Digital Control Techniques for Single-Phase Power Factor Correction Rectifiers

Tightening governmental regulations and industry standards for input current harmonics and input power factor correction (PFC) of common electronic devices such as servers, computers and televisions continues to increase the need for high-performance, low-cost power factor correction controllers. In response to this need, digital non-linear carrier (DNLC) PFC control has been developed and is presented in this thesis. DNLC PFC control offers many unique advantages over existing PFC control techniques in terms of design simplicity, low harmonic current shaping over a wide load range including CCM and DCM operation and a reliable, inexpensive digital implementation based on low-resolution analog-to-digital converters (A/D\u27s) and digital pulse width modulator (DPWM). Implementation of the controller requires no microcontroller or digital signal processor (DSP) programming, and is well suited for a simple, low-cost integrated-circuit realization. DNLC PFC control is derived and analyzed for single-phase universal input PFC boost rectifiers. Further analysis of the operation of digitally controlled PFC rectifiers leads to the development of voltage loop compensator design constraints that avoid limit-cycling of the voltage loop. It is demonstrated that voltage loop limit-cycling is unavoidable when using traditional PFC control techniques un- der certain output loading conditions. However, it is also shown that voltage loop limit-cycling is avoidable under the same operating conditions when a DNLC PFC controller is implemented. Additionally, a unique output voltage sensing A/D is also developed that improves the PFC voltage loop transient response to load transients when paired with the DNLC PFC controller. Experimental results are shown for a 300W universal input boost PFC rectifier

Differential-mode EMI reduction in a multiphase DCM flyback converter

Switched converters are a source of electromagnetic interference (EMI) due to the hard switching and abrupt edges in the current and voltage waveforms. Multiphase converters can reduce the EMI at the source, minimizing the conducted EMI generation, without changing dramatically the normal operation of the circuit. Input filter can be greatly reduced, radiated EMI is lower, and internal EMI problems are minimized. This paper is focused on exploring multiphase converters as a topological technique to reduce conducted differential-mode EMI generation at the source, considering some no idealities of the multiphase converter

Converter based electrochemical impedance spectroscopy for fuel cell stacks

Fuel cells are important devices in a hydrogen-based chain of energy conversion. They have distinctive advantages over batteries with their higher energy density and faster refueling speed, which make them attractive in stationary power supplies and heavy-duty vehicles. However, the high cost and low durability associated with modern fuel cells are still hindering their wider commercialization. Besides developing more reliable and lower cost materials and advanced assemblies of cells and stacks, a practical and effective diagnostic tool is highly needed for fuel cells to identify any abnormal internal conditions and assist with maintenance scheduling or application of on-board mitigating schemes. Conventionally, linear instruments were used for fuel cell EIS, however, limited to single cells or short stacks only as a laboratory testing method. With recent developments, EIS enabled by switching power converters are capable of being applied to a high-power stack directly. This approach has the potential for practical field applications such as a servicing tool for fuel cell manufacturers or an on-board diagnostic tool of a moving vehicle. Previous works on converter based EIS have made a few different attempts at conceptually realizing this solution while several significant issues were not well recognized and resolved yet. As such, this thesis explores further on this topic to address the flexibility of EIS perturbation generation, the perturbation frequency range, and the linkage between fuel cell EIS requirements and the converter design to push for its readiness for practical implementations. Several new solutions are proposed and discussed in detail, including a total software approach for existing high-power converters to enable wide-frequency-range EIS, a redesign of the main dc/dc converter enabling wide-frequency-range perturbations, and a separate auxiliary converter as a standalone module for EIS operation. A detailed analysis of oscillations brought by converter based EIS in powertrains is also presented

Generation and sampling of quantum states of light in a silicon chip

Implementing large instances of quantum algorithms requires the processing of many quantum information carriers in a hardware platform that supports the integration of different components. While established semiconductor fabrication processes can integrate many photonic components, the generation and algorithmic processing of many photons has been a bottleneck in integrated photonics. Here we report the on-chip generation and processing of quantum states of light with up to eight photons in quantum sampling algorithms. Switching between different optical pumping regimes, we implement the Scattershot, Gaussian and standard boson sampling protocols in the same silicon chip, which integrates linear and nonlinear photonic circuitry. We use these results to benchmark a quantum algorithm for calculating molecular vibronic spectra. Our techniques can be readily scaled for the on-chip implementation of specialised quantum algorithms with tens of photons, pointing the way to efficiency advantages over conventional computers

Implementing low power consumption in standby mode in the case of power supplies with power factor correction

This work analyzes different options to implement low power consumption in Switching Mode Power Supplies (SMPSs) with Power Factor Correction (PFC) when they are in standby mode. The standard SMPSs for power levels higher than 100 W are made up of two stages: a classical PFC stage based on a Boost Converter operating in the Continuous Conduction Mode and a second stage based on any type of isolated DC-DC converter. The value of the resistive sensors needed by the PFC control stage determines a standby consumption higher than 0.5 W if the power supply has to be designed to operate in the Universal Range of line voltages. This fact makes it very difficult to comply with European Ecodesign Regulations. To overcome this problem, several solutions are proposed and analyzed in this paper, the most promising being implemented in a real SMPS prototype.This work has been supported by the Spanish Government under Project MINECO-13-DPI2013-47176-C2-2-R and the Principality of Asturias under the grant “Severo Ochoa” BP14-85 and by the Project FC-15-GRUPIN14-143 and by European Regional Development Fund (ERDF) grants.2017 Applied Power Electronics Conference and Exposition (APEC