Why do manufacturers now choose film capacitors?

Early DC support film capacitors used electrolytic capacitors. With the development of thin film capacitor technology, especially the development of the base film technology and the use of segmentation technology for metallization, not only the volume of the film capacitor is becoming smaller and smaller. The product's withstand voltage level has remained at a considerable level, and now more and more companies use high-temperature polypropylene film capacitors as DC support capacitors. And why are more manufacturers now switching to film capacitors?

1. The frequency characteristics are stable and the high frequency characteristics of the product are good.

At present, most of the controllers have a switching frequency of about 10 kHz, which requires high frequency performance of the product. This requirement is a problem for electrolytic capacitors and polyester film capacitors.

2. Film capacitor can withstand reverse voltage

The electrode of the film capacitor is a nano-scale metal evaporated on the film. The product is non-polar, so it is very convenient for the user, and does not need to consider the problem of the positive and negative electrodes. For the electrolytic capacitor, if it exceeds 1.5 When the reverse voltage of the double Un is applied to the electrolytic capacitor, it causes a chemical reaction inside the capacitor. If this voltage continues for a long enough period of time, the capacitor will explode or the electrolyte will flow out as the internal pressure of the capacitor is released.

3. High rated voltage, no need for series and balancing resistors

In order to increase the output power, the bus voltage of hybrid vehicles and fuel cell vehicles is constantly increasing. The typical battery voltages available on the market today are 280V, 330V and 480V. The matching capacitors are not the same, but generally choose 450V, 600V, 800V, and the capacity is from 0.32mF to 2mF.

4. Strong anti-surge current capability

Capable of withstanding large currents, the use of wave cutting technology and capacitor coating thickening technology can improve the product's inrush current temperature and mechanical impact.

5. Good product safety and strong overpressure resistance

Since the film capacitor has a self-healing phenomenon, and the film capacitor is designed according to the standard of 1EC61071, the capacitor anti-surge voltage capability is greater than 1.5 rated voltage, and the capacitor adopts the split film technology, the capacitor theoretically does not cause short-circuit breakdown. Phenomenon, which greatly improves the safety of this type of capacitor, the typical failure mode is open circuit. The peak voltage capability of the capacitor in a particular application is also an important indicator of capacitance. In fact, for electrolytic capacitors, the maximum surge voltage allowed to withstand is 1.2 times, which forces the user to have to consider the peak voltage instead of the nominal voltage.