This paper focuses on the design and evaluation of a Passive Common-noise Canceller (PCC) intended to mitigate Common Mode (CM) noise in large-capacity inverters and establish cooling structures of PCC for continuous operation. Electrification in large mobility such as aircraft for CO2 reduction requires large-capacity inverters and safety, making Electromagnetic Interference (EMI) reduction critical, and hence, this paper addresses this issue. The authors proposed cooling structures of the PCC with two different heat flow paths and applied to a motor drive system for evaluation. The effectiveness of the PCC was confirmed through significant cancellation in CM voltage and current. Moreover, the authors demonstrated that the cooling structures of the PCC are effective and operated continuously with natural air cooling, resulting in numerous advantages such as high environmental durability. This finding is critical as it proves the feasibility of the PCC, indicating its potential for practical application in large-scale inverters.