Implementation Of Ćuk Converter With Integrated Magnetics For Residential Solar Applications

Abstract

Rooftop solar is becoming a popular source of energy for electricity generation. An optimal photovoltaic interface has ripple-free terminal currents and compact system design along with a high step-up ratio. The Ćuk converter is an ideal choice for such applications due to its unique quality of continuous current flow at both the terminals and the wide operating range. This reduces the noise, need for filtering, and electromagnetic interference issues. With the use of coupled inductor, the Ćuk converter can adequately operate with ripple-free input or output current. With the use of additional windings along with the coupled inductor, either in the form of inductor or isolation transformer, ripple-free currents can be obtained at both input and output terminals. However, only a minority of the users easily adapt Ćuk converter and its variants for their needs due to the complications in terms of the design method and absence of a rational design strategy for obtaining the suitable magnetics design that yields 'zero-ripple' terminal currents. This thesis presents an innovative, definitive method with an analytical basis for determining the component values that cater to a broad range of applications for a Ćuk converter with integrated magnetics and compares it with the basic and coupled inductor based Ćuk converter topologies. The descriptive analysis is carried out with the aid of the MATLAB scripts developed and the theoretical results are validated with the help of simulation models created using the PLECS software platform. Analysis-Led Design (ALD) tool has been developed for facilitating parameter estimation for critical topologies using MATLAB and Excel spreadsheets. This serves as an initial framework and can be utilized for the parameter estimation of other topologies with integrated magnetics. The design of the magnetic components and equivalent modeling is carried out using ANSYS and the designed converter has been implemented for experimental validation. Traditionally, control of the Ćuk converter has been extremely complicated due to unstable higher-order transfer function and non-minimum phase behavior. For the chosen topology with integrated magnetics, control techniques have been investigated and performance analysis is carried out on a system level.