scholarly journals A novel digital modulation scheme for multilevel cascaded H-bridge inverters in high power AC drives

2021 ◽  
Author(s):  
Mouzhi Dong
Keyword(s):  
Sampling Period ◽  
Harmonic Spectrum ◽  
Modulation Scheme ◽  
Switching Frequency ◽  
Variable Speed Drives ◽  
Line Voltage ◽  
Ac Drives ◽  
Power Cell ◽  
Three Phase ◽  
Modulation Schemes

The multilevel cascaded H-bridge (CHB) inverters are widely used in megawatt variable speed drives, where the voltage level normally varies from seven to thirteen and the number of active switching devices used in the inverter is in the range of 36 to 72. The design of a simple modulation scheme for such inverters with superior harmonic performance is a challenging task. This project presents a novel digital multilevel modulation (DMM) scheme for multilevel CHB inverters. This scheme is very simple, flexible and easy to implement. To generate gate signals for all the active switches in the inverter, the scheme needs only to calculate a three-phase sine function once followed by a number of subtractions in each sampling period. In this project, the principle of the proposed modulation scheme is elaborated and its harmonic performance is analyzed. Comparisons are carried out between the DMM scheme and carrier based modulation schemes including phase-shifted and level-shifted modulations. It is demonstrated that the harmonic performance of the DMM scheme is on par with the best of carrier based modulation techniques. On the inverter side, line-to-line voltage THD of inverter output for the proposed modulation scheme is as low as IPSD modulation scheme. On the line side, line current THD is as low as phase-shifted modulation scheme because of balanced poser consumption in each power cell. Under the condition of device switching frequency unchanged, a new algorithm is developed to combine the advantages from both phase-shifted and IPD modulation schemes and conquer the drawback of both schemes. The simulation result shows that new modulation scheme has almost same line-to-line voltage harmonic spectrum from light to rated load with balanced power cells.

scholarly journals A novel digital modulation scheme for multilevel cascaded H-bridge inverters in high power AC drives

2021 ◽  
Author(s):  
Mouzhi Dong
Keyword(s):  
Sampling Period ◽  
Harmonic Spectrum ◽  
Modulation Scheme ◽  
Switching Frequency ◽  
Variable Speed Drives ◽  
Line Voltage ◽  
Ac Drives ◽  
Power Cell ◽  
Three Phase ◽  
Modulation Schemes

The multilevel cascaded H-bridge (CHB) inverters are widely used in megawatt variable speed drives, where the voltage level normally varies from seven to thirteen and the number of active switching devices used in the inverter is in the range of 36 to 72. The design of a simple modulation scheme for such inverters with superior harmonic performance is a challenging task. This project presents a novel digital multilevel modulation (DMM) scheme for multilevel CHB inverters. This scheme is very simple, flexible and easy to implement. To generate gate signals for all the active switches in the inverter, the scheme needs only to calculate a three-phase sine function once followed by a number of subtractions in each sampling period. In this project, the principle of the proposed modulation scheme is elaborated and its harmonic performance is analyzed. Comparisons are carried out between the DMM scheme and carrier based modulation schemes including phase-shifted and level-shifted modulations. It is demonstrated that the harmonic performance of the DMM scheme is on par with the best of carrier based modulation techniques. On the inverter side, line-to-line voltage THD of inverter output for the proposed modulation scheme is as low as IPSD modulation scheme. On the line side, line current THD is as low as phase-shifted modulation scheme because of balanced poser consumption in each power cell. Under the condition of device switching frequency unchanged, a new algorithm is developed to combine the advantages from both phase-shifted and IPD modulation schemes and conquer the drawback of both schemes. The simulation result shows that new modulation scheme has almost same line-to-line voltage harmonic spectrum from light to rated load with balanced power cells.

scholarly journals A PV FED Three Phase Switched Z-source Multi Level Inverter for Induction Motor Drives

2018 ◽  
Vol 9 (1) ◽  
pp. 24
Author(s):  
Sinu KJ ◽  
G. Ranganathan
Keyword(s):  
Induction Motor ◽  
Motor Drives ◽  
Multilevel Inverter ◽  
Voltage Source ◽  
Switching Frequency ◽  
Induction Motor Drives ◽  
Line Voltage ◽  
Voltage Source Inverters ◽  
High Switching Frequency ◽  
Three Phase

<p>Generally induction motor drives posses higher harmonic contents in line voltage and current due to high switching frequency used in inverters. Conventional induction motor drives employ two level voltage source inverters which has THD in level of 50%. This paper presents a switched z-source multilevel inverter which has voltage boosting capability and has lesser THD level in comparison with conventional two level voltage source inverters. This drive is fed from a photo voltaic source because of its voltage boosting capability. A single phase five level switched z-source inverter is initially designed and considered as single cell and three such cells are created for powering three phase induction motor. The proposed three cell PV source switched z-source multilevel inverter for three phase induction motor is simulated in MATLAB/Simulink software to verify merits of proposed IM drive</p>

scholarly journals Analysis and performance evaluation of a three-phase sparse neutral point clamped converter for industrial variable speed drives

2021 ◽  
Author(s):  
Davide Cittanti ◽  
Mattia Guacci ◽  
Spasoje Mirić ◽  
Radu Bojoi ◽  
Johann Walter Kolar
Keyword(s):  
Degrees Of Freedom ◽  
Performance Comparison ◽  
Neutral Point ◽  
Modulation Scheme ◽  
Phase System ◽  
Variable Speed ◽  
Variable Speed Drives ◽  
Chip Area ◽  
Three Phase ◽  
Clamped Converter

Abstract This paper analyzes the operation and characterizes the performance of a three-phase three-level (3-L) Sparse Neutral Point Clamped converter (SNPCC) for industrial variable speed drives (VSDs). The operating principle of the SNPCC, which advantageously employs a lower number of power transistors than a conventional 3-L inverter, is described in detail, focusing on the AC-side differential-mode and common-mode voltage formation and on the DC-side mid-point current generation processes. The degrees of freedom in the SNPCC modulation scheme are defined and several switching sequences are investigated. Afterwards, the stresses on the active and passive components (e.g. semiconductor losses, machine phase current ripple, DC-link capacitor RMS current, etc.) are calculated by analytical and/or numerical means, enabling a straightforward performance comparison among the identified switching sequences. The most suited modulation strategy for VSD applications is then selected and a chip area sizing procedure, aimed at minimizing the total semiconductor chip size, is applied to a 800V 7.5kW three-phase system. The performance limits of the designed SNPCC are evaluated and finally compared to the ones of conventional 2-L and 3-L solutions, highlighting the promising cost/performance trade-off of the analyzed topology.

scholarly journals Simplified Space Vector Pulse Width Modulation Based on Switching Schemes with Reduced Switching Frequency and Harmonics for Five Level Cascaded H-Bridge Inverter

2018 ◽  
Vol 7 (2) ◽  
pp. 127
Author(s):  
B. Sirisha ◽  
Dr. P. Satishkumar
Keyword(s):  
Pulse Width Modulation ◽  
Low Frequency ◽  
Industrial Applications ◽  
Harmonic Spectrum ◽  
Switching Frequency ◽  
Segment Sequence ◽  
Space Vector ◽  
Switching Sequence ◽  
Line Voltage ◽  
Filter Size

This paper presents a simplified control strategy of SVPWM with a three segment switching sequence and 7 segment switch frequency for high power multilevel inverter. In the proposed method, the inverter switching sequences are optimized for minimization of device switching sequence frequency and improvement of harmonic spectrum by using the three most derived switching states and one suitable redundant state for each space vector. The proposed 3-segment sequence is compared with conventional 7-segment sequence similar for five level Cascaded H-Bridge inverter with various values of switching frequencies including very low frequency. The output spectrum of the proposed sequence design shows the reduction of device switching frequency and states current and line voltage. THD this minimizing the filter size requirement of the inverter, employed in industrial applications. Where  sinusoidal output voltage is required<em>.</em>

scholarly journals Finite Control Set MPC with Fixed Switching Frequency Applied to a Grid Connected Single-Phase Cascade H-Bridge Inverter

Energies ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 5475 ◽  
Author(s):  
Roberto O. Ramírez ◽  
Carlos R. Baier ◽  
José Espinoza ◽  
Felipe Villarroel
Keyword(s):  
Predictive Control ◽  
Optimization Problems ◽  
Experimental Tests ◽  
Power Converter ◽  
Harmonic Spectrum ◽  
Modulation Scheme ◽  
Switching Frequency ◽  
Multiple Control ◽  
Finite Control ◽  
Control Set

Finite control set model predictive control (FCS-MPC) has been widely investigated in recent years due to its ability to handle optimization problems with multiple control objectives in a diverse variety of systems. Moreover, its direct implementation in digital-based systems has made it an attractive strategy in static power converter applications. However, its characteristics such as variable switching frequency and spread harmonic spectrum limit the use of standard MPC due to power losses, audible noise, steady-state performance, and resonances. To mitigate these problems and extend the FCS-MPC applications to new areas, this paper proposes a new hybrid predictive control scheme, capable of achieving a harmonic spectrum distribution similar to that obtained with a pulse-width modulation scheme. The proposed strategy is based on a system model to generate an optimization, and, at the same time, an input restriction in the cost function of the standard FCS-MPC. This new approach is validated through experimental tests carried out in a grid-connected Cascaded H-bridge inverter.

scholarly journals A New SVPWM Strategy for Three-Phase Isolated Converter with Current Ripple Reduction

Energies ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4966
Author(s):  
Sheng Wang ◽  
Huaibao Wang ◽  
Hao Ding ◽  
Ligen Xun ◽  
Sifan Wu
Keyword(s):  
Electromagnetic Interference ◽  
Cost Effective ◽  
Modulation Scheme ◽  
Switching Frequency ◽  
Switching Loss ◽  
Matrix Converters ◽  
Switching Losses ◽  
Three Phase ◽  
Modulation Control ◽  
Current Ripple

Three-phase isolated matrix converters enable bidirectional power conversion and galvanic isolation, and they are suitable for widespread applications in industry. However, excessive DC-link current ripple not only increases the inductor loss and switching loss but also causes more electromagnetic interference and grid current distortion. Traditionally, increasing DC-link inductance or switching frequency can reduce the current ripple to a certain extent, but it is not cost-effective due to the bulky size of the inductor and higher switching losses. To address the above issue, optimizing the modulation control strategy is more attractive. This paper proposes a new SVPWM strategy to reduce the current ripple. First, the inherent limitation of the conventional modulation scheme is revealed. Then, the new optimal modulation scheme is proposed for the isolated matrix converters to reduce the current ripple without increasing the DC-link inductor or switching frequency. Moreover, the power density of the system is effectively increased. Finally, simulation in a MATLAB environment and a laboratory prototype of the isolated matrix converter have been built to verify the effectiveness of the proposed strategy.

scholarly journals Common-Mode Voltage Harmonic Reduction in Variable Speed Drives Applying a Variable-Angle Carrier Phase-Displacement PWM Method

Energies ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2929
Author(s):  
Abraham Marquez Alcaide ◽  
Vito Giuseppe Monopoli ◽  
Xuchen Wang ◽  
Jose I. Leon ◽  
Giampaolo Buticchi ◽  
...  
Keyword(s):  
Carrier Phase ◽  
Harmonic Distortion ◽  
Harmonic Spectrum ◽  
Hydraulic Systems ◽  
Variable Speed ◽  
Common Mode ◽  
Variable Speed Drives ◽  
Phase Displacement ◽  
Common Mode Voltage ◽  
External Component

Electric variable speed drives (VSD) have been replacing mechanic and hydraulic systems in many sectors of industry and transportation because of their better performance and reduced cost. However, the electric systems still face the issue of being considered less reliable than the mechanical ones. For this reason, researchers have been actively investigating effective ways to increase the reliability of such systems. This paper is focused on the analysis of the common-mode voltage (CMV) generated by the operation of the VSDs which directly affects to the lifetime and reliability of the complete system. The method is based on the mathematical description of the harmonic spectrum of the CMV depending on the PWM method implementation. A generalized PWM method where the carriers present a variable phase-displacement is developed. As a result of the presented analysis, the CMV reduction is achieved by applying the PWM method with optimal carrier phase-displacement angles without any external component and/or passive filtering technique. The optimal values of the carrier phase-displacement angles are obtained considering the minimization of the CMV total harmonic distortion. The resulting method is easily implementable on mostly off-the-shelf mid-range micro-controller control platforms. The strategy has been evaluated in a scaled-down experimental setup proving its good performance.

Variable Switching Frequency PWM for Three-Phase Four-Wire Split-Capacitor Inverter Performance Enhancement

2021 ◽  
pp. 1-1
Author(s):  
Riccardo Mandrioli ◽  
Aleksandr Viatkin ◽  
Manel Hammami ◽  
Mattia Ricco ◽  
Gabriele Grandi
Keyword(s):  
Performance Enhancement ◽  
Switching Frequency ◽  
Three Phase ◽  
Split Capacitor

scholarly journals AC Current Ripple in Three-Phase Four-Leg PWM Converters with Neutral Line Inductor

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1430
Author(s):  
Aleksandr Viatkin ◽  
Riccardo Mandrioli ◽  
Manel Hammami ◽  
Mattia Ricco ◽  
Gabriele Grandi
Keyword(s):  
Numerical Simulations ◽  
Pulse Width Modulation ◽  
Neutral Line ◽  
Experimental Tests ◽  
Performance Comparison ◽  
Design Parameters ◽  
Switching Frequency ◽  
Three Phase ◽  
Ac Current ◽  
Current Ripple

This paper presents a comprehensive study of peak-to-peak and root-mean-square (RMS) values of AC current ripples with balanced and unbalanced fundamental currents in a generic case of three-phase four-leg converters with uncoupled AC interface inductors present in all three phases and in neutral. The AC current ripple characteristics were determined for both phase and neutral currents, considering the sinusoidal pulse-width modulation (SPWM) method. The derived expressions are simple, effective, and ready for accurate AC current ripple calculations in three- or four-leg converters. This is particularly handy in the converter design process, since there is no need for heavy numerical simulations to determine an optimal set of design parameters, such as switching frequency and line inductances, based on the grid code or load restrictions in terms of AC current ripple. Particular attention has been paid to the performance comparison between the conventional three-phase three-leg converter and its four-leg counterpart, with distinct line inductance values in the neutral wire. In addition to that, a design example was performed to demonstrate the power of the derived equations. Numerical simulations and extensive experimental tests were thoroughly verified the analytical developments.

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