Galvanic Isolation and Output LC Filter Design for the Low-Voltage DC Customer-End Inverter

In this paper the need for a better design of the galvanic isolation and the output filter inductor in the customer-end inverter (CEI) of the low voltage DC (LVDC) network is discussed. The galvanic isolation can be implemented either with a 50 Hz transformer after the CEI or with an isolated DC-DC converter between the DC network and the CEI. However, the 50 Hz transformer solution adds a significant amount of volume and mass to the system. Based on calorimetric measurements conducted with the current system in which the galvanic isolation is implemented with the former method, the minimum requirements for the isolated DC-DC converter are presented and a comparison is carried out. For the system to be cost efficient the DC-DC converter should result in reduced lifetime cost compared with the transformer solution. In the output filter part a design method for an amorphous core filter inductor based on minimization of the lifetime cost is presented.