Power Electronics Converter

In recent times, the need for energy consumption is drastically increasing to fulfill the global requirements of commercial and domestic consumer demands. Energy generation using conventional methods such as oil and gas are not appreciated in the modern era since they are the major contributors for pollution and global warming. To tackle these issues, energy generation using hybrid renewable energy is being opted and studied universally. However, renewable energy sources have their fair share of drawbacks such as photovoltaic systems rely on the surrounding irradiance and temperature, wind system experiences irregular wind speed, and fuel cells are expensive and less efficient. Also, the energy extracted from renewable sources persist with stochastic behavior. To deal with these issues, researchers utilize different power electronic devices such as inverters, active power filters, voltage regulators, power quality conditioners, and DC-DC converters. Among these power electronic devices DC-DC converters are highly effective for DC voltage regulation and to improve the efficiency of renewable energy systems. Appropriate selection of the DC-DC converter is an important factor that has significant contribution in overall performance of the power systems. Besides, the selection of an efficient DC-DC converter topology, for its optimum operation integration of a suitable control technique is equally important. This paper highlights the characteristics of available and on-going trends of non-isolated converters that includes buck-boost, single ended primary inductor converter, cuk, z-source, zeta, and hybrid DC-DC converters based on the performance parameters that are analyzed using MATLAB Simulink. Control techniques that include proportional integral derivative (PID), slide mode control (SMC), model predictive control (MPC), state space modeling (SSM), and fuzzy logic control (FLC) are also discussed considering the parameters settling issue, response time and complexity while integrating with non-isolated DC-DC converters in power systems.

Wide bandgap (WBG) device-based power electronics converters are more efficient and lightweight than Silicon-based converters. WBG devices are an enabling technology for many motor drive applications and new classes of compact and efficient motors. This paper reviews the potential applications and advances enabled by WBG devices in ac motor drives. Industrial motor drive products using WBG devices are reviewed and the benefits are highlighted. This paper also discusses the technical challenges, converter design considerations and design trade-offs in realizing the full potential of WBG devices in motor drives. There is a trade-off between high switching frequency and other issues such as high dv/dt and electromagnetic interference. The problems of high common mode currents and bearing and insulation damage, which are caused by high dv/dt, and the reliability of WBG devices are discussed.

This paper proposes a novel non-isolated single-input dual-output three-level dc-dc converter (SIDO-TLC) appropriate for medium and high voltage applications. The SIDO-TLC is an integration of the three-level buck and boost converters, whose output voltages are regulated simultaneously. Reducing voltage stress across semiconductor devices, improving efficiency, and reducing inductors size are among the main merits of the new topology. Moreover, due to the considerably reduced volume of the step-down filter capacitor, a small film capacitor can be used instead, whose advantages are lower ESR and a longer lifespan. A closed-loop control system has been designed based on a small-signal model derivation in order to regulate the output voltages along with the capacitors' voltage balancing. In order to verify the theoretical and simulation results, a 300 W prototype was built and experimented. The results prove the afore-mentioned advantages of the SIDO-TLC, and the high effectiveness of the balancing control strategy. Furthermore, the converter shows very good stability, even under simultaneous step changes of the loads and input voltage. Index Terms-Multiport converter, non-isolated dc-dc converter, single-input dual-output dc-dc converter (SIDOC), single-input dual-output three-level dc-dc converter (SIDO-TLC), three-level converter.

—Reliability of power converters is crucial for mission critical systems. Among the components that are susceptible to failure, power semiconductor devices are one of the major causes of the power converter failures. This paper focuses on the remaining useful lifetime (RUL) estimation of degraded power MOSFETs which are stressed by thermal cycling. The relative change in on-state resistance is identified as the fault signature. A data-driven RUL estimation algorithm based on a linear approximation model is proposed. The empirical coefficients are estimated by the classical least squares, where the outliers are removed by random sample consensus (RANSAC) algorithm. A sliding window approach is used to track the non-linearities. The window size, threshold value and number of samples used by RANSAC are optimized with the genetic algorithm. The accuracy of the proposed RUL estimation tool is verified on a number of thermally aged discrete power MOSFET data.

In this paper we present an approach for real-time simulation and Hardware-in-the-Loop (HIL) testing of Modular Multilevel Converters (MMCs) that rely on switching models while supporting system level analysis. Using the Latency Based Linear Multistep Compound (LB-LMC) approach, we achieved a 50 ns simulation time step for systems composed of several MMC converters and for converters of various complexity. To facilitate system level testing, we introduce the use of a serial communication-based (Aurora) interface for HIL testing of MMC converters and we ana-lyzed the effect that communication latency has on the accuracy of the HIL test. The simulation and HIL results are validated against an MMC laboratory prototype.

In modular distributed architectures, the adoption of a communication method that is at the same time robust and has a low and predictable latency is of utmost importance in order to support the required system dynamics. The aim of this paper is to evaluate the consequences of the random jitter on machine drives distributed control, caused by the messages' re-transmission in case of an error in the received data. To achieve this goal, two different Forward Error Correction (FEC) techniques are introduced in the chosen protocol, so that the recipient of the message can correct random errors without the need of any additional round trip delays needed to request and obtain a re-transmission. Experimentally validated simulations are used to evaluate the impact of random network derived jitter on a real world closed loop control system for distributed power electronic converters.

—The sideband current harmonics, as parasitic characteristics in permanent magnet synchronous machine drives with space vector pulsewidth modulation technique, will increase the corresponding electromagnetic loss, torque ripple, vibration, and acoustic noises. Therefore, fast yet accurate evaluation of the resultant sideband current harmonic components is of particular importance during the design stage of the drive system. However, the inevitable magnetic saturation and cross-coupling effects in interior permanent magnet synchronous machine drives would have a significant impact on the current components, while the existing analytical sideband current harmonic model neglects those effects. This paper introduces a significant improvement on the analytical model by taking into account these effects with corresponding nonlinear factors. Experimental results are carried out to underpin the accuracy improvements of the predictions from the proposed model over the existing analytical one. The proposed model can offer a very detailed and insightful revelation of impacts of the magnetic saturation and cross-coupling effects on the corresponding sideband current harmonics.

A high-step-up DC/DC converter for renewable energy systems is proposed. The proposed structure provides high voltage gain by using a coupled inductor without the need for high duty cycles and high turn ratios. The voltage gain is increased through capacitor-charging techniques. In the proposed converter, the energy of the leakage inductors of the coupled inductor is reused. This feature reduces the stress on the switch. Therefore, a switch with low ON-state resistance can be used in the proposed converter to reduce losses and increase efficiency. The main switch is placed in series with the source. Therefore, the converter can control the energy flow from the source to the load. The operating principle is discussed in detail, and a steady state analysis of the proposed converter is conducted. The performance of the proposed converter is verified by experimental results.

In this paper, a new symmetric multilevel inverter is proposed. A simple structure for the cascaded multilevel inverter topology is also proposed, which produces a high number of levels with the application of few power electronic devices. The symmetric multilevel inverter can generate 2n+1 levels with a reduced number of power switches. The basic unit is composed of a single and double source unit (SDS-unit). The application of this SDS-unit is for reducing the number of power electronic components like insulated gate bipolar transistors, freewheeling diodes, gate driver circuits, dc voltage sources, and blocked voltages by switches. Various new algorithms are recommended to determine the magnitude of dc sources in a cascaded structure. Furthermore, the proposed topology is optimized for different goals. The proposed cascaded structure is compared with other similar topologies. For verifying the performance of the proposed basic symmetric and cascaded structure, results from a computer-based MATLAB/Simulink simulation and from experimental hardware are also discussed.

In order to fulfill the increasing demands of energy requirements using the eco-friendly methods of energy generation instead of conventional hazardous methods that have caused severe damages globally. Hybrid renewable energy sources (HRES) are utilized for energy generation for developing smart cities and to make the power systems efficient. HRES systems are designed considering the advance requirements of energy consumption. As the technology is evolving, scientists have developed power saving appliances that operates on low level DC voltage. Since different appliances have different DC voltage ratings, to operate them efficiently multi-level DC voltages are often required. Conventional power systems offer single input and single output (SISO) configuration that cannot fulfill the power requirements of domestic and commercially utilized appliances. However, multi-input multi-output (MIMO) configuration is suitable to fulfil the multi-level voltage requirements. DC-DC converters are responsible to deliver the stable output power in HRES systems. This paper presents implementation of MIMO network using buck-boost converters. The proposed system is simulated in MATLAB Simulink with all possible scenarios. To control the operation of a buck-boost converter, individual control technique is integrated to sustain the desired output value during intermittent conditions. For that purpose, proportional integral (PI) is utilized as a control technique, that regulates the operation of a buck-boost converter with different input and output settings. Keywords-DC-DC converters, buck-boost converter, hybrid renewable energy sources, single-input single output, multi-input multi output, proportional integral.

This paper presents an implementation of the
SenseGaN current sensing technique using Gallium Nitride
(GaN) transistors as representative of Wide Bandgap (WBG)
semiconductors. For effective feedback control, fast over-current
protection, and diagnostics-prognostics developments, precise
current measurement becomes more crucial. While the integration
and miniaturization of power semiconductors are getting
more feasible to operate at higher current as well as switching
frequency, most of the available current measurement techniques
have some technical challenges such as bandwidth limitations,
higher power dissipation, and sensitivity variations. SenseGaN
technique is along with the integration of semiconductors to
monitor the power module current without significant effects
on power stage performance and opens a new era for smart
devices in future power electronics; however, implementation of
this method in practice, has some difficulties that needs to be
addressed for careful design consideration. This paper verifies the
concept in WBG-based power converters with Spice simulations
and mathematical analysis. Finally, a prototype using power
650V-GaN is successfully tested at 150kHz.

This paper proposed several alternative novel matrix converter topologies based on the structure of a dual bridge matrix converter with certain advantages over the conventional matrix converter topologies. It is presented that, by utilizing 3-transistor inverter at the load side of any indirect matrix converter family could lead to a major reduction in the high performance but expensive transistor count. One of the novel matrix converter topology is realized by employing as low as 12 transistors as opposed to 18 transistors as in the conventional or dual bridge or 15 transistors in the sparse matrix converter. Despite the reduced number of transistors, this topology ensures four-quadrant operation, unity power factor, no dc-link energy storage, and high quality voltage-current waveforms. This paper also shows the realization effort could reduce the transistor count further to only 6, which fulfils all the desirable features of a matrix converter and having unidirectional power flow capability for somewhat limited but suitable applications. Thus, these circuits could prove to be attractive in applications requiring high cost switching components such as new silicon carbide or gallium nitride based devices. Proposed topologies are analyzed theoretically to verify the characteristics of this converter family. Simulation results of a 6-transistor topology are provided to validate the performance and feasibility of the novel topologies.

—Different modulation techniques used to control multilevel converters can be classified based on the selected converter topology and optimization goals. Among all proposed modulation methods low switching frequency modulation techniques are very popular for multilevel converters yet non-real time low switching frequency methods cannot be applied to multilevel converters with unequal or varying DC values because these modulation techniques rely on look up tables and the size of look up tables will be huge in this case. This paper proposes a new modular multilevel converter (MMC) structure with unequal DC values. Some well-known low switching frequency modulation techniques and the commonly used PWM based methods are compared and using the new low switching frequency modulation technique called minimal total harmonic distortion (THD) modulation for MMC with unequal DC values is proposed. The PSCAD simulation results show that the new converter topology with unequal DC values has much lower THD compared to the typical MMC. Modulation algorithm is implemented in digital signal processor (DSP) and controller hardware in the loop (CHIL) implementation in RTDS verifies the real-time performance of the algorithm.

Because of many features of multilevel inverters, its applications in industries are not negligible. This paper proposes a new topology for multilevel inverters that has been obtained from series blocks of sub multilevel inverter. One of the issues in this kind of inverters is quantity of switches. The proposed inverter consists of fewer number of power electronic switches which leads to lower switching loss, weight, and cost in comparison with conventional inverters. Another advantage of this structure is its modular capability. In this paper, three algorithms are considered to determine the size of DC voltage source and eventually accuracy of proposed inverter has been approved by PSCAD/EMTDC software.

—The double-star converter (DSC) is a recently introduced medium-voltage 4-level multilevel inverter topology, with a reduced number of active switches. This topology has several advantages over existing commercial topologies (single dc-source, no clamping elements, no bidirectional switches or flying capacitors), which can satisfy the needs of several medium voltage applictions such as pumps, fans and compressors. The main challenge with this topology is the voltage balance of the three dc-link capacitors across the modulation index range. Classic controllers require sophisticated PWM techniques with closed loop compensation to maintain the capacitor voltages balanced. In this paper, a control algorithm based on model predictive control (MPC) is applied to the DSC, allowing a direct regulation of the converter output currents while simultaneously ensuring the dc-link capacitors voltage balance. Simulation results show the effectiveness of MPC when applied to this converter.

Characteristics of a small scale wind turbine using Permanent Magnet Synchronous Generator and connected to a grid through a reduced switches count converter (two legs only) are studied in this paper. Active power output corresponding with the input is given with the reactive power produced by the wind turbine regulated at 0 MVAr. Variable wind speed is optimum for drive train performance at 10 m/s (at maximum power coefficient point). When wind speed changes, the turbine moves away from its optimal tip speed ratio until maximum power point tracking forces the turbine to operate at its optimal speed. The generator torque is regulated by controlling the generator current based on the principle of field oriented control where a decoupling between the field and torque current components is achieved. The generator reference voltage and the converter switching signals are synthesized using the principle of space vector modulation. A 5.7 kW grid-connected variable speed wind turbine is simulated using Matlab/Simulink to study the feasibility of the proposed control technique.

This paper introduces a new hybrid topology of multilevel inverter capable of generating 21-level output voltage. The proposed topology is built using the combination of cross-switched bridge and a conventional full H-bridge. Compared to the conventional topologies and other hybrid topologies, the newly introduced multilevel inverter has the ability to maximize the number of voltage levels utilizing lower number of DC voltage sources, integrated bipolar transistor (IGBT) switches and gate drivers. A low frequency modulation technique is used to generate the ideal multilevel output voltage and gate pulses. Furthermore, the proposed topology is validated by building a hardware prototype and obtaining relevant experimental results. The acquired simulated and experimental results indicate the proper functioning of the proposed hybrid topology along with the compatibility of the applied modulation technique.

Silicon Carbide (SiC) power semiconductor devices
are expected to achieve better performance than silicon power
devices in high-switching-frequency, high-power and hightemperature
applications. Several commercial SiC MOSFETs
and SiC Schottky diodes are available on the market, and SiC
power devices with higher power ratings are expected in the
future. This paper presents a performance projection method
and a scalable loss model for both SiC MOSFETs and SiC
Schottky diodes. The performance projection method provides
estimated parameters also for upcoming devices with higher
power ratings than currently commercially available. These
parameters are used in the scalable loss models to estimate power
losses. The performance projection and scalable loss model are
established based on data from Cree抯 product datasheets. The
loss breakdown analysis of a SiC DC-DC boost converter is
presented to demonstrate the proposed performance projection
method and scalable loss model.

A new three phase three transistor voltage source inverter has recently appeared in the literature which has attractive features compared to the conventional voltage source inverter topologies. In particular, it requires a less number of costly switching devices, such as high performance transistors. This inexpensive design is considered to be advantageous in medium to high power application requiring traditional silicon based power electronic transistors or with newly-evolving yet expensive Silicon Carbide or Gallium Nitride based power semiconductor devices. This paper investigates the realization of the inverter circuit using several different PWM techniques. Theoretical analyses and simulation results are provided to verify the performance and feasibility of the proposed concept.

Power converter is one of the key assemblies in modern wind turbines. In modern wind turbines with variable speed generator configurations, i.e. Doubly Fed Induction Generator or Synchronous Generator, back to back power converters are introduced to control the speed and torque of generator, the active and reactive power fed into the Grid. The power converter in variable speed wind turbines is an essential assembly which is sensitive to failures. The power converter malfunction will cease the operation of wind turbine and generate disturbance to the Grid. Recently, it has been widely accepted in wind industry the power converter should be robust, and have good capability of fault tolerance. Meanwhile, the fault-tolerant methods need to be cost-effective and easy to implement. Fault tolerance control in power converter usually contains the following steps, i.e., fault detection and diagnosis, fault isolation, reconfiguration. The sensor for fault tolerance also needs to be taken into account. There are several types of faults in power converter, e.g., open-switch of IGBT, short-switch of IGBT, DC-link fault. This paper gives an overview of different fault-tolerant methods for power converter of wind turbines, by analysing these methods in detail. We finally conclude some interesting areas for future research.

This paper discloses a novel topology for a voltage source inverter with certain advantages over conventional topologies. In particular, the circuit uses only three high performance transistor switches rather than six switches as in the conventional three leg inverter circuit. Thus, this circuit could prove to be attractive in applications requiring high cost switching components such as new silicon carbide and gallium nitride based devices. In addition to the three switches, two low cost thyristors are used per phase to provide commutation from positive to negative current. Theoretical analysis and simulation results are provided to verify its performance and feasibility.

Distributed generations (DGs) have been increasingly employed in AC microgrids to provide carbon-free power supply. To coordinate multiple DGs, careful attention must be paid to the synchronization stability of their interfaced inverters. Otherwise, low-frequency oscillations and even loss of synchronism may occur and pose a great threat to the system. The conventional solutions towards this issue are to derive the microgrid state-space model and evaluate its stability based on the roots of the characteristic equation. However, tremendous efforts shall be spent on modeling as the number of DG increases. This paper provides an alternative way, which localizes the target of system synchronization stability into individual inverters. It is revealed and proven that microgrid synchronization stability can be guaranteed if all the inverters are designed to have passive synchronization behaviors. To fulfill this requirement and achieve a satisfactory phase margin, an auxiliary controller is designed to reshape frequency-power characteristics of inverters. Finally, case studies of a three-DG microgrid verify the theoretical findings as well as the effectiveness of the auxiliary controller.

This paper proposes a dual-switch DC-DC converter with high-voltage gain for solar Photovoltaic (PV) systems. High-voltage gain is obtained by combining the coupled inductor (CI) and switched-capacitor (SC) voltage boosting techniques. Combining CI and SC techniques, the design flexibility is increased, and low voltage stresses on the semiconductor devices are achieved, which leads to the adoption of low-voltage-rating semiconductor devices with low ON-state resistance resulting in low switching and conduction losses. Unlike the conventional boost converter, thanks to the existence of leakage inductance, the output diode turns off naturally in the proposed converter, which suppresses the reverse-recovery problem and losses. Operation principle and steady-state analysis are discussed to show the advantages of the proposed DC-DC converter. To verify the operation of the proposed converter, a performance comparison is provided. Moreover, the simulation of a 200 W converter with 20 V input and 400V output is carried out using PLECS Blockset.

This Paper proposes a novel three-level, three-port, bidirectional dc-dc converter (TLTPBC). Through the bidirectional battery port, the TLTPBC guarantees the continuous flow of energy to the load when the system is deprived of the input source during faults. Owing to reduction of voltage stress across semiconductor devices, the proposed converter is appropriate for medium and high voltage applications, such as transportation systems, residential and office buildings. Moreover, the size of the passive components is reduced which is the inherent advantage of the three-level structures. The results demonstrate the proposed merits of the converter, and verify that the output voltage is well regulated both in presence and absence of the input source. Keywords-Bidirectional, three-level three-port bidirectional dc-dc converter (TLTPBC), dc-dc converter, multiport converter, three-level dc-dc converter.

The paper presents a reliable high power density
smart solar charge controller (SCC) for standalone energy
systems. In this project, a low cost high power density solar
charge controller with the function to disconnect the battery
during overcharging or deep-discharging and to protect the load
during overvoltage or high-current as well as to reconnect the
battery or load when the faults are removed is proposed. The
proposed solar charge controller is equipped with LCD to display
the state of charge (SOC), battery voltage, charging current and
load current. These are used to obtain the accurate and efficient
disconnecting/ reconnecting action which is capable of protecting
the battery and load whereas LED indicator is featured to show
the status of the systems. All control functions are implemented
in software with a single-chip 32-bit microcontroller. This solar
charge controller is developed to make high efficient and reduce
the current market price of charge controller to an affordable
level. For verification of the proposed solar charge controller, the
1.2kW prototype has been built and tested.

In this study a new high step-up dc-dc converter is presented. The operation of the proposed converter is based on the capacitor switching and coupled inductor with a single active power switch in its structure. A passive voltage clamp circuit with two capacitors and two diodes is used in the proposed converter for elevating the converter's voltage gain with the recovered energy of the leakage inductor, and for lowering the voltage stress on the power switch. A switch with a low (on) DS R can be adopted to reduce conduction losses. In the generalized mode of the proposed converter, to reach a desired voltage gain, capacitor stages with parallel charge and series discharge techniques are extended from both sides of secondary side of the coupled inductor. The proposed converter has the ability to alleviate the reverse recovery problem of diodes with circuit parameters. The operating principle and steady-states analyses are discussed in detail. A 40W prototype of the proposed converter is implemented in the laboratory to verify its operation.

Lithium-ion batteries are more suitable for the application of electric vehicle due to high energy and power density compared to other rechargeable batteries. However, the battery pack temperature has a great impact on the overall performance, cycle life, normal charging-discharging behaviour and even safety. During rapid charge transferring process, the internal temperature may exceed its allowable limit (46 0 C). In this paper, an analysis of internal temperature during charge balancing and discharging conditions is presented. Specific interest is paid to the effects of temperature on the different rate of ambient temperature and discharging current. Matlab/Simulink Li-ion battery model and quasi-resonant converter base balancing system are used to study the temperature effect. Rising internal temperature depends on the rate of balancing current and ambient temperature found in the simulation results.

The microturbine generation (MTG) system are becoming the popular source of distributed generation (DG) due to their fuel flexibility, reliability and power quality. The MTG system is a complicated thermodynamic electromechanical system with high speed of rotation, frequency conversion and its control strategy. In spite of several techniques to control high speed of microturbine is not accurate and reliable due to their anti-interference problem. This paper presents a fuzzy logic controlled MTG system for grid connected and islanded mode of operation. The development of fuzzy logic based speed governor includes input and output membership function with their respective members. The load variation on MTG system is performed using conventional PI controller and fuzzy logic controller are implemented in Matlab/Simulink and their results are compared with each other. The simulation result of MTG system shows the performance improvement of fuzzy logic governor over a conventional governor.

In recent years renewable sources such as solar, wave and wind are used for the generation of electricity. Wind is one of the major renewable sources. The amount of energy from a Wind Energy Conversion System (WECS) depends not only on the wind at the site, but also on the control strategy used for the WECS. In assistance to get the appropriate wind energy from the conversion system, wind turbine generator will be run in variable speed mode. The variable speed capability is achieved through the use of an advanced power electronic converter. Fixed speed wind turbines and induction generators are often used in wind farms. But the limitations of such generators are low efficiency and poor power quality which necessitates the variable speed wind turbine generators such as Doubly Fed Induction Generator (DFIG) and Permanent Magnet Synchronous Generator (PMSG). A high-performance configuration can be obtained by using a PMSG and a converter in combination AC-DC-AC connect between stator & rotor points for providing the required variable speed operation.

The problem of AC voltage regulation based onAC-AC buck-boost converter is discussed in presence of resistor load variations and voltage source variations as well. The design methodology of cascaded proportional-integral (PI) controller via singular perturbation technique is presented where two-time-scale motions are artificially induced in the closed-loop system. Stability conditions imposed on the fast and slow modes and sufficiently large mode separation rate can ensure that the full-order closed-loop system achieves the desired properties in such away that the desired output voltage is maintained. The existence of stable limit cycle in the fast motion subsystem gives the robustness of the output voltage value in the presence of the re-sistor load variations and amplitude of voltage source variations. The method of singular perturbations is used throughout the paper. Numerical simulations for AC-AC buck-boost converter are presented.

This work presents a study on the theoretical and practical design of Coupled Inductor based Non-Isolated bidirectional converters of high voltage ratio. Coupled Inductor can be regarded as a tapped Inductor having windings with different individual characteristics and it can be modeled in terms of an ideal transformer. Usually transformer based DC-DC topologies are utilized in conventional bi-directional DC-DC converters because of the natural property of a transformer to provide the benefit of isolation. Moreover soft switching techniques such as Zero-voltage switching (ZVS) and Zerocurrent switching (ZCS) are achieved to increase efficiency by decreasing the switching losses. Unfortunately the use of more than 4

Recently, the Electric vehicles (EV) became more popular. The construction of the EV charging stations is important in order to satisfy the energy demand of large quantity of electric vehicles. This paper presents design and simulation of EV charging station using three-level converter in the grid-side as well as in the EV-side. The charging station architecture with an AC/DC conversion and DC/DC charging units is proposed. The proposed charging strategy is tested to evaluate its performance and compare its benefits. The performance of the proposed PI controller is simulated using MATLAB/SIMULINK package. The simulation results show that the proposed PI controller has a quite lower overshoot and settling time as compared with the conventional controllers.

Multilevel power converters are becoming increasingly used in several sectors: energy, grid-tie renewable energy systems, High voltage direct current (HVDC) power transmission, and a multitude of industrial applications. However, the multilevel converters consist of several drives and a high number of power switches, which leads to a considerable cost and an increased size of the device. Thus, a novel topology of a multilevel bidirectional inverter using a reduced number of semiconductor power components is proposed in this paper. Without any diode clamped or flying capacitor, only nine switches are used to generate nine voltage levels in this new topology. The proposed multilevel converter is compared with the conventional structures in terms of cost, the number of active power switches, clamped diodes, flying capacitors, DC floating capacitors, and the number of DC voltage sources. This comparative analysis shows that the proposed topology is suitable for many applications. For optimum control of this multilevel voltage inverter and to reduce switching losses in power semiconductors, a hybrid modulation technique based on fundamental frequency modulation and multi-carrier-based sinusoidal pulse-width modulation schemes is performed. The effectiveness of the proposed multilevel power converter is verified by simulation results.

The production of electricity from the solar energy system has led to decrement in environmental pollution, dependency on fossil fuels, and rescue from health-related problems. Despite having numerous benefits, its integration deteriorates the quality of power supply due to (i) Harmonics (ii) variability in voltage, which plays a vital role. This paper is attempting to explore techniques that can mitigate the harmonics and at the same time control voltage in the course of photovoltaic array integration to the load. Here Cascaded H-Bridge multilevel inverters of distinct levels have been designed, analyzed, and compared. Among them, the most favorable 23-level (having total harmonic distortion below 5% as per IEEE-519) of Cascaded H-bridge multilevel inverter is applied as an effective and efficient power electronic interfacing strategy for solar energy integration. The simulation is carried out for performance validation using MATLAB/ SIMULINK software. The subsequent work guidelines regarding the cost of the multilevel inverter as an interfacing device are proposed.

PWM technique can reduce switching and harmonic losses of the inverter. Hybrid PWM inverter utilizes half of the switches to operate at low-frequency signal and the other half of the switches to operate at high-frequency signal to reduce switching loss. But switching loss and heat dissipation among switches are uneven which reduces system reliability. Three-phase symmetrical hybrid sinusoidal PWM inverter is proposed where all switches operate at low and high-frequency signals alternatively which removes unequal switching loss and heat dissipation between switches. Switching loss, heat dissipation and total harmonic distortion of SHSPWM inverter don't vary from HPWM. The SHSPWM inverter is simulated without and with a pie filter in MATLAB/Simulink software to understand performance differences. SHSPWM performance is compared with Sinusoidal PWM, Sixty-Degree PWM and Trapezoidal PWM. The analysis was done by varying modulation index and carrier frequency to see inverter output variation.

Engineers have to fulfill multiple requirements and strive towards often competing goals while designing power electronic systems. This can be an analytically complex and computationally intensive task since the relationship between the parameters of a system's design space is not always obvious. Furthermore, a number of possible solutions to a particular problem may exist. To find an optimal system, many different possible designs must be evaluated. Literature on power electronics optimization focuses on the modeling and design of particular converters, with little thought given to the mathematical formulation of the optimization problem. Therefore, converter optimization has generally been a slow process, with exhaustive search, the execution time of which is exponential in the number of design variables, the prevalent approach. In this thesis, geometric programming (GP), a type of convex optimization, the execution time of which is polynomial in the number of design variables, is proposed and demonstrated as an efficient and comprehensive framework for the multi-objective optimization of non-isolated unidirectional DC/DC converters. A GP model of multilevel flying capacitor step-down converters is developed and experimentally verified on a 15-to-3.3~V, 9.9~W discrete prototype, with sets of loss-volume Pareto optimal designs generated in under one minute. It is also demonstrated how the GP model can be used to determine the sensitivity of the optimized designs to the design parameters. Furthermore, a general procedure for deriving GP models is presented and demonstrated on the example of inductors for higher power applications. Finally, using the example of the seven-switch flying capacitor converter, it is shown how in cases where a converter-level GP model is not possible, component-level GP models can be coupled with a circuit simulator to perform efficiency optimization quickly. This hybrid approach is used to design a wide input and output voltage range, 2~A output current converter IC. The results show that GP is of great value to both researchers and practicing engineers. The methods demonstrated for deriving GP models of power converters are extendable to other converter topologies, allowing for the creation of a rigorous mathematical framework for the optimization of power electronics that guarantees globally optimum designs generated quickly.

Several industrial applications require high power inverter with sinusoidal waveforms with minimum distortion. For
medium and high power applications, it is difficult to attain depending on a single switch. Therefore, the concept of multilevel
inverters where introduced in 1974. At present situation multilevel inverter is becoming more popular due to its staircase out put
whose characteristics is closer to the characteristics of sinusoidal waveform. But generally it has some disadvantages like,
requirement of increased number of switches and complex pulse width modulation methods to reduce harmonics. The cascaded H-bridge

multilevel inverter requires least number of components to achieve various voltage level by which the quality output is
obtained. However as the number of voltage levels m grows, the number of active switches increases according to 2× (m-1) for the
cascaded H Bridge. Here, the novel multilevel inverter topology with reduced number of power switches is proposed and the
switching frequency is getting reduced. The power quality of the proposed system is improved by using selective harmonic
elimination (SHE) method. The whole system is numerically reformed developing MATLAB/SIMULINK and the simulation
results are presented.

Multilevel converter is the high-tech technology for high power medium voltage applications. Inverters are made up off power electronic devices that convert DC quantity into AC quantity. But these devices harvest non-sinusoidal signal and this signal holds harmonics. So as to overcome this problem a multilevel inverter especially in our case we have developed a cascaded multilevel inverter (CMLI) topology in 31-level. We have drafted the recommended inverter topology with the minimum switch count and lower total harmonic distortion [THD]

Recent advances in power-electronics technologies facilitate the integration of distributed generations (DGs), such as renewable energy resources (RESs) and distributed energy storage systems (DESSs). The “microgrid” concept is formed when a number of DGs and loads are coupled together through power electronics converters. To maintain the power balance of a microgrid and perform the grid-forming function, DESSs should be properly controlled through the interfaced power converters. This thesis aims to analyze and overcome several issues
regarding the coordination and control of DESSs, with the focus on the following aspects: fundamental power sharing among DESSs, unbalanced power sharing among DESSs, harmonic power sharing among DESSs, and the synchronization stability of Voltage source inverter (VSI) with DESSs.

Demand for induction motor is ever-growing. With increasing demand, a necessity arises to find efficient motor controlling method. PWM technique is efficient method used to vary voltage and frequency within inverter. A comparative study of five different PWM techniques of three-phase inverter for best induction motor drive performance is presented here using Simulink simulation. Sinusoidal PWM, Sixty-Degree PWM, Trapezoidal PWM, Third Harmonic Injected PWM (THIPWM), Space Vector PWM techniques are presented here. Motor parameters like rotor speed, rotor steady speed obtaining time etc. along with inverter output voltage THD & current THD were observed by varying modulation index, carrier frequency and load torque of motor drive. The simulation result shows that THIPWM exhibits the best induction motor drive performance compared to other PWM techniques. Using THIPWM, effect of high carrier frequency on rotor current, stator current, electromagnetic torque etc. is also presented here.

Buck-boost converters are widely used in the development of DC-DC converters. Several techniques and algorithms have been introduced to improve the transient response of buck-boost converters. However, due to the opposite trends of the output current change and the output voltage change, undershoot or overshoot in the output voltage still seems to be inevitable. In order to overcome this problem, a novel boost-buck converter architecture is proposed to build a fast transient response DC-DC converter. The converter consists of a cascaded configuration of the boost and buck stages. The boost stage converts the input voltage to the shared capacitor voltage and the buck stage supplies energy to the load by converting the shared capacitor voltage to the output voltage. By harnessing the energy stored in the shared capacitor, the transient response of the boost buck converter can be improved to 2 µs in a step-up load current change of 1 A with an output-voltage ripple of 15 mV.

Fossil fuels are the only measure to encounter the day today life activities. Slowly the depended resources are getting depleted and continuous exposure towards it is resulting in the negative effect on the environment. More to the point, energy demand of the world has increased in past few decades and therefore the society is searching for an alternate viable solution. Solar photovoltaic (SPV) energy is widely used among the renewable energy sources and the photovoltaic cell can directly convert solar energy into electricity. On the other hand, efficiency of SPV cell is negatively affected during the fractional shading state. Fractional shading conditions occur on the photovoltaic systems due to the passing clouds in the sky, nearby building shadow, moving objects, tree etc. As a result, power generated from the photovoltaic system is less than the expected value. One of the best solutions for this issue will be the multiple array configurations scheme. In this proposed article, conventional SPV array configuration such as series parallel (SP), bridged linked (BL) and honeycomb (HC) are
compared under different cases with the newly proposed complete cross tied configuration to yield the possible peak power for different fractional shading states. This approach can be done with 4×4 SPV array under six different shading cases and the simulations of all shading cases are implemented using MATLAB/Simulink respectively

Power converter is a key component in micro-scale energy harvesting systems. Micro-scale energy harvesting has become an increasingly viable and promising area for powering ultra-low power systems. Switched-capacitor (SC) power converters that use capacitors as energy storage elements offer much better power density than switched-inductor counterparts and are thus attractive in low-power area-constrained applications. Switched-capacitor (SC) converters have shown tremendous promise in this regard due to favorable device utilization and scaling trends, and the emergence of high-density silicon-compatible capacitor technologies. With the rising integration levels used to increase digital processing performance, there is a clear need for multiple independent on-chip supplies in order to support per-IP or block power management. The growing demand for both performance and battery life in portable consumer electronics requires SoCs and power management circuits to be small, efficient, and dynamically powerful. This paper first reviews various design techniques for implementing high density On-chip Switched-capacitor (SC) power converters and secondly suggests the best technique to solve aspects of power converter design: Area Density, Power Consumption & Efficiency.

Thermal processing of solid state alloys is carried out in order to improve their technological properties by modifying their structure. One of the possible ways of heat treatment is indirect electrical resistance heating i.e. annealing. The main parameters of the heat treatment are the maximal temperature and temperature-time profile heating of the material. In this paper it is presented the three-phase AC/AC power converter based on thyristor power control and microprocessor control technology. In this way the traditional modes of heat treatment control (auto-transformers, control transformers, control switch relay, etc.) are replaced with contemporary and flexible power electronic units. In this paper it is presented a concrete AC/AC pulse controlled in , so called  „burst mode“,  that achieves efficient and precisely controlled electroresistive annealing of massive metal parts.