Comparative analysis of methods for designing digital control point of load converters

A hardware platform consisting of a point of load (POL) converter with a digital controller is built. The digital controller is analyzed and designed using digital redesign and direct digital approaches. The digital controller parameters are designed employing analytic methods for continuous and discrete systems, including the Bode graph method, discrete time frequency method and root locus method. The cross over frequency and phase margin are compared. Then the digital redesign and direct digital approaches are verified by experimentation. The steady state performances and dynamic responses are analyzed comparatively. Theoretical analysis and experimental results suggest that using the direct digital approach lowers the output voltage adjustment rate and improves the dynamic response speed.