Power electronics converters are devices that change parameters of electric power, such as voltage and frequency, as well as between AC and DC. They are essential parts of both advanced drives, for machines and vehicles, and energy systems to meet required flexibility and efficiency criteria. In energy systems both stationary and mobile, control and converters help ensure reliability and quality of electric power supplies.
This reference in two volumes is useful reading for scientists and researchers working with power electronics, drives and energy systems; manufacturers developing power electronics for advanced applications; professionals working in the utilities sector; and for advanced students of subjects related to power electronics.
Volume 1 covers converters and control for drives, while Volume 2 addresses clean generation and power grids. The chapters enable the reader to directly apply the knowledge gained to their research and designs. Topics include reliability, WBG power semiconductor devices, converter topology and their fast response, matrix and multilevel converters, nonlinear dynamics, AI and machine learning. Robust modern control is covered as well. A coherent chapter structure and step-by-step explanation provide the reader with the understanding to pursue their research.
Inspec keywords: harmonic distortion; three-term control; switching convertors; DC-DC power convertors
Other keywords: DC-DC power convertors; power electronics; three-term control; next-generation drives; switching convertors; control system synthesis; insulated gate bipolar transistors; harmonic distortion; wide band gap semiconductors; energy systems; power system control
Subjects: Drives; General and management topics; Power electronics, supply and supervisory circuits; d.c. machines; Education and training; Control of electric power systems; General electrical engineering topics; DC-DC power convertors
Wide band gap (WBG) materials are an interesting class of semiconductors that offer a key criterion to the modern technological applications in terms of their high efficiency, high-frequency power applications, and high operating temperature and voltage. The famous families of the WBG semiconductors are the silicon carbide (SiC), the gallium nitride (GaN), the gallium oxide (Ga2O3), the diamond, and the aluminum nitride (AlN). Attention has turned to work on basic electronic devices like Schottky diodes, solar cells, IGBT transistors, and HEMTs using the WBG semiconductors to perform the characteristics of the device and to reach the suitable properties for the desired technological applications.
In this chapter, we present the basic physical properties and the principle techniques for the characterization of the WBG materials. We present also the physics background of some powerful semiconductor devices based on WBG materials which allow an important achievement in the recent research and development requested by the modern technologies and the highly advanced science of such class of semiconductor materials. We conclude this chapter by a case study where we investigate the interface state of the Schottky contact based on 4H-SiC as a WBG material. The studied contacts are formed by a metal (molybdenum/tungsten) deposited on a WBG semiconductor (4H-SiC). The analysis of these contacts is made via the current-voltage (I-V) measurement of different temperatures. As a result of this study, the existence of the inhomogeneity of the interface metal/4H-SiC is evidenced by the temperature behavior of the physical parameters characterizing these structures.
Renewable energy sources have received considerable attention during the past two decades, owing to the advantages in terms of the absence of greenhouse gas emissions, cleanliness, and sustainability. With the growing energy crisis and environmental consciousness, the global perspectives are in the direction of promoting sustainable technologies. The wind and solar energy conversion systems under such a perspective are found very promising. Therefore, these two renewable technologies are the main focus of this chapter.
The power electronic converters interfacing play a vital role in the solar and wind energy conversion system with a maximum conversion efficiency. These converters can introduce reliability challenges to the system if not properly designed. A reliability index of a power electronics converter is calculated in terms of design, operation, maintenance, and performance assessment. Generally, the converter failure rate contributes to its overall cost of energy. In this regard, one of the significant challenges facing is reliability.
The overall purpose of a reliability analysis is to analyze failure and its impact on systems and to develop a rigid and reliable system.
This chapter focuses on the reliability of the used power electronic systems applied for wind energy conversion system (WECS) and solar energy conversion system (SECS).
The ever-increasing global environmental concerns, the introduction of new energy sources to the power grid, added to the rapid technological development of power electronics, and control of electric drives, have recently provided new opportunities to reduce CO2 and other polluting material emissions, toward a next generation of electrified transport systems.
The integration of power electronics has experienced a massive penetration in modern transportation systems such as electric vehicles (EV), ships, and rail applications, thereby playing a major role in the reduction of polluting emissions, either by decreasing the dependency on fossil fuels or by helping to increase the efficiency in hybrid systems.
In this context, the electrification of transport systems has resulted in the development of several configurations for hybrid and full-electric power-train arrangements, both introducing the use of high-performance electrical machines and power electronics drives.
Due to the critical importance of transportation systems in the society and economy, aspects such as safety, availability, sustainable operation, and efficiency constitute a central part in the design process. Therefore, electronic power converters must be analyzed in terms of voltage levels, power density, and system redundancy, among other criteria. Moreover, the infrastructure required to operate the new large-scale electric transportation systems must consider energy storage, charging capabilities, and accomplishment with renewable energies policies. These features introduce several challenges for the next generation of electrification transportation systems, which are examined within this chapter.
Multilevel inverter (MLI) topologies have gained more attention in many applications. These MLIs can classify into standard/traditional and hybrid/advanced structures. The conventional MLIs, including neutral-point-clamped (NPC), flying capacitor (FC), and cascaded H-bridge (CHB), have some structural/topological and control/modulation drawbacks which limit their applications. Many novel topologies have been reported to overcome structural constraints associated with these topologies. Likewise, several new control/modulation methods have been introduced to improve the performance of classical converters under various operating conditions. This chapter aims to review and shed light upon the merits and demerits of these recent contributions. To this end, at first, the limitations of well-established standard multilevel converters are highlighted. Then new topologies introduced in the recent 5 years are discussed along with their applications. Recent advances made in the control and modulation methods of MLIs are also addressed. A comparative case study is conducted between the conventional three-level NPC and one of the recently proposed topologies (3L-NPCI2) by simulation and experimental results. Finally, some challenges and future trends in the development of this technology are highlighted.
In this chapter, different multilevel level inverters, which have been presented in the literature, were studied. These studies included the calculation of the key equations that can be considered as the characteristics of topology, such as the count of the switches, IGBTs, DC voltage sources, the variety in the magnitudes of the DC voltage sources, the total blocked voltage by the switches, and the maximum count of switches that are switched on to pass the output current. In the end, a comparative study was done using some of these topologies to determine the advantages and demerits of these topologies toward the conventional H-bridge inverter. The results of these comparisons were studied, and it has resulted that some of these topologies show better features in some parameters. However, they may show worse results in the other parameters. Moreover, the meaning of optimization in multilevel inverters was described and applied to a multilevel inverter topology.
This chapter reports a design for linear and nonlinear switching-mode oscillator based on GaN high electron mobility transistors (HEMTs) for wireless power transfer (WPT) applications. The linear oscillator is based on a lower power depletion-type GaN-HEMT, while the nonlinear oscillator is implemented using a higher power enhancement-type GaN transistor. In-house advanced design system (ADS)-based model has been used for designing the lower power oscillator, while a commercial LTSpice model has been implemented for designing the higher power oscillator. The oscillators are designed and simulated using computer-aided software (CAD) and then realized and tested with transmitting and receiving coils. The realized linear-mode oscillators show good efficiency of dc-to-ac conversion (up to 45%) with lower total harmonic distortion (THD) in the order of 10%. This makes those oscillators proper for electromagnetic interference (EMI) sensitive applications. On the other side, the switching-mode oscillators provide higher efficiency up to 90%, which is optimal for designing high power WPT systems.
In this chapter, the idea of partial power processing is elaborated in detail. First, the concept is divided into two groups of differential power processing (DPP) and series partial power converters (S-PPCs). The focus of this chapter is mainly S-PPCs. Second, the S-PPCs are discussed considering the configuration of the converters. To analyze and demonstrate the behavior of S-PPCs, there are a variety of parameters like partiality, non-active power processing, and DC-DC topology requirements. The parameter's concept is explained and the methods of applying these parameters to S-PPCs are described. In the last section, numerous examples of S-PPCs application in different fields are presented and for each application at least one S-PPC topology is depicted and investigated.
In this chapter, first, some applications for the N-phase to m-phase matrix converter were expressed. Then, the procedure of modeling matrix converters was described. After, three different control methods of the positive, negative, and combined, based on the PWM techniques, were proposed. These control methods can synthesize the desired even if there are unbalances at the input or output sides. If the switching frequency is chosen so higher than the input and output frequencies, the generated harmonics will be almost around the switching frequency. So they can be eliminated by using a low-pass filter.
DC-DC converters play a major role in a various applications in automobile engineering, portable electronics and LED drivers. In this work, basic converters like Buck and Boost converters operating in continuous conduction mode (CCM) considering the non-ideal parameters are modelled using volt-sec and amp-sec balance equations. The equations were simulated using MATLAB®/Simulink® software using appropriate step time, solver and the transients in inductor current and capacitor voltage were observed. Later, using the state space averaging (SSA) technique the transfer function of inductor current to duty ratio (G id) and output voltage to duty ratio (G vd) were derived. The parameters like low-frequency gain, gain margin (GM), phase margin (PM), crossover frequency, and stability were analysed using MATLAB software. It was found the non-ideal boost converter showed instability under constant voltage operation due to the presence of right half plane (RHP) zero. In order to validate the obtained transfer function using SSA, a new control technique called circuit averaging technique was used. The validation was performed using LTspice software tool. The frequency response of G id and G vd obtained using MATLAB and LTspice software tools showed a perfect match.
Electric traction drive prefers direct torque control due to its simplicity and easy implementation on permanent magnet machines (PMMs). Variable switching frequency, as well as more torque and flux ripples, are the key challenges of conventional direct torque control. A modified switching table-based direct torque control has been widely adapted for controlling the PMM drives. Artificial intelligent-based switching table substitutes the switching table and hysteresis comparator provides a significant reduction in current harmonic distortion, torque, and flux ripple, which shows a greater advantage in speed control for smart electric vehicles. In this chapter, artificial intelligence-based multisector direct torque control is analyzed for a suitable voltage vector selection to minimize torque and stator flux ripple. To demonstrate, a comparison of the intended switching tables shows the virtues of each switching table on the performance of the multisector direct torque control strategy. This premises on the theory of keeping the divergence between the commanded torque and the calculated torque as small as possible and does not provide information on the conduction time mode of three-phase switching. It adapts changes in the three phase-current waveform to keep electromagnetic torque consistent, eliminating the commutation torque ripple that would have occurred with conventional direct torque control (CDTC). Simulation results are taken in MATLAB®/Simulink®, and it is observed that the PMM ripples are reduced, particularly at high rotational speeds.
This chapter has presented the design and implementation of an auto-tuning based on the MRFT tuning method for the class of digitally controlled voltage-mode dc-dc buck converters. The presented auto-tuning is simple and consists of short test and tuning stages, and it guarantees stability through allowing the specification of the gain or phase margin - all without requiring any knowledge of the converter or load parameters. The chapter provides a theoretical background on the MRFT, as well as an explanation of how the test stage is adapted to dc-dc switching power converters. The derivation of optimal tuning rules for the class of digitally controlled voltage-mode dc-dc buck converters is also given in detail. Besides guaranteeing a specified gain margin, the tuning rules are also optimized for dynamic performance of the considered class of converters. It is shown through an experiment on a test converter that the MRFT auto-tuned controller performs closely to an optimized controller designed with full knowledge of the test converter's parameters. It is finally noted that even for dc-dc buck converter designs that have LC parameters outside the design range used in developing the tuning rules, the auto-tuning still guarantees a stable performance with the specified gain margin and through that provides an acceptable performance.
Analysis of a SM DC-DC buck and boost converters dynamics using the LPRS methodology is proposed. Some design aspects are considered too. The buck converter model can be directly transformed to a RFS, which allows one to directly apply the LPRS method for analysis of the SM converter dynamics and control design. The boost converter model was transformed from a switching model to a RFS too. However, the plant dynamics after this transformation are nonlinear. And there two different approaches to analysis: linearization of the nonlinear dynamics and the use of the formulation of the LPRS for a nonlinear plant, with subsequent derivation of the LPRS function. Both options are explored in this book chapter, and the analysis of the boost converter was carried for both the linear and the nonlinear dynamic models. The functionality of the LPRS method, which features exact determination of the frequency and amplitude of chattering and possibility of analysis of external signal propagation, was fully utilized in the presented development. Chattering (ripple) in inductor current and output voltage, as well as, the effect of source voltage fluctuations, which may come from rectification of AC voltage, were analyzed through the concepts of the LPRS method. It was possible to identify the reason and explain the effects of the source voltage fluctuations, which are a combination of AM and input signal propagation effects. The proposed analysis is supported by simulations and experimental results. The presented methodology makes it a superior tool of analysis of SM DC-DC buck and boost converters.
Fractional calculus is considered nowadays as a true option for modelling and efficiency enhancement of power electronic converters. This chapter addresses the integration of fractional calculus into a control strategy to regulate the output of the basic configurations of buck, boost, or buck-boost converter from a practical perspective. The strategy considers a non-integer approach to investigate its effectiveness in controlling minimum and non-minimum phases systems. A standard PID controller structure is used to integrate the fractional-order derivative and integral through a biquadratic approximation of the Laplacian operator. The viability and effectiveness of the resulting controller is corroborated numerically and experimentally through its physical implementation. Fast response, stable regulation and good tracking characteristic were the most remarkable results.
The adjustable speed drives reduce the energy loss over fixed speed drives leading to a significant amount of energy cost savings in various industry applications. Particularly, the demand for high-power adjustable speed drives in medium-voltage capacity are continuously growing in industries due to the increase in production demand, low operating cost, and economy of scale. Nevertheless, the development of medium-voltage drives involves various requirements and challenges on the line-side or grid-side (e.g., total harmonic distortion, power factor, LC resonance), motor-side (e.g., motor winding derating, dv/dt, common-mode voltage, LC resonance), and semiconductor devices (e.g., switching frequency, reliability, series connection). The power converters and control methods play a key role in addressing the medium-voltage adjustable speed drive challenges. In this chapter, the latest developments in medium-voltage drive technologies including applications, semiconductor devices, power converter topologies, and control methods are presented. Finally, the future trends of medium-voltage drives, and conclusions are summarized in this chapter.