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This paper proposes a new FPGA based architecture for digital pulse width modulators which takes advantage of dedicated digital clock manager (DCM) blocks present in modern FPGAs and applies manual placement techniques to match internal delays for high linearity.The proposed hybrid DPWM uses a synchronous counterbased coarse-resolution block and a DCM based fine-resolution block implementing a synchronous delay line.The design was successfully implemented on a low-cost Xilinx Spartan-3 FPGA with 9-bit resolution with a switching frequency of 1 MHz. Linearity was manually optimized using the presented technique which reduced the integral non-linearity error by 0.5 LSB.

SUMMARYThis paper considers the application of the skewed structured singular value to the robust stability of systems subject to strictly real parametric uncertainty. Three state-space formulations that counteract the discontinuous nature of this problem are detailed. It is shown that the calculation of the supremum of the structured singular value over a frequency range using these formulations transforms into a single skewed structured singular value calculation. Like the structured singular value, the exact calculation of the skewed structured singular value is an NP-hard problem. In this work, two efficient algorithms that determine upper and lower bounds on the skewed structured singular value are presented. These algorithms are critically assessed using a series of robustness analysis tests on a safety-critical experimental drive-by-wire vehicle.

Abstract-This paper considers the application of the skewed structured singular value to the robust stability of systems subject to strictly real parametric uncertainty. Three statespace formulations that counteract the discontinuous nature of this problem are detailed. It is shown that the calculation of the supremum of the structured singular value over a frequency range using these formulations transforms into a single skewed structured singular value calculation. Like the structured singular value, the calculation of the exact value of the skewed structured singular value is a NP-hard problem, therefore alternative, less computationally demanding algorithms to determine upper and lower bounds are necessary. Two algorithms that determine upper and lower bounds on the skewed structured single value are presented. These algorithms are critically assessed by performing a robust stability analysis on a safety-critical experimental drive-by-wire vehicle.

Abstract-The trend in next-generation switched-mode power supplies will lead to modular, scalable solutions which deliver power efficiently over a wide range of operation. This paper details a new approach to introduce more advanced control features to improve system efficiency into these scalable solutions. While these methods have been incorporated into multi-phase converters in the past, they all require the distribution of information among the individual converters. An advantage of the proposed method is that it does not require such communication signals between the individual power supplies and is therefore fully scalable and cost effective. A system comprising of individual, smart converters is proposed where each converter regulates its respective output power to a level with high efficiency. Converters not required for the delivered output power are shut down. The proposed approach is analysed theoretically. Implementation details for an FPGA experimental prototype system are given. The system performance for a four converter prototype system is analysed and discussed. The efficiency obtained is compared with the efficiency of a multi-phase system with phase-shedding operation and the efficiency of a system with independent power converters without phase shedding support.