Analysis And Design Optimization Of Multiphase Converter

Future microprocessors pose many challenges to the power conversion techniques. Multiphase synchronous buck converters have been widely used in high current low voltage microprocessor application. Design optimization needs to be carefully carried out with pushing the envelope specification and ever increasing concentration towards power saving features. In this work, attention has been focused on dynamic aspects of multiphase synchronous buck design. The power related issues and optimizations have been comprehensively investigated in this paper. In the first chapter, multiphase DC-DC conversion is presented with background application. Adaptive voltage positioning and various nonlinear control schemes are evaluated. Design optimization are presented to achieve best static efficiency over the entire load range. Power loss analysis from various operation modes and driver IC definition are studied thoroughly to better understand the loss terms and minimize the power loss. Load adaptive control is then proposed together with parametric optimization to achieve optimum efficiency figure. New nonlinear control schemes are proposed to improve the transient response, i.e. load engage and load release responses, of the multiphase VR in low frequency repetitive transient. Drop phase optimization and PWM transition from long tri-state phase are presented to improve the smoothness and robustness of the VR in mode transition. During high frequency repetitive transient, the control loop should be optimized and nonlinear loop should be turned off. Dynamic current sharing are thoroughly studied in chapter 4. The output impedance of the multiphase v synchronous buck are derived to assist the analysis. Beat frequency is studied and mitigated by proposing load frequency detection scheme by turning OFF the nonlinear loop and introducing current protection in the control loop. Dynamic voltage scaling (DVS) is now used in modern Multi-Core processor (MCP) and multiprocessor System-on-Chip (MPSoC) to reduce operational voltage under light load condition. With the aggressive motivation to boost dynamic power efficiency, the design specification of voltage transition (dv/dt) for the DVS is pushing the physical limitation of the multiphase converter design and the component stress as well. In this paper, the operation modes and modes transition during dynamic voltage transition are illustrated. Critical dead-times of driver IC design and system dynamics are first studied and then optimized. The excessive stress on the control MOSFET which increases the reliability concern is captured in boost mode operation. Feasible solutions are also proposed and verified by both simulation and experiment results. CdV/dt compensation for removing the AVP effect and novel nonlinear control scheme for smooth transition are proposed for dealing with fast voltage positioning. Optimum phase number control during dynamic voltage transition is also proposed and triggered by voltage identification (VID) delta to further reduce the dynamic loss. The proposed schemes are experimentally verified in a 200 W six phase synchronous buck converter. Finally, the work is concluded. The references are listed

Novel Digital Control Schemes Of Dynamic Current Sharing For Multiphase Buck Converter

High frequency load transient response and dynamic voltage scaling are two most important performance metrics in multiphase voltage regulator design to support high current dynamic loads, such as processor. As load frequency is increased up to MHz range or the regulator is enforced to run in boost operation mode during dynamic voltage downward transition, the voltage regulator suffers from imbalanced phase current which can introduce extra power loss and electrical stress on power components thus degrade the reliability of the overall system. In this paper, positive current sharing during high frequency load transient and negative current sharing during dynamic voltage downward transition are thoroughly studied. Load frequency detection scheme for disabling the nonlinear PWM control loop in high frequency transient is presented, and protection in the loop is proposed to accurate cycle by cycle current limiting scheme to crank the maximum current and mitigate the beat frequency oscillation are proposed. Critical design parameters in MOSFET driver IC design and adaptive voltage positioning (AVP) loop bandwidth are optimized. Dynamic power loss is reduced due to suppressed circulating current among phases. Experiment results are provided as verification of the analyses and solutions. © 2013 IEEE

New Insights On Dynamic Voltage Scaling Of Multiphase Synchronous Buck Converter: A Comprehensive Design Consideration

This paper comprehensively investigates the powerrelated issues and introduces new control schemes in dynamic voltage scaling (DVS), which is now used in modern multi-core processor and multiprocessor system-on-chip to reduce operational voltage under light load conditions. With the aggressive motivation to boost dynamic power efficiency, the design specification of voltage transition (dv/dt) for the DVS is pushing the physical limitation of the multiphase converter design and the component stress. In this paper, the operation modes and modes transition during dynamic voltage transition are illustrated. Critical dead-times of driver IC design and system dynamics are first studied and then optimized. The excessive stress on the control MOSFET which increases the reliability concern is captured in boostmode operation. Feasible solutions are also proposed and verified by both simulation and experimental results. CdV/dt compensation for removing the adaptive voltage positioning effect and a novel nonlinear control scheme for smooth transition are proposed for dealing with fast-voltage positioning. Optimum phase number control during dynamic voltage transition is also proposed and triggered by voltage identification delta to further reduce the dynamic loss. For experimental verification, a 200 W, six-phase synchronous buck converter is implemented with the proposed schemes. © 1986-2012 IEEE

Analysis And Design Of Distributed Transformers For Solar Power Conversion

In this paper, a high efficiency, low profile design of distributed transformers (DT) for grid-tied photovoltaic (PV) inverter is presented. The proposed DTs fully integrated into the dual-flyback converter maximize the DC/DC stage efficiency in whole load conditions. The developed DTs with the built-in current sensing transformer allows the converter works in boundary conduction mode (BCM) or discontinues conduction mode (DCM) due to the variable nature of solar power with zero current switching (ZCS). Analytical loss model is established to optimize the value of magnetizing inductance which determines the switching frequency and converter overall efficiency. Various techniques are also taken to minimize the winding loss of the DTs. The experimental prototype employing the DTs achieves over 96% efficiency at full load condition. © 2011 IEEE

Design And Analysis Of Three-Port Dc/Dc Converters For Satellite Platform Power System

Mass is one of the most important design constraints for the satellite power system. In order to achieve maximal solar power harvesting, battery charge/discharge control, and bus voltage regulation, normally several independent converters will be required, resulting in a heavy and bulky power system. This paper proposes a compact and efficient solution by using integrated three-port converter to achieve all above-mentioned functions within one single converter, therefore much lighter and smaller than the conventional system. The three-port topology is obtained by simply adding a switch and a diode to the conventional half-bridge converter. Moreover, zero-voltage switching is realized for all switches to reduce switching loss. The topology and circuit design is discussed in detail. In addition, the system construction is introduced, which adopts a distributed structure to obtain redundancy and maximize solar power harvesting for each individual PV panel. The proposed design is verified by experimental results. © 2011 IEEE

New Insights On Multiphase Synchronous Buck Converter Design: A Comprehensive Consideration

This paper comprehensively discusses the multiphase power converter design and introduces new control schemes in dynamic operations, which are now used to supply the power for modern Multi-Core processor (MCP) and multiprocessor System-on-Chip (MPSoC). With the aggressive motivation to boost dynamic power efficiency, the design specification of the VR is pushing the physical limitation of the multiphase converter design and the component stress as well. In this paper, the operation modes and PWM drive interface to achieve phase shedding are first illustrated. Robust driver operation is ensured when exiting the tri-state for long time. Nonlinear control scheme is introduce to minimize the voltage excursion during load transient. CdV/dt compensation for removing the AVP effect and novel nonlinear control scheme for smooth transition are proposed for dealing with fast voltage positioning. For experimental verification, a 400 W six phase synchronous buck converter is implemented with the proposed schemes. © 2013 IEEE

Low Voltage Flyback Dc-Dc Converter For Power Supply Applications

In this paper, we design a low voltage DC-DC converter with a flyback transformer. The converter will be used as a biased power supply to drive IGBTs. The flyback transformer using planar EI-core is designed and simulated using ANSYS PExprt software. Besides, anLT3574 IC chip from Linear Technology has been chosen for converter control. Finally, the converter modeling and simulation are presented and PCB layout is designed. © 2011 IEEE

Analysis And Design Of Dynamic Voltage Regulation In Multiphase Buck Converter

Ni 1-xMg xO thin films across the full compositional range were formed by a low-cost sol-gel spin coating method. Optical transmission of the resultant films in the ultraviolet-visible spectral region increased to as high as 90% upon sintering, and X-ray diffraction verified an increase in crystallinity for sintering temperatures up to 1000 °C, with root mean square roughness below 1 nm when sintered between 600 and 800 °C. The lattice parameter of the rock salt Ni 1-xMg xO films showed a linear shift with increased magnesium concentration, consistent with a Vegard\u27s Law relationship between the two binaries. Optical energy gaps from 3.6 to \u3e 6.5 eV were realized by adjusting the composition of the Ni 1-xMg xO films, demonstrating the suitability of the ternary for optical devices in the UV-C spectral region. © 2012 Elsevier B.V. All rights reserved

Effects of Specialized Curing on the Income and Behavior of Tobacco Growers

Qingshuitang Village near the Qingmuchi Village is taken as the control region, which has similar status of social economy and flue-cured tobacco cultivation and has not implemented specialized curing. Permanent residents above the age of 18 in the two villages are investigated. Due to the dispersibility and randomness of samples, questionnaires are sent out randomly considering the differences in age, sex, education level, economic income and planting area. Excel is used to conduct statistics and analysis of survey data. Result shows that specialized curing has significant higher incentive effect on economic income of tobacco growers than the non-specialized curing. Tobacco growers in specialized curing area have apparently different attentive focus of future development, compared with the growers in non-specialized curing area. Specialized curing area focuses more on the improvement of technology, management and supporting industries; while growers in non-specialized curing area think that working outside is main way to improve the current situation. However, there are certain problems in specialized curing needed to be improved, such as operation mechanism, internal management, extension and application. Finally, it is pointed out that we should correctly handle the relationship between the income increase from specialized curing and the economic development, subject clarification and support enhancement, so as to ensure the sustainable development of specialized curing and to improve the economic income of tobacco growers effectively.Specialized curing, Economic income, Questionnaire survey, Tobacco growers, Flue-cured tobacco, China, Community/Rural/Urban Development,

Effects of Specialized Curing on the Income and Behavior of Tobacco Growers

Qingshuitang Village near the Qingmuchi Village is taken as the control region, which has similar status of social economy and flue-cured tobacco cultivation and has not implemented specialized curing. Permanent residents above the age of 18 in the two villages are investigated. Due to the dispersibility and randomness of samples, questionnaires are sent out randomly considering the differences in age, sex, education level, economic income and planting area. Excel is used to conduct statistics and analysis of survey data. Result shows that specialized curing has significant higher incentive effect on economic income of tobacco growers than the non-specialized curing. Tobacco growers in specialized curing area have apparently different attentive focus of future development, compared with the growers in non-specialized curing area. Specialized curing area focuses more on the improvement of technology, management and supporting industries; while growers in non-specialized curing area think that working outside is main way to improve the current situation. However, there are certain problems in specialized curing needed to be improved, such as operation mechanism, internal management, extension and application. Finally, it is pointed out that we should correctly handle the relationship between the income increase from specialized curing and the economic development, subject clarification and support enhancement, so as to ensure the sustainable development of specialized curing and to improve the economic income of tobacco growers effectively