Design of a Calorimetric Measurement System for Determination of the Power Losses in Magnetic Components

The challenges in measuring and recording the power loss in magnetic components are critical and require attention. This is based on the development of new grid topologies, inverters/rectifiers and the associated progress in semiconductor technology, e.g. gallium nitride (GaN) semiconductors, which increase the switching frequencies for chokes and enable use in higher frequency ranges. Conventional precision power meters reach their measuring limits and deliver increasingly higher inaccuracies of >10%. In order to offer an alternative in measurement technology, a closed single-chamber calorimeter has been developed, which can measure a power loss of 1000 W at a current of up to 500 A with a frequency range of 25 kHz. The single-chamber calorimeter determines this power loss via the heat dissipation of a device under test (DUT) in a homogeneous environment to a cooling circuit and the measuring chamber walls, taking into account potential error variables such as the heat loss via the electrical conductor of the DUT, varying thermal properties of the cooling media or additional interfering heat sources (fans to generate the homogeneous airfield within the measuring chamber). In the future, the system will be expanded to include a variably adjustable operating temperature and a dynamic software code for recording the varying thermal properties of the air in the measuring chamber.