With the increasing demand for fast, cheaper, and efficient power converters come the need for a single-stage power factor correction (PFC) converter. Various single-stage PFC converter proposed in the literature has the drawback of high DC bus voltage at the input side and together with the shift to wide bandgap switches like GaN drives the converter cost higher. However, an interleaved topology with high-frequency isolation was proposed in this research work due to the drastic reduction in the DC bus voltage and extremely low input current ripple thereby making the need for an EMI filter circuit optional.   Meanwhile, this research work focuses on adapting the proposed topology for a high voltage low current application (EV charger - 400V, 7KW) and low voltage high current application (telecom power supply - 58V,  58A) owing to cost benefits. However, all single-stage PFC are faced with the drawback of second-order (100Hz) output harmonic ripple. Therefore, the design and simulation presented a huge peak to peak ripple of about 50V/3A and 26V/26A for the EV charger and telecom power supply case, respectively. This created the need for the design of a ripple cancellation circuit as the research required a peak to peak ripple of 8V and 200mV for the EV - charger and telecom power supply, respectively.   A novel output passive ripple cancellation technique was developed for the EV charger case due to the ease it offers in terms of control, circuit complexity and extremely low THDi when compared with the active cancellation approach. The ripple circuit reduced the 50V ripple to 431mV with the use of a total of 2.2mF capacitance at the output stage.   Despite designing the passive technique, an active ripple cancellation circuit was designed using a buck converter circuit for the telecom power supply. The active approach was chosen because the passive has a slow response and incurs more loss at a high current level. Adding the active ripple cancellation circuit led to a quasi-single stage LLC PFC converter topology. A novel duty-ratio feedforward control was added to synchronize the PFC control of the input side with the buck topology ripple cancellation circuit. The addition of the ripple circuit with the feedforward control offered a peak to peak ripple of 6.7mV and a reduced resonant inductor current by half.   After analysis, an extremely low THDi of 0.47%, PF of 99.99% and a peak efficiency of 97.1% was obtained for the EV charger case. The telecom power supply offered a THDi of 2.3%, PF of 99.96% with a peak efficiency of 95%.

Energy harvesting is identified as an alternative solution for powering implantable biosensors. It can potentially enable the development of self-powered implants if the harvested energy is properly handled. This development implies that batteries, which impose many limitations, are replaced by miniature harvesting devices. Customized interface circuits are necessary to correct for differences in the voltage and power levels provided by harvesting devices from one side, and required by biosensor circuits from another. This thesis investigates the available harvesting sources within the human body, proposes various methods and techniques for designing power-efficient interfaces, and presents two CMOS implementations of such interfaces. Based on the investigation of suitable sources, this thesis focuses on glucose biofuel cells and thermoelectric harvesters, which provide appropriate performance in terms of power density and lifetime. In order to maximize the efficiency of the power transfer, this thesis undertakes the following steps. First, it performs a detailed analysis of all potential losses within the converter. Second, in relation to the performed analysis, it proposes a design methodology that aims to minimize the sum of losses and the power consumption of the control circuit. Finally, it presents multiple design techniques to further improve the overall efficiency. The combination of the proposed methods and techniques are validated by two highly efficient energy harvesting interfaces. The first implementation, a thermoelectric energy harvesting interface, is based on a single-inductor dual-output boost converter. The measurement results show that it achieves a peak efficiency of 86.6% at 30 μW. The second implementation combines the energy from two sources, glucose biofuel cell and thermoelectric harvester, to accomplish reliable multi-source harvesting. The measurements show that it achieves a peak efficiency of 89.5% when the combined input power is 66 μW. / Energiskörd har identifierats som en alternativ lösning för att driva inplanterbara biosensorer. Det kan potentiellt möjliggöra utveckling av själv-drivna inplanterbara biosensorer. Denna utveckling innebär att batterier, som sätter många begränsningar, ersätts av miniatyriserade energiskördsenheter. Anpassade gränssnittskretsar är nödvändiga för att korrigera för de skillnader i spänning och effektnivå som produceras av de energialstrande enheterna, och de som krävs av biosensorkretsarna. Denna avhandling undersöker de tillgängliga källorna för energiskörd i den mänskliga kroppen, föreslår olika metoder och tekniker för att utforma effektsnåla gränssnitt och presenterar två CMOS-implementeringar av sådana gränssnitt. Baserat på undersökningen av lämpliga energiskördskällor, fokuserar denna avhandling på glukosbiobränsleceller och termoelektriska energiskördare, som har lämpliga prestanda i termer av effektdensitet och livstid. För att maximera effektiviteten hos effektöverföringen innehåller denna avhandling följande steg. Först görs en detaljerad analys av alla potentiella förluster inom boost-omvandlare. Sedan föreslår denna avhandling en designmetodik som syftar till att maximera den totala effektiviteten och effektförbrukningen. Slutligen presenterar den flera designtekniker för att ytterligare förbättra den totala effektiviteten. Kombinationen av de föreslagna metoderna och teknikerna är varierade genom två högeffektiva lågeffekts energigränssnittskretsar. Den första inplementeringen är ett termoelektriskt energiskördsgränssnitt baserat på en induktor, med dubbla utgångsomvandlare. Mätresultaten visar att omvandlaren uppnår en maximal effektivitet av 86.6% vid 30 μW. Det andra genomförandet kombinerar energin från två källor, en glukosbiobränslecell och en termoskördare, för att åstadkomma en tillförlitlig multi-källas energiskördslösning. Mätresultaten visar att omvandlaren uppnår en maximal effektivitet av 89.5% när den kombinerade ineffekten är 66 μW. / <p>QC 20170508</p> / Mi-SoC

The project deals with the design of a switch-mode power supply (SMPS) with a medium and high power output. The power supply uses multiphase control switching. Electric energy is converted through a series parallel LLC resonant circuit to reach the maximum efficiency with a small size and cost efficiency of the designed power supply. The semiconductor switches use ZVS (Zero Voltage Switching) on the primary side and ZCS (Zero Current Switching) on the secondary side of the converter. The design of the converter is based on the knowledge of the high power output converters (types of switching, art topologies) and resonant topologies (series resonant circuit – SRC, parallel resonant circuit – PRC and series parallel circuit –SPRC). The design of the converter was done theoreticaly and tested by using simulation program. The simulation and partial tests served to build prototype the Interleaves Converter (ILLC). The function of the converter was tested in laboratory. The laboratory results have been compared with the theoretical and the simulation results.