Development of a Testbench for Multi-Factor Aging with High Frequencies for Electric Machine Insulation

The trend toward higher switching frequencies in inverters increases the electric stress on insulation and emphasizes the importance of life cycle assessment. This life cycle assessment strongly depends on reliable test results. In this work, a test bench is presented for the purpose of multi-factor aging of insulation samples, combining high frequencies and high voltage peaks. This test bench offers very realistic continuous loads and enables reliable aging forecasts even at high switching frequencies. It features a novel fast-switching voltage source capable of switching high DC voltage, providing high customizable high-frequency bipolar voltage pulses with four separate half bridges. This work shows the design of such a test bench and its power source and highlights the main challenges of such a test bench. It combines the electric aging effects with additional stresses like thermal loads. In addition, the device under test (DUT) and the test bench have to be monitored over long time spans. Therefore, the voltage source is designed to be capable of detecting the breakdown of the DUT and communicating the breakdown event over the CAN bus to a programmable logic controller (PLC), enabling precise logging of the DUT lifetime.