Investigation of voltage stresses inside Adjustable Speed Drives

This paper investigates the effect of voltage stress on the voltage insulation components inside regenerative Active Front End (AFE) Adjustable Speed Drive (ASD). The paper shows that high potential voltage insulation issue may exist on various components inside the ASD and cause earlier failures under very long cable or multiple drive conditions. A simplified system model to describe this phenomenon is described, the voltage stresses inside the drive under different grounded condition are analyzed, and their conclusions are verified by both simulation and experimental results. It is concluded that a much higher voltage stress may exist in different location of the drive under different grounding systems. Appropriately designing the insulation components is critical to protect the drive.