A novel control principle for a high frequency transformer based multiport converter for integration of renewable energy sources

This paper presents a novel approach to control power flow inside a high frequency transformer based multiport DC-DC converter. A multiport converter can interface a number of power sources and sinks with control of power flow among them. In a renewable energy sources (RES) integration scheme, the multiport converter operates like an accumulator where it collects power from each RES and dispatches it to the load port. Typically, power flow between any two ports happens through the leakage inductance of the transformer by imposing a required phase shift between fundamental component of two square wave voltages, impressed at the ports. However, each port is connected with the other ports by some inductance and hence the power flow from a particular source port to load port is not decoupled and can not be controlled independently. This paper proposes decoupling of source ports by eliminating the load port leakage inductance with a negative inductance, emulated by voltage injection in series with leakage inductance. A three port transformer based system is simulated to validate the principle. A scaled prototype of the three port transformer is designed and the effect of load port leakage inductance is analyzed through experiment.