An Online Identification Method of Thermal Dissipation State for Forced Air-cooled System of Power Converters

Thermal stress is the primary cause of malfunction and failure in power modules. As the main heat dissipation component, the heatsink plays a significant role in improving the reliability of power converters. However, due to the continuous accumulation of dust and impurities on the heatsink's air inlet side, the thermal dissipation performance of the cooling system constantly declines, which influences the reliable operation of power modules. In this article, a computational fluid dynamics (CFD)-based simulation analyzes the declining mechanism of the heatsinks' thermal transfer performance. Moreover, a novel online method is proposed for the cooling system's thermal dissipation state identification. This method regards the steady-state thermal resistance as the feature parameter of the thermal dissipation state evaluation. And a parameter identification method is employed to identify the steady-state thermal resistance due to the difficulty of obtaining it in the transient thermal process. In addition, an ac/dc/ac pulsewidth modulation (PWM) converter is built for verification. The experimental results demonstrate that the proposed method enables accurate and fast identification of the cooling systems' thermal dissipation state. It can be one of a solution for replacing the existing off-line manual periodic detection method, which helps improve detection efficiency and decrease maintenance costs.