resist when encountering inrush current

[0006] 3. Due to the relatively large area of ​​the module unit design of the traditional T-shaped safety film element, when the fuse is blown, the area of ​​the cut-off plate is too large, so the capacitance loss is too large

When the capacitor is operated continuously for a long time, the capacitance value decays too fast, and the capacitor needs to be replaced frequently to ensure normal operation

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