Advances in Power Electronics http://www.hindawi.com The latest articles from Hindawi Publishing Corporation © 2016 , Hindawi Publishing Corporation . All rights reserved. An Improved Control Strategy for a Four-Leg Grid-Forming Power Converter under Unbalanced Load Conditions Mon, 29 Aug 2016 10:27:24 +0000 http://www.hindawi.com/journals/ape/2016/9123747/ This paper proposes an improved multiloop control strategy for a three-phase four-leg voltage source inverter (VSI) operating with highly unbalanced loads in an autonomous distribution network. The main objective is to balance the output voltages of the four-leg inverter under unbalanced load conditions. The proposed control strategy consists of a proportional-integral (PI) voltage controller and a proportional current loop in each phase. The voltage controller and the current control loop are, respectively, used to regulate the instantaneous output voltage and generate the pulse width modulation (PWM) voltage command with zero steady-state tracking error and fast transient response. A voltage decoupling feedforward path is also used to enhance the system robustness. Since the outer voltage loop operates in the synchronous reference frame, tuning and stability analysis of the PI controller is far from being straightforward. In order to cope with this challenge, the stationary reference frame equivalent of the voltage controller in the rotating frame is derived. Subsequently, a systematic design based on a frequency response approach is provided. Simulation results are also carried out using the DIgSILENT PowerFactory software to verify the effectiveness of the suggested control strategy. Mohammad Reza Miveh, Mohd Fadli Rahmat, Mohd Wazir Mustafa, Ali Asghar Ghadimi, and Alireza Rezvani Copyright © 2016 Mohammad Reza Miveh et al. All rights reserved. Space Vector Modulation Technique for 3-Level NPC Converter with Constant Switching Frequency Thu, 14 Jul 2016 14:26:03 +0000 http://www.hindawi.com/journals/ape/2016/6478751/ This paper presents a simple Space Vector Modulation (SVM) methodology for a three-level NPC converter. Nearest three vectors (NTV) and corresponding duty cycles are deduced through simple generic mathematical expressions. Extra degrees of freedom of NPC converter are used to fully benefit from SVM advantages and to control the switching frequency. Simulation and experimental results are presented and discussed to validate the proposed methodology. Imen Ouerdani, Hafedh Ben Abdelghani, Afef Bennani Ben Abdelghani, Daniel Montesinos-Miracle, and Ilhem Slama-Belkhodja Copyright © 2016 Imen Ouerdani et al. All rights reserved. Optimal Method for Catastrophic Faults Diagnosis in RC Ladder Network Mon, 11 Jul 2016 08:57:22 +0000 http://www.hindawi.com/journals/ape/2016/7176981/ The RC ladder network has been analyzed for various catastrophic fault detection using minimal number of measurements. Generally, electronic circuit testing procedure is very exhaustive and includes higher cost; the presented approach will save fault diagnosis time. It is not possible to analyze the big RC ladder network to give the good fault coverage, so the ladder network has been broken into segments of different sizes. However, if segment size is small, it will cause more area overhead compared to bigger step size in terms of the interconnections and pins on the integrated circuit. A systematic and detailed analysis for one-step, two-step, three-step, and four-step RC ladder networks has been carried out for various faults and optimal step size is proposed. It has been investigated that three measurements are optimal to localize different catastrophic faults in a RC ladder network. Abhilasha Rani Goel and Mohd Wajid Copyright © 2016 Abhilasha Rani Goel and Mohd Wajid. All rights reserved. High-Voltage Converter for the Traction Application Wed, 29 Jun 2016 10:58:17 +0000 http://www.hindawi.com/journals/ape/2016/4705709/ High-voltage converter employing IGCT switches ( V) for traction application is presented. Such a power traction drive operates with an unstable input voltage over  V DC and with an output power up to 1200 kW. The original power circuit of the high-voltage converter is demonstrated. Development of the attractive approach to designing the low-loss snubber circuits of the high-frequency IGCT switches is proposed. It is established on the complex multilevel analysis of the transient phenomena and power losses. The essential characteristics of the critical parameters under transient modes and the relation between the snubber circuit parameters and the losses are discussed. Experimental results for the prototype demonstrate the properties of new power circuit. The test results confirm the proposed high-voltage converter performance capability as well as verifying the suitability of the conception for its use in the Russian suburban train power system and other high-voltage applications. Sergey Volskiy, Yury Skorokhod, and Dmitriy Sorokin Copyright © 2016 Sergey Volskiy et al. All rights reserved. A Control Method for Balancing the SoC of Distributed Batteries in Islanded Converter-Interfaced Microgrids Tue, 14 Jun 2016 12:27:19 +0000 http://www.hindawi.com/journals/ape/2016/8518769/ In a low-voltage islanded microgrid powered by renewable energy sources, the energy storage systems (ESSs) are considered necessary, in order to maintain the power balance. Since a microgrid can be composed of several distributed ESSs (DESSs), a coordinated control of their state-of-charge (SoC) should be implemented, ensuring the prolonged lifespan. This paper proposes a new decentralized control method for balancing the SoC of DESSs in islanded microgrids, without physical communication. Each DESS injects a current distortion at 175 Hz, when its SoC changes by 10%. This distortion is recognized by every DESS, through a phase-locked loop (PLL). In order to distinguish the origin of the distortion, each DESS injects a distortion of different time duration. This intermediate frequency has been selected in order to avoid the concurrence with the usual harmonics. The DESSs take advantage of this information and inject a current proportional to the SoC. Implementing this strategy, a comparable number of charging/discharging cycles for each DESS are achieved. Furthermore, an active filter operation, implemented in the rotating frame for each individual harmonic, is integrated in the control of the distributed generation units, supplying nonlinear loads with high-quality voltage. The effectiveness of this method is verified by detailed simulation results. Spyros I. Gkavanoudis, Konstantinos O. Oureilidis, Georgios C. Kryonidis, and Charis S. Demoulias Copyright © 2016 Spyros I. Gkavanoudis et al. All rights reserved. Realization of SVM Algorithm for Indirect Matrix Converter and Its Application in Power Factor Control Wed, 09 Sep 2015 14:00:41 +0000 http://www.hindawi.com/journals/ape/2015/740470/ Compared with AC-DC-AC converter, matrix converter (MC) has several advantages for its bidirectional power flow, controllable power factor, and the absence of large energy storage in dc-link. The topology of MC includes direct matrix converter (DMC) and indirect matrix converter (IMC). IMC has received great attention worldwide because of its easy implementation and safe commutation. Space vector PWM (SVM) algorithm for indirect matrix converter is realized on DSP and CPLD platform in this paper. The control of the rectifier and inverter in IMC can be decoupled because of the intermediate dc-link. The space vector modulation scheme for IMC is discussed and the PWM sequences for the rectifier and inverter are generated. And a two-step commutation of zero current switching (ZCS) in the rectifier is achieved. Input power factor of IMC can be changed by adjusting the angle of the reference current vector. Experimental tests have been conducted on a RB-IGBT based indirect matrix converter prototype. The results verify the performance of the SVM algorithm and the ability of power factor correction. Gang Li Copyright © 2015 Gang Li. All rights reserved. An IFOC-DSVPWM Based DC-Link Voltage Compensation of Z-Source Inverter Fed Induction Motor Drive for EVs Thu, 13 Aug 2015 12:42:52 +0000 http://www.hindawi.com/journals/ape/2015/185381/ The drop in DC-link voltage of adjustable speed drives (ASD) occurs mainly due to the increase in output power demands. This may lead to inefficient operation and eventually the tripping of the drive. This paper presents a Double Space Vector Pulse Width Modulation (DSVPWM) technique for boosting and compensating the DC-link voltage of Z-source inverter (ZSI). The DSVPWM technique estimates the required shoot through period of the Z-source inverter to maintain the DC-link voltage constant at the desired level through capacitor voltage control. The DSVPWM can obtain maximum boost at any given modulation index in comparison to simple boost control (SBC) method. It also utilizes the dead time more effectively. The speed control of the ZSI fed induction motor drive is done by employing indirect field-oriented (IFO) control method. A 32-bit DSP (TMS320F28335) is used to implement the IFOC-DSVPWM method for ZSI. The power structure and the modulation technique are well suited for electric vehicle application. Ananda Kumar Akkarapaka and Dheerendra Singh Copyright © 2015 Ananda Kumar Akkarapaka and Dheerendra Singh. All rights reserved. Online Junction Temperature Cycle Recording of an IGBT Power Module in a Hybrid Car Mon, 02 Mar 2015 07:47:13 +0000 http://www.hindawi.com/journals/ape/2015/652389/ The accuracy of the lifetime calculation approach of IGBT power modules used in hybrid-electric powertrains suffers greatly from the inaccurate knowledge of application typical load-profiles. To verify the theoretical load-profiles with data from the field this paper presents a concept to record all junction temperature cycles of an IGBT power module during its operation in a test vehicle. For this purpose the IGBT junction temperature is measured with a modified gate driver that determines the temperature sensitive IGBT internal gate resistor by superimposing the negative gate voltage with a high-frequency identification signal. An integrated control unit manages the measurement during the regular switching operation, the exchange of data with the system controller, and the automatic calibration of the sensor system. To calculate and store temperature cycles on a microcontroller an online Rainflow counting algorithm was developed. The special feature of this algorithm is a very accurate extraction of lifetime relevant information with a significantly reduced calculation and storage effort. Until now the recording concept could be realized and tested within a laboratory voltage source inverter. Currently the IGBT driver with integrated junction temperature measurement and the online cycle recording algorithm is integrated in the voltage source inverter of first test vehicles. Such research will provide representative load-profiles to verify and optimize the theoretical load-profiles used in today’s lifetime calculation. Marco Denk and Mark-M. Bakran Copyright © 2015 Marco Denk and Mark-M. Bakran. All rights reserved. Hybrid Control for Bidirectional Z-Source Inverter for Locomotives Sun, 15 Feb 2015 11:25:59 +0000 http://www.hindawi.com/journals/ape/2015/264374/ Electric traction uses three phase locomotives in main line services. Three phase locomotives consist of voltage source inverters for driving the traction motors. This paper proposes a hybrid algorithm for bidirectional Z-source inverters in accelerating region of operation of locomotives. The speed control method adopted is same as that in the existing three phase locomotives which is variable voltage variable frequency. Bidirectional Z-source inverter is designed for getting the same output power as in voltage source inverter fed locomotives. Simulation is done in all regions of traction speed curve, namely, acceleration, free running, and braking by regeneration. The voltage stress across the devices and modulation index are considered while analyzing the proposed control algorithm. It is found that the modulation index remains at a high value over the entire range of frequencies. Due to the higher value of modulation index the harmonics in the inverter output voltage is reduced. Also the voltage stress across devices is limited to a value below the device rating used in the present three phase locomotives. A small scale prototype of the bi-directional Z-source inverter fed drive is developed in the laboratory and the hybrid control was verified in the control topology. Vasanthi Vijayan and S. Ashok Copyright © 2015 Vasanthi Vijayan and S. Ashok. All rights reserved. Design and Implementation of Three-Level DC-DC Converter with Golden Section Search Based MPPT for the Photovoltaic Applications Thu, 12 Feb 2015 10:09:04 +0000 http://www.hindawi.com/journals/ape/2015/587197/ In many photovoltaic (PV) energy conversion systems, nonisolated DC-DC converters with high voltage gain are desired. The PV exhibits a nonlinear power characteristic which greatly depends on the environmental conditions. Hence in order to draw maximum available power various algorithms are used with PV voltage/current or both as an input for the maximum power point tracking (MPPT) controller. In this paper, golden section search (GSS) based MPPT control and its application with three-level DC-DC boost converter for MPPT are demonstrated. The three-level boost converter provides the high voltage transfer which enables the high power PV system to work with low size inductors with high efficiency. The balancing of the voltage across the two capacitors of the converter and MPPT is achieved using a simple duty cycle based voltage controller. Detailed simulation of three-level DC-DC converter topology with GSS algorithm is carried out in MATLAB/SIMULINK platform. The validation of the proposed system is done by the experiments carried out on hardware prototype of 100 W converter with low cost AT’mega328 controller as a core controller. From the results, the proposed system suits as one of the solutions for PV based generation system and the experimental results show high performance, such as a conversion efficiency of 94%. Chouki Balakishan, N. Sandeep, and M. V. Aware Copyright © 2015 Chouki Balakishan et al. All rights reserved. Transient Stability Enhancement of Multimachine Power System Using Robust and Novel Controller Based CSC-STATCOM Wed, 04 Feb 2015 08:07:57 +0000 http://www.hindawi.com/journals/ape/2015/626731/ A current source converter (CSC) based static synchronous compensator (STATCOM) is a shunt flexible AC transmission system (FACTS) device, which has a vital role as a stability support for small and large transient instability in an interconnected power network. This paper investigates the impact of a novel and robust pole-shifting controller for CSC-STATCOM to improve the transient stability of the multimachine power system. The proposed algorithm utilizes CSC based STATCOM to supply reactive power to the test system to maintain the transient stability in the event of severe contingency. Firstly, modeling and pole-shifting controller design for CSC based STATCOM are stated. After that, we show the impact of the proposed method in the multimachine power system with different disturbances. Here, applicability of the proposed scheme is demonstrated through simulation in MATLAB and the simulation results show an improvement in the transient stability of multimachine power system with CSC-STATCOM. Also clearly shown, the robustness and effectiveness of CSC-STATCOM are better rather than other shunt FACTS devices (SVC and VSC-STATCOM) by comparing the results in this paper. Sandeep Gupta and Ramesh Kumar Tripathi Copyright © 2015 Sandeep Gupta and Ramesh Kumar Tripathi. All rights reserved. Comprehensive Analysis and Experimental Validation of an Improved Mathematical Modeling of Photovoltaic Array Tue, 13 Jan 2015 10:19:47 +0000 http://www.hindawi.com/journals/ape/2015/654092/ This paper proposes a simple, accurate, and easy to model approach for the simulation of photovoltaic (PV) array and also provides a comparative analysis of the same with two other widely used models. It is highly imperative that the maximum power point (MPP) is achieved effectively and thus a simple and robust mathematical model is necessary that poses less mathematical complexity as well as low data storage requirement, in which the maximum power point tracking (MPPT) algorithm can be realized in an effective way. Further, the resemblance of the P-V and I-V curves as obtained on the basis of experimental data should also be taken into account for theoretical validation. In addition, the study incorporates the root mean square deviation (RMSD) from the experimental data, the fill factor (FF), the efficiency of the model, and the time required for simulation. Two models have been used to investigate the I-V and P-V characteristics. Perturb and Observe method has been adopted for MPPT. The MPP tracking is realized using field programmable gate array (FPGA) to prove the effectiveness of the proposed approach. All the systems are modeled and simulated in MATLAB/Simulink environment. Satarupa Bal, Anup Anurag, Mrutyunjaya Nanda, and Suman Sourav Copyright © 2015 Satarupa Bal et al. All rights reserved. A Low-Power Voltage Limiter/Regulator IC in Standard Thick-Oxide 130 nm CMOS for Inductive Power Transfer Application Thu, 18 Dec 2014 00:10:11 +0000 http://www.hindawi.com/journals/ape/2014/317523/ This paper presents a novel CMOS low-power voltage limiter/regulator circuit with hysteresis for inductive power transfer in an implanted telemetry application. The circuit controls its rail voltage to the maximum value of 3 V DC employing 100 mV of comparator hysteresis. It occupies a silicon area of only 127 µm × 125 µm using the 130 nm IBM CMOS process. In addition, the circuit dissipated less than 1 mW and was designed using thick-oxide 3.6 V NMOS and PMOS devices available in the process library. Stepan Lapshev and S. M. Rezaul Hasan Copyright © 2014 Stepan Lapshev and S. M. Rezaul Hasan. All rights reserved. Battery Energy Storage System for PV Output Power Leveling Tue, 16 Dec 2014 10:50:36 +0000 http://www.hindawi.com/journals/ape/2014/796708/ Fluctuating photovoltaic (PV) output power reduces the reliability in power system when there is a massive penetration of PV generators. Energy storage systems that are connected to the PV generators using bidirectional isolated dc-dc converter can be utilized for compensating the fluctuating PV power. This paper presents a grid connected energy storage system based on a 2 kW full-bridge bidirectional isolated dc-dc converter and a PWM converter for PV output power leveling. This paper proposes two controllers: a current controller using the d-q synchronous reference and a phase-shift controller. The main function of the current controller is to regulate the voltage at the high-side dc, so that the voltage ratio of the high-voltage side (HVS) with low-voltage side (LVS) is equal to the transformer turns ratio. The phase-shift controller is employed to manage the charging and discharging modes of the battery based on PV output power and battery voltage. With the proposed system, unity power factor and efficient active power injection are achieved. The feasibility of the proposed control system is investigated using PSCAD simulation. Rajkiran Singh, Seyedfoad Taghizadeh, Nadia Mei Lin Tan, and Jagadeesh Pasupuleti Copyright © 2014 Rajkiran Singh et al. All rights reserved. Adaptive PID Controller Using RLS for SISO Stable and Unstable Systems Tue, 07 Oct 2014 09:55:16 +0000 http://www.hindawi.com/journals/ape/2014/507142/ The proportional-integral-derivative (PID) is still the most common controller and stabilizer used in industry due to its simplicity and ease of implementation. In most of the real applications, the controlled system has parameters which slowly vary or are uncertain. Thus, PID gains must be adapted to cope with such changes. In this paper, adaptive PID (APID) controller is proposed using the recursive least square (RLS) algorithm. RLS algorithm is used to update the PID gains in real time (as system operates) to force the actual system to behave like a desired reference model. Computer simulations are given to demonstrate the effectiveness of the proposed APID controller on SISO stable and unstable systems considering the presence of changes in the systems parameters. Rania A. Fahmy, Ragia I. Badr, and Farouk A. Rahman Copyright © 2014 Rania A. Fahmy et al. All rights reserved. Development of Control Structure for Hybrid Wind Generators with Active Power Capability Tue, 02 Sep 2014 13:22:17 +0000 http://www.hindawi.com/journals/ape/2014/890945/ A hierarchical control structure is proposed for hybrid energy systems (HES) which consist of wind energy system (WES) and energy storage system (ESS). The proposed multilevel control structure consists of four blocks: reference generation and mode select, power balancing, control algorithms, and switching control blocks. A high performance power management strategy is used for the system. Also, the proposed system is analyzed as an active power filter (APF) with ability to control the voltage, to compensate the harmonics, and to deliver active power. The HES is designed with parallel DC coupled structure. Simulation results are shown for verification of the theoretical analysis. Mehdi Niroomand and Dong-Jun Won Copyright © 2014 Mehdi Niroomand and Dong-Jun Won. All rights reserved. Fast Hybrid MPPT Technique for Photovoltaic Applications: Numerical and Experimental Validation Tue, 03 Jun 2014 06:42:30 +0000 http://www.hindawi.com/journals/ape/2014/125918/ In PV applications, under mismatching conditions, it is necessary to adopt a maximum power point tracking (MPPT) technique which is able to regulate not only the voltages of the PV modules of the array but also the DC input voltage of the inverter. Such a technique can be considered a hybrid MPPT (HMPPT) technique since it is neither only distributed on the PV modules of the PV array or only centralized at the input of the inverter. In this paper a new HMPPT technique is presented and discussed. Its main advantages are the high MPPT efficiency and the high speed of tracking which are obtained by means of a fast estimate of the optimal values of PV modules voltages and of the input inverter voltage. The new HMPPT technique is compared with simple HMPPT techniques based on the scan of the power versus voltage inverter input characteristic. The theoretical analysis and the results of numerical simulations are widely discussed. Moreover, a laboratory test system, equipped with PV emulators, has been realized and used in order to experimentally validate the proposed technique. Gianluca Aurilio, Marco Balato, Giorgio Graditi, Carmine Landi, Mario Luiso, and Massimo Vitelli Copyright © 2014 Gianluca Aurilio et al. All rights reserved. Synchronous Current Compensator for a Self-Balanced Three-Level Neutral Point Clamped Inverter Tue, 29 Apr 2014 07:53:45 +0000 http://www.hindawi.com/journals/ape/2014/620607/ This paper presents a synchronous current control method for a three-level neutral point clamped inverter. Synchronous reference frame control based on two decoupled proportional-integral (PI) controllers is used to control the current in direct and quadrature axes. A phase disposition pulse width modulation (PDPWM) method in regular symmetrical sampling is used for generating the inverter switching signals. To eliminate the harmonic content with no phase errors, two first-order low pass filters (LPFs) are used for the currents. The simulation of closed-loop control is done in Matlab/Simulink. The Vertex-5 field programmable gate array (FPGA) in Labview/CompactRio is used for the implementation of the control algorithm. The control and switch pulse generation are done in independent parallel loops. The synchronization of both loops is achieved by controlling the length of waiting time for each loop. The simulation results are validated with experiments. The results show that the control action is reliable and efficient for the load current control. Remya Krishna, Deepak E. Soman, Sasi K. Kottayil, and Mats Leijon Copyright © 2014 Remya Krishna et al. All rights reserved. A Dynamic Model for Direct and Indirect Matrix Converters Tue, 08 Apr 2014 07:18:52 +0000 http://www.hindawi.com/journals/ape/2014/864203/ The complicated modulation algorithm and the high switching frequency are two main hindrances in the analysis and simulation of matrix converters (MCs) based systems. To simplify the analysis and accelerate the simulation of MCs, a unique dynamic model is presented for the MC, which is independent of MC type (direct or indirect) and the modulation algorithm. All the input and output variables are transferred to the respective reference frames and their relations and limits are calculated. Based on the proposed equations, an equivalent circuit model is presented which can predict all the direct and indirect matrix converters dynamic and steady state behaviors without the need for small simulation time steps. Validity of the proposed model is evaluated using simulation of the precise model. Moreover, experimental results from a laboratory matrix converter setup are provided to verify the accuracy of the simulation results. Mohamad Hosseini Abardeh and Reza Ghazi Copyright © 2014 Mohamad Hosseini Abardeh and Reza Ghazi. All rights reserved. A Torque Discontinuity Free New Hybrid PWM Approach for High Speed Induction Motor Drives Wed, 02 Apr 2014 09:40:49 +0000 http://www.hindawi.com/journals/ape/2014/281267/ This paper designs a hybrid speed controller in which a Sine Triangle Pulse Width Modulated (SPWM) inverter is used below the base speed and a square wave inverter is employed above the base speed. The two inversion techniques complement each other for their advantages and disadvantages below and above the base speed. This paper proposes a unique strategy for the transition between SPWM and square wave by simply setting the frequency of the carrier signal equal to zero. The proposed methodology in a way uses only one inversion technique and realizes a seamless transition from the SPWM to square wave compared to conventional method in which modes are simply switched from SPWM to square wave and vice versa when the speed changes above and below the base speed, respectively. Computer simulations show that the proposed technique has smoother torque transition and thus a better speed response compared to conventional approach of inverter mode switching around the base speed. The performance of proposed hybrid approach is also validated on a small prototype induction motor through experimental results. Habibur Rehman, Roufin Mahmood, and Taimoor Shah Copyright © 2014 Habibur Rehman et al. All rights reserved. Simulation to Implementation as Good Practices for Teaching Power Electronics to Undergraduate Students: Fuzzy Sliding Mode Control for DC Motors Mon, 24 Feb 2014 13:34:37 +0000 http://www.hindawi.com/journals/ape/2014/697263/ How can students be given experience in the confused realities of engineering processes? How can undergraduate students be convinced that processes can be analyzed and improved? Computer simulations properly designed and applied could answer these challenges revolutionizing education in Power Electronics. In recent years, computer simulation has been commonly used in education to motivate students in their learning and help teachers to improve their teaching level. The present paper focuses on developing a speed controller for DC motors starting from theoretical aspects, passing through simulations, and finally reaching a control prototype. The control theory is based on a nonlinear technique known as Sliding Mode Control (SMC) involving artificial intelligence for optimization such as Fuzzy Logic (FL), Adaptive Neurofuzzy Inference Systems (ANFIS), and Genetic Algorithms (GAs). Paul Cepeda, Pedro Ponce, and Arturo Molina Copyright © 2014 Paul Cepeda et al. All rights reserved. An FPGA Chaos-Based PWM Technique Combined with Simple Passive Filter for Effective EMI Spectral Peak Reduction in DC-DC Converter Mon, 24 Feb 2014 12:47:37 +0000 http://www.hindawi.com/journals/ape/2014/383089/ A new and simple but effective electromagnetic interference suppression technique based on field programmable logic array (FPGA) technology to provide a significant EMI noise attenuation in DC-DC converters is discussed. The voltage controlled boost converter for EMI reduction is analyzed using FFT under traditional PWM technique and chaotic mode operation. This technique aids the DC-DC converters to comply in specified EMI limits and replace conventional bulky passive filter with a simple passive filter. A prototype model has been tested and hardware results show significant reduction of EMI in chaotic mode operation of the boost converter. Sudhakar Natarajan and Rajasekar Natarajan Copyright © 2014 Sudhakar Natarajan and Rajasekar Natarajan. All rights reserved. An FPGA Based Controller for a SOFC DC-DC Power System Sat, 28 Dec 2013 09:09:53 +0000 http://www.hindawi.com/journals/ape/2013/345646/ Fuel cells are an attractive option for alternative power and of use in a variety of applications. This paper proposes a state space model for the solid oxide fuel cell (SOFC) based power system that comprises fuel cell, DC-DC buck converter, and load. In this investigation we have taken up a case study for SOFC feeding a DC load where a DC-DC buck converter acts as the interface between the load and the source. A proportional-integral (PI) controller is used in conjunction with pulse width modulation (PWM) that computes the pulse width and switches the MOSFET at the right instant so that the desired voltage is obtained. The proposed model is validated through extensive simulation using MATLAB/SIMULINK. Controller for the fuel cell power system (FCPS) is prototyped using XC3S500E development board containing a SPARTAN 3E Xilinx FPGA that simplifies the entire control circuit besides providing additional flexibility for further improvement. The results clearly indicate improved performance and validate our proposed model. Kanhu Charan Bhuyan, Sumit Kumar Sao, and Kamalakanta Mahapatra Copyright © 2013 Kanhu Charan Bhuyan et al. All rights reserved. Control of DFIG Wind Turbines Based on Indirect Matrix Converters in Short Circuit Mode to Improve the LVRT Capability Thu, 12 Dec 2013 14:00:54 +0000 http://www.hindawi.com/journals/ape/2013/157431/ Nowadays, the doubly-fed induction generators (DFIGs) based wind turbines (WTs) are the dominant type of WTs. Traditionally, the back-to-back converters are used to excite the rotor circuit of DFIG. In this paper, an indirect matrix converter (IMC) is proposed to control the generator. Compared with back-to-back converters, IMCs have numerous advantages such as higher level of robustness, reliability, and reduced size and weight due to the absence of bulky electrolytic capacitor. According to the recent grid codes wind turbines must have low voltage ride-through (LVRT) capability. In this paper a new crowbar system is proposed so that along with the control system it protects the IMC from large fault currents and supports the grid voltage dips during grid faults. This crowbar system is provided using the existing converter switches to establish a short circuit mode without any extra circuitry. Even in severe fault conditions, the duration of short circuit mode is quite small so the control system will be activated shortly after the fault to inject reactive power as required by new LVRT standards. Therefore, the new LVRT standards are well satisfied without any extra costs. PSIM simulation results confirm the efficiency of the proposed method. Ahmad Khajeh and Reza Ghazi Copyright © 2013 Ahmad Khajeh and Reza Ghazi. All rights reserved. Selection of Design Parameters to Reduce the Zero-Sequence Circulating Current Flow in Parallel Operation of DC Linked Multiple Shunt APF Units Sun, 08 Dec 2013 09:59:50 +0000 http://www.hindawi.com/journals/ape/2013/381581/ Capacity enhancement and operational flexibility are two of the important limitations of the centralized shunt APF () unit. These limitations can be conquered by the operation of multiple APF units in parallel and connected back to back by a common DC link capacitor. In that case, a circulating current (CC) flows within the units. This CC flow becomes out of control when the units operate in hysteresis based current controlled mode. One of the difficulties of this CC flow control or reduction is the variable switching frequency of the units. In this paper, the model for CC flow is derived by the switching dynamics study of the units. It is found that the selection of design parameters plays an important role in the amount of CC flow. Detailed simulation, analysis, and real-time performance show how the selection of design parameters affects the CC flow and the reduction of CC flow can also be achieved at an acceptable level by the proper selection of design parameters. Shafiuzzaman K. Khadem, Malabika Basu, and Michael F. Conlon Copyright © 2013 Shafiuzzaman K. Khadem et al. All rights reserved. Development of a New Research Platform for Electrical Drive System Modelling for Real-Time Digital Simulation Applications Tue, 06 Aug 2013 11:23:49 +0000 http://www.hindawi.com/journals/ape/2013/719847/ This paper presents the research platform for real-time digital simulation applications which replaces the requirement for full-scale or partial-scale validation of physical systems. To illustrate this, a three-phase AC-DC-AC converter topology has been used consists of diode rectifier, DC link, and an IGBT inverter with inductive load. In this topology, rectifier as well as inverter decoupled and solved separately using decoupled method, which results in the reduced order system so that it is easy to solve the state equation. This method utilizes an analytical approach to formulate the state equations, and interpolation methods have been implemented to rectify the zero-crossing errors, with fixed step size of 100 μsec is used. The proposed algorithm and the model have been validated using MATLAB simulation as m-file program and also in real-time DSP controller domain. The performance of the real-time system model is evaluated based on accuracy, zero crossing, and step size. S. Umashankar, Mandar Bhalekar, Surabhi Chandra, D. Vijayakumar, and D. P. Kothari Copyright © 2013 S. Umashankar et al. All rights reserved. Variable Speed Drive Characterization: Review of Measurement Techniques and Future Trends Wed, 31 Jul 2013 08:33:18 +0000 http://www.hindawi.com/journals/ape/2013/968671/ The significant advances in power electronics have permitted the implementation of sophisticated methods for control of electric motors. Each innovative electrical apparatus for industrial and automotive application must be correctly and exhaustively tested, both during the developing process and finally for the compliance test. The development of a new electrical system should be associated with a parallel design of an ad hoc measurement system, whose performance should be defined according to the features of the system under test. In recent years, the increasing interest for sensorless electric motor drives involved the development and implementation of a wide set of control techniques. This paper reviews the state and the trends of measurement techniques and instruments applied for the experimental characterization of variable speed drives. Edoardo Fiorucci, Giovanni Bucci, Fabrizio Ciancetta, Daniele Gallo, Carmine Landi, and Mario Luiso Copyright © 2013 Edoardo Fiorucci et al. All rights reserved. A 25 kW, 25 kHz Induction Heating Power Supply for MOVPE System Using L-LC Resonant Inverter Wed, 17 Jul 2013 10:20:24 +0000 http://www.hindawi.com/journals/ape/2013/584129/ A topology named L-LC resonant inverter (RI) for induction heating (IH) applications takes most of the merits of the conventional series and parallel resonant schemes, while eliminating their limitations. In this paper, fundamental frequency AC analysis of L-LC RI is revisited, and a new operating point is suggested featuring enhanced current gain and near in-phase operation as compared to the conventional operating point. An approximate analysis of the circuit with square-wave voltage source is also described highlighting the effect of auxiliary inductor on the source current waveform. The analysis also leads to an optimum choice of the auxiliary inductance. The requirements of the metal organic vapour phase epitaxy (MOVPE) system in which a graphite susceptor is required to be heated to 1200°C demanding a 25 kW, 25 kHz IH power supply, the configuration of developed IH system, and experimental results are presented. Mangesh Borage and Sunil Tiwari Copyright © 2013 Mangesh Borage and Sunil Tiwari. All rights reserved. Performance Analysis of Grid Integrated Hydro and Solar Based Hybrid Systems Mon, 17 Jun 2013 11:31:19 +0000 http://www.hindawi.com/journals/ape/2013/697049/ The renewable energy systems (RESs) are an attractive option to electrify the community as they are environment friendly, free of cost, and all-pervading. The efficiency of these energy systems is very low and can be improved by integrating them in parallel. In this paper, hydro (7.5 kW) and solar systems (10 kW) are taken as RESs and connected with the utility grid. Due to the intermittent nature of both the hydro and photovoltaic energy sources, utility grid is connected to the system for ensuring the continuous power flow. The hydro power generation system uses the self excited induction generator (SEIG) and converters. The AC/DC/AC converter is used as interface to connect the hydro turbine to the utility grid to adjust the generated voltage to the utility grid voltage. The solar generation system is the combination of PV array, boost converter, and solar inverter. The control of both the hydro and solar power plants is provided through the constant current controller. The analysis has been done to verify the existence of the proposed system. Results demonstrate that the proposed system is able to be put into service and can feed the community. Sweeka Meshram, Ganga Agnihotri, and Sushma Gupta Copyright © 2013 Sweeka Meshram et al. All rights reserved. Implementation of Novel Technique for Selective Harmonic Elimination in Multilevel Inverters Based on ICA Mon, 17 Jun 2013 09:17:29 +0000 http://www.hindawi.com/journals/ape/2013/847365/ Eliminating the specific harmonics especially low-order harmonics of the output voltage of 9-level inverter using SHE-PWM control scheme is investigated. Harmonic minimization is the intricate optimization problems because the nonlinear transcendental equations have multiple local optima. Increasing the degrees of freedom in the suggested method means that the number of switching angles increases. The suggested method is able to eliminate high number of undesired harmonics. As the number of switching angles increases, using either traditional iterative techniques or resultant theory method gets useless. In this paper to overcome this problem the imperialist competitive algorithm (ICA) is used. Also a DC-DC converter is used to enhance the SHE performance in the range for which the conventional SHE methods do not have any solution. Experimental and simulation results of a 9-level inverter show that the proposed method effectively minimizes a large number of particular harmonics so the total harmonics distortion of output voltage will be lower. Ali Ajami, Mohammad Reza Jannati Oskuee, and Ata Ollah Mokhberdoran Copyright © 2013 Ali Ajami et al. All rights reserved.