The characterisation platform for the more electrical aircraft domain at IRT Saint Exupéry has been expanded with the arrival of a new electric motor test bench to work in conjunction with hysteresisgraph purchased in 2015. It supports the ‘technology bricks’ sub-domain research into characterising and modelling electromagnetic losses. The idea is to improve the accuracy of calculations in order to reduce the error margin in future designs, ensuring better efficiency for embedded electric motors.

MEASURING ELECTROMAGNETIC LOSSES WHILE SIMULATING REAL CONDITIONS

This test bench was tailor-made for IRT Saint Exupéry by Intest. Its unique feature is its ability to measure electromagnetic losses very accurately while closely replicating conditions on board an aircraft. Over time, temperatures in its climatic chamber can range between -55°C and +150°C.

The test bench has three drivelines with a maximum torque of 0.1, 1 and 10 newton metres. Each driveline has a driving and braking motor capable of testing all the possible configurations (driving or generating, with or without load).

The first driveline is mounted on air bearings to ensure no contact between its fixed and rotating parts. This design makes it extremely accurate, up to 100 µNm (micro newton metres), similar to measuring the weight of a 3-cm hair at a distance of 10 cm. It can thus measure electromagnetic losses without being affected by any mechanical disturbances linked to the bearings. The third driveline can test high-speed electric motors running at full power up to 24,000 rotations per minute.

MEASURING ELECTROMAGNETIC LOSSES WHILE SIMULATING REAL CONDITIONS

This test bench supplements the Brockhaus Hysteresisgraph MPG-200 purchased by IRT Saint Exupéry in 2015 to measure magnetisation and electromagnetic losses in magnetic materials, a phenomenon that occurs when you magnetise a magnetic material. The hysteresisgraph generates magnetic fields in electrical steel sheets, a special kind of steel that amplifies the magnetic flux density. It can generate and regulate magnetic flux density or magnetic field waveforms with totally free shapes (sine, triangle, square…). What makes it unusual is its ability to do this in two perpendicular directions. The machine can thus produce 2D turning magnetic fields. And, with its frequency bandwidth up to 1 MHz along with its ability to regulate any time combination of magnetic field values, you can create more than just a sinusoidal field, thus getting much closer to replicating the actual fields found in electric motors than you can with more classic test means.

THE ‘TECHNOLOGY BRICKS’ SUB-DOMAIN OF THE IRT SAINT EXUPÉRY’S MORE ELECTRICAL AIRCRAFT DOMAINS

The use of electricity is becoming increasingly widespread in an attempt to increase the power efficiency, eco-efficiency and reduce the weight of future means of transport. To make it competitive the voltage, power density and reliability of all the elements in the electromechanical conversion chain – converters, filters, harnesses and electric motors – must be increased.

The introduction of more powerful electrical components, such as “wide-bandgap semiconductors” is one of the disruptive developments that will lead to great increases in the power density. We also need to work on other components such as electric machines to ensure they are adapted to cope with the issues linked to the use of these new components and also to reduce their losses.
Research underway at this sub-domain is focusing on these technology and methodology challenges and is looking to show the improvement of the power density by making technology demonstrators.

A TECHNOLOGY PLATFORM AVAILABLE FOR PARTNERS

Current project work has already resulted in several scientific papers being presented at prestigious conferences (ICEM 2016, SGE 2016, Intermag 2017). The main companies involved in the Integration IRT Saint Exupéry project, for which this test bench has been developed are Airbus, Liebherr, Safran and Zodiac Aerospace. They are benefiting from the skills of Laplace Laboratory (UMR CNRS/INP Toulouse/UT3 3 Paul Sabatier). These test means may already be used by other partners within other IRT Saint Exupéry projects.