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This work offers a fault-tolerant strategy that uses a combination of a hardware-based and a control-based faulttolerant methods for multilevel (ML) cascaded H-bridge (CHB) converters. The possibility of a switch failure in an ML converter is higher than a conventional inverter due to the increased number of power electronics switches. Although the event of a single switch failure is more likely, nonetheless, the fault tolerant operation of a ML converter with two or more faulty switches needs to be addressed as well. This article first offers a hardware topology that can bypass the faulty H-bridge cell and replace it with an auxiliary cell, in the event of a single switch failure. Then, it enhances the hardware topology with a modulation-based faulttolerant method for the event of more than one defective switch. Using this strategy, the CHB converter will be able to operate with maximum achievable output voltage in the post-fault condition. Experimental results are presented for a seven-level CHB converter for the validation of the theoretical outcomes. [ABSTRACT FROM AUTHOR]

This paper presents a torque ripple minimization method for a permanent magnet synchronous motor (PMSM) drive system that utilizes a modified quasi-Z-source (qZS) inverter. The proposed modified qZS network is designed by adding an extra switching device to the conventional qZS topology and provides a wider range of capabilities for inverter input voltage control, e.g., both step-up and step-down operations. It also allows for modification of the traditional switching sequence selection scheme when using the space vector modulation (SVM) for switching. The provided flexibilities are leveraged to develop a control system that minimizes the torque ripples during PMSM operation while satisfying conventional control objectives such as shaft speed control. The control system is comprised of an input voltage optimization subsystem with the goal of torque ripple minimization, which provides the reference for a cascaded modulated model predictive control subsystem for the modified qZS network control, and a motor side predictive control subsystem. The control system employs a new switching sequence selection scheme for SVM modulation to further reduce PMSM torque ripples. Experimental results are provided to validate the theoretical outcomes. [ABSTRACT FROM AUTHOR]

This paper develops a modulation based fault-tolerant (FT) strategy for restoring the operation of three-phase modular multilevel converters (MMCs) with faulty switches. This FT strategy is based on a proposed modified space vector modulation (SVM) technique that generates balanced line-to-line (line) voltages even in the case of a fault occurrence. In the postfault operation, the proposed strategy is able to restore the fundamental amplitude of the line to the neutral (load) voltages to that of the normal operation condition with a slightly increased voltage stress over the switches in the faulty phase. In this paper, first a brief background about MMCs and SVM technique is provided. Then, the proposed FT strategy and the modified SVM technique are presented. Finally, several simulation and experimental results are provided to validate operation of the proposed strategy. [ABSTRACT FROM AUTHOR]

This paper proposes a new modulated model predictive control method for the control of modular multilevel converters (MMCs) in voltage source converter-high voltage dc systems. The proposed method retains the advantages of the conventional finite control set-model predictive control methods by programing the nonlinear properties of the MMC into the design calculations while minimizing the ac line and circulating current ripples and steady-state error by generating modulated switching signals with a fixed switching frequency. In this paper, first, the predictive modeling of the MMC is provided. Next, the proposed control method is described. Then, the application of the proposed method to an MMC system is detailed. Finally, experimental results from an MMC system connected to a three-phase grid are provided to validate the theoretical outcomes. [ABSTRACT FROM AUTHOR]

This study presents a power electronics rapid prototyping platform that can be used to implement a wide range of power conversion circuits and systems quickly and inexpensively. The proposed platform features a modular structure, which is consisted of a control board and a power board. The control board includes adjustable signal conditioning circuitry, adjustable gate driving circuits, networking interfaces, and a fast processing unit that can be programmed easily using MATLAB Simulink code generation tools. The power board houses current and voltage sensors and electric sockets that could be used for implementing various power stage circuits. A case study involving the use of the proposed platform for constructing a buck converter is discussed. A cost evaluation of the proposed platform has also been provided. [ABSTRACT FROM AUTHOR]

This work proposes a new multiobjective modulated model predictive control (MPC) method for control of power electronic converters. The proposed method retains the advantages of conventional MPC methods in programing the nonlinear effects of the converter into the design calculations to improve the overall dynamic performance of the system and builds upon that by offering a new modulation technique for MPC to minimize the voltage and current ripples through by using a fixed switching frequency. To demonstrate the effectiveness of the proposed method, it has been used to overcome the stability problems caused by a constant power load in a multi converter system as a case study. Experimental results from a prototype cascaded converter system are provided to validate the theoretical outcomes. [ABSTRACT FROM PUBLISHER]

This paper presents a new high-frequency modulation method for multilevel converters. The proposed method provides a broad linear operating range and can be digitally implemented with minimal computational effort. This modulation method creates a phase voltage composed of a rectangular component superimposed on the top of a quasi-square-shaped reference function. The reference functions are defined such that the utilization of the dc-link voltage is maximized in any modulation index, while the dv/dt of the switches is always the minimum possible value. In order to implement the proposed method, an update time that is much shorter than the fundamental period is defined in the algorithm for updating the rectangular components of the reference voltage. The high-frequency rectangular component can then be imposed on the reference function to generate the final switching function by switching between two voltage levels during the time between two update instances. Several experimental results are provided to evaluate the performance of the proposed method and to compare its operation to conventional methods. [ABSTRACT FROM PUBLISHER]

This study proposes a fault-tolerant scheme for an impedance-sourced cascaded H-bridge (CHB) converter that can fully restore the converter operation to the pre-fault conditions without any hardware intervention. The proposed faulttolerant scheme has three key elements: a new quasi-z-source CHB converter, a modified modulation method for the introduced z-source CHB, and a modified implementation of the fundamental phase shift compensation (FPSC) method. In case of a fault on one of the inverter switches, the proposed fault-tolerant scheme enables the z-source CHB to generate balanced line-to-line voltages with the same amplitude as the pre-fault voltages, while evenly distributing an inevitable voltage stress increase over all converter switches. In this study, first a brief review of CHB converters and the FPSC method is provided. Then the proposed fault-tolerant scheme is introduced. Finally, several experimental results from a prototype converter are provided to validate the operation of the proposed strategy. [ABSTRACT FROM AUTHOR]

This paper proposes a new fault-tolerant strategy for a multilevel converter with an integrated impedance-source network. The proposed fault-tolerant strategy leverages the flexibility provided by the impedance-source network to implement the fundamental phase-shift compensation (FPSC) method in order to restore operation of a multilevel converter with one or more faulty switches to the prefault conditions. In case of a fault occurrence, the proposed fault-tolerant strategy makes the most use of the remaining converter capacity and generates balanced line-to-line voltages, while evenly distributing an inevitable voltage stress increase, over all converter switches. In this paper, first, a brief background about an impedance-source based cascaded H-bridge converter and a suitable modulation method for it is provided. Then, the FPSC method is explained and the proposed fault-tolerant strategy based on this method is introduced. Finally, several experimental results from a prototype converter are provided to validate the operation of the proposed strategy. [ABSTRACT FROM PUBLISHER]

This paper proposes a new fault-tolerant strategy for the purpose of revamping the performance of three-phase multilevel (ML) converters with faulty switches. The proposed fault-tolerant strategy is based on an adaptation of the modified space vector modulation (SVM) technique to the fundamental phase-shift compensation method. The proposed fault-tolerant strategy generates balanced line-to-line voltages with increased voltage levels in the faulty condition. In this paper, first a brief background about cascaded H-bridge (CHB) ML converters and SVM technique is provided. Then the proposed fault-tolerant strategy and the modified SVM technique are presented. Finally, several experimental results are provided to validate operation of the proposed strategy. [ABSTRACT FROM AUTHOR]

This paper proposes a new fault-tolerant strategy to revamp performance of three-phase multilevel converters with a single faulty switch. The proposed fault-tolerant strategy is based on the application of a modified selective harmonic elimination (SHE) technique in conjunction with the fundamental phase-shift compensation method. The proposed fault-tolerant strategy makes the most use of the converter capacity in the faulty condition, generates balanced line voltages, and eliminates a wide range of lower order harmonics to limit the total harmonic distribution of the converter voltages in the faulty condition. In this paper, first, a brief background about cascaded H-bridge multilevel converters and SHE technique is provided. Then, the proposed fault-tolerant strategy and the modified SHE technique are presented. Finally, several experimental results are provided to validate the operation of the proposed strategy. [ABSTRACT FROM PUBLISHER]

In this study, fault-tolerant operation of multilevel cascaded H-bridge (CHB) inverters is presented and a novel switching strategy based on space vector modulation is proposed. A faulty power switch in high power converters can lead to expensive downtime, loss of productivity and increased costs. Various power switch faults and their influence on space vector diagram of CHB inverters are investigated. In the event of a fault, the output voltage of inverter is reduced and redundant switching states are used to generate balanced line-to-line voltages. By adding some devices to the basic structure, CHB inverter will operate with maximum achievable output voltage. Simulation and experimental results are shown for a five-level CHB inverter to validate the proposed modulation technique. [ABSTRACT FROM AUTHOR]