Simulation study on the improvements of machining accuracy by using smart materials

Smart rheological materials represented by giant electrorheological fluid (GERF) have attracted considerable attention in vibration isolation, microfluidics, and robotics. The traditional control method is primarily to adjust the amplitude of the constant voltage. This paper introduces a GERF damper that works in squeeze mode and uses varying pulse width modulation (PWM) voltage for damping adjustment. The influence of PWM voltage parameters on the damping characteristics of the damper is analyzed through experiments. The similarities and differences between the constant voltage and PWM voltage are discussed. PWM voltage can obtain larger equivalent damping with small duty cycles. A parametric model is established based on the squeeze flow principle to describe the damping characteristics of the damper. The root mean square error between the experimental and model results is less than 0.015, which verifies the accuracy of the model. The results of the vibration platform test show that the PWM voltage control can adjust the transmissibility of the damper in the frequency domain. The amplitude of the vibration is reduced by 56% in the time domain. This study provides a new damping adjustment method for GERF dampers.

In this thesis, a boost chopper using PV (Photovoltaics) system and PWM (Pulse Width Modulation) voltage type power converter were constructed to provide a pleasant environment to the patients in the hospital wards by controlling temperature, humidity and air-conditioning & heating. For the stable modulation of solar cell, synchronizing signal and control signal were processed using one chip microprocessor. Power converter system was constructed with booster chopper and voltage source inverter and test was carried out for both devices. Constant voltage control method was used to track a maximum power point at boost converter control. For the inverter control, synchronizing signal and control signal were processed by microprocessor for the stable modulation according to the switching theory of SPWM (Sinusoidal Pulse Width Modulation) and directions to each sector. Test was carried out for inverter control using SPWM control method. In addition, grid voltage was detected and this grid voltage and inverter output were operated at the same phase for the phase locking with PWM voltage source inverter so that surplus power could be linked to grid. This characteristic was applied on the temperature and humidity sensors in the general buildings and buildings having specific purposes such as hospitals. The good dynamic characteristic of inverter could be obtained by these applications. Also, PWM voltage inverter maintains a high power factor and low-frequency harmonic output so that power can be supplied in the load as well as system.

The number of voltage levels available in pulsewidth modulation (PWM) voltage source inverters can be increased by using a split-wound coupled inductor within each inverter leg and interleaved PWM switching of the upper and lower switches. The magnetizing inductance of the symmetrical split-wound inductor filters the high-frequency PWM voltage differences between the upper and lower switches. The same inductor presents a three-level PWM voltage at the inverter output terminals, with the winding leakage inductance being located in series with the low-frequency output current. Deadtime PWM signal delays can be reduced as DC-rail short circuits are not possible: as a result, the quality and voltage range of the PWM output is improved. Since the inductor windings are technically exposed to high-frequency PWM AC voltages with no DC components, device voltage drops help to reduce the buildup of winding DC currents. Theoretical analysis and a sample design case are presented to illustrate how to design suitable inductors for the various topologies. Simulation and experimental results are used to illustrate the operation of the proposed inverter structures.

This work proposes a methodology to estimate core losses under pulsewidth modulation (PWM) or dc bias ripple voltage excitations. A special hysteresisgraph was built to measure toroidal samples under pulsed voltages. An experimental methodology, based on the principles of ferromagnetism, was implemented to investigate minor loop losses in toroidal samples of oriented and nonoriented FeSi. Triangular induction waveforms with constant dB/dt were generated. The results demonstrated that minor loops produced by PWM voltage, do not affect the major hysteresis loop losses nor the losses of other minor loops measured at different points of the major loop. In these experiments, minor loop losses under PWM voltage were very similar to minor loop losses under dc bias ripple voltage. Aspects of the behavior of minor loop losses as a function of amplitude and magnetic flux density are reported in this work.

Multilevel inverters have gained significant attention in recent years due to their ability to achieve higher voltage and lower harmonic distortion compared to conventional two-level inverters. Pulse width modulation (PWM) techniques play a crucial role in controlling multilevel inverters by generating the required switching signals for their power electronic devices. This paper presents a comprehensive comparative analysis of various PWM techniques employed in multilevel inverters, including sinusoidal pulse width modulation (SPWM), space vector pulse width modulation (SVPWM), carrier-based pulse width modulation (CBPWM), and selective harmonic elimination (SHEPWM). Each PWM technique's advantages, limitations, and suitability for different multilevel inverter topologies are discussed. Furthermore, recent advancements and hybrid PWM techniques are also examined to explore potential improvements in performance and efficiency. This paper aims to provide researchers, engineers, and practitioners with valuable insights into selecting the most appropriate PWM technique for their specific multilevel inverter applications, considering factors such as performance requirements, cost constraints, and ease of implementation.

With the introduction and wide acceptance of gate-turnoff power drives, e.g., bipolars, power FETs, GTOs, the switching behaviour of converters has reached the point where further improvements in firing and switching networks bring out only marginal benefits. Consequently, the research interests in the area of static converters have been shifting toward improving the process of power conversion through a combination of novel circuit topologies and improved voltage and harmonic control PWM (pulsewidth modulation) techniques. As a result, several such techniques have been proposed lately. Although these techniques are clearly superior to the original sine PWM technique, little or conflicting data is available about their merits relative to each other. A critical evaluation of the aforementioned PWM techniques on the basis of application is provided, thereby giving the framework and guidelines for the selection of the best technique for each area of application.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

This paper proposes the pulse width modulation (PWM) technique for the five-phase open-end winding induction motor (FPOEWIM) drive fed from five-phase dual inverter (FPDI) with a single dc source. The selected method gives the advantages of reduced switching losses specifically for induction motor drives working with higher power factors with the elimination of common-mode current (CMC). The method also reduces the computational burden over the processing unit. The proposed PWM technique is explained in detail with the implementation algorithm. The algorithm is used to select the proper switching states based on the reference vector location. Further, the proposed PWM technique is analyzed for the switching losses. The reduction in the switching losses is supported with the switching loss function (SLF) analysis. The SLF for the proposed PWM technique is plotted and compared with the conventional sinusoidal PWM (SPWM) technique. The presented method is simulated and the results are given. The validation of simulated results is done using the experimental results.

End turn grading with resistive–capacitive coupling experiences severe electrothermal stress when subjected to pulse width modulation (PWM) voltage. In this paper, several experiments and simulations were carried conducted for four types of end turn grading. First of all, the temperature rise in the end turn grading increased with a decrease in rise time. When the rise time was less than 500 ns, the temperature rise at the terminal was higher owing to the increased capacitive current coupled from the main wall insulation. Further, the current in the linear region exhibited minimal variation at different fundamental frequencies resulting in synchronized the temperature rise at the terminal and overlap. Furthermore, the jump voltage was the key factor influencing temperature rise in end turn grading, confirmed by comparing different voltage magnitudes. Finally, the transient behaviour of the maximum field in the stress grading material was determined at rise time. The experimental and simulation results indicate that balancing and interdependently addressing the electrical and thermal stress protection in end turn grading is crucial. The study aims to provide an experimental and theoretical foundation for an insulation system of inverter‐fed rotating machinery operating under PWM voltage.

The Flying Capacitor Multi Level Inverter (FCMLI) has a great advantage with respect to the availability of voltage redundancies. This work proposes a switching pattern for a modified inverter structure. It is used to improve the performance of chosen single phase five level H-bridge type FCMLI as compared to conventional FCMLI. The chosen multi level inverter is simulated for various multicarrier based Pulse Width Modulation(PWM) techniques for a resistive load. The PWM techniques include Phase Disposition (PD) PWM, Phase Opposition and Disposition (POD) PWM, Alternative Opposition and Disposition (APOD) PWM, Carrier Overlapping (CO) PWM, Phase Shift (PS) PWM and Variable Frequency (VF) PWM and the harmonics of the output voltages are observed for various modulation indices. The performance of chosen FCMLI is confirmed through MATLAB-SIMULINK based simulation. It is observed that sinusoidal reference with PODPWM provides output with relatively low distortion. Its also seen that COPWM strategy is found to perform better since it provides relatively higher fundamental RMS output voltage.

This paper presents a novel switching sequence for Space Vector Advanced Pulse Width Modulation generation for Z source inverter. The Performances of an inverter depends on what type of modulation strategies is used to switch. There exists different types of classical and advanced Pulse Width Modulation (PWM) techniques to switch the traditional Voltage Source Inverter (VSI).The advanced PWM techniques are superior to classical PWM techniques in respect of load current ripple, Total Harmonic Distortions, switching losses. The same concept of advanced PWM techniques for VSI is applicable for Z-Source Inverter. This paper proposes certain vector sequences based on advanced PWM techniques for ZSI. The proposed vector sequences are analyzed in respect of load/line current ripple based on stator flux ripple concept. The superiority of the advanced PWM techniques over classical is verified by simulation study of a ZSI in PSim9.1.1 Environment for R-L and different motor load conditions.

The five-phase loads with Multi-Level Inverters (MLI) are preferred by industries in high and medium power applications due to lower switching loss, voltage stress across switches, etc. The controlling of a five-phase motor drive is done by Pulse Width Modulation (PWM) techniques. This paper discusses different multi carrier PWM techniques, such as Level Shifting Carrier (LSC) PWM and Phase Shifting Carrier (PSC) PWM techniques available for controlling the inverter drive. The simulation is carried out for all PWM techniques and load voltage, voltage THD, Common Mode Voltage (CMV), and DC-link voltages are noted and compared among the PWM techniques.

The increasing integration of renewable energy sources such as solar and wind energy into modern power grids necessitates advanced power conversion technologies. Solid-state transformers (SSTs) play a critical role in this context, particularly in the low/medium-voltage dc to medium-voltage ac conversion stage. However, the performance of SST is heavily influenced by the employed pulse width modulation (PWM) technique used in switching of the power converter. Conventional PWM methods often lead to significant harmonic distortion and power losses, limiting overall system efficiency and thermal stability. This work presents an advanced trapezoidal-triangular carrier-based PWM technique designed to reduce the total harmonic distortion (THD) and power loss of the cascaded H-bridge (CHB) multilevel inverter (MLI) used in SST. The proposed approach is evaluated through comprehensive simulations in MATLAB/Simulink and PLECS, achieving an unfiltered output voltage THD of 16% and total power loss of 10.76 kW for a 300 kW CHB inverter, both improvements over existing PWM techniques. A scaled-down laboratory prototype is developed and tested to experimentally validate the simulation results. The findings confirm that the proposed PWM strategy effectively enhances the performance of the CHB inverter deployed in the SST, making it a promising solution for efficient and reliable renewable energy integration into the power grid.

Carrier-based sinusoidal pulse-width modulation techniques for flying capacitor modular multi-level cascaded converter

When calculating the permanent magnet (PM) eddy current loss (ECL) in the interior permanent magnet synchronous machine (IPMSM) under pulse width modulation (PWM) voltage source inverter (VSI) supply, it is very important to take the high frequency harmonic voltages (HFHVs) in the input voltage into consideration because most of the PM ECL in IPMSM with distributed windings is caused by them [1–2]. However, common finite element analysis (FEA) with sinusoidal current source supply isn’t able to take the HTHVs into consideration and the coupled field-circuit time-stepping FEA under PWM VSI supply with fine time step is needed for the calculation, which is very time-consuming especially when conducting 3D FEA to take the end effect and axial segmentation into consideration. A hybrid method with the combination of 2D FEA and analytical method has been proposed in [3] for fast calculating the PM ECL considering axial segmentation. However, the 2D time-stepping FEA with fine time step, which takes several hours for one case study, is still needed for the PM ECL calculation under one load condition with the method proposed in [3]. In this paper, the analytical method in [3] is further developed and applied for the PM ECL calculation of an IPMSM applied in the HEV application [4]. Rather than calculating the PM ECL with the average flux density passing through the PM as input [3], the relationship between arbitrary HFHV and the corresponding PM ECL is established. Hence, the total PM ECLs can be calculated with the FFT results of the input line-line voltage directly without time-stepping FEA at a given load condition.

DC drive systems controlled by pulse-width modulation (PWM) techniques are expected to replace the conventional phase-controlled systems. This is due to their simple control, high reliability, low cost and fast response. This paper presents the performance of a single-phase DC drive system controlled by uniform PWM full-bridge DC-DC converter. Two different uniform PWM control techniques are considered; PWM with bipolar voltage switching and PWM with unipolar voltage switching. The overall system is simulated using PSpice where the different modes of operation, circuit voltages and currents and current harmonic spectrum are presented. The motor performance characteristics such as current, speed and torque are also presented and discussed.