CPSS TPEA Vol.6 No.1 (March 30, 2021)
Sachin ANGADI, Udaykumar R YARAGATTI, Yellasiri SURESH, and Angadi B RAJU
In India, the demand for water is continuously increasing due to the growing population. Approximately 16.5% of all country’s electricity used to pump this water is from fossil fuels leading to increased pump Life Cycle Cost (LCC) and Green House Gas (GHG) emissions. With the recent advancement in power electronics and drives, renewables like solar photovoltaic and wind energy are becoming readily available for water pumping applications resulting in the reduction of GHG emissions. Recently, research towards AC motor based Water Pumping Systems (WPS) has received a great emphasis owing to its numerous merits. Further, considering the tremendous acceptance of renewable sources, especially solar and wind, this paper provides a detailed review of single-stage and multi-stage WPS consisting of renewable source powered AC motors. The critical review is performed based on the following figure of merits, including the type of motor, power electronics interface and associated control strategies. Also, to add to the reliability of solar PV WPS, hybrid Wind-PV WPS will be discussed in detail. Readers will be presented with the state-of-the-art technology and research directions in Renewable Energy-based WPS (REWPS) to improve the overall system efficiency and hence reduce the payback period.
Zhijia WANG and Udaya Kumara MADAWALA
3-phase cage induction machines, operated in two series-connected and one-isolated (TSCAOI) winding configuration, have been proposed to generate standalone single-phase electricity at variable speeds for renewable energy conversion systems. However, the steady-state behaviour and performance of this particular generator are not yet to be theoretically investigated. This paper therefore presents the first theoretical investigation based on the steady-state equivalent circuit model for standalone TSCAOI configured generators. Moreover, this paper is the first to adopt the winding function approach to derive a dynamic mathematical model for TSCAOI configured generators. This approach not only eliminates the cumbersome mathematical manipulation required in all previous papers related to TSCAOI configured generators but also provides a visual insight into the resulting winding distribution of the machine. In order to investigate the load and excitation characteristics pertinently, the dynamic model is transformed into two different equivalent circuit models by appropriate selected transformation matrix. Using these two models, this paper identified the impacts of system parameters on the load and excitation characteristics, as well as on the level of voltage unbalance. Experimental results of a prototype generator under various operating conditions are presented, together with simulated results, to demonstrate the accuracy of the proposed investigations.
Mustafa Ergin ŞAHİN, Frede BLAABJERG, and Ariya SANGWONGWANİCH
The need for energy storage devices especially in renewable energy applications has increased the use of supercapacitors. Accordingly, several supercapacitor models have been proposed in previous researches. Nevertheless, most of them require an intensive test to obtain the model parameters. These may not be suitable for an initial simulation study, where a simple model based on the datasheet is required to evaluate the system performance before building the hardware prototype. A simplified electrical circuit model for a supercapacitor (SC) based on the voltage-current equation is proposed in this paper to address this issue. This model doesn’t need an intensive test for accuracy. The structural simplicity and decent modelling accuracy make the equivalent electrical circuit model very suitable for power electronic applications and real-time energy management simulations. The parameters of the proposed model can be obtained from the datasheets value with a minimum test requirement. The experimental method to provide the parameters of the supercapacitor equivalent circuit is described. Based on the proposed method, the supercapacitor model is built in Matlab/Simulink, and the characteristics of equivalent series resistance (ESR) measurement and cycle life are compared with datasheets. The simulation results have verified that the proposed model can be applied to simulate the behaviour of the supercapacitor in most energy and power applications for a short time of energy storage. A supercapacitor test circuit is given to test the charge and discharge of supercapacitor modules. The experimental results are suitable for simulation results.
Kumari SHIPRA, Rakesh MAURYA, and Shambhu N. SHARMA
In this paper Brayton-Moser passivity-based control (BM-PBC) methodology is developed for an on-board battery charger for plug-in electric vehicles(PHEVs). The main features of this electric vehicle (EV) charger include improved power quality, reduced filter size and voltage stress across the switches and fast dynamic response. In this paper, a dynamic model of the three-level (TL) boost power factor correction (PFC) converter is developed using the Brayton-Moser formulation. Then, the Brayton-Moser based control technique is designed by injecting a virtual resistor in series with the input inductor. Further, the stability analysis of the proposed controller is also carried out using energy balance approach. To improve the dynamic performance and reduce the steady state error, a PI controller is integrated with the aforesaid controller. Therefore, the controller comprises of BM-PBC and the PI controller is implemented for the TL boost PFC converter as a battery charger and its performances are investigated under various operating modes with the help of MATLAB/Simulink. Furthermore, power quality of charger is assessed by monitoring source current total harmonic distortion (THD) under different operating conditions. It is also observed that the proposed system provides THD less than 5% in source current which satisfies IEC 61000-3-2 Class C standard. The performance of the aforesaid controller is also compared with the conventional PI controller. In order to validate the proposed controller, a prototype model of same specifications is tested in hardware in loop and obtained test results are also presented.
Jayadeep SRIKAKOLAPU, Sabha Raj ARYA, and Rakesh MAURYA
In this work, an adaptive observer supported fundamental extractor is developed to estimate the fundamental components of the load current for a three phase distribution static compensator (DSTATCOM) under nonlinear load. Main variations in the proposed work are the fundamental drawing out from the distorted load current and estimation of PI controller gains. With this observer, salp swarm optimization algorithm (SSOA) is used for estimation of DC PI controller and AC PI controller gains. The estimated gains are used for DC bus voltage and AC terminal voltage error minimization respectively. This optimization algorithm commendably progresses the initial random solutions and converge to optimum. Pareto optimal solutions are approximated in SSOA with prodigious convergence and coverage. The SSOA can search unknown spaces and can deal with real world problems for solutions. The suggested control scheme with the optimized gain values has controlled the power quality issues like improving the total harmonic distortion (THD) of grid current and decreasing burden of reactive power on the grid caused due to a nonlinear load. The laboratory performance of the considered system with adaptive observer using d-SPACE-1104 has been provided for implementation work.
Hossein KHOUN-JAHAN, Amin Mohammadpour SHOTORBANI, Mehdi ABAPOUR, Kazem ZARE,
Seyed Hossein HOSSEINI, Frede BLAABJERG, and Yongheng YANG
Cascaded multilevel inverter (CMI) topology is prevalent in many applications. However, the CMI requires many switches and isolated dc sources, which is the main drawback of this type of inverter. As a result, the volume, cost and complexity of the CMI topology are increased and the efficiency is deteriorated. This paper thus proposes a switched-capacitor-based multilevel inverter topology with half-bridge cells and only one dc source. Compared to the conventional CMI, the proposed inverter uses almost half the number of switches, while maintaining a boosting capability. Additionally, the main drawback of switched-capacitor multilevel inverters is the capacitor inrush current. This problem is also averted in the proposed topology by using a charging inductor or quasi-resonant capacitor charging with a front-end boost converter. Simulation results and lab-scale experimental verifications are provided to validate the feasibility and viability of the proposed inverter topology.
Michael ANTIVACHIS, Pascal Samuel NIKLAUS, Dominik BORTIS, and Johann Walter KOLAR
Pairing wide-bandgap (WBG) inverters with high-speed motors results in compact and effi cient motor drives, but requires special attention on electromagnetic interference (EMI) aspects. This paper focuses on electromagnetic compatibility (EMC) of high-speed motor drives, supplied by a DC source. In order to protect the nearby equipment from the EMI noise of the WBG inverter, a fi lter that complies with conducted EMI regulations is placed at the inverter DC input-side. However, there is no clear mandate requiring from inverters to comply with conducted EMI regulations at the AC output-side, where only the motor is placed. For this reason, there is no full consensus whether it is necessary to use an output fi lter, and if so, what type of output fi lter would be suitable, i.e., if differential-mode (DM), common-mode (CM) or both DM/CM output fi lter would fi t best. A full sine-wave output fi lter (FSF) is proposed in this paper, that features both DM and CM attenuation, and capacitors connected to the DC link. Besides the several well established benefi ts of a FSF, such as purely sinusoidal motor currents and the protection of the motor against high du/dt originating from the fast switching of the semiconductor devices, a FSF at the inverter output-side, also reduces the CM EMI emissions at the inverter input-side. Namely, since the inverter housing, the motor housing and the interconnecting shielded cable are all grounded, CM emissions generated at the inverter output-side are directly mapped to the inverter input-side, i.e., there is an input-to-output CM noise interrelation. A FSF reduces the output-side CM EMI emissions and thus mitigates the input-to-output CM noise mutual influence. Two types of FSF (c-FSF and d-FSF) are comparatively evaluated, in terms of volume, losses and EMI performance. The theoretical consideration are tested within the context of a high-speed 280 krpm, 1 kW motor drive, with 80 V DC supply. The experimental results validate the good performance of the proposed filter concept.
Li ZHANG, Haoxin YANG, Kui WANG, Yalei YUAN, Yi TANG, and Wai Kuan LOH
Three-level (3L) converters have been widely used in industry for decades. Compared to the three-phase-three-wire (3P3W) 3L inverter, the three-phase-four-wire (3P4W) one is able to supply the unbalanced loads but has to afford much larger filter inductors because the neutral wire provides a path for high-switching zero-sequence currents. To save filter inductances, a neutral inductor is proposed to insert in the neutral wire. Meanwhile, a complete design methodology is put forward to design the filter inductors and the neutral inductor. With low-frequency zero-sequence currents flowing through the neutral wire, the three-phase load voltages might become unbalanced and/or distorted. To improve the voltage quality, a resonant controller, with the resonant frequency at fundamental output frequency (fo), is presented to add into the zero-sequence voltage loop for balancing load voltages; concurrently, the other resonant controller, with the resonant frequency at 3fo, is presented to insert in the zero-sequence voltage loop or neutral current loop for mitigating voltage distortion. Finally, all of the proposed works are verified on a 3P4W T-type inverter.