This paper proposes a space vector-based pulse width modulation scheme that incorporates common-mode voltage elimination and bus clamping for a dual six-phase inverter configuration driving an asymmetrical six-phase motor with open-end stator windings. The proposed scheme completely eliminates the common-mode voltage generated by both inverters. Additionally, the employed switching sequence enables bus clamping, which reduces switching losses compared to conventional patterns. The clamping strategy also ensures balanced power loss distribution among the switching devices. By eliminating the resultant common-mode voltage, the scheme allows for the use of a shared DC-link between the two inverters. Furthermore, it suppresses non-torque-producing harmonics in the stator windings of the ASPM and achieves higher DC bus utilization compared to conventional six-phase drive configurations. The effectiveness of the proposed scheme is validated through extensive simulations conducted in the MATLAB/Simulink environment.

The need for sinusoidal voltage waveforms with adjustable amplitude and frequency is essential in many applications. Power electronics converter-based supplies with pulse-width modulation (PWM) introduce high-order harmonics at their output and the use of filters is mandatory to remove the harmonic distortion. However, output filters are undesired in some specific applications such as B-H meter of magnetic devices because they act as the inverter output load together with the actual load affecting the measurement results. This paper explains the principles of operation and design considerations of a controlled AC power supply with nearly sinusoidal output. The proposed AC power supply consists of switching-mode DC-DC converters connected at the DC links of asymmetric cascaded H-bridges (ACHB). The proposed AC power supply offers a nearly sinusoidal output even at high-current low-voltage outputs. A modular compact 63-level supply is designed for the special case of the B-H meter and the simulation results are presented.

Proportional-resonant and repetitive controllers are widely used for grid current control in single-phase grid-connected inverters. This paper presents a comparative study of the performance of these two controller types in mitigating low-order harmonics with a descriptive analysis of their design. Moreover, low-order harmonics arising from the dead time in single-phase highly efficient and reliable inverter concept (HERIC) are investigated. Then, a novel scheme based on the harmonic decoupling network and second-order generalized integrator is designed to extract the low-order harmonics from the grid current. These extracted components are subtracted from the reference current to efficiently attenuate the low-order components. Experimental studies show an efficient mitigation of the low-order harmonics with the proposed scheme.

This paper introduces a new soft-switched high gain converter topology with Input Current Smoother (ICS) capability to mitigate Normalized Peak Inverse Voltage (NPIV). By employing soft switching techniques, the converter achieves significant reductions in switching losses and improved overall efficiency, making it ideal for high-frequency applications. The proposed converter enhances voltage gain while minimizing voltage stress on power semiconductors, overcoming the limitations of conventional step-up converters. The paper provides a detailed description of the converter's operation principles, configuration, and steady-state analysis. Performance comparisons with existing topologies demonstrate superior voltage gain, minimized voltage stress on semiconductors, negligible input current ripple, and remarkable efficiency. Finally, simulation results demonstrate the advantages of the proposed converter by using PSCAD software.

A virtual voltage vector based direct torque control (DTC) scheme with enhanced DC bus utilization for an asymmetrical six-phase induction motor (ASPIM) with open-end stator windings is proposed in this paper. In this scheme, the voltage vectors generated by two six-phase, two-level voltage source inverters (VSI) connected to both sides of the stator windings are combined to obtain a virtual voltage (VV) space vector structure in the ASPIM. While generating the virtual voltage vectors it is ensured that the following three conditions prevails in the system: 1) elimination of resultant common mode voltage (CMV) across the stator windings, 2) elimination of triplen order harmonic voltages from the individual 3-phase windings, and 3) nullification of non-torque producing harmonic voltages. Conditions 1 and 2 facilitate the use of a common DC-link for both the VSIs without causing circulation of common mode currents through the stator windings. The third condition obliterates the large, non-torque-producing harmonic currents and consequent losses in the system. The proposed scheme can provide significantly higher DC bus utilization compared to the conventional schemes, for the same DC-link voltage. The effectiveness of the proposed scheme is verified by carrying out simulations using MATLAB-Simulink software, under transient and steady-state operating conditions of the drive.

Voltage spikes during the switching transients play an important role in determining the power losses in hard-switching converters. These spikes are functions of several factors at the instant of switching such as DC-link voltage, load current, transistor and diode switching delay times, reverse recovery current of the diode, parasitic capacitance and inductance of the circuit. This paper introduces a numerical approach to accurately model the switching power losses of a single-phase H-bridge (SPHB) inverter. The data required to obtain the equivalent resistance is extracted from the experimental double-pulse tests (DPTs). Then, the concept of local and global rms currents is considered to incorporate the effect of pulse width modulation (PWM) in the estimation of the switching losses. The results are computed for unipolar and bipolar PWM schemes. Finally, the reflection rule is utilized to obtain an equivalent output resistance for the inverter switching losses.

Compared to bipolar, unipolar PWM (UPWM) is advantageous for switching the single-phase H-bridge inverter as it generates an output differential voltage with lower THD. However, the oscillatory nature of the common-mode voltage in UPWM contributes to the ground current in single-phase grid-connected PV inverters, which is the motivation of the various transformerless inverters with UPWM. Although, the benefits of UPWM (mainly the good characteristics of output differential voltage) in existing transformerless inverters is somehow missing. In this paper, after analyzing different switching schemes of HERIC (highly efficient and reliable inverter concept) converters, a modified UPWM is proposed in which the full sawtooth carrier and sinusoidal reference waveforms (changing between negative and positive maximums) are compared in order to increase the number of voltage pulses and reduce the THD of grid current. The superiority of the proposed UPWM has been confirmed by comparative simulation studies over a 1-kW single-phase grid-connected PV inverter.

In this paper, a complete model of faulty multiphase permanent magnet synchronous machines (PMSMs) is presented in phase domain when the machine is fed by voltage-source inverters (VSIs). The presented model is helpful for implementing the simulation model of the machine when it is supplied by voltage inputs. Then, an orthogonal fault-specific transformation matrix is introduced to acquire the machine model in vector-space decomposition (VSD) domain. This model is helpful in the sense that it establishes mathematic relations between the stationary components of machine currents in multi-star (MS) and VSD domains. Based on these relations and along with transformation of VSD components to synchronous and anti-synchronous reference frames, a current sharing strategy is obtained to distinguish the contribution of each three-phase winding set to the developed torque under faulty conditions. The reference values in VSD domain are set so that the lowest ohmic losses are dissipated under faulty conditions.

Several modelling approaches of multiphase machines have been proposed in literature to control the machine in healthy or faulty conditions. The variety of the models may confuse the researchers to select the proper ones. In this paper, vector space decomposition (VSD), multi-star (MS), and decoupled MS (DMS) models are developed with detailed explanations for triple three-phase (or asymmetric nine-phase) permanent magnet synchronous machine (PMSM). It is shown that the machine differential equations are not fully decoupled in DMS modelling. The presented approaches can be extended to any types of multiple three-phase PMSM. Also, two new models are introduced with the use of specific transformation matrices in order to provide the current sharing between different three-phase winding sets and for compensation of current harmonics arising from inverter nonlinearities or machine structure. These models are necessary to design the parameters of the control system in order to have the optimum dynamic response.

Multi-phase AC drives have gained interest and popularity in the research field of full-electric aircraft (FEA). Without excessive complication, they improve highly relevant aspects of the drive including fault-tolerance, which is crucial for air transportation. In this paper, a novel concept is proposed for the electric propulsion system for the aircraft, combining the redundancy of a six-phase Permanent Magnet Synchronous Motor with the modularity of multilevel cascaded H-bridge converters. The proposed system increases the flexibility, performance, and reliability of the electric power train. A mathematical model of the drive has been set up and some simulations exploiting different operating modes have been successfully carried reporting the main results in this paper.

Hardware-in-the-loop (HIL) simulation is a technique that is being used increasingly in the development and test of complex systems. Real-world testing of an intricate system in a field-like power plant can be challenging, time-consuming, expensive, and hazardous. HIL emulators allow engineers to test devices thoroughly and efficiently in a virtual environment with high reliability and minimum risk of defect. In this paper, the complete electric power system (including generator, turbine-governor, excitation system, transmission lines, transformer, external grid and related loads) is implemented in a MATLAB/Simulink environment. Different virtual instrument pages are modeled in the graphical programming language of LabVIEW which enable fast and reliable measurement functions such as data acquisition, archiving, real-time graphical display and processing. The interaction between MATLAB and LabVIEW is accomplished by generating a Pharlap ETS Targets*.dll file which enables the two software to exchange real-time data. Also, a real 1518-kW excitation system is considered as a test case for the introduced HIL system. This equipment is connected to LabVIEW software through a National Instrument PXI technology. Different scenarios (electrical frequency/active power change, voltage step response, etc.) are simulated in the designed power system emulator (PSE). The validity of the implemented model for the excitation system is verified by finding good matching between MATLAB and HIL simulation results.