Developing DC-DC Converter Control in Simulink

Model-Based Design of a DCDC Converter using Simulink, Simscape and Stateflow

This workflow reference covers the design, analysis, and software development for a Single Ended Primary Inductor Converter, commonly known as SEPIC, which is powered by a 12 Volt lithium-ion battery and is converting voltage to 18 Volt to power 36 LEDs divided in 6 module with each 6 LEDs in series. The developed software include a simplified BMS (battery management system) to watch over the battery status, supervisory logic to coordinate mode of operation and two closed-loop controllers (SEPIC voltage and LEDs current).

This project has been deveoped around a Texas instrument LED kit (codename: TMDSDCDCLEDKIT). It uses a F28069 ControlCard.
This application is interesting because:
* The SEPIC is using medium to high switching frequency (100 kHz)
* LEDs are current controlled using 20 kHz switching.
* Filter design plays an important role in getting current and voltage signals as proper inputs to the controllers

Both controllers are PI controllers which were modeled, simulated tuned and verified within the Simulink platform. Because the converter was modeled appropriately, the PI parameters derived in simulation can be used directly on hardware with good results.

Workflow

This demo covers a typical power electronics development workflow, divided in 5 sections:

System Modeling: Model the converter and calculate the most efficient operating region
Thermal Analysis: Determine power losses and the thermal behavior of the converter
Control Design and Tuning: Design control algorithm based on time/frequency domain specification
Logic Design, Verification and Verification: Design supervisory logic and implement unit testing
Embedded Code Generation: Implement power electronic controls on an embedded platform