climate chambers to experience temperature and humidity. The system is equipped with thermal and electrical signal monitoring systems. Key capacitor parameters can be measured online, such as voltage, ripple current, capacitance, case temperature, and hotspot temperature (for special samples with integrated thermal sensors). By configuring the internal structure and the power stack control, the capacitor testing system can emulate different electrical stresses with the following advantages. ■ Different ripple current/voltage and dc voltage can be emulated by configuring the test bench, and the dc and ac capacitors can be concurrently tested. FIG 2 The dc and ac power cycling test setup. (a) Configuration of the testing system. (b) Left: 6-unit, 19 " industrial rack array; right: detailed configuration of one rack. December 2022 z IEEE POWER ELECTRONICS MAGAZINE 25