IET Power Electronics
Volume 11, Issue 10, 28 August 2018
Volumes & issues:
Volume 11, Issue 10
28 August 2018
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- Author(s): Mohammad Mohebbi ; Michael L. McIntyre ; Joseph Latham
- Source: IET Power Electronics, Volume 11, Issue 10, p. 1621 –1627
- DOI: 10.1049/iet-pel.2017.0942
- Type: Article
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This study presents a filter-based control scheme for an H-bridge inverter with an output inductor-capacitor filter. This approach relies only on a single output voltage measurement to reduce the system cost as well as measurement noise and disturbance injected by output current and/or inductor current measurements. Also, the proposed control algorithm is robust against parameter discrepancy. A Lyapunov stability analysis is performed to demonstrate the control objective is met and that all signals in the closed loop system are stable. Experimental results demonstrate excellent voltage tracking, insensitivity to the load and system parameter variations, and low output voltage distortion as well as the stability of the system under both linear and non-linear loads.
- Author(s): Wilmar Martinez ; Camilo Cortes ; Masayoshi Yamamoto ; Jun Imaoka
- Source: IET Power Electronics, Volume 11, Issue 10, p. 1628 –1639
- DOI: 10.1049/iet-pel.2017.0361
- Type: Article
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Reconfiguration, sizing and downsizing of the storage unit, in electrically propelled vehicles, are techniques that have been reported effective to improve the shelf life and performance of the storage cells. However, these solutions might decrease the rated voltage of the storage unit and therefore DC-DC converters with high voltage gain are suitable solutions to connect these low-voltage units to the motor drive, keeping a good performance of the vehicle. Moreover, parasitic resistances presented in the components of these converters have proved to influence the efficiency and the voltage gain of the converter. The ideal voltage gain of four high step-up converters is analysed, derived, and compared. These converters were selected because of their potential to be applied in electric mobility and their similarity in the techniques that use to achieve high voltage gain: interleaving phases and magnetic integration. One of the analysed topologies is proposed by the authors. Afterwards, the parasitic resistance effect is analysed to obtain the non-ideal voltage gain and the efficiency of these four topologies. Finally, the topology that presents the best trade-off between the non-ideal voltage gain and the efficiency is experimentally tested with a 100 W prototype
- Author(s): Krishna Sarker ; Debashis Chatterjee ; Swapan K. Goswami
- Source: IET Power Electronics, Volume 11, Issue 10, p. 1640 –1651
- DOI: 10.1049/iet-pel.2017.0818
- Type: Article
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This study develops a framework for optimisation of rotor side converter (RSC) switching to eliminate lower-order harmonic injection of a doubly fed induction generator connected to a grid. A biogeography based optimisation (BBO) technique is used for this purpose. Three level inverters operating in either 120° or 180° modes at slip frequency are usually employed for the RSC to reduce switching losses. Non-sinusoidal rotor injected voltages by RSC generates undesirable stator harmonics based on the operating rotor speed. Induced harmonics in the stator are analysed and computed. A modified switching strategy is developed to reduce stator harmonics at different speeds. A BBO-based technique is used to compute the switching angles off-line controlled with minimum injected harmonics at closed intervals of modulation indices. These angles are stored in processor memory for an on-line application using mixed model equations which have low memory usage. Various simulations are executed and supported by suitable experiments with a practical machine for verification of the proposed model which provided satisfactory results.
- Author(s): Amir Farakhor ; Mehdi Abapour ; Mehran Sabahi
- Source: IET Power Electronics, Volume 11, Issue 10, p. 1652 –1660
- DOI: 10.1049/iet-pel.2017.0687
- Type: Article
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This study discusses the derivation of the continuous input current high-voltage gain DC–DC converters. These converters are very suitable for renewable energy sources such as photovoltaic power systems since high-output-voltage gain is required for grid connection and continuous input current is necessary for better input current regulation. In these structures, coupled inductors are used along with voltage multiplier cells to improve the voltage gain. Passive clamps are also applied to recover the remained energy in the coupled inductors and improve the efficiency. Regenerative snubbers mitigate the voltage stress on the main switch. Various advantages of the studied converters make them suitable for renewable energy sources with low-output DC voltage. A thorough comparison section is provided to assess the performance of the presented converters. For simplicity, a converter is selected and analysed in details and design guidelines are presented. The experimental setup is implemented in the laboratory to prove the proper operation of the converter.
- Author(s): Guilherme H.F. Fuzato ; Cassius R. Aguiar ; Renan F. Bastos ; Ricardo Q. Machado
- Source: IET Power Electronics, Volume 11, Issue 10, p. 1661 –1672
- DOI: 10.1049/iet-pel.2017.0788
- Type: Article
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The connection of distributed generation systems powered by fuel cells (FCs) to the grid requires power electronics devices with high voltage gain, high capability of power processing and high levels of current absorbed from the direct current (dc) source. In this context, the authors propose the use of an interleaved boost with voltage multiplier (IBVM) converter connected to a FC and a voltage source inverter (VSI) to form a micro grid. To manage the power delivered by the FC in grid-connected operation, they propose two different control structures, mode 1 (FC cascade control) and mode 2 (controlling FC operating point). In mode 1, the dc-link voltage is adjusted by the dc/dc converter, while the injected current is controlled by the VSI. On the other hand, in mode 2, the VSI is responsible to keep the dc-link stable, while the dc/dc converter controls the current injected into the grid by means of the FC current reference. Since the VSI control structure has been exhaustively investigated in the literature, in this study, they evaluate the impact of the proposed control structures in the dc-side and also the IBVM efficiency. Finally, they conclude the study outlining the main points discussed.
- Author(s): Mudasir Ahmed Memon ; Saad Mekhilef ; Marizan Mubin
- Source: IET Power Electronics, Volume 11, Issue 10, p. 1673 –1680
- DOI: 10.1049/iet-pel.2017.0486
- Type: Article
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This study presents selective harmonic elimination pulse width modulation technique-based hybrid asynchronous PSO-Newton-Raphson (APSO-NR) algorithm for the elimination of undesired harmonics in cascaded H-bridge multilevel inverter. The proposed algorithm is applicable to all levels of MLI having equal and non-equal DC sources. In the proposed method, ring topology-based APSO algorithm is hybrid with NR method. APSO worked as a global search technique and NR is used for the refinement of best solutions. APSO-NR is applied to the seven-level inverter to eliminate fifth and seventh harmonics. In simulations, the performance of the proposed algorithm is compared with genetic algorithm, bee algorithm and particle swarm optimisation. The results proved that the proposed algorithm is efficient, and gives more precise firing angles in less number of iterations with high capability of tackling local optima. For the 48% of modulation index range, APSO-NR minimised the fitness function value lower than (10−25). The proposed algorithm is validated through the experimental implementation of the three-phase seven-level inverter.
- Author(s): Li Jin and Shanxu Duan
- Source: IET Power Electronics, Volume 11, Issue 10, p. 1681 –1688
- DOI: 10.1049/iet-pel.2017.0862
- Type: Article
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1681
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The reflux power and current stress of three-level dual active bridge (3L-DAB) become very large under the conventional phase shift (CPS) control, especially when the voltage conversion ratio is unequal to one or working with light load. To improve the performance, reflux-power-optimised (RPO) and current-stress-optimised (CSO) have been investigated in many literatures. However, the current stress variation with RPO control, the reflux power variation with CSO control, and the relations between the two optimal strategies have not been decided yet. Thus, a detailed comparative analysis is presented in this study. The operation principle of 3L-DAB under CPS, RPO and CSO control strategies is briefly described. The reflux power and current stress comparison among the three strategies is performed within different ranges of transmission power and voltage conversion ratio. The RPO and CSO control strategies are approximately equivalent when the voltage conversion ratio is less than 1/4, and they can minimise the reflux power as well as the current stress in the whole power range. An experimental prototype was developed to verify the correctness of the theoretical analysis.
- Author(s): Manlin Chen ; Li Peng ; Bowen Wang ; Jingbo Kan
- Source: IET Power Electronics, Volume 11, Issue 10, p. 1689 –1697
- DOI: 10.1049/iet-pel.2017.0709
- Type: Article
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Phase-locked loop (PLL) plays an important role in the grid-connected converters. PLL should have the ability of filtering the harmonics under the non-ideal grid voltage. Recently, the signal cancellation technique is one of the advanced methods for filtering the harmonics. However, the existing signal cancellation techniques are not able to filter all harmonics by finite operators. This study proposes an extended trigonometric function delay signal cancellation (ETFDSC) to filter all harmonics completely under the adverse grid conditions. Furthermore, the proposed ETFDSC can be flexibly applied to eliminate the harmonic series fast under the various grid conditions. Consequently, a novel PLL based on the ETFDSC (ETFDSC-PLL) is designed to track the grid phase very accurately and fast. It is noteworthy that the grid phase can be extremely fast detected by proposed ETFDSC-PLL under some adverse grid conditions, especially under unbalanced conditions. Furthermore, the ETFDSC-PLL is self-adjustable to the fundamental frequency deviations, and the excellent filtering capability and fast dynamic response can be achieved, even under large frequency variations. Finally, the simulation and experimental results are presented to validate the filtering capability and transient performances of the proposed PLL.
- Author(s): Ali Shagerdmootaab ; Shahram Pourazadi ; Mehrdad Moallem ; Carlo Menon
- Source: IET Power Electronics, Volume 11, Issue 10, p. 1698 –1705
- DOI: 10.1049/iet-pel.2017.0622
- Type: Article
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This study presents modelling and control of a high-voltage ratio flyback converter for driving capacitive loads including smart material dielectric elastomer actuators (DEAs). These actuators find various applications including artificial muscles, optical devices, smart skin, and acoustics but require high actuation voltages. To this end, a high-voltage bidirectional flyback converter for driving a capacitive load is studied in terms of modelling and control and applied to a DEA. The state-space model of the converter is obtained for the capacitor charge and discharge modes when the converter operates in the continuous conduction mode and used to obtain a load voltage controller using the feedback linearisation method. The converter can be used to regenerate the capacitor charge into the dc source. The proposed hardware and control strategy was built and validated by driving DEA capacitive loads operating at high voltages around 4 kV. The experimental results are presented which validate the performance of the proposed converter and its control strategy.
- Author(s): Li Po ; Li Ruiyu ; Shao Tianying ; Zhang Jingrui ; Fang Zheng
- Source: IET Power Electronics, Volume 11, Issue 10, p. 1706 –1717
- DOI: 10.1049/iet-pel.2017.0835
- Type: Article
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A composite adaptive model predictive control (MPC) scheme is proposed to mitigate model mismatches due to parameter uncertainties and disturbances in controller designs for DC–DC boost converters. First, a model-based feedforward compensator based on a cascade proportional-integral (PI) MPC controller was developed as a current reference to improve the dynamic response performance. Then, an observer was employed to construct an accurate model and thereby avoid overcompensation and poor prediction due to model mismatch. Finally, a finite control set MPC was implemented to select a suitable switching state with which to realise output voltage regulation. Compared with a traditional PI MPC, the proposed controller has a rapid dynamic response, and compared with an unknown offset free MPC, the proposed controller is well suited to a simplified model. The proposed methods and benefits were validated by simulations in MATLAB/Simulink and by experiments on an NI Compact RIO rapid control prototype test bench.
- Author(s): Mohammad Maalandish ; Seyed Hossein Hosseini ; Tohid Jalilzadeh
- Source: IET Power Electronics, Volume 11, Issue 10, p. 1718 –1729
- DOI: 10.1049/iet-pel.2017.0752
- Type: Article
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In this study, a non-isolated high step-up direct current (dc)/dc converter with a diode–capacitor is presented. To obtain high-voltage gain, the voltage multiplier units (diode–capacitor) can be extended to n stages which are used between the phases in up section and down section of the proposed converter. By increasing the number of voltage multiplier units, the nominal value of the components decreases. Therefore, the maximum voltage value of diodes and power switches compared with the output voltage is decreased and finally, the normalised voltage of these devices will decrease, significantly. In addition, the power level of the proposed converter can be increased for different values of duty cycles and voltage multiplier units and also leads to high efficiency. To illustrate the advantages of the proposed converter, comparison results with other topologies are provided. The principle of operation at n = 1, 2 stages, both theoretical analysis and experimental results of two prototypes in 100 and 250 W with operating at 40 kHz are provided.
- Author(s): Zhiyong Dai ; Shuaishuai Lv ; Julius K. Mwaniki ; Juxiang Zhang
- Source: IET Power Electronics, Volume 11, Issue 10, p. 1730 –1737
- DOI: 10.1049/iet-pel.2017.0503
- Type: Article
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In this study, a global observer-based method is proposed for variable frequency AC systems of more electric aircraft (MEA) to estimate positive- and negative-sequence components and their parameters. Looking at the measurable grid voltage as a parameterised system containing the unknown coefficient – voltage frequency, a mathematical model based on three-phase grid voltage is established. According to the obtained dynamic model, a global observer is developed to achieve the estimation of positive- and negative-sequence voltage components and their frequency, amplitudes and phase angles with zero steady-state error. Different from most existing methods which are developed for constant frequency AC grids and only have local convergence, a Lyapunov-based argument proof provided in this study shows that the proposed observer is able to achieve global asymptotic convergence in theoretical sound. Also, it ensures that the addressed global observer method has a better stability and faster dynamic performance for variable frequency AC grids of MEA. Both simulations and experimental results are provided to validate the proposed global observer scheme.
Sensorless control of an H-bridge inverter with output inductor-capacitor filter
Effect of inductor parasitic resistances on the voltage gain of high step-up DC–DC converters for electric vehicle applications
Modified harmonic minimisation technique for doubly fed induction generators with solar-wind hybrid system using biogeography-based optimisation
Study on the derivation of the continuous input current high-voltage gain DC/DC converters
Evaluation of an interleaved boost converter powered by fuel cells and connected to the grid via voltage source inverter
Selective harmonic elimination in multilevel inverter using hybrid APSO algorithm
Comparative analysis of three-level dual active bridge DC–DC converter between reflux-power-optimised and current-stress-optimised phase shift control
PLL based on extended trigonometric function delayed signal cancellation under various adverse grid conditions
Control of a high-voltage bidirectional dc–dc flyback converter for driving DEAs
Composite adaptive model predictive control for DC–DC boost converters
High step-up dc/dc converter using switch-capacitor techniques and lower losses for renewable energy applications
Global accurate estimation of positive- and negative-sequence voltage components for variable frequency AC systems
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