PSU Prototype Triples Longevity Using Film Capacitors Instead of Electrolytic

May 07, 2019 by Scott McMahan

Most electrical appliances use switch mode power supplies to convert alternating current from a wall plug to direct current. The issue, however, is that power supplies tend to be error-prone, which also shortens the lifespan of the terminals.

Researchers at the Karlsruhe Institute of Technology (KIT) have now developed a much longer-lasting power supply that they say is less error-prone. (See photo above courtesy of Markus Breig, KIT).

The often used switching power supplies are lightweight and compact, but the built-in electrolytic capacitors makes them also error-prone. Film capacitors are known to be much more durable. On the other hand, film capacitors take up to ten times more space.

Integrated Microprocessor Helps Compensate for Fluctuations

Scientists at the Lichttechnisches Institut (LTI) at KIT have now developed a digital control technique that allows the use of film capacitors with only slightly increased space demands.

The control method uses a power supply with a built-in microprocessor. The method detects disturbing environmental influences, so that, for example, higher voltage fluctuations can be compensated. As a result, storage capacitors with a smaller capacity are sufficient.

With the film capacitors, the failure rate of the switching power supplies can be reduced, and, therefore, the longevity of the terminals can be multiplied many times.

Michael Heidinger of LTI summarized the benefits pointing out that the use of the film capacitors eliminates the primary failure cause of power supplies, the electrolytic capacitors. He also notes that depending on the design, that using film capacitors instead can triple the operating time, resulting in much less maintenance.

In applications such as aviation, electric cars, and industrial purposes, where reliability is important, this added longevity is a big advantage, he commented.

Powerful Microprocessors Make the Technology Possible

This technology has only become possible with the proliferation of very powerful microprocessors, according to Heidinger who suggests that you can compare the digitization of power supplies with the technological leap from analog to digital photography. The technology for the digitization of power sources offers other advantages such as enabling remote maintenance and the related integration into the Internet of Things.

A functional prototype was set up at the institute and measurement results, including dynamic and lifetime measurements, of the prototype, are available.

The researchers are now seeking industry partners to design power supplies based on their existing prototype.