Multiport DC-DC conversion incorporating integrated magnetics for renewables

Abstract

Multi-port converter design and analysis presents one of the most intriguing challenges in the incorporation of renewables in the power grid. Choice of topology is of paramount importance to improve the power conditioning. To this effect, the integrated Cuk topology achieves multiple objectives : low EMI, low component count, simplified MPPT tracking and power management, reduction of filter capacitor requirement, high efficiency. This is achieved by integrating all the magnetic components on a single core, and addition of soft-switching capability thereof. This thesis revisits the concept of integrated magnetics and formulates an elegant solution procedure to the problem of zero-ripple. It investigates the idea of utilizing the concept of a coupled-inductor filter on a three-port converter and removes the need for an external filter, thereby almost introducing an effective DC-DC transformer. The pre-FEM(finite element modelling) selection and design of the core and circuit aspects have been explained in this thesis. The simulation results are presented using PLECS. Additionally, some FEM results are added for the reduced three-winding structure. The validation of some design parameters are also discussed.A soft-switching scheme has also been demonstrated for a two-port converter with integrated magnetics. This has an active-clamp ZVS turn-on circuit with the addition of a ZCS turn-off. The design of the external components and simulation results for the same are presented as well.