Design of the airflow passage structure for improving the thermal performance of the power conversion system

In order to operate a Power conversion system (PCS) reliably, which is used for solar or wind power generation and energy storage systems, a design engineer of a PCS must evaluate that the junction temperature of power semiconductor devices, such as an Insulatedgate bipolar transistor (IGBT) module, meets the design criteria in the cooling design stage. An engineer must have evaluation procedure to design the airflow passage structure of a PCS in a way that the heat generated from inside of the system can be effectively exhausted externally. This study investigated the thermal performance of a PCS for four different airflow passage structures using the airflow rate of the heat sink attached to the IGBT module as an evaluation index. Out of the suggested airflow passage structures, the structure using the upper supply-lower exhaust type without the cooling fan for the reactor, which forms the air curtain around the airflow passage guide of the IGBT module and the louver of the maintenance door, has been found to perform the best thermal performance. In this design, the airflow rate of the heat sink was approximately 14 % larger than the required rate, with the junction temperature of the IGBT module of 132.2 °C, which satisfied the cooling design criteria. When the ventilation area of the supply is increased by approximately 2.3 times and the thickness of the filter reduced by 10 mm, the airflow rate of the heat sink can reach up to 700.4 m3hr-1, and in this case, the design criteria of the IGBT module can be satisfied even in an overload condition of 106.7 % of the rated load.