Design and stability analysis of interleaved flyback converter control using Lyapunov direct method with FPGA implementation
Document Type
Article
Publication Date
9-1-2020
Abstract
Isolated DC-DC converters are preferred in the design of power supplies, for better safety and isolation purpose. Challenging task in the design of controllers for the converters is, compensating the effects of nonlinearity of switching and other components. This paper proposes the nonlinear controller design technique for isolated switching power supplies. Interleaved topology is chosen to achieve high output voltage and power. Voltage mode control of interleaved flyback converter (IFC) is illustrated using the Lyapunov direct method. It supports fast dynamic responses and simple to design. The Euler-Lagrangian model of the converter is used to derive the state model. It is based on energy equations that include dynamics of nonlinear inductive, resistive effects of transformer and switching devices. Flyback converters with different turns ratio are connected in cascade to attain high voltage gain. The primary side is designed with a parallel structure to handle the high current at the input side, and the secondary side is constructed with a series structure to have high output voltage at the output terminal. State observer is developed to ensure noise tolerant system design with reduced cost of implementation. It eliminates the use of the current sensor by estimating the primary current of each converter. The voltage spikes across the power semiconductor devices are suppressed by RCD snubber and interleaving topology to reduce switching losses. Circulating current between the converters is suppressed by non-overlapping switching. Fourth-order system is derived for interleaved converter. Stability analysis has been carried out for various values of system gain using describing functions harmonic linearization method. The converter is found to be stable for gains less than 0.55. Losses due to various components are analyzed and presented. Sixteen-bit control architecture is chosen to realize the digital controller. IFC (150 W) prototype is designed with the controller and implemented using Nexys 4 Artix-7 FPGA.
Keywords
Interleaved, Flyback converter, Euler-Lagrangian model, Lyapunov method, Digital controller, FPGA
Divisions
sch_ecs
Funders
None
Publication Title
Electrical Engineering
Volume
102
Issue
3
Publisher
Springer
Publisher Location
ONE NEW YORK PLAZA, SUITE 4600, NEW YORK, NY, UNITED STATES