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Neways Electronics International NV

02/23/2021 | Press release | Distributed by Public on 02/23/2021 03:06

High switching frequency in a GaN enabled PV inverter

As System Innovator Neways is working on different innovation projects. One of these projects is the European GaNext project where we are building an Intelligent Power Module (IPM) together with our international partners to remove existing barriers for adopting the Gallium Nitride (GaN) technology for practical solutions. Our share is to build an extremely compact solar inverter (PV inverter) that incorporates both the GaN technology and the IPM to contribute to the miniaturization of power applications.

Therefore, we are using a two stage approach. At first we are building a PV inverter using GaN devices and second we will build a PV inverter using the Intelligent Power Module.

To reduce the size we need to increase the switching frequency. Therefore, we defined requirements and started on the implementation of our PV inverter using GaN devices. Consortium partner Cambridge GaN Devices Ltd. (CGD) provided the 650V GaN components, and other consortium partner Sumida provided the inductors. The effect of the increased switching frequency is immediately seen: Only two coils of 33 cm3 are well capable of converting the fluctuating solar voltage to a clean DC voltage rail at a power rating of 3 kW. Another set of two coils are used in the transformerless inverter stage. These compact inductors help us in achieving one of the most important targets of this project - a power conversion density of 1 kW/l.

This high power density is only possible due to the high switching frequency. The PV inverter is dimensioned to operate at switching frequencies up to 500 kHz. Although, from technology perspective, GaN is capable of much higher switching frequencies, the switching frequency is a tradeoff between coil losses, switching losses, coil dimensions and many more parameters.

The first GaNext discrete PV inverter prototype: the four coils are clearly visible. The 650V GaN devices are hidden below the large power PCB and mounted close to the heatsink for optimum thermal interfacing to the passive cooled heatsink below.

A large effort was spent to determine the optimum frequency for this application using simulations and calculations. The benefits of an increased frequency are a reduced energy storage and a reduced inductance value, directly influencing the size. But the relative size reduction decreases with increased frequency, and the associated losses increase, as can be seen in the figure below. Based on these parameters an optimum switching frequency can be determined.

Frequency tradeoff 3KW Boost converter

We will further continue to check on the capabilities in this application and also investigate its limits

GaNext Consortium Partners:

United Kingdom
Cambridge GaN Devices, CSA Catapult, Lyra Electronics Ltd.

Netherlands
Neways Electronics International N.V., Besi Netherlands BV, Eindhoven University of Technology, Signify

Germany
advICo microelectronics GmbH, Maccon Elektroniksysteme GmbH, Infineon Technologies AG, SUMIDA Components & Modules GmbH, Technische Universit├Ąt Dortmund, Fraunhofer IMS