A comparison of steady-state characteristics of buck-type DC-DC converter using DSP

In this paper, we describe the relationship between the control constants and the output voltage regulation characteristics of a buck DC/DC converter for a digital control system using P-I-D control, the minimum phase FIR filter, and the moving average constructed from digital signal processors. Furthermore, the digital control method and its control constants were studied comparatively from the perspective of suppressing the oscillations based on the limit cycle. We found that when an 8-bit analog-to-digital (A-D) converter having a quantization width of about 80 mV was used, we could obtain excellent results similar to the minimum phase FIR filter and the moving average, achieve an excellent output voltage regulation of less than 1.3% for fluctuations from a light load to the rated 2 A for the target 10 V, and suppress oscillations to less than 20 mV. In the P-I-D control method, adequate output voltage regulation characteristics were obtained, but oscillations could not be suppressed. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 90(5): 1–10, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20357