Dipankar De
@iitbbs.ac.in
Assistant Professor, School of Electrical Sciences, IIT Bhubaneswar
IIT Bhubaneswar
EDUCATION
PhD: Indian Institute of Science Bangalore, India (Power Electronics)
RESEARCH, TEACHING, or OTHER INTERESTS
Electrical and Electronic Engineering, Engineering
Scopus Publications
Scholar Citations
Scholar h-index
Scholar i10-index
Scopus Publications
Guddy Satpathy and Dipankar De
Springer Science and Business Media LLC
Tulasi Rao Burle, Guddy Satpathy, and Dipankar De
Springer Science and Business Media LLC
Suman Maharana, Silpashree Sahu, Ravi Krishnamurthy Bhat, Sujit Kumar, and Dipankar De
Springer Science and Business Media LLC
Guddy Satpathy and Dipankar De
Springer Science and Business Media LLC
Burle Tulasi Rao and Dipankar De
Institute of Electrical and Electronics Engineers (IEEE)
S A Sai Sumukh, Burle Tulasi Rao, and Dipankar De
IEEE
This paper proposes a new SEPIC-based ZCS high gain boost converter. The novel topology ensures soft-switching of active switch and output-side diodes. Achieving high voltage gain and efficient power conversion are the critical requirements in converters for RES applications. Switching losses in active switch and diode reverse recovery losses are two common factors for reduced efficiency in many of the converters reported in the literature. These losses are alleviated by soft-switching in the proposed converter, and the quadratic-boost input stage ensures high gain along with the VMC. A three-winding coupled inductor is used in the power circuit to enhance the boost factor further. The proposed Quad-Boost-Quasi-Resonant-SEPIC (QBQRS) converter is analyzed in detail, including the loss distribution among the converter’s components, and compared with similar converters. The converter has lower active switch stress and aggregate diode voltage stress compared to similar topologies reported in the literature. Finally, the concept of the proposed converter is verified through MATLAB-Simulink simulation studies.
Ravi Krishnamurthy Bhat, Dipankar De, Silpashree Sahu, and Sujit Kumar
IEEE
In this paper, an optimised modulation strategy for a multi-port converter consisting of two dual active bridges with a common input stage is proposed to reduce the link current stresses in either bridge. The switching losses are reduced through zero-voltage switching in a wide range of operating conditions in the proposed optimization method. Controlled by the Triple phase shift (TPS) scheme, the typical operating modes are identified with respect to the phase-shift limits for a Dual Active Bridge. The same method is then extended to a second DAB with one common phase shift with respect to the input bridge and two additional phase shifts. The proposed optimization required simple computation compared to that with penta phase shift optimization for three-port converter, however it has certain operation power ranges where optimization can not be achieved. A trade-off study between the selection of transformer turns ratio and the non-optimization zones are highlighted.
Dulam Anusha, Dipankar De, Aparna Chandrakant Tiwari, and Silpashree Sahu
IEEE
Increasing inertia of the grid connected system using HVDC converter integrated wind farm system is a popular solution now-a-days. This paper deals with such a system with appropriate modelling and control of synthetic inertia of the grid connected system. VSC-HVDC based Modular Multilevel Converter (MMC) and its internal controllers (DC Voltage and current controller) are employed for the application along with inertia emulation control and generator emulation control. Coordinated control technique is implemented in which wind turbines participate in the frequency support of the main grid along with stored energy in the MMC DC link without the use of communication cables. This paper emphasizes the effect of the design of various control loops in the synthetic inertia modelling and a detailed frequency domain modelling is carried out for different control loops to analyse the performance of the system. The concept is validated through PLECS based back-to-back MMC interfacing main grid and wind system through 400km HVDC line.
Burle Tulasi Rao and Dipankar De
IEEE
This paper presents a high gain DC-DC configuration using coupled inductor and voltage multiplier circuit suitable for PV application. In order to reduce the current stress at the input side, the interleaved configuration is used at the input. The voltage multiplier circuit not only ensures the high voltage gain but also provides an effective clamping of the switch voltage stress. The proposed configuration achieves a high reduction in the switch voltage stress compared to the similar configurations with a high gain structure. The proposed configuration is presented with the comparison of voltage gains, and active switch stress levels across the switches for similar topologies. The converter input current is continuous and due to interleaved configuration along with quadratic boost configuration, the input side inductance is decreased. The various modes of operation of the converter and the simulation results are presented.
Burle Tulasi Rao, Dipankar De, and Debjit Chattopadhyay
IEEE
In this paper, reliability of multi-phase coupled inductor based DC-DC boost converter is analyzed. The use of DC-DC converters in integrated power conversion systems has increased enormously in the recent times. A detailed study on the various reliability and loss factors in multi-phase interleaved converter is demonstrated. The continuous input and output current boost converter is studied with the PV converter at the input. A detailed study for a multi-phase converter is carried out with different numbers of converter units, different operating temperatures, and different irradiation levels of the PV converter. Extensive mathematical modeling and analysis of various converters in terms of failure rates are carried out summarizing the mean time to failure under the same operating scenarios. The MTTF of the system is estimated using Markov reliability models. The effect of the component selection and number of parallel paths on Mean time to failure are analyzed in detail. The concepts are verified through simulation studies using MATLAB-simulink.
Burle Tulasi Rao and Dipankar De
Institute of Electrical and Electronics Engineers (IEEE)
A high voltage gain single switch DC-DC converter with efficient leakage energy recovery is presented in this brief. Effective leakage energy recycling is an important requirement in this class of converters with coupled inductors to overcome the high voltage stress across semiconductor devices. The proposed converter effectively recycles the leakage energy of the coupled inductor through a passive clamp circuit to the load. Hence, the efficiency of the converter is improved considerably. The proposed converter has the lowest switch voltage stress among other similar topologies, thereby making it feasible to select a low rating switch for the same boost gain. The converter has a lower sum of diode voltage stress and improved reverse recovery performance of the output side diode as well. The converter performance has been evaluated on the basis of different factors like efficiency, switch voltage stress, diode voltage stress, etc. The proposed converter performance is compared with that for various competitive topologies and is observed to be performing better. The effect of leakage inductance variation is studied on the gain of the converter. The proposed concept is verified via simulation and experimental prototype.
Sahu Mithun, Dipankar De, Burle Tulasi Rao, Akshat Vijaywargiya, and Niladri Bihari Puhan
IEEE
This paper focuses on the extension and associated analysis of advanced Space Vector PWM techniques (SVPWM) reported in the literature to the over-modulation zone of operation. The over-modulation operation is separated into two zones in conventional manner namely, zone-I and zone-II. The combination of sequence 0121 (in under modulation zone) and 121 (in over modulation zone during switching interval only) to achieve reduction in high frequency flux ripple while the low frequency components due to over-modulation remains nearly unchanged. This method is compared with 012 (in under modulation zone) and 12 (in over modulation zone during switching interval only) sequence. In both the cases, a smooth transition between linear and over modulation zones can be achieved. The analysis is carried out for computing RMS stator flux ripple and the harmonic distortion factor for different frequency of operation. The theoretical observation are verified through simulation and experimental studies.
Guddy Satpathy, Burle Tulasi Rao, and Dipankar De
IEEE
This paper presents a reduced DC voltage-fed transformer-less D-STATCOM with improved configurations embedding Z-source element at the AC side. The additional Z-source element helps to achieve additional boost factor and the same has been derived from conventional Z-source derived DCDC converters. In the proposed configuration, no shoot through state is required and DC bus voltage of the converter does not have any zero state. The bidirectional switches added in the Z-source converter conducts only during the free-wheeling period of the converter operation and hence associated power losses are minimal in these bidirectional switches. A simple configuration based on inductor-capacitor-diode and an advanced coupled inductor based configurations are proposed. The various modes of operation, closed loop control in STATCOM mode, the leakage current-path analysis and its detailed performance evaluation are presented. The proposed configuration requires nearly (1/4) times the DC bus voltage (PV stack voltage) compared to standard single stage direct PV fed converters like HERIC, H5 etc. Simulation results are presented to validate the effectiveness of the proposal.
Guddy Satpathy and Dipankar De
IEEE
This paper presents a set of new topology configurations that enable the active filter to operate at reduced DC link voltage with minimal number of switches. The topology reduces the DC voltage by half of that of the conventional topologies. However, due to its configuration provides path for the leakage current via DC supply, inverter switches and the grid. The issue of the leakage current is mitigated in a further modified topologies. A detailed comparison of various derived topologies on the basis of DC bus requirement, switch VA and stored inductance energy is presented in this paper. A suitable controller and modulation scheme is adopted for proposed configurations. The simulation and experimental results are presented in order to verify the effectiveness of the proposed scheme.
Abinash Dash, MK Kharabela Mohanta, Dipankar De, Potnuru Abhishek, and Alberto Castellazzi
IEEE
Bi-directional dual active bridge (DAB) converter, due to non-ideal behavior and switching characteristics, a flux walking phenomenon appears in high frequency (HF) transformer and results in the transformer’s saturation in transient and steady state operating conditions. The saturation effect of the HF transformer affects severely damage the DAB converter performance. This study focuses on the transformer model based analysis and mitigates the magnetizing saturation problem in the DAB converter. In this paper, a practical transformer is modelled and simulated, considering the B-H curve data of the high-frequency transformer. A control strategy is proposed to force average magnetizing current of the transformer is to zero to overcome the saturation problem of the HF transformer. The proposed concept is validated through MATLAB simulink simulation and experimental studies from 1kW laboratory prototype of Dual Active Bridge converter.
Christian Klumpner, Mohamed Rashed, Dipankar De, Chintan Patel, and Greg Asher
Institution of Engineering and Technology (IET)
[Correction added on 3 April 2021, after online publication. The article title and How to cite sections are updated as "Experimental evaluation of an energy storage system for medium voltage distribution grids enabling solid state substation functionality and How to cite this article: Klumpner C, Rashed M, De D, Patel C, Asher G. Experimental evaluation of an energy storage system for medium voltage distribution grids enabling solid‐state substation functionality. IET Smart Grid. 2021;1–12. https:// doi.org/10.1049/stg2.12019 ".] Abstract “Smart grids” is a new concept of managing the power transfer in modern grids that will rely not only on the on‐line processing of a variety of consumption and generation power data but will also need new hardware to facilitate a flexible and efficient conversion and storage of electrical power to maintain grid stability under fast changing operating conditions. This paper presents the results of the experimental evaluation of a 1.5MJ/ 25kW energy storage system connected directly to a medium voltage grid to provide fast and flexible grid control capabilities. The demonstrator consists of a supercapacitor stack connected to a low‐voltage DC bus via interleaved converters whilst connection to the medium voltage grid is done either via a low voltage inverter and step‐up 50Hz transformer or via a cascaded modular multilevel converter fed by dual active bridge converters isolated by medium frequency transformers. The experimental features demonstrated are fast power peak levelling, reactive current injection, grid fault ride through whilst maintaining a high round trip efficiency over a wide power range. The concept on which the demonstrator was designed facilitated the implementation of the solid‐state substation with integrated energy storage concept that can further increase flexibility and reliability of future grids.
Suman Maharana, Srija Mukherjee, Dipankar De, and Alberto Castellazzi
IEEE
This paper presents an operating point dependent dead-time compensation for the dual active bridge DC-DC converter operating in a hybrid optimized condition. This optimization sets a trade-off between input capacitor stress and the converter losses. However the presence of dead-time effect in any bridge type circuit leads to variation in different phase shifts and associated adverse effect on the active power transfer. The effect of dead time on the optimization process is analyzed at various operating conditions and a novel dead-time compensation the technique is proposed on the basis of switching instant link current direction obtained from the emulation of link current. Moreover, a complete closed-loop transfer function is derived and transient response of the output voltage with respect to a step change in the voltage reference is observed in both conditions (with and without compensation). An improved system dynamics is achieved with the compensation in terms of quick rising and settling time. Finally the effectiveness of the compensation technique is verified through the MATLAB-Simulink simulation model and 1kW experimental laboratory prototype.
Suman Maharana, Dipankar De, and Alberto Castellazzi
IEEE
In this work, a performance optimization for dual active bridge is focused with a novel zero-voltage-switching-zone identification in instantaneous link current-transmitted power plane with the variation of inner and outer phase shifts. The proposed solution provides the soft switching zones for all switches along with an effective mapping of any general modulation objective like link current optimization.
Suman Maharana, Srija Mukherjee, Dipankar De, Abinash Dash, and Alberto Castellazzi
Institute of Electrical and Electronics Engineers (IEEE)
High-frequency-link power-conversion is gaining popularity in recent days due to reduction of the size and weight of the converters for various applications. The performance of the dual active bridge heavily depends on the nature of modulation strategy used and on the loading conditions. Look-up table (LUT) based output power and output voltage dependent modulation strategies to investigate the peak current stress and harmonics in high-frequency link current is proposed in this article. The modulator is, thus, simple to implement. The peak stress, the harmonics (total demand distortion) in link current, and associated losses due to the proposed techniques are compared in four main cases, namely, first, single-phase shift, second, dual-phase shift, third, triple phase shift, and, fourth, modified phase shift (MPS)-I, -II, and -III. In MPS-I, weighted aggregate of harmonic currents minimization including fundamental component is carried out to achieve the minimum conduction losses in the magnetic elements. The same method is extended for minimizing the peak-to-peak ripple in the link current as MPS-II. In MPS-III, the desired total demand distortion in the ac-link current is enforced. The variation of voltage transfer ratio between input and output is taken into consideration using two-dimensional (2-D) LUT. Moreover, the requirement of 2-D LUTs are eliminated by using suitable curve-fitting exercise for the output load voltage variation and 1-D LUTs of coefficients. A detailed simulation study, associated mathematical analysis of the methods adopted and experimental verification are presented from 1 kW prototype.
Burle Tulasi Rao, Dipankar De, Utkarsha Dey, and Konapala Satyadeep
IEEE
This paper deals with a generalized interleaving technique applied to parallel connected DC-DC converters. When the operating conditions for each of the converters (like input voltages, power sharing etc.) are different, the fixed interleaving technique with equal amount of phase shift among the carriers become inefficient due to improper ripple cancellation in the combined current. A variable interleaving technique with generalized approach is proposed in this work. The algorithm will seamlessly work for ‘n’ number of converters in parallel to optimize their combined ripple current. The analysis and results are presented for four and five parallel converters to demonstrate the effectiveness of the proposal.
Burle Tulasi Rao and Dipankar De
IEEE
In this paper, a novel high gain DC-DC converter with an additional injected DC voltage is presented. The injected voltage helps to achieve a high voltage gain compared to the conventional converters and it controls the maximum voltage gain. The proposed solution is based on a modified Ĉuk converter and it gives the advantage of continuous input/output current like Ĉuk converter. Moreover, the solution overcomes the drawback of the Ĉuk converter in achieving a high boost factor. The additional injected voltage is derived from the same input voltage through an isolated path without affecting the continuous input current significantly. The working principle, steady state analysis, the effect of parasitic losses and a detailed comparative study under continuous conduction mode are presented. The proposed scheme is verified through MATLAB Simulink based model at 40 V to 400 V for 600 W power level.
Srija Mukherjee, Abinash Dash, Dipankar De, and Alberto Castellazzi
IEEE
The efficiency of the dual active bridge depends on amount of reactive power flows through the link and the RMS link current. This paper reports and analyses a trade-off study in minimization of reactive power and fundamental link current in dual active bridge converter using triple phase shift-based modulator. The conventional reactive power optimization method results in high zero portion in the link voltage and increases the peak of the link current and associated switch stresses. Firstly, an attempt is made to obtain the minimum link current and it results in increased reactive power exchange. Secondly, a novel modulator scheme based on online calculation is proposed to achieve desired trade-off between reactive power and fundamental current component in the transformer AC link. The detailed loss evaluation, analysis and experimental verification are presented in order to verify the proposed scheme.
Tikuna Behera and Dipankar De
Institution of Engineering and Technology (IET)
In flexible AC transmission systems, conventional transformers with tap changing mechanism in ‘Sen’ transformer configuration is a cost effective approach for independent active and reactive power flow control compared to voltage source converter-based solutions. ‘Sen’ transformer regulates the power flow by injecting a series voltage in the transmission line with a specific magnitude and phase angle with respect to the line current flowing through it. The accuracy of such injected voltage depends on the number of available taps in the transformer. However, with limited number of taps the conventional ‘Sen’ transformer results in a limited number of operating points, leading to large steady state error for a given design. This study discusses different types of ‘Sen’ transformer configurations, tap control schemes and proposes an improved tap selection technique with tap reversal arrangement for enhanced operation of ‘Sen’ transformer for power flow control. The proposed method increases the number of operating points, which leads to smaller steady state error with improved copper utilisation and increased tap changing complexity. The new tap changing algorithm and its implementation techniques are described in detail. The proposed configuration is analysed against similar configurations and is verified through a 160 MVA Simulink model.
Srija Mukherjee, Abinash Dash, Dipankar De, and Alberto Castellazzi
IEEE
High frequency link power conversion is gaining popularity in recent days due to reduction of the size and weight of the converters for various applications. The performance of the dual active bridge heavily depends on the nature of modulation strategy used and on the loading conditions. Look-up table based load dependent modulation strategies to minimize harmonics in high frequency link current is proposed in this paper. The modulator is thus simple to implement. The harmonics in link current (and associated losses) due to proposed technique are compared in four main cases, namely i) single phase shift, ii) dual phase shift iii) triple phase shift and iv) Modified Phase Shift (MPS) -I and -II. The modulator is effectively combined with closed loop voltage controller to achieve fixed output voltage operation. The modulation strategy works effectively for entire range of power transfer and it effectively reduces the high frequency losses in the converter at the cost of slight increase in RMS value of the link current. In MPS-I weighted aggregate of harmonic currents minimization including fundamental component is carried out and MPS-II ensures operation within specified harmonic distortion level. A detailed simulation study and associated mathematical analysis of the method adopted are presented. Moreover, the high frequency copper losses are estimated from physical measurement of resistance values of transformer and inductor (using a high precision RLC meter) at harmonic frequencies and compared for various power level for all the cases.