​Power converters are found in phone and computer chargers and just about every other electrical device you can think of. These ubiquitous components could benefit from an emerging power electronics technology—mechanical energy storage—that has the capacity to substantially reduce energy losses and enable new, more compact form factors.

In inductor-based converters, electricity is stored in the form of a magnetic field and the output voltage is adjusted to meet the specifications of the device being powered. Here, the researchers replaced the inductor with a piezoelectric material. It is the mechanical deformation of this material that allows energy to be stored. A device of this kind can store much more energy than a conventional device of equivalent size—and the increase in energy storage capacity is even greater at high frequencies. At 1 MHz, for example, the device can store 24 times more energy than an equivalent inductor-based device. This advance will enable new form factors, including very thin ones (under 1 mm) that would be ideal for phones and tablets. The material also offers the advantages of lower losses and higher yields.

The researchers also developed a device to manage the switching sequence and effectively regulate the output voltage. They are now working on making the system even smaller by integrating the controller into a dedicated ASIC and by leveraging MEMS processes to integrate the mechanical resonator. The system was tested successfully at up to 180 W, which means it could address 80% of the power converter use cases on the market.