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Summary: In this work, an isolated modular resonant circuit with effective voltage regulation is presented as front‐end for multilevel inverter system to interface renewable sources of energy with micro grid. Inputs of each module of the converter are connected to low‐voltage DC sources. Modular‐structured module outputs may be linked in sequence or parallel to attain the desired DC link capacitor voltage for multilevel inverter. The proposed converter overcomes imbalance in the capacitor voltage of diode‐clamped inverter structure. Interleaved phase shift of 90° is supplied among the gate pulses of all four modules that minimizes the input‐side current ripples. An effective zero voltage switching (ZVS) is achieved over wide load range using duty cycle and frequency‐duty cycle double control method to improve system performance at light load condition. Adopting powder core magnetics and low forward voltage insulated‐gate bipolar transistors (IGBTs) reduces magnetic and conduction loss. A 12‐kW prototype of the designed modular resonant converter was verified by experimentation with a different‐level diode‐clamped inverter structures. [ABSTRACT FROM AUTHOR]

Hypervisors enable cloud computing model to provide scalable infrastructures and on-demand access to computing resources as they support multiple operating systems to run on one physical server concurrently. This mechanism enhances utilization of physical server thus reduces server count in the datacenter hence driving the benefits of reduced IT infrastructure setup and maintenance costs along with power savings. The paper evaluates the system resources (CPU, Memory, Network, and Disk I/O) performance of three hypervisors, namely ESXi, XenServer and KVM in a CloudStack environment using the SIGAR-Framework for consolidated application workloads with concurrently running virtual machines. Based on the results, the paper recommends the hypervisors suitability for system resources intensive applications. The three hypervisors are carefully chosen to represent three categories (full virtualized, para-virtualized, and hybrid virtualized). We have created a private cloud using open source cloud computing software CloudStack. Hypervisors are deployed as hosts in the CloudStack in the respective clusters. Consolidated workloads are generated using open source load generator tools on multiple virtual machines of hypervisors and important system resources information is gathered using SIGAR framework. [ABSTRACT FROM AUTHOR]