Reliability enhancement of multilevel inverters through SVPWM-based thermal management methodology

This paper introduces design and validation of space vector pulse width modulation (SVPWM) algorithm for reliability enhancement of multilevel inverters. Thermal overheating is the main cause of shortened-lifetime and open-circuit faults of power devices. It may result from ageing of semiconductor materials due to continuous operation and various operating conditions. Degradation and faults of cooling system are also of the major causes of overheating in power components. The proposed algorithm is applied when an overheating is detected in any of the semiconductor devices and helps to alleviate the overheating from the affected device and thereby preventing the overall system from malfunction. The proposed methodology relies on using the redundancy property between the switching states in multilevel inverters to continuously evaluate a cost function of the junction temperature of the overheated devices for all possible switching sequences, then it selects the optimal relieving switching sequence. Therefore, the lifetime of the overheated device can be considerably elongated. The proposed algorithm has been designed, simulated, and experimentally validated using a T-type three-level inverter system.