The increasing need for higher efficiency, weight and volume reduction in embedded applications is a starting point of this study which focuses on a pre-sizing methodology of power converters based on virtual prototyping tools to avoid physical prototypes. From a general point of view, the mutualisation of a three-phase inverter with the help of a power sharing system is introduced. The proposed design approach optimises N inverters and a {one inverter + N-power sharing system} topologies based on a generalised modelling and a virtual prototyping tool. The presented results based on a 3 kW-270 V DC bus application show that in addition to the switching frequency and the ambient temperature, the number of sequential loads is also a key of the optimisation parameters. Therefore the proposed methodology based on an optimisation process allows the power designers to compare N inverters and {one inverter + N-power sharing system} as a function of the load number N.