This study presents the tools required to create a modular and scalable multi-port converter structure, suitable for bidirectional power flow. A class of converters is defined based on the active bridge as basic building block. Any number of active bridges can be combined to form a multi-port converter with any number of ports. For modelling of the converter, a Fourier-based method is introduced to find an analytical converter model. Moreover, a scalable control method is proposed for these multi-port converters: power-balance control. The method uses Newton-optimisation in order to reduce the circulating currents. Experimental verification on a prototype shows the methods operate as expected.