Performance Test of a 450 V Polymer Aluminium Electrolytic Capacitor

CIE/SDU has developed a new high voltage polymer Aluminium electrolytic capacitor technology which will be suitable for higher working voltages up to 450 V. In cooperation with FH Kiel and Vitesco a test rig setup was developed to test the performance of this capacitors. The single capacitors had a stack structure and a capacitance of 32 muF in a 10 x 55 x 40 mm Aluminum can. The ESR of the device was measured to 30 mOhm at 40 kHz. The test rig consisted of two independent cooling circuits for the inverter, one cooling circuit for the power modules and one cooling circuit for the capacitor. The capacitors can be operated at different temperatures via a cooling liquid. The thermal behavior was monitored with a thermos camera. Semikron eMPack(r) power module have been used. The performance of the capacitor was tested in the voltage range from 1-400 V and temperatures from room temperature up to 66 deg C. The capacitors can be cooled well and show a homogeneous temperature distribution Ripple currents up to 15 A @20 kHz have been applied. Simulations and measurements of the parasitic inductance indicate values of 11.8 respectively 12.8 nH. A comparative test with a metallized film capacitor 80 muF/450 V from Epcos has also been conducted. Proposals of an optimization of the manufacturing processes are developed, resulting in a better connection of the capacitors to the busbar, lower stray inductances, and an improved electrical performance.