V2 controllers are popular in the industry and academia owing to their simple control loop implementation and fast load transient response. However, transient performance and fast-scale stability status depend on the effective series resistance (ESR) of the output capacitor. In many applications, a large ESR of the output capacitor is not acceptable due to large ripple voltage at the output and poor efficiency. However, a small ESR makes the poles complex conjugate, thus, transient performance degrades. Using an average model, this paper derives an analytical expression of minimum ESR to make the closed-loop poles real. The minimum ESR boundary varies if the input voltage or compensating ramp slope changes. Based on the ESR boundary, designers can choose the right controller to enhance stability boundary and transient response of the buck converter. A prototype buck converter is fabricated and the analytical boundary is validated experimentally.
In this proposed work, a fifth order single-input-single-output (SISO) high level DC-DC converter is approximated by utilizing time-moments (TMs) and Markov-parameters (MPs) of system and desired lower-order (LO) model with the help of Jaya algorithm. Firstly, the TMs and MPs are determined for HO system and desired LO model. These TMs and MPs are utilized to construct the objective function. In the objective function, the errors between TMs and MPs of the HO converter system and LO converter model are desired to be minimized. By minimizing the objective function, determination of unknown coefficients of desired LO converter model is accomplished. In this determination process, the minimization of steady state error is ensured by steady state matching. Then, ascertainment of stable LO converter model is fulfilled by exploiting Hurwitz stability criterion. To prove the applicability and efficacy of proposed methodology, responses, time-domain specifications and error-indices are presented.
In this article, a single-phase switched capacitor (SC) based multi-input multi-level inverter has been proposed. The proposed topology offering beneficial features such as boosting output voltage, multi-input and self-balancing nature of SCs using symmetrical dc sources. The attractive feature of the proposed topology is that, it can generates 9, 11 and 13-level output voltage without any structural changes/disruption. Besides, the proposed inverter topology solves the issue of large current spikes due to paralleling of SCs with de source. The soft charging of SCs is handled by a dedicated circuit in the proposed topology. Comparision of the the proposed multilevel topology to other SC-MLIs topologies in use helps demonstrate its benefits. Results are presented of the proposed topology and has been validated under both steady and dynamic loading conditions.
In this research proposal, order reduction of interval modelled higher order (HO) boost converter is presented by exploiting modified Routh approximation and Padé approximation. The fifth order boost converter is modelled with the help of state space averaging technique. The interval modelling of HO fixed coefficient system is done by incorporating the $\pm 5\%$ variations in system parameters due to uncertainty. The approximation of HO boost interval system is done by utilizing modified Routh approximation for unknown denominator coefficients and Padé approximation for unknown numerator coefficients. The responses and tabular comparison are also provided in support of proposed methodology.
In this paper, a hydrogen-based energy storage system (ESS) is proposed for DC microgrids, which can potentially be integrated with battery ESS to meet the needs of future grids with high renewable penetration. Hydrogen-based ESS can provide a stable energy supply for a long time but has a slower response than battery ESSs. However, a combination of battery and hydrogen storage provides stable energy for an extended period of time and can easily handle the sudden demands and surpluses of the microgrid. One of the main challenges in this system is the integration of power electronics with fuel cell technology to convert renewable energy into electricity seamlessly. This paper proposes a system that uses an isolated DC-DC converter to activate clean hydrogen production using an electrolyzer and then pressurize the hydrogen to store in a tank. The pressured hydrogen becomes an essential input to the fuel cell, which regulates and transforms it into electricity. The electricity produced is then transferred to the grid using a DC-DC boost converter. A Simulink model of the hybrid system with a 1 kV DC bus voltage is used to demonstrate the hydrogen production and fuel cell behavior based on the demand and surplus power of the loads. The proposed system simulates aspects of the power conversion, electrolyzer, storage tank, and fuel cell needed for the proposed hybrid ESS. Due to its economic feasibility, the polymer electrolyte membrane (PEM) is the primary technology considered for the electrolyzer and fuel cell.
This paper presents a new impedance network inverter topology called an improved enhanced-boost quasi-Z-source inverter (improved-EBqZSI). The proposed improved-EBqZSI topology employs five capacitors, seven diodes, and five inductors in the impedance network to increase the boost factor. It provides continuous input current, lower voltage stress on capacitors and diodes, and lower current stress on inductors. Additionally, the improved-EBqZSI has higher gain at a lower duty ratio; it can operate at a higher modulation index, thus reducing stress across the inverter switches. The paper presents the operation of the inverter in shoot-through (ST), and non-shoot-through (NST) states, mathematical analysis, computer simulation, and experiment results. A laboratory prototype has been developed to validate the simulation results for the high gain capability.
The article deals with developing a novel solar-powered electric drive-train (SPED) that integrates a multifunctional dual power on-board charger (DP-OBC) incorporating an N-phase switched reluctance motor (SRM). The re-leveraging of the drive-train power electronics and phase windings eliminates the requirement of a separate on-board charging module. The integrated multifunctional DP-OBC can simultaneously utilize two power sources for charging the battery storage system (BESS). When at a standstill, the electric vehicle (EV) BESS can be charged simultaneously via multiple sources, i.e., AC grid plus rooftop solar PV system or DC source plus rooftop solar PV system. Thus, dual power charging ensures a continuous power supply to the battery chargers even when solar energy is unavailable. The proposed SPED during propulsion is reconfigured as an N-phase asymmetrical half-bridge (AHB) configuration simultaneously powered via BESS and rooftop solar PV system, allowing simultaneous driving and charging operation, which increases the driving range. In addition, the proposed SPED employs the same number of power electronics components as in the N-phase AHB configuration, supernumerary reducing the component footprint of the EV charging system. Experiments on a prototype 1.1 kW 4-phase SRM are presented for validating propulsion and different charging modes of the proposed SPED.
This paper presents an analytical novel method to estimate the core loss developed across the Pole Phase Modulated Multiphase Induction Motor using a combined electromagnetic and stress analysis method. The flux density distribution with losses developed is estimated from the 3D electromagnetic field analysis. The compressive stress developed due to shrinking across the stator and the tensile stress caused due to centrifugal force in the rotor part is calculated. The stress analysis helps to optimize the electromagnetic design by predicting the core loss coefficient and permeability which are the crucial parameters for the loss estimation and electromagnetic characteristics of PPMIM. The combined analysis determines the core loss and the vibrational, noise behavior of the designed motor. The estimated loss using the proposed method is validated experimentally.
The paper proposes an interleaved Power factor correction (PFC) Rectifier integrated active power filter (APF). The interleaving helps to reduce individual switch stress and improves input current by reducing the ripple. While integrating the interleaved structure with APF, an inherent problem of the structure becomes prominent and creates disturbance in both PFC and APF. The problem is discussed thoroughly and remedy proposed by introducing the diode leg.
A novel hysteresis controller-based DTC is proposed to improve the steady-state low-speed performance in terms of torque and flux ripple reduction, flux regulation, and current distortion for a five-phase open-end winding induction motor. The proposed method uses 30 virtual voltage vectors in 10 sectors which are obtained from the combination of two inverters switching states and categorized as large vectors, medium vectors, and small voltage vectors. In classical DTC, 20 virtual voltage vectors are used which are generated from dual Inverter configuration used for all possible speeds and generate higher torque and flux ripple and flux instability under low speeds. In the proposed method, a new hysteresis controller-based DTC is introduced in dual inverter-controlled five-phase open-end winding induction motors to improve steady-state performance with the usage of separate lookup tables under both high and low speeds. To nullify flux instability under low speeds, small active voltage vectors are used instead of null vectors during torque error 0 and flux error +1. The proposed DTC method and classical DTC methods are verified through MATLAB/Simulink software.
This paper proposes a single-phase single-stage high gain six switch four-port (6S4P) converter with a novel modulation scheme. The four ports are 1) a low voltage DC port 2) a high voltage DC port, 3) AC port1 and 4) AC port2. For effective operation of the proposed converter, novel Rectified Inverse Level-shifted Sinusoidal Pulse Width Modulation (RILSPWM) and Phase-shifted Rectified Level-shifted Sinusoidal Pulse Width Modulation (PRLSPWM) schemes are proposed and employed. The proposed converter along with the modulation scheme achieves high voltage gain for both DC and AC ports, and also the ac ports are operated with different magnitudes and frequencies. Thus, improving the power density and reliability of the proposed converter with reduced cost. The performance of the proposed converter is evaluated in the MATLAB/Simulink environment, and the results are presented.
With the ever-growing demand of internet-based services globally, the power demand and energy consumption in data centres are consistently rising. To enhance the efficiency of the power conversion stages from the medium voltage (MV) utility grid to the low voltage (LV) level in data centres, smart transformer (ST) provides a prominent solution. Thereby, significantly decreasing the number of cascaded power conversion stages, ensuing lesser complexity, high reliability, high power density/efficiency of data centre power supplies. In this paper, a multi-terminal (MT) ST is proposed for data centres, and particularly its uninterrupted power supply (UPS) mode of operation for continuity of power supply is explored. The MTST is an extension of the ST by replacing the dual-active bridge in the isolation stage with a multi-active bridge. This allows the ST to have multiple LVdc ports which are utilized for server loads in the data centres and also to exchange power from renewable sources/energy storage systems. The MTST can also be operated as an UPS at times of power outages. The simulation of the proposed system is done in PSCAD software to verify its operation in UPS mode, ensuring uninterrupted power to the data centres.
This paper presents a three-stage (Medium Voltage (MV), DCDC, and Low Voltage (LV)), either side grid-connected Power Electronic Transformer (PET) system. The MV stage of the PET system is realized using multiple IGBT based HB cells. Each phase's last HB cell is terminated to a SiC MOSFET based 2L Voltage Source Inverter (VSI). The H-Bridge (HB) Cells are switched in stair-case mode to reduce switching losses in the MV stage. The VSI is switched at a high frequency, resulting in a net higher switching frequency, ensuring a sinusoidal profile in the MV stage. When compared to Si IGBT-based solutions, the proposed PET systems achieve the same effective switching frequency with reduced semiconductor loss in the MV stage. The proposed technique ensures that HB cells manage active power while the VSI unit handles reactive power. This allows the VSI DC link voltage to be realized via a floating DC link. A voltage balancing mechanism is proposed that maintains the VSI's DC link voltage at a desirable level. The DC link voltages of all the MV cells are naturally regulated by operating Series Resonance Converters (SRCs) at resonance in the DCDC stage. The proposed control is verified experimentally in a 5 kV A, 600 V(MV Grid)/100 $V$ (LV grid) PET system.
Low reliability is a critical concern in multilevel inverters due to the necessity for more semiconductor devices and capacitors. Therefore, this paper presents a new fault-tolerant multilevel inverter (FTMLI) topology with more redundant states, which allows the inverter to handle single/multiple switch open circuit (OC) faults. In addition, this topology achieves an output voltage gain of two, which enables the usage of a reduced DC voltage source at the input side to obtain the rated output voltage. It preserves its voltage levels and rated power during normal and fault-tolerant operations with inherent capacitor voltage balancing. The performance of the inverter is verified at various switch fault cases through MATLAB/Simulink environment, and the results are found satisfactory.
Voltage regulation of DC-DC converters is a prime requirement in any DC power application. The use of various frequency-dependent elements, variation in inputs, particularly converters integrated with renewable energy sources (RES), and load variations affect the desired output. Therefore, close loop control of converters becomes essential. However, to design robust controller knowledge of converter dynamics, including transient and steady-state, is necessary. This paper presents detailed dynamic modelling of the Re-lift Luo buck converter (RLBC) using the average state-space modelling method. The RLBC converter can provide step-up and step-down output simultaneously. The integrated converter (RLBC) has many energy storage elements, making it a higher-order system. Controller and simulation of a higher-order system are complex and time-consuming. Therefore, reduced order models are obtained using pad’ e approximation. Further, a suitability analysis of controllers is carried out using stability boundary theory. Therefore, a robust, suitable intelligent fuzzy controller is designed for RLBC converter with a detailed analysis of converters. The study is verified through simulation in MatLab Simulink. Finally, it is believed that the analysis carried out in this study could be helpful for higher-order boost converters controllers design.
The increasing number of electric vehicles (EVs) puts a burden on the utility grid and necessitates extensive renewable energy integration to meet the EV load demand. Wireless charging is a safe with inherent isolation and a highly automatic way to charge EVs. However, the addition of a communication link between the charging station and the EVs can make wireless charging more vulnerable to cyber-attacks. The effect of cyber-attack on series-series compensated wireless charging of EVs are analyzed in detail. This paper proposes a new cyber-resilient, grid-interactive, photo-voltaic (PV)/battery energy storage (BES)-based wireless charging configuration which is resilient to cyber-attacks. The cyber-resilient charging has been achieved using estimation-based primary side control of a high-frequency AC inverter. The power flow operation in grid-connected and stand-alone modes for parallel charging of multiple EVs is explained in detail. The proposed configuration of wireless charging of EVs has been verified in MATLAB/Simulink and LTspice platforms. The results show coordinated power flow among PV, BES, and grid to charge EVs with a constant current - constant voltage charging profile under variable solar irradiations.
Some conventional frequency-weighted model reduction methods yield unstable reduced-order models (ROM) even for originally stable systems. Further, in some instances, existing approaches give a stable reduced model that differs significantly from the actual model, resulting in considerable approximation error. To overcome the above issues, this work presents a new frequency-weighted model reduction method using an innovative structure of frequency-weighted Gramians. The suggested approach ensures ROM stability and minimal inaccuracy in frequency-response approximations. The numerical examples support the effectiveness of the proposed technique and compared to conventional methods, the suggested approach offers consistent results, illustrating its usefulness.
In this paper, a comparative study of ferrite and powder core based filter inductors for a unified battery charging power conversion system is presented. The focus of this paper is to explore an improved inductor design procedure for powder core inductors and benchmark it against ferrite core based inductor designs. The well-known area-product approach is used as a starting point for the process of inductor design. The impact of fringing has been incorporated in the ferrite core-based design and the impact of DC bias has been incorporated in the powder core-based design. A 400 W buck converter-based unified battery charger hardware prototype is developed in the laboratory. Three candidate filter inductor designs are considered and implemented, and the performance of the designed filter inductors have been evaluated using small-signal and large signal measurements. The inductor losses are quantified and their performance under varying DC bias conditions is evaluated.
This paper proposes a single-stage, single-phase ac-ac converter based on the Dual Active Bridge converter. The converter is formed by two three-legged bridge circuits interlinked by a high-frequency transformer. The converter has a symmetrical structure, and the modulation strategy for both bridges are similar. The three-legged bridge act as a low-frequency ac to high-frequency ac converter. The high-frequency outputs of the primary and secondary side bridges are used for dual active bridge power flow through a high-frequency transformer. The converter has regulated dc buses at both bridges. By selecting the high-frequency transformer turns ratio appropriately, the converter can be designed to have a flattop DAB inductor current. The flattop DAB current has a low RMS value and improves the soft switching performance of the converter. Also, by employing the sinusoidal pulse width modulation, the converter draws sinusoidal current at unity power factor from the ac Input. The control strategy and modulation technique of the converter are explained. Experimental waveforms from a 1kW hardware prototype are provided for verification.
A phase shift full bridge (PSFB) converter used to interface solar panels to a grid-tied inverter is considered in this work. This paper proposes a model for controlling the PSFB converter's input voltage for Maximum power point tracking (MPPT). The model includes the influence of resonant inductance of the PSFB converter and ensures a better replication of the dynamic and DC gain response while considering the inverter operation in grid connected mode. The proposed low-frequency model is validated by comparison with a switching circuit model at MPP operating point in open-loop. The validation is done in the MATLAB Simulink environment.
