Hybrid Cascaded H-Bridge Multilevel-Inverter Induction-Motor-Drive Direct Torque Control for Automotive Applications

International audienceThis paper presents a hybrid cascaded H-bridge multilevel motor drive direct torque control (DTC) scheme for electric vehicles (EVs) or hybrid EVs. The control method is based on DTC operating principles. The stator voltage vector reference is computed from the stator flux and torque errors imposed by the flux and torque controllers. This voltage reference is then generated using a hybrid cascaded H-bridge multilevel inverter, where each phase of the inverter can be implemented using a dc source, which would be available from fuel cells, batteries, or ultracapacitors. This inverter provides nearly sinusoidal voltages with very low distortion, even without filtering, using fewer switching devices. In addition, the multilevel inverter can generate a high and fixed switching frequency output voltage with fewer switching losses, since only the small power cells of the inverter operate at a high switching rate. Therefore, a high performance and also efficient torque and flux controllers are obtained, enabling a DTC solution for multilevel-inverter-powered motor drives

THD Analysis of a Seven, Nine, and Eleven Level Cascaded H-Bridge Multilevel Inverter for Different Loads

A multilevel inverter is implemented for generating the required staircase AC voltage of output from various steps of voltages of DC sources. The multilevel inverter gives a better harmonic spectrum and a compatible quality of output. This article delves into an analytical analysis of the total harmonic distortion (THD) of different multilevel inverters which employ a multicarrier PWM technique. This technique is implemented for operating the switches at their respective angle of conduction. This paper deals with various cascaded H-Bridge multilevel inverters (CMI) with various loads that are modelled by implementing the MATLAB/Simulink platform. The output gives a better result of the proposed model in terms that it is helpful towards reducing the THD and the losses of switching

OPTIMAL PULSE WIDTH MODULATION OF MULTILEVEL INVERTERS FOR MEDIUM VOLTAGE DRIVES

Ph.DDOCTOR OF PHILOSOPH

Induction Motors

AC motors play a major role in modern industrial applications. Squirrel-cage induction motors (SCIMs) are probably the most frequently used when compared to other AC motors because of their low cost, ruggedness, and low maintenance. The material presented in this book is organized into four sections, covering the applications and structural properties of induction motors (IMs), fault detection and diagnostics, control strategies, and the more recently developed topology based on the multiphase (more than three phases) induction motors. This material should be of specific interest to engineers and researchers who are engaged in the modeling, design, and implementation of control algorithms applied to induction motors and, more generally, to readers broadly interested in nonlinear control, health condition monitoring, and fault diagnosis

Modulation and control strategies for multilevel five-phase open-end winding drives

Industrial and automotive trends clearly demonstrate an increased interest in medium- and high-power variable speed drives. Despite constant progress in the technology, the semiconductor characteristics are still the bottleneck in drive designs, due to their limitations to block high voltage (several kilovolts) and conduct high current (several hundreds of amperes per-phase). For this reason and numerous other advantages, solutions based on multilevel inverters and multiphase machines are considered in recent years. The open-end winding drives are an alternative approach for drives construction. This thesis investigates carrier based pulse width modulation schemes for five-phase open-end winding drives. Two drive topologies, with isolated dc-links of two inverters, are considered. The first one consists of two two-level inverters and a five-phase machine. The second topology utilises one three- and one two-level five-phase inverter. It is shown that the same drive structure can produce a different number of phase voltage levels, when different dc-link voltages of two inverters are in use. Hence, dc-link voltage ratio is considered as an additional degree of freedom. An open-end winding structure that comprises of two two-level inverters offers harmonic performance equivalent to three- and four-level single-sided supply. The second drive structure under analysis is able to produce four, five and six voltage levels, depending on utilised dc-link voltage ratio. Modulation schemes are classified in two categories. So-called coupled modulation schemes are developed under the assumption that open-end winding drives are equivalent to certain single-sided multilevel solutions. This enables the application of slightly modified modulation methods for multilevel inverters, to the open-end winding configurations. As a consequence, number of utilised voltage levels can be higher than the sum of two inverters’ number of levels. However, this boost in number of levels relies on simultaneous switching in two inverters’ legs connected to the same drive phase,which causes so-called dead-time spikes. The second group, referred to in this thesis as decoupled modulation schemes, rely on the separate modulation of two inverters, using voltage references obtained by splitting the overall phase voltage reference, proportionally to inverters’ dc-link voltages. Hence, this kind of modulation offers somewhat worse harmonic performance, when compared to coupled modulation schemes. Special attention is paid to the stability of dc-link voltage levels, which is one of the most important figures of merits of quality for multilevel drives. Using a novel analysis approach, it is demonstrated that utilisation of optimal harmonic performance offered by coupled modulation methods leads to unstable dc-link voltages, but only in the cases where dc-link voltage ratio is used for increment of available number of voltage levels. Decoupled modulation methods offer stable dc-link voltages, regardless of drive configuration. One of the drawbacks of the analysed open-end winding drives is the need for two isolated dc sources, which form dc-link voltages of two inverters. For that reason, a possibility to use only one dc-source in open-end winding drives with isolated inverters is considered. Analysis shows that both drive topologies can be operated using so-called bulk and conditioning inverter control, where bulk inverter is supplied from an active dc source, but operates in staircase mode, while conditioning inverter performs high-frequency pulse width modulation, in order to suppress low-order harmonic content. This kind of operation is investigated in details for two specific configurations in which two inverters never operate at the same time in PWM mode, when coupled modulation methods are used. Comparison of the results shows that topology which comprises from one three- and one two-level inverter is more suitable for this kind of control. Together with previously analysed configurations and modulation strategies, dynamic performance of this novel drive is tested under the closed-loop speed control. Experimental results show that open-end winding drives are suitable for a wide range of applications

A review of architectures and concepts for intelligence in future electric energy system

Renewable energy sources are one key enabler to decrease greenhouse gas emissions and to cope with the anthropogenic climate change. Their intermittent behavior and limited storage capabilities present a new challenge to power system operators to maintain power quality and reliability. Additional technical complexity arises from the large number of small distributed generation units and their allocation within the power system. Market liberalization and changing regulatory framework lead to additional organizational complexity. As a result, the design and operation of the future electric energy system have to be redefined. Sophisticated information and communication architectures, automation concepts, and control approaches are necessary in order to manage the higher complexity of so-called smart grids. This paper provides an overview of the state of the art and recent developments enabling higher intelligence in future smart grids. The integration of renewable sources and storage systems into the power grids is analyzed. Energy management and demand response methods and important automation paradigms and domain standards are also reviewed.info:eu-repo/semantics/publishedVersio

A Medium-Voltage Inverter-Fed IM Drive Using Multilevel 12-Sided Polygonal Vectors, With Nearly Constant Switching Frequency Current Hysteresis Controller

In this paper, a current error space vector (CESV)-based hysteresis current controller for a multilevel 12-sided voltage space vector-based inverter-fed induction motor (IM) drive is proposed. The proposed controller gives a nearly constant switching frequency operation throughout different speeds in the linear modulation region. It achieves the elimination of 6n +/- 1, n = odd harmonics from the phase voltages and currents in the entire modulation range, with an increase in the linear modulation range. It also exhibits fast dynamic behavior under different transient conditions and has a simple controller implementation. Nearly constant switching frequency is obtained by matching the steady-state CESV boundaries of the proposed controller with that of a constant switching frequency SVPWM-based drive. In the proposed controller, the CESV reference boundaries are computed online, using the switching dwell time and voltage error vector of each applied vector. These quantities are calculated from estimated sampled reference phase voltages. Vector change is decided by projecting the actual current error along the computed hysteresis space vector boundary of the presently applied vector. The estimated reference phase voltages are found from the stator current error ripple and the parameters of the IM

ESSE 2017. Proceedings of the International Conference on Environmental Science and Sustainable Energy

Environmental science is an interdisciplinary academic field that integrates physical-, biological-, and information sciences to study and solve environmental problems. ESSE - The International Conference on Environmental Science and Sustainable Energy provides a platform for experts, professionals, and researchers to share updated information and stimulate the communication with each other. In 2017 it was held in Suzhou, China June 23-25, 2017

NASA Tech Briefs, Spring 1977

Topics: NASA TU Services: Technology Utilization services that can assist you in learning about and applying NASA technology; New Product Ideas: A summary of sel~ted innovations of value to manufacturers for the development of new products; Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Life Sciences; Mechanics; Machinery; Fabrication Technology; Mathematics and Information Sciences