In Circuit Frequency Response Analysis for Control Design and Monitoring of Power Converters
In power electronic applications, frequency response analysis (FRA) data is used to analyze the plant, design the control and verify the control design. Traditionally, external equipment is used to measure the frequency response by breaking the feedback path and injecting signals inside the closed loop system. This limits the use of FRA to design time of the converter. Recently in-circuit FRA measurement techniques have been presented. However, most techniques so far have required either special hardware to run, like FPGA, or required host processing power to do the complete computation. The aim of this research is to: • Design an in-circuit frequency response measurement algorithm that can run in a cycle efficient manner without any host computation requirements and is easily embedded into a commercial microcontroller used for controlling the power stage. • Highlight the constraints and assumptions under which in-circuit FRA can work, along with limits of in-circuit FRA such as noise performance and frequency bands. • Develop and demonstrate use of the designed in-circuit FRA on DC-DC, AC-DC and DC-AC converters, proving and highlighting the wide applicability of the developed technique for rapid control design. • Apply the developed in-circuit FRA for monitoring and diagnostic applications, showcasing applicability for extending capabilities with digital control of power converters.