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Power Electronics, Machines and Drives (PEMD 2010), 5th IET International Conference on

Date 19-21 April 2010

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  • Table of contents

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  • Invited address

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  • Comparison of losses in IGBT based voltage and current source converters using a single switching pole approach

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    This paper compares the efficiencies of insulated gate bipolar transistor-based voltage and current source inverters. Test circuits that replicate the functionality of a single switching pole of each converter topology are used to measure the switching trajectories and loss characteristics of the semiconductor devices. These results are then used to simulate the losses for complete 3-phase voltage and current source inverters. Switching losses are shown to be dominant in the voltage source inverter whilst conduction loss is dominant in the current source inverter. It is shown that neither power converter operates more efficiently than the other over the complete operating range, with an equivalently rated voltage source inverter being preferable at lower power levels and the current source inverter being more efficient at higher power levels. View full abstract»

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  • Saving energy using energy efficient motors:A case study

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    India is among the top growing countries in casting and forging units. These units consume a large portion of electrical energy produced in our country. The work presented in the paper explore the possibility to minimize the wastage of energy in casting and forging units. A careful study of working of Hammers & Instantaneous load analysis of motors has been carried out to compare with different make equal rating motors. The plant under study had 138 motors of various ratings. The already installed motors have poor efficiency and also operate at poor power factor. There were no efficiency standards for polyphase induction motors. So standard motors were designed with efficiencies high enough to achieve the allowable rise in temperature for the ratings. There is a variation in the efficiency for a given h.p rating from around 74% to 94 %. There is an increasing number of manufacturers who have started making energy efficient motors. We have procured data sheets for these motors and then replaced the existing plant motors with energy efficient motors. Then comparison of standard motors with energy efficient motors based on number of parameters viz. voltage, current, power, power factor has been made.. The costing and payback period for use of energy efficient motors has also been calculated. We have taken various motors already installed in the units and taken readings of rating, Voltage, Current, Power and Power Factor. Then replaced these motors with energy efficient motors and again took the above readings. After this the total tariff was calculated and the payback period was found out. The study reveals that replacing standard motors with energy efficient motors, the total motor load of the plant comes to 804.59kW as compared to 870 kW of the previous arrangement. Besides leading to cost saving, this has also increased the efficiency of the plant. View full abstract»

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  • Optimal flux loss model based of speed sensorless vector control induction motor

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    The paper presents a cheap and accurate loss model based controller to improve the efficiency and the power factor of the speed sensorless controlled induction motor. The proposed controller calculates the optimal air gap flux verifying high efficiency especially at light load, improving the power factor, and stable operation for a high load step disturbance. The proposed model is cheap where no additional hardware is required. The accuracy and the fast response of the proposed controller in comparison with an online search control method are proved by the experiment results. The efficiency, and the power factor improvements for speed sensorless induction motor by using the optimal flux compared with the rated flux are examined experimentally. View full abstract»

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  • A new compact high power, low voltage variable speed drive for the Renewable and Offshore markets

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    A new voltage source drive has been developed by Converteam. This drive uses a 3-level Neutral Point Clamped (NPC) inverter topology and has a nominal power rating of 2.5MW. It is targeted primarily at the Renewable and Offshore markets but ultimately can be used in all of the markets served by Converteam. This paper gives a technical description of our new product and explains how it meets and in some cases exceeds all the requirements of our markets. View full abstract»

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  • Current signature analysis of induction machine rotor faults using the fast orthogonal search algorithm

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    This paper presents a method of detecting rotor faults in induction motors using the fast orthogonal search (FOS). Proper online monitoring of motors is important to ensure safe operation, timely maintenance, and efficiency. One method to detect rotor faults is to monitor the stator current spectrum for fault harmonics. Conventional methods that use the FFT for spectral analysis are inadequate for motors that are prone to transient conditions. Changing operating conditions during the sampling time may cause the spectrum to become smudged, reducing the amplitude of the fault signatures causing them to become undetectable. Reducing the sampling time minimizes the effects of smudging, however a fine resolution must still be maintained to distinguish between harmonics. This is especially important when operating under light-load since the fault signatures will be very close to the fundamental frequency. Therefore a balance between resolution and sampling time must be achieved, which is difficult with the FFT. This paper will demonstrate through simulation that FOS is able to achieve eight times the resolution of the FFT for the same data length. Therefore FOS is a promising choice for rotor fault detection in motors where long periods of steady-state are unavailable, and for motors operating with less than full-load. View full abstract»

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  • Nanocrystalline cored transformer design and implementation for a high current low voltage dc/dc converter

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    Transformers are considered critical components that influence high power converter dynamic response, efficiency, and size. High permeability nanocrystalline cores are being increasingly utilized in designs due to their high saturation flux density, high power density, and lower power loss, for a given volume. This paper presents the design and implementation of a high frequency nanocrystalline cored transformer operating at 14 kHz, and used in a high current low voltage dc-dc converter with a 600 V input, and an 8 V, 1000 A output requirement. Power loss analysis and leakage inductance calculation are derived to evaluate the transformer performance. Simulation and experimental results are also presented to validate the design. View full abstract»

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  • High step-up boost converter with coupled inductor and switched capacitor

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    Many industrial applications require non-isolated high step-up single-phase DC/DC converters. Some existed conventional DC/DC converters have the disadvantages of large duty cycle, high switch voltage stress and high peak current. The proposed converter can provide very high voltage gain without extreme duty cycle due to the voltage doubler cell, which is composed of a coupled inductor, a switched capacitor and an additional diode. The converter with active clamp scheme can recycle the leakage energy. Unfortunately, it increases the topology complexity. The presented converter, which employs the passive lossless clamp circuit instead of the active clamp circuit, can achieve the similar functions and show better performance than its active-clamp counterpart. High efficiency and high power density is achieved due to the leakage energy recycle and output diode reverse-recovery alleviation. View full abstract»

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  • Performance analysis of ZVT interleaved high step-up converter with built-in transformer

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    A non-isolated high-efficiency high step-up interleaved DC/DC converter is proposed for photovoltaic and fuel cell grid-connected power applications. The proposed converter consists of an interleaved structure, a built-in transformer and two sets of active clamp circuits. The built-in transformer can provide high voltage conversion ratio and increase the system efficiency without an extreme duty cycle compared with the conventional boost converter. The leakage inductance of the built-in transformer removes the output diode reverse-recovery problem. The active clamp scheme can suppress the surge voltage of the power MOSFETs and recycle the leakage energy. The operation principle of the converter is analyzed and verified. A 1 kW prototype with 40V input and 380V output is implemented and tested to show the performance of the proposed converter. View full abstract»

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  • Design and implementation of a VRM based on secondary-side controller LM5035A

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    Opto-couplers are always the bottleneck of the performance of the voltage regulator modules (VRMs). By employing secondary-side controllers, opto-couplers can be eliminated, resulting in the expansion of the system bandwidth, the improvement of the transient response performance and reliability. This paper describes high power density, high efficiency secondary-side controlled VRM. Implementation details and experimental results are given. View full abstract»

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  • Adaptive control of a switch mode dc-dc power converter using a Recursive FIR predictor

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    The classical Recursive Least Squares (RLS) algorithm is used in many adaptive control strategies. Unfortunately, these schemes often require significant signal processing and microprocessor hardware to implement. This can be a problem in cost sensitive systems. For this reason, this paper proposes the application of an alternative technique for the adaptive control of power electronic converter circuits. Specific attention is given to the adaptive control of a dc-dc converter. The method is computationally efficient and based around a Dichotomous Coordinate Descent (DCD) algorithm. The proposed controller uses an adaptive PD+I structure which, alongside the DCD algorithm, offers an effective alternative to a conventional Proportional-Integral-Derivative (PID) controller. View full abstract»

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  • A simple predictive control technique of power electronic transformers with high dynamic features

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    The paper deals with control methodologies of power electronic transformers (PET) which include a single-phase medium-frequency (MF) electromagnetic transformer. Reference is made to a PET configuration having dc-links either in high-voltage or in low-voltage sides. Both primary and secondary windings of the ferrite-core transformer are supplied by a voltage-source-inverter (VSI, on high-voltage side) and by a voltage-source-rectifier (VSR, on low-voltage side) which impose square-wave voltages. The proposed control strategy has the aim to define the optimised delay between primary and secondary voltages which allows us to obtain the power instantaneously demanded by the load, ensuring fast dynamic response and maximization of the power/current ratio. The control algorithm is based on algebraic equations derived from the mathematical model of the considered system by means of proper simplifications. The used predictive technique gives good results also in four quadrants operations. An application to a traction drive is analyzed. View full abstract»

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  • Sliding Mode Observation of capacitor voltage in multilevel power converters

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    In this paper a sliding mode observer is designed and applied to a two-port multi-cellular power converter topology in order to observe the DC-link capacitor voltages. Among different sliding mode observers, the Sliding Mode Observer (SMO) using equivalent control approach has been selected for use because of its robustness against uncertainties in system equations. Simulation is carried out using SABER software. For practical results the controller is implemented on a TMS320C6713 DSP and two ACTEL FPGAs. The observer equations are implemented on an FPGA using a fixed-point system programmed in VHDL. View full abstract»

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  • A new synchronous frame single-phase PLL algorithm with a decoupling network

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    A new synchronous frame single-phase PLL algorithm with a decoupling network is presented. It applies the synchronous frame transformation but omits the effort to generate the orthogonal component. The β axis signal is set directly to zero. A decoupling network is employed to eliminate the cross couplings in the dq axis. This algorithm can detect the amplitude of the input signal while has simple structures compared to the conventional synchronous frame PLLs. View full abstract»

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  • Single stage grid converters for battery energy storage

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    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (198 KB)  

    Integration of renewable energy systems in the power system network such as wind and solar is still a challenge in our days. Energy storage systems (ESS) can overcome the disadvantage of volatile generation of the renewable energy sources. This paper presents power converters for battery energy storage systems (BESS) which can interface medium-voltage batteries to the grid. Converter topologies comparison is performed in terms of efficiency, common mode voltage and redundancy for a 6kV series connected medium voltage batteries with a nominal power of 5MVA to act as a battery charger/discharger. View full abstract»

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  • Robust repetitive feedback control of a three-phase grid connected inverter

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    This paper discusses the design of a repetitive feedback controller for a grid-connected two-level three-phase voltage-source inverter connected between a DC source and the grid through an LCL filter. The controller incorporates a classical two loop feedback of the output current and the capacitor current in addition to a repetitive feedback loop. The results show that the proposed technique improves the steady state error and the total harmonic distortion of output current in presence of utility harmonics. View full abstract»

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  • Novel permanent magnet linear generator topology for wave energy conversion

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    A novel topology for a permanent magnet linear generator for wave energy conversion is proposed. It aims to increase power density and to eliminate uneven air gap flux distribution caused by the longitudinal ends; this is done by eliminating stator and rotor yokes and by introducing a new flux path. Analytical and FEM studies are used to analyse the concept and to compare it to existing machines. Results and design challenges are discussed. View full abstract»

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  • Power conversion for wave energy applications

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    Wave energy converters require a power conversion stage to convert the variable output from an electrical generator into a constant voltage and frequency for grid connection. To enable further development in grid integration of wave energy converter systems, this paper looks at the main power conversion considerations in converting wave energy into electrical energy and reviews current power converter topologies. In particular, the paper highlights the trade-off between energy storage, which brings about improved power quality, and improved reliability due to the absence of capacitors. View full abstract»

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  • Thermal model of an induction generator in oscillating water column wave energy converter

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    A thermal model for an induction generator in a renewable energy application is presented. The thermal resistances used in the model are found from steady state testing in an appropriate environment. The cooling in this application is inherently better than that normally experienced by this type of generator and thus a rating above nameplate can be achieved continuously. View full abstract»

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  • C-GEN, a lightweight direct drive generator for marine energy converters

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    C-GEN is a new topology of direct-drive permanent magnet generator being developed at University of Edinburgh. The main benefits are reduced overall system mass and ease of manufacturing, due to the use of an air-cored winding, but with a modular PM rotor consisting of C-core modules. A 15kW rotary prototype has been fitted and tested on a commercially available wind turbine. Initial sizing studies for wind indicate that the C-GEN concept will be up to 50% lighter than conventional iron cored PM direct drive generators [10]. In addition to wind the C-GEN has applications in marine energy converters. The authors are working with four marine developers to investigate the feasibility of C-GEN for their technology. The results from two of those studies will be presented in this paper namely; Aquamarine Oyster device - near shore wave energy converter, Scotrenewables SRTT device - tidal current energy converter. In order to find the most optimum solution for the specific application; electromagnetic, thermal, structural and economical design aspects of the generator are defined and coupled using an analytical design tool. To evaluate different design variations an optimization tool is developed based on genetic algorithm. All these considerations make the optimised generator design a very close optimum solution for the “real-world”. View full abstract»

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  • Design and commissioning of a 30 kW direct drive wave generator

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    The Trident Energy TE 5 is a prototype wave energy converter operating on the principle of having direct-drive linear generators mounted above the water surface, coupled to floats moving under the rig deck. This paper describes aspects of the TE 5 design, including its generators, power electronic systems and the conception of its marine structure. View full abstract»

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  • Induction rim-drive for a marine propulsor

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    The design of a line-start rim-driven induction motor specifically for use in a marine propulsor/thruster is described. This paper explores the use of a hybrid ‘canned’ induction rotor design in which a conventional ‘deep-bar’ cage is replaced by a simple cage with a low radial depth, along with a series of air-gap cans to provide environmental shielding, and a conducting rotor can to simplify the rotor design. An overview of the design process to the ‘final’ design for the proposed induction rim-drive is explained, along with details of the two-dimensional finite element models and simulation results. An appraisal of the merits of the rim-driven design, compared to a benchmark industrial induction motor, is also discussed. View full abstract»

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  • Investigation of superconducting fault current limiter application in a power-dense marine electrical network

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    Power-dense, low-voltage marine electrical systems have the potential for extremely high fault currents. Limitation of fault currents is very attractive in a marine vessel, particularly in terms of switchgear cost, size, and weight, and reducing damage at the point of fault. This study shows that superconducting fault current limiters (SFCLs), even with relatively small impedances, are highly effective at reducing prospective fault currents. For the marine system investigated, various possible SFCL deployment strategies were found to be effective, particularly at the bus-tie location which can limit the fault current to approximately half the unrestricted value with an impedance of 0.1Ω. However, the chosen fault current limitation scheme will depend significantly on the vessel's electrical topology, the fault current contribution of each of the generators, and the properties of the SFCL device. View full abstract»

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