Highly Sensitive and Wide-Dynamic-Range Multichannel Optical-Fiber pH Sensor Based on PWM Technique.

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.

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.

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.

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.

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

The theoretical developments are described which form the basis for specifying the most appropriate reference signal that should be used in the carrier-based pulse width modulation (PWM) technique at any given carrier frequency and fundamental voltage. The load current distortion factor is used to compare the performances of various reference signals. The performances of the traditional carrier-based PWM techniques, using sinusoidal reference signals, are established to provide a means for comparison. A modified square-wave reference is shown to provide a low current distortion at very low carrier frequencies. A modified PWM technique can be adopted to lower the current distortion at very low carrier frequencies and also at large fundamental magnitudes. The reference signal that minimizes the current distortion is shown to be dependent upon the fundamental magnitude and the carrier frequency. >

It is difficult to make a structure of multilevel inverter for the efficient conversion of dc to ac having a smaller number of power electronic components, less switching losses, less voltage stress on switches, and a greater number of output voltage levels. To breakthrough this problem, a modification is performed in the existing H-bridge multilevel inverter to form a switch ladder modified H-bridge multilevel inverter (SLMHB-MLI). Moreover, for the minimization of maximum voltage rating on the switches and optimization of switching sequence of the multilevel inverter, a novel pulse width modulation (PWM) technique is proposed in this research. Furthermore, in SLMHB-MLI, the novel PWM technique is integrated with an ANDed PWM technique for the variation of output voltage magnitude. The usefulness of the proposed topology and PWM technique are confirmed via comparison with previous topologies simulation and experimentation, respectively.

An improved random SVPWM for zero voltage switching three phase inverter

This work is part of the development of a new flying remote operative vehicle (ROV) to provide aerial images of geo-localized area. The thrust of the flight is provided by a propeller coupled to a permanent magnet synchronous motor (PMSM) with external rotor (outrunner). This motor is driven by a frequency inverter using a pulse width modulation (PWM) technique via a long energy cable. Sensorless control technique based on the extended Kalman filter (EKF) is used in order to overcome the speed sensor problems and to reduce the weight of the ROV. Using a PWM technique and a long energy cable, overvoltages occur at the motor terminals which can affect the motor insulation, increase the motor heating and generate electromagnetic interference to the embedded electronics. To overcome these problems, a sinusoidal filter placed at the inverter output is used. The common mode current created by the long energy cable and the parasitic capacitances of the system is also discussed. The modeling of the overall system let us to make a simulation by using Matlab/Simulink software including the SimPowerSystems libraries.

Because of its high computation speed, shorter Because of its high computation speed, shorter design period, and higher density, the use of Field Programmable Gate Array (FPGA) has gained a lot of attention in the design and practical implementation of PWM (Pulse width modulation) techniques for MLI (Multilevel Inverter) structures. PWM techniques are designed to reduce switching losses, voltage stress of switches, total harmonic distortion (THD) and to increase the number of output voltage levels of inverter structures. This paper presents an Automatic Pulse Sequence Selector (APSS) for the Novel PWM technique by using FPGA LabVIEW software. The pulse sequence selection is done by using the sample index generated by the reference sinusoidal wave. By the automatic selection of specific pulse sequences from the sequences, the output wave of the inverter structure will be closer to the reference sinusoidal wave. The THD of the inverter output wave will be less than compared to direct feeding of those pulses to MLI structures. Using MATLAB/Simulink, a simulation study is performed on developed MLI structures for the validation of the proposed design. Comparison between the FFT analysis of these inverter structures verifies the efficacy of the design.

A carrier-based, three-phase pulse-width modulation (PWM) technique for the control of motor drives that uses a stepped waveform as the reference signal is presented. The theoretical derivation of the stepped reference signal from a square-wave reference is described. Comparisons with existing sinewave PWM techniques, adopting third-harmonic boosting and regular sampling techniques, show that the square-wave PWM has a superior performance at low carrier frequencies. The adopted stepped reference waveform is shown to improve upon the square-wave strategy at high carrier frequencies. The practical realization of the PWM technique is described using performance criteria such as minimum pulse-widths, peak carrier frequencies, and the current harmonic distortion. >

It is well known that small power brushless DC motor (BLDCM) drives have been widely applied to the information technology industry, especially for fan and spindle applications. For small power applications of BLDCM drives, due to the use of battery and limited space for heat dissipation, reduction of power consumption is one of the main concerns for the development of pulse-width modulation (PWM) technique. This paper presents a novel PWM technique for small power BLDCM drives, which significantly reduces the conduction losses, and thereby dramatically reducing the heat dissipation. Comparative results with conventional PWM technique are fully explored to highlight the advantages of the presented novel technique. Experimental results derived from an FPGA-based spindle drive are presented to confirm the theoretical analysis.

Common mode voltage (CMV) variations in the dual inverter fed induction motor drives causes unwanted shaft voltage and bearing currents resulting in reduced the life time. Single dc-link dual inverters topologies eliminate CMV but generate a poor quality of output voltage with circulating currents. Exploiting the new pulse pattern for the isolated dc-link dual inverter, new scalar pulse width modulation (PWM) methods are proposed in this paper using the freedom of selection reference signals and carrier signals. These scalar PWM techniques reduce CMV to maximum permissible limits with good quality of output voltage. PWM techniques proposed in this paper can also be extended to N-level inverter. To validate the proposed PWM techniques numerical studies are carried out in MATLAB/simulink environment.