Thermally compensated discontinuous modulation strategy influence on DC-link capacitor current of CHB converters

CHB converters have been intensively considered for various applications. However, a reliability issue has emerged due to the higher number of power devices, particularly power semiconductor devices and capacitors, which have been identified as major sources of failure. Although continuous efforts have been made to enhance the reliability of power semiconductors through methods such as active thermal control, there is a noticeable absence of discussion regarding the reliability of capacitors. This is significant since capacitors are the components most prone to failure in power converters. In this study, the root mean square (RMS) current of the DC-link capacitor in a CHB converter is derived when applying thermally compensated discontinuous modulation for power semiconductors. To validate the obtained findings, the derived equations are experimentally tested using a proof-of-concept setup.