Regatron AG in Switzerland manufactures interesting power supplies, derived from the bidirectional models of programmable power supplies TC.GSS series where energy can flow in both directions. 

In these two derivative versions, only one-direction converting systems is active, therefore there are two opposite possibilities. The units TC.GSX can only work as sources, where energy can flow only from main supply to the load. Instead TC.GXS can only sink, energy can flow only from the regenerative load to the main supply. 

Both these models have a very good power factor correction system. TC.GSX should be used as alternatives to classic TC.P series where harmonic content in the input current must be avoided. 

Information: http://www.regatron.com/gss  or mail to regatron@axu.it