No abstract

Recent work has shown the feasibility of integrating nonparametric frequency-domain system identification functionality into digital controllers for switched-mode pulse-width modulated (PWM) dc-dc power converters. The resulting discrete-time frequency response can be used for design, diagnostic, or self-tuning purposes. The success of these applications depends on the fidelity of the identified frequency responses and the degree to which the process is automated, as well as the costs, in terms of gate count, time duration of identification, and effect on output voltage, incurred to obtain these benefits. This paper demonstrates the feasibility of incorporating fully automated frequency response measurement capabilities in digital PWM controllers at relatively low additional cost. In particular, it is shown that relatively accurate and smooth frequency response data can be obtained using a Verilog-coded implementation with low tens of thousands of logic gates and about 10 kB of memory. The identification process can be accomplished in several hundred milliseconds and the output voltage can be kept within specified bounds during the entire process. Experimental results are provided for four different PWM dc-dc converters, including a synchronous buck with two different filter capacitors, a boost operating in continuous conduction mode (CCM), and a boost operating in discontinuous conduction mode (DCM).

This paper discusses harvesting of low-power density incident plane waves for electronic devices in environments where it is difficult or impossible to change batteries and where the exact locations of the energy sources are not known. As the incident power densities vary over time and space, distributed arrays of antennas with optimized power-management circuits are introduced to increase harvested power and efficiency. Scaling in array size, power, dc load, frequency, and gain is discussed through three example arrays: a dual industrial-scientific-medical band Yagi-Uda array with a low-power startup circuit; a narrowband 1.96-GHz dual-polarized patch rectenna array with a reconfigurable dc output network designed for harvesting base-station power; and a broadband dual-polarized 2-18-GHz array with multi-tone performance. The efficiency of rectification and power management is investigated for incident power densities in the 1-100-W/cm range.