Multi-phase Buck is widely used in Voltage Regulator Modules design because of its low cost and simplicity. But this topology also has a lot of drawbacks. One of the most fundamental drawback is that it has narrow duty cycles when it operates at high switching frequency with low output voltage (for example 1V). Narrow duty cycles yield high switching loss which limits the switching frequency of Buck; making it difficult to design a Buck based VRM that can achieve high efficiency at a high switching frequency. In this thesis three new non-isolated full bridge topologies will be introduced to solve the aforementioned problems of Buck. One is a new non-isolated full bridge topology, this new topology use a transformer to extend the duty cycle and it capable to achieve zero voltage switching. Experimental results demonstrate that it has significant advantages over multi-phase Buck. In some applications when huge output current is required, several converters are paralleled to supply the current that is not an optimal solution. Two two-phase non-isolated full bridge topologies are proposed to solve this problem. They double the output power of one-phase non-isolated full bridge, and achieve higher efficiency with fewer switches compared with parallel two non-isolated full bridge converters. Non-isolated VRM usually is used for personal computers, VRM for servers is called power pod, and usually isolation is required for power pod due to safety considerations. Server usually require much more power than personal computers, their power consumption is around several KW. To provide the power for the server a few power modules will need to be paralleled, this kind solution is expensive and make current sharing complex. In this thesis two new two-phase isolated full bridge topologies are proposed. They are capable to operate at soft switching mode. And they double the output power compared with conventional full bridge converter. Compared with parallel two full bridge converters, they can achieve higher efficiency with fewer switches. / Thesis (Ph.D, Electrical & Computer Engineering) -- Queen's University, 2008-02-28 09:53:50.23

Aim: The reason we made this report were to investigate what companies in Gävle implied was the most important factor for successful sales. The various questions to be answered are:   1. How important is the relationship in B2B? (Business to business)  2. Will VRM change the work with relationships within B2B?  3. How big influence on the B2B sales has the price?    Method:To investigate which factor is most important, we used a qualitative approach in which interviews with three people was carried out. A hermeneutic perspective to literature and analyze was used, where each interview were analyzed individually. We also used a deductive approach to draw conclusions.  Conclusions:The result we got was that the CRM system were common and a goodas problems were highlighted. Such were the work with relationships, the relationship with the customer was important, when it comes to B2B (business to business) sales. It was implied that the price impact on the sales were relatively small and the factor that decided whether it would end in a sale or not, was the relationship. Three common factors that were perceived as common factors were work with relationships, prices of products and central agreements.   Suggestions for future research: What this report does not address is how the current VRM services for B2B companies, where the program's only task is to find interested customers. Contribution of the thesis: We have found that the relationship between company and customer are essential for profitable sales in the B2B and that CRM-system facilitates the work with relationships.

This thesis presents a Mixed Linear/Switching Control (MLSC) scheme for voltage regulator modules (VRM). The MLSC employs two loops of feedback compensation, inner-loop switching compensation and outer-loop linear regulation. The purpose of the switching compensation is to linearize and stabilize the buck converter under the influence of switching noise and load variation. With switching compensation, the linearized plant of the buck converter can be simplified to a first-order stable transfer function at low frequencies. Accordingly, the outer-loop linear controller can be easily designed to regulate the output voltage using the linear control theory. The advantage of the proposed MLSC scheme is two-fold: easy to design and of low circuit complexity. There is no need of using any current detecting resistor and PWM generator, and also the stability and performance can be easily met by choosing positive controller coefficients. A 12V/1V single-phase VRM with proposed control is designed and simulated, which shows an output regulation with 0.4% steady- state output error and 7% load regulation error in response to the load current steps from 60A/1A to 1A/60A, at a slew rate of 60A/µsec.

Since the early 80s, the computer industry has undergone great expansion. Processors are becoming faster and more powerful. Power management issues in computing systems are becoming more complex and challenging. An evolution began when the high-performance Pentium processor was driven by a non-standard, less-than-5V power supply, instead of drawing its power from the 5V plane on the system board. A so-called Voltage Regulator Module (VRM), is put close to the processor in order to provide the power as quickly as possible. Nowadays, for desktop and workstation applications, VRM input voltage has moved to the 12V output of the silver box. In the meantime, microprocessors will run at very low voltage (below 1V), will consume up to 100A of current, and will have dynamics of about 400A/us. This work presents an investigation of three 12V VRM topologies: the synchronous buck converter, the tapped-inductor buck converter and the active-clamp couple-buck converter. The limitations of today¡¯s synchronous buck approach are identified. The extreme duty cycle of the current topology makes it difficult to design an efficient VRM with decent transient response. The tapped-inductor buck and the active-clamp couple-buck converters are discussed as solutions. The transient response and efficiency of each type of converter are compared. Ripple cancellation is also addressed. The analytical and experimental results are presented: The tapped-inductor buck can improve the efficiency, but suffers a voltage spike, which nullifies its candidacy; the active-clamp couple-buck converter can improve the efficiency while maintaining good transient response, and it is therefore a good candidate for 12V VRMs. / Master of Science

The thesis provides further details related to the company purchasing activities (procurement). Using both theoretical and practical knowledge it gives further details on new phenomena related to purchasing process. The thesis is made of three main parts. The first one explains terms further used in the thesis. The next section provides more details on the most obvious trend which is movement from traditional understanding of purchasing to the attempts to build a relationship with the supplier. Besides this key phenomenon there are further examples/trends given. The last section relates to the explanation of how the proper purchasing process should be set-up in the global corporation.

With fast development of semiconductor industry, the transistors in microprocessors increase dramatically, which follows the Moore’s law. As a result, the operating voltages of the future microprocessors follow the trend of decreasing (sub 1V) while the demanding currents increase (higher than 100A). Furthermore, the high slew rates during the transient will reach 1200 A/us. All these impose a serious challenge on a Voltage Regulator (VR) or Voltage Regulator Module (VRM). In order to meet requirements of the next generation microprocessors, four new ideas are proposed in this thesis. The first contribution is an accurate analytical loss model of a power MOSFET with a Current-Source Driver (CSD). The impact of the parasitic components is investigated. Based on the proposed loss model, a general method to optimize the CSD is presented. With the proposed optimization method, the CSD improves the efficiency from 79.4% using the conventional voltage source driver to 83.6% at 12V input, 1.5V/30A output and 1MHz. The second contribution is a new continuous CSD for a synchronous buck converter. The proposed CSD is able to drive the control and Synchronous Rectifier (SR) MOSFETs independently with different drive currents enabling optimal design. At 12V input, 1.5 V/30A output and 1MHz, the proposed CSD improves the efficiency from 79.4% using a conventional voltage source driver to 83.9%. The third contribution is a new discontinuous CSD. The most important advantage of the new CSD is the small inductance (typically, 20nH at 1MHz switching frequency). A hybrid gate drive scheme for a synchronous buck converter is also proposed. The idea of the hybrid gate driver scheme is to use the CSD to achieve switching loss reduction for the control MOSFET, while use the conventional voltage source driver for the SR. At 12V input, 1.3V/25A output and 1MHz, the proposed CSD improves the efficiency from 80.7% using the voltage source driver to 85.4%. The final contribution is new self-driven zero-voltage-switching (ZVS) non-isolated full-bridge converters for 12V input VRM applications. The proposed converter achieves the duty cycle extension, ZVS operation and SRs gate energy recovery. At 12V input, 1.3V output and 1MHz, the proposed converter improves the efficiency from 80.7% using the buck converter to 83.6% at 50A. / Thesis (Ph.D, Electrical & Computer Engineering) -- Queen's University, 2009-04-23 08:59:12.699

Tidigare forskning har visat att bilförare tenderade att underskatta hastigheten de färdas i med ca 20%. Forskning har även visat att hastighetsupplevelse hos bilförare kan påverkas av ett utökat Field of View (FoV) vilket resulterar i lägre hastighetsval (Pretto et al., 2009; Schütz et al., 2015; Lidestam, Eriksson & Eriksson, 2019). Utöver FoV har även virtuella vägmarkeringar (VRM), visats ha potentialen att påverka hastighetsval genom att bistå bilförare med ytterliggare visuell information kring dennes omgivning (Lidestam, Eriksson & Eriksson, 2019). Attityder gentemot system som syftar till att påverka bilförares hastighetsval har studerats (Wall et al., 2013), med det finns luckor i forskning gällande hur dessa upplevs av bilförare med ADHD. Vidare har även upprepning av körningar med samma konstellationer av visuella stimuli har visats påverka hastighetsval vilket skulle tyda på perceptuell inlärning sker under bilkörning (Lindestam, Eriksson & Eriksson, 2019). Syftet med den aktuella studien var att undersöka huruvida VRM påverkade hastighetsval samt hur de upplevs av bilförare med respektive utan ADHD. Studien ämnade att göra detta genom att besvara följande frågeställningar 1. a. Hur upplevdes VRM? b. Finns det en skillnad i upplevelsen av VRMs mellan bilförare med ADHD och utan ADHD? 2. Vilken effekt har ADHD, FoV, VRM och replikat på självvald hastighet? Resultaten visade att upplevelsen av VRM inte skiljde sig signifikant mellan de två guppen, trots detta skattades samtliga frågor kring upplevelsen av VRM högre av bilförare med ADHD än bilförare utan ADHD. Körningarna rapporterades som signifikant mer koncentrationskrävande av bilförare utan ADHD. Replikat och FoV uppvisade en signifikant interaktionseffekt på hastighetsval. Framtida forskning kan med fördel studera hur VRM kan utformas för att upplevas som mer hjälpsamma samt hur de bör implementeras för att bilförare ska vilja använda dem vid körningar. Det är viktigt att framtida forskning i området även inkluderar bilförare med ADHD för att säkerställa att system som utformas även är gynnsamma för dessa bilförare.

The challenges imposed on Voltage Regulator Modules (VRM) become difficult to be achieved with the conventional multiphase buck converter commonly used on PC motherboards. For faster data transfer, a decrease in the output voltage is needed. This decrease causes small duty cycle that is accompanied by critical problems which impairs the efficiency. Therefore, these problems need to be addressed. Transformer-based non-isolated topologies are not new approaches to extend the duty cycle and avoid the associated drawbacks. High leakage, several added components and complicated driving and control schemes are some of the trade-offs to expand the duty cycle. The objective of this work is to present a new dc-dc buck-based topology, which extends the duty cycle with minimum drawbacks by adding two transformers that can be integrated to decrease the size and two switches with zero voltage switching (ZVS). Another issue addressed in this thesis is deriving a small signal model for a two-input two-phase buck converter as an introduction to a new evolving field of multi-input converters.

L’apparition de convertisseurs multicellulaires parallèles entrelacés et magnétiquement couplés a conduit ces dernières années à améliorer les performances des convertisseurs (densité de puissance, efficacité, dynamique,...). Il existe plusieurs topologies d’entrelacement qui utilisent des Transformateurs Interphases. L’objectif principal de cette étude est de trouver parmi ces topologies celles qui sont les mieux adaptées à un contexte d’intégration d’électronique de puissance pour minimiser la taille et réduire les pertes. Une première étape de modélisation a permis d’effectuer une étude comparative de quelques topologies. Un procédé de permutation des phases d’alimentation a été présenté afin de réduire les ondulations du courant de phases et les pertes ohmiques. Les résultats obtenus valident qualitativement l’avantage de la solution retenue par rapport à la solution standard. Enfin, la réalisation pratique d’un prototype de convertisseur modulaire utilisant des Transformateurs Inter-phases est abordé. Il s’agit d’un régulateur chargé d’alimenter les microprocesseurs (1,2V/100A) (Voltage Regulator Module (VRM)) à 5 modules. Les résultats expérimentaux montrent l’avantage de l’utilisation des Transformateurs Inter-phases par rapport à la solution classique / During the last years, using coupled parallel interleaved converters enhances converters performances (power density, efficiency, transient response,...). There are several possible interleaved coupled topologies that use Inter-phases Transformers. The main objective of this study is to find among these topologies the best adapted configuration in a context of power electronics integration in order to minimize converter size and to reduce losses. A model is proposed to compare some topologies. An optimal modified sequence of phase order to reduce current ripple and ohmic losses is presented. The obtained results validate the advantage of the coupled solution compared to the standard solution. At last, the implementation of a modular power converter using Inter-phases Transformers is shown. It is a Voltage Regulator Module (1,2V/100A) that consists of five identical modules. Experimental results show the advantage of using Inter-phases Transformers compared to conventional solution

Commodity projection studies anticipate an exponential increase in copper demand and decreasein mill grade of deposits currently exploited globally. Most of this demand is driven by theindispensable use of copper in electrification and currently, the growing demand in the contextof the green transition. To meet this challenge while supplying society with copper, producerssuch as Boliden AB have plans for exploration and expansion projects to increase their reservesand in turn increase production through efficient measures. As grinding is a bottleneck to mineralprocessing and the most energy intensive, more efficient comminution systems are beingconsidered for environmental sustainability. These are required to have lower energyconsumption while achieving the required liberation or better for subsequent processing byflotation. Consequently, the literature review shows there is a research query on whether more can beexpected from comminution to optimise for downstream processing. With most publishedresearch being on particles with a P80 less than 100 μm, there exists a gap in investigating theeffect of grinding on flotation for coarser size fractions which this degree project focuses on.Importantly, it includes evaluating chalcopyrite liberation and flotation performance when usinga Novel Comminution Device. Three grinding mills were considered, a vertical roller mill (VRM),a Novel Comminution Device (NCD), with a rod mill as the reference mill. The scope of this studywas an analysis of the mill products’ particle size distribution, chalcopyrite liberation andinvestigation of the flotation performance of the products from the three mills. This was done ona Cu-Au-Ag ore from the Boliden Aitik mine in northern Sweden. Particle size distribution (PSD) analysis revealed that at comparable P80 values, the VRMproduced particles had broader PSD curves than the rod mill, while the NCD provided a steeperproduct size distribution than its reference rod mill products. The chalcopyrite liberation analysisusing QEMSCAN automated mineralogy showed that for samples split into three size fractions, -45 μm, +45/-90 μm and +90 μm, the VRM and rod mill products had their highest proportion offree to liberated particles within the intermediate size fraction while for the NCD sample this waswithin the fine fraction. Overall, the NCD product had the highest free to liberated particles acrossall fractions. From shape analysis based on scanning electron microscopy (SEM) images, it wasobserved that the NCD produced particles with the higher elongation than the VRM and rod mill. The flotation performance was assessed with respect to the mass pull, kinetics, grade andrecovery in the concentrate and separation efficiency. The rougher batch flotation tests indicatedthat flotation of the VRM ground samples had higher mass pull, Cu recovery, faster kinetics andlower Cu grade than the samples from the reference rod mill. This was also a similar outcome forthe NCD with the exception of higher mass pull at an increased collector dosage in the rod millcase. For all the mills, the general trend showed that an increase in P80 was associated withreduced mass pull. Overall, at similar flotation conditions, despite having one of the coarsest P80s,the NCD product showed the fastest Cu recovery kinetics, highest total recovery and selectivityindex. The rod mill reference test samples gave the highest grade but the lowest recovery. The findings illustrate that there is a significant difference in PSD broadness between productsfrom different mills at comparable P80. The differences in flotation performance between thethree mill products were mainly attributed to differences in liberation, potential differences insurface activation between wet and dry grinding methods and to some extent, steepness of thePSD curve. Based on the high recovery yet low grade of the NCD ground product, this is best suitedfor the rougher flotation stage. Future studies should therefore include cleaner stage flotation andoptimisation tests for the NCD with respect to reagent dosages and hydrodynamic conditions.