Browsing by Author "Gautam, Aditya R"

Now showing 1 - 12 of 12

Adaptive Sliding Mode Based Loss-Free Resistor for Power-Factor Correction Application
(IEEE, 2019-07) Gautam, Aditya R
The emulation of virtual resistance finds various applications in the power processing industry. This paper proposes a novel notion of adaptive sliding mode based loss free resistor (ASLFR). This is achieved by allowing the input power of the power-out power-in (POPI) system to vary, in order to accommodate the load demands. In this paper, the concept is illustrated for power-factor correction (PFC) applications. The ASLFR is used to achieve the dual purpose of harmonics-free rectification along with excellent system response under load and line transients. The scheme serves itself as an efficient single-stage PFC solution. A generic mathematical formulation of the scheme is presented, which can be used for different converters. Then on, a boost topology, operating in continuous conduction mode, is chosen to demonstrate theoretical developments and to showcase the effectiveness of the scheme. The robustness of the proposed controller to any line or load variation is established. A fast voltage recovery with almost no undershoot/overshoot is achieved at transients by using the proposed controller. Additionally, a qualitative analysis is provided to demonstrate the expediency of the proposed ASLFR. The theoretical claims are well supported by simulation as well as experimental results.
Adaptive SMC for the Second-Order Harmonic Ripple Mitigation: A Solution for the Micro-Inverter Applications
(IEEE, 2019-08) Gautam, Aditya R
There have been several advanced topologies proposed by the community for micro-inverter applications. However, many such applications suffer from unwanted second-order harmonic current ripple at dc input. Moreover, in the absence of suitable passive filter or ripple compensator, the second-order harmonics ripple may propagate into the dc source. This results in several problems to the system, related to system efficiency, life, cost, size, reliability, and stability. This paper proposes an adaptive sliding-mode controller to shape the output impedance of the boost-circuit of quasi-switched boost inverter such that the propagation of the ripple from dc link to the dc-input source is resisted. The quasi-switched boost inverter is one of the advanced and suitable topologies for the micro-inverter applications. The adaptive nature of the proposed controller improves the transient performance of the system at the line-load transients unlike some existing solutions, which affects dynamics adversely to achieve ripple mitigation objective. The controller ensures voltage regulation within 5% at dc link. The proposed control technique is verified using a lab-prototype of 500 W quasi-switched boost inverter.
A comprehensive study and analysis of second order harmonic ripple in DC microgrid feeding single phase PWM inverter loads
(IEEE, 2016-10) Gautam, Aditya R
The paper presents a detailed analysis of second order harmonic ripple in a DC microgrid. A boost converter feeding PWM inverter load is considered and equivalent circuit is proposed. The effect of the size of input capacitor, output capacitor and inductor of boost converter, on this ripple has been investigated. The proposed model has been validated through experimentation and simulation.
Constant power loads and their effects in DC distributed power systems: A review
(Elsevier, 2017-05) Gautam, Aditya R
The penetration of dc distributed power systems is increasing rapidly in electric power grids and other isolated systems to cater demand for cheap, clean, high quality, and uninterrupted power demand of modern society. DC systems are more efficient and suite better to integrate some of the renewable energy sources, storage units, and dc loads. A dc distributed power system usually consists of large number of power electronic converters connected in cascad0ed configuration to satisfy the power quality and voltage magnitude requirements of the sources and loads. Tightly-regulated power converters in the aforementioned settings exhibit negative incremental impedance and behave as constant power loads (CPLs), and tend to destabilize their feeder systems and upstream converters. The presence of CPLs reduces effective damping of the system leading to instability of the whole system and present significant challenge in the system operation and control. In-depth knowledge of the instability effects of constant power loads (CPLs), available stabilizing techniques and stability analysis methods, is imperious to the young researchers, system designers, system integrators, and practicing engineers working in the field of dc power systems and emerging applications of dc power. This paper is intended to fill this gape by documenting present state of the art and research needs in one article. Modeling, behaviour and effects of typical CPL are discussed and a review of stability criteria used to study the stability of dc power systems are reviewed with their merits and limitations. Furthermore, available literature is reviewed to summarize the techniques to compensate the CPL effect. Finally, discussion and recent challenges in the dc distribution systems.
Control Strategies and Power Decoupling Topologies to Mitigate 2ω-Ripple in Single-Phase Inverters: A Review and Open Challenges
(IEEE, 2020) Singh, Dheerendra; Gautam, Aditya R
This paper provides a comprehensive review of the control approaches and the power-decoupling topologies to mitigate 2ω -ripple problem in the single-phase inverters, its solutions, and discusses open challenges yet to be addressed. The cause and effects of 2ω -ripple problem and its solution based on the passive and active power-decoupling techniques are discussed. A subcategory of the active power-decoupling technique nominated as the control-oriented compensation technique is reviewed in detail, this technique can achieve the ripple-mitigation at the source through the control but not necessarily adds extra circuit or active filter to the system. The control-oriented compensation techniques can be applied in the two-stage DC-DC-AC converters and the single-stage inverters having a front-end control capability with the H-bridge such as in the quasi-switched-boost inverters. The merits and associated challenges of these techniques are listed and summarized in a tabular form. Finally, a conclusive discussion with open challenges is presented
DC bus voltage regulation in the presence of constant power load using sliding mode controlled dc-dc Bi-directional converter interfaced storage unit
(IEEE, 2015) Gautam, Aditya R
The paper presents a robust sliding mode controller for a dc/dc, bidirectional converter interfacing storage unit to ensure dc bus voltage regulation in a stand-alone dc microgrid. The dc bus supplies a combination of a constant power load and conventional resistive load. In order to enhance the battery life, a state-of-charge based charging algorithm is also implemented. Depending on the measured dc bus voltage, the controller selects the appropriate operating mode of the converter. The effectiveness of the proposed controller has been validated through simulation results.
A double input DC to DC buck-boost converter for low voltage photovoltaic/wind systems
(ICGSEE, 2013-03) Gautam, Aditya R
A Double input DC to DC converter for low voltage energy sources applications is proposed in this paper. The proposed converter is buck-boost converter which can step up or step down the input voltage according to output voltage required at load end. The converter is able to boost up voltage of energy sources such as solar photovoltaic and wind energy system of relatively low voltage. The converter is designed considering double input, in which same or different type of two inputs can be used individually or simultaneously. Modes of operation of converter are described in detail and simulation experimental results are presented.
A double input SMV controlled DC/DC buck-boost converter for solar PV/wind energy sources
(IEEE, 2014) Gautam, Aditya R
A sliding mode voltage control (SMVC) based double input buck-boost converter for low voltage solar/wind applications, is proposed in this paper. The proposed double input converter is suitable to maintain output voltage constant at DC bus, irrespective of interruption in availability of solar/wind sources individually or simultaneously both due to climatic conditions rather than individual converter for each source. Controller used is PID-type-PWM based SMVC which is one of the robust controllers and suitable for wind/solar power applications. Modes of operation of converter are described in detail and simulation experimental results are presented.
ISMC for Boost-Derived DC–DC–AC Converter: Mitigation of 2ω-Ripple and Uncertainty, and Improvement in Dynamic Performance
(IEEE, 2020-04) Gautam, Aditya R
In controller design, the classical control techniques have their distinct advantages and capabilities. The integral slidingmode control (ISMC) leverages the merits of such control techniques by allowing their merger with the sliding-mode control (SMC). ISMC is composed of two components, a nominal control designed using any methodology and a discontinuous-SMC, and thus the system can have specified performance with high degree of robustness. The proposed work achieves multiple objectives, i.e., mitigates 2ω-ripple, ensures robustness, and improves dynamic performance. The proposed ISM-based controller amalgamates SMC with a new dual-loop adaptive PID-control (as the nominal control). The discontinuous-SMC part ensures robustness against the matched-uncertainty, i.e., disturbances entering through the input channel such as parametric variations, exogenous disturbances, modeling-error, and the nominal control mitigate 2ω-ripple at the input of dc-dc-ac converter. Moreover, the adaptive nature of nominal control improves the system performance at the large line-load transients unlike the conventional control. Furthermore, the proposed controller supports the reduction of 2ω-ripple at the input of converter. The proposed control scheme is validated using 1-kW prototype.
Ripple Mitigation With Improved Line-Load Transients Response in a Two-Stage DC–DC–AC Converter: Adaptive SMC Approach
(IEEE, 2018-04) Gautam, Aditya R
A substantial pulsation of the second-order harmonic current ripple with angular frequency 2ω is reflected at the input of a single-phase inverter when loads are supplied at its output with angular frequency ω. Moreover, this ripple back-propagates and injects into the source in the absence of a bulky dc-link passive filter, an active compensator or a suitable digital controller with a front-end converter in the two-stage converter. This paper proposes a new adaptive sliding mode control for a two-stage dc-dc-ac converter to reduce proliferation of ripple without compromising dynamic performance. The front-end boost converter in the considered two-stage converter interfaces a battery bank and single-phase inverter fed loads. The control shapes the output impedance of the boost converter to reduce the ripple component at battery input. Second, the proposed controller achieves good dynamic performance at line and load transients. A fast voltage recovery with small undershoot/overshoot can be achieved at transients using the proposed controller. The proposed technique is validated using a hardware of the 1-kW two-stage converter.
Second order harmonic ripple reduction in DC microgrid using sliding mode control approach
(IEEE, 2016) Gautam, Aditya R
A single phase inverter feeding AC loads injects a substantial pulsation of the second order harmonic current (SHC) ripple at DC link. Moreover, this ripple may propagate to the DC source in the absence of the suitable controller or large size DC link capacitor. This paper proposes a SHC ripple reduction technique based on the sliding mode control for the DC microgrid application. The control technique utilizes the concept of the output impedance shaping of the DC source in order to resist the propagation of the ripple to input. A non-isolated boost converter topology has been considered as a voltage booster. This converter feeds the single phase inverter loads, and also acts as the output impedance shaping tool of the source. The proposed control technique is verified using MATLAB-simulink.
Second-order Harmonic Ripple Mitigation: A Solution for the Micro-Inverter Applications
(IEEE, 2018) Gautam, Aditya R
Single-phase inverter suffers an unwanted second-order ripple at DC input of it. A substantial amount of this ripple may propagate through the system components and inject into the DC source. This causes several problems; related to system efficiency, life, cost, size, reliability and stability. This paper proposes an adaptive non-linear sliding mode controller for quasi-switched boost inverter used mainly in microinverter applications. The proposed controller shapes the output-impedance of the boost circuit of quasi-switched boost inverter such that the propagation of the ripple to DC source is resisted. The proposed control technique is verified using Matlab-Simulink.