The KIT-developed power supply unit reduces maintenance expenditure for electric devices. (Photo: Markus Breig, KIT)

From the charging unit for a smartphone to the power supply of a laptop or washing machine to LED lights or the charging station for an electric car — switching power supplies are omnipresent in electrical devices. They convert the alternating current from the house line into the direct current needed by the device. The problem: power supplies are susceptible to errors that can reduce the service life of end devices. Researchers at Karlsruhe Institute of Technology (KIT) have developed a power supply with a significantly increased service life.

Switching supplies used today are of light weight and compact design, but also susceptible to errors due to the incorporated electrolytic capacitors. Film capacitors would have much longer service lives, however, they need up to ten times more space. Scientists at KIT’s Light Technology Institute (LTI) have now developed a digital control method that will enable switching power supplies to use film capacitors that need only slightly more space.

The control method runs on a microprocessor integrated into the supply. It detects disturbing environmental impacts, such that for example, higher voltage fluctuations can be balanced. Hence, storage capacitors of reduced capacity are sufficient. Michael Heidinger, LTI, summarizes the advantages: “Use of these film capacitors eliminates the main cause of failure for power supplies — electrolytic capacitors. Depending on the design, service life may be increased by a factor of up to three.” The result is a much-reduced maintenance expenditure. “This is a big advantage, in particular in areas where highest reliability is required, such as in aviation, electric cars, or industrial applications.”

This technology has become feasible only with the use of high-performance microprocessors, Heidinger says. “Digitization of power supply units can be compared with the technological leap from analog to digital photography.” The technology also enables other advantages of digitization, such as remote maintenance capability and integration into the Internet of Things.