AT&S increases voltage for the era of electromobility

“How can we build electric cars which are not simply copies of the combustion engine, but rather copies of a smartphone?” The ability of printed circuit boards to integrate components, miniaturisation, cost reduction and their energy efficiency will play a key role in this development.

Printed circuit boards are the foundation of our digital world. They enable increasingly complex electrical connections on ever smaller space for a great number of chips and other components that are necessary for electronic devices ranging from smartphones to modern ventilators. Printed circuit boards increasingly also form the basis for supplying power at the required voltage for a variety of devices and their components.

Let’s take a smartphone, for example: the power supply transforms the alternating current from the power point into a low-voltage direct current and thus charges the battery. The countless electronic components in the smartphone, such as chips, sensors, antennas, cameras, microphone and speakers, all require different voltages, meaning that the current has to be transformed several times. In this process, energy is lost in the form of heat, Hannes Voraberger, Head of the Research and Development department of AT&S in Leoben, explains. A dual problem: on the one hand, the devices heat up; on the other hand, the smartphone needs to be plugged in again sooner because of the energy loss.

When using printed circuit boards to supply electronics with power, AT&S is now increasing voltage: “The main driver of the coming years is e-mobility, switching from combustion engines to electrical machines,” Voraberger explains. While smartphones make do with only a few volts, motors require voltages of 600 to 800 volts to perform properly. From hybrids to electric cars, trucks or buses – they all need electronic systems that transform power as required for the different purposes. “From direct current to alternating current from the battery to the motor, or from alternating current to direct current from the power grid to the battery, from high voltage to low and vice versa. Significant losses occur during the transformation, which we aim to halve through our developments,” the Head of R&D describes the challenge.

To that end, AT&S entered into a partnership with one of the globally leading research institutes, the Center for Power Electronics Systems (CPES), which emerged from the renowned Virginia Tech (VT) University. “AT&S has gained its excellent reputation in the world with printed circuit boards, the circuits to connect all transistors and semiconductors in mobile devices. About ten years ago, the supply of semiconductors, the chips, with power was added. AT&S is excellent at portables, smartphones and computers — but now we are dealing with new portables, and those are electric cars,” explains Dushan Boroyevich, Director of CPES and Associate Vice President for Research and Innovation in Energy Systems at Virginia Tech.

“The question is: how can we build electric cars that are not simply copies of the combustion engine, but rather copies of a smartphone? This is how we came to work with AT&S,” says Boroyevich in a Zoom conference with the AT&S blog. “So far, power electronics are grouped in large boxes, using solder joints or screwed connections — with printed circuit boards, we can integrate the different levels of the circuits, use plastics for insulation and heat distribution and also connect them with the necessary storage of smaller amounts of energy. This will move our cars, supply the motor with energy. It will look the same as in a smartphone – a little larger, but the principle is the same,” the scientist explains. “CPES does not manufacture anything, but we have hundreds of people with crazy and amazing ideas. AT&S, in turn, knows how to produce and scale these things.”

One of the projects in which AT&S collaborates with CPES is the development of a reference module for an on-board charger, a charger integrated into electric cars, which can be used to simply connect an electric vehicle to a household power point. This involves multiple challenges: printed circuit boards with the ability to transform high voltages along with heat development, reduced energy losses, miniaturisation and substantially lower costs than with the current design.

A new material for the conductors — silicon carbide, chemical formula SiC — together with higher frequencies for the transmission of electricity will enable this development, Voraberger explains. “Silicon carbide can transform the current to very high voltages and very fast; the temperature is lower and therefore cooling is not a problem. This will be one of the key solutions for electromobility, which we will use for 600 to 800 volts.” At the moment, the transformers necessary for power supply require a great amount of space in electric cars. In the future, this will be a small box, which in turn saves weight and increases the range.

The objective is to develop not only the necessary printed circuit boards but a reference module for manufacturers, an overall solution for the integration of all components in one box: “The shorter the conductor paths in electrical engineering, the better because less power is lost. This why we are working to achieve a high degree of miniaturisation and integration of components,” says Voraberger. “Currently, a small percentage of energy is lost in each transformation along the way – from power generation to the power point, from the power point to the battery, from the battery to the motor and other components. We aim to at least halve this loss, or even better, reduce it to a quarter.”