The urgent need to address climate change and biodiversity loss requires minimizing the environmental impacts of Power Electronics (PE) products across all life cycle stages. However, current literature lacks comprehensive models that effectively link design parameters with environmental impacts across the entire product life cycle. In response, this paper presents a Parametric Life Cycle Assessment (PLCA) model designed to support the ecodesign process for PE products. The proposed PLCA model establishes a dynamic cause-effect chain between design parameters and environmental impacts, enabling designers to develop, evaluate, and optimize ecodesign scenarios throughout the product life cycle. By integrating environmental considerations early in the design process and incorporating circular economy strategies such as repair and reuse, the model overcomes the limitations of traditional single-indicator approaches. A case study application on a DC-DC buck converter demonstrates the effectiveness of PLCA model in identifying key design parameters, supporting the development of circular scenarios, and monitoring the reduction of environmental impacts. This work advances the operationalization of ecodesign in the PE industry, aligning product development with stringent environmental regulations and long-term sustainability objectives.