Minimum-time digital control with raster surfaces

Minimum time is theoretically the fastest a fixed topology converter can recover from large-signal reference, line, and load disturbances. It is made possible through curved geometric control surfaces. Previous researchers spent significant effort approximating closed forms for these curved surfaces-a tedious but necessary step for analog circuit implementation. Numerical open-form surfaces, nearly impossible to implement on analog circuits, were tested on a digital signal processor using raster surfaces composed of pixels. These forms apply to a broad set of DC-DC converters. Simulations that compare fast disturbance recovery and tight performance envelopes demonstrate the benefits of minimum-time control. Hardware techniques show that minimum-time control is possible with only a few memory accesses and logical comparisons, operations even low-end digital processors can perform. The numerical form makes fewer approximations and applies to a much broader set of DC-DC converters.