scholarly journals Application of SHEPWM in Helicopter Transient Electromagnetic Based on the Subsection Control Approach

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Lihui Gao ◽  
Shengbao Yu ◽  
Chunxia Jiang ◽  
Nan Chen ◽  
Renhui Chen ◽  
...  
Keyword(s):  
Mirror Symmetry ◽  
Pulse Width Modulation ◽  
High Efficiency ◽  
Switching Frequency ◽  
Detection Accuracy ◽  
Switching Loss ◽  
Control Approach ◽  
Time Frequency ◽  
Transient Electromagnetic ◽  
Harmonic Elimination

Guaranteeing the quality of the transmitting current under low switching frequency conditions is the crucial point in the helicopter transient electromagnetic (HTEM) system which affects the efficiency and exploration accuracy. HTEM requires high efficiency and low switching loss of the inverter power supply due to the facts that HTEM uses air-launched and air-received measurement methods, and the power storage capacity of the airborne transmitting system is limited. Paradoxically, low switching frequency directly affects the transmitting waveform quality and thereby affects the detection accuracy. In this study, we present a semiperiodic mirror symmetry selective harmonic elimination pulse width modulation (SHEPWM) based on the subsection control approach to balance transmitting current quality and switching loss. In the SHEPWM method, the semiperiodic mirror symmetry SHEPWM nonlinear equations are established by the time frequency domain information of the inverter output voltage and resolved by the artificial neural network (ANN) algorithm to attain switching time sequence of desired transmitting current. The simulation and experimental results verify the effectiveness of the SHEPWM subsection control strategy, which can reduce the switching loss while ensuring the current waveform quality and detection accuracy.

MSHE-PWM Control of Modular Multilevel Direct Current Transmission System

2015 ◽  
Vol 9 (1) ◽  
pp. 553-559
Author(s):  
HU Xin-xin ◽  
Chen Chun-lan
Keyword(s):  
Pulse Width Modulation ◽  
Reactive Power ◽  
Balance Control ◽  
Electric Energy ◽  
Access Point ◽  
Experimental Result ◽  
Switching Frequency ◽  
Pwm Control ◽  
Harmonic Elimination

In order to optimize the electric energy quality of HVDC access point, a modular multilevel selective harmonic elimination pulse-width modulation (MSHE-PWM) method is proposed. On the basis of keeping the minimum action frequency of the power device, MSHE-PWM method can meet the requirement for accurately eliminating low-order harmonics in the output PWM waveform. Firstly, establish the basic mathematical model of MMC topology and point out the voltage balance control principle of single modules; then, analyze offline gaining principle and realization way of MSHEPWM switching angle; finally, verify MSHE-PWM control performance on the basis of MMC reactive power compensation experimental prototype. The experimental result shows that the proposed MSHE-PWM method can meet such performance indexes as low switching frequency and no lower-order harmonics, and has verified the feasibility and effectiveness thereof for optimizing the electric energy quality of HVDC access point.

The Development of Near-source Electromagnetic Methods in China

2018 ◽  
Vol 23 (1) ◽  
pp. 115-124 ◽  
Author(s):  
Guo-qiang Xue
Keyword(s):  
High Efficiency ◽  
Academic Research ◽  
Electromagnetic Method ◽  
Detection Accuracy ◽  
Wide Field ◽  
Transient Electromagnetic Method ◽  
Transient Electromagnetic ◽  
Detection Technology ◽  
Deep Depth ◽  
Central Loop

Near-source electromagnetic technology has been developed and applied in the exploration of petroleum, metallic ore, coal, and engineering geology due to its high efficiency, high detection accuracy, and deep depth of investigation. In this paper, research and applications of the frequency-domain electromagnetic sounding method (FDEM), wide-field electromagnetic method (WFEM), modified central-loop transient electromagnetic method (TEM), and short-offset grounded-wire TEM (SOTEM) with obvious near-source characteristics, were reviewed and analyzed. From the 1960s to 1990s, the FDEM method and equipment were extensively developed in China. These methods have played important roles in the exploration of coal resources. Based on controlled source audio-frequency magnetotelluric (CSAMT) and FDEM methods, a new method has been developed by deriving a new expression to calculate apparent resistivity. This method, which is referred to as WFEM, has been studied, applied, and received great attention in China. To increase work efficiency and reduce the influence of local transverse anisotropy on the detection processes, a modified central-loop TEM detection technology based on the central loop transient electromagnetic method was developed in China. The advantages of SOTEM in near-source surveys with high resolution and increased depth detection stimulated academic research interest to further develop grounded-wire TEM techniques. [Figure: see text]

scholarly journals A High-Efficiency Three-Level ANPC Inverter Based on Hybrid SiC and Si Devices

Energies ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1159 ◽  
Author(s):  
Zhijian Feng ◽  
Xing Zhang ◽  
Jianing Wang ◽  
Shaolin Yu
Keyword(s):  
Silicon Carbide ◽  
High Efficiency ◽  
The Other ◽  
Switching Frequency ◽  
Parallel Operation ◽  
Switching Loss ◽  
Hybrid Scheme ◽  
Excellent Performance ◽  
Switching Losses ◽  
The Cost

Silicon carbide (SiC) devices have excellent performance, such as higher switching frequency and lower switching loss compared with traditional silicon (Si) devices. The application of SiC devices in inverters can achieve higher efficiency and power density. In recent years, the production process of SiC devices has become more mature, but the cost is still several times that of traditional Si devices. In order to balance cost and efficiency, replacing only some of the Si devices with SiC devices in a topology is a better choice. This paper proposed a high-efficiency hybrid active neutral point clamped (ANPC) three-level inverter which has only two SiC devices and the other devices are Si devices. A specific modulation strategy was applied to concentrate switching losses on the SiC devices and reduce the on-state loss through parallel operation during freewheeling intervals. Theoretical efficiency curves and experimental verification of the proposed hybrid scheme with Si-only and SiC-only schemes were carried out.

scholarly journals Research on hybrid SHEPWM based on different switching patterns

2019 ◽  
Vol 10 (4) ◽  
pp. 1875 ◽  
Author(s):  
Tao Jing ◽  
Alexander Maklakov ◽  
Andrey Radionov ◽  
Sergei Baskov ◽  
Aleksandra Kulmukhametova
Keyword(s):  
Pulse Width ◽  
Pulse Width Modulation ◽  
Effective Means ◽  
Switching Frequency ◽  
Harmonic Elimination ◽  
Switching Patterns ◽  
Control Scheme ◽  
Selective Harmonic Elimination ◽  
Simulation Results ◽  
Additional Hardware

<span>This paper presents a hybrid pulse width modulation (HPWM) strategy based on different switching patterns of selective harmonic elimination pulse width modulation (SHEPWM) for the three-level neutral point clamped (3L-NPC) converter. Specific low-order harmonics can be eliminated by SHEPWM at low switching frequency, while the remaining high-order harmonics can be selected to be simply filtered by additional hardware. Large oscillation waveform usually occurs in the transition instant between two diverse modulation situations, therefore switching between distinct switching patterns can be problematic if no effective means is taken, especially when the effect of smooth and fast transition at any time is considerable. A universal and valid control strategy, which maintains the high-quality output voltage and current, is proposed and implemented in this paper to address this issue. Simulation results obtained from MATLAB/SIMULINK are presented to analyze the performance and validate the feasibility and effectiveness of this control scheme.</span>

scholarly journals Investigation and Experimental Validation of Sideband Harmonic Vibration of IPMSM with and without Skewed Slots for EVs

2021 ◽  
Vol 12 (4) ◽  
pp. 223
Author(s):  
Zhenkang Feng ◽  
Daohan Wang ◽  
Chen Peng ◽  
Wentao Feng ◽  
Bingdong Wang ◽  
...  
Keyword(s):  
Pulse Width Modulation ◽  
High Efficiency ◽  
Torque Ripple ◽  
Synchronous Machines ◽  
Switching Frequency ◽  
Permanent Magnet Synchronous Machines ◽  
Steady State Operation ◽  
Voltage Harmonics ◽  
The Magnetic Field ◽  
Vector Control Strategy

Due to their advantages of high power density and high efficiency, permanent magnet synchronous machines (PMSMs) are widely used in the field of electric vehicles (EVs). Vibration and noise are important indicators for evaluating the performance of PMSMs, and the skewed slot method is now widely used to mitigate the torque ripple and noise of motors. In the vector control strategy, the space vector pulse width modulation (SVPWM) method produces sideband voltage harmonics with a frequency near the switching frequency. These harmonics act on the magnetic field to generate an excitation force with a frequency near the switching frequency. This paper compares and analyzes the sideband harmonic current and the exciting force of a skewed slot motor and a straight slot motor during steady-state operation. The research results show that the skewed slot method can effectively mitigate the vibration and noise caused by sideband harmonics.

scholarly journals Performance Evaluation of Eleven-Phase Induction Machine with Different PWM Techniques

2015 ◽  
Vol 12 (1) ◽  
pp. 1
Author(s):  
M.I. Masoud ◽  
A.S. Abdelkhalik
Keyword(s):  
Comparative Study ◽  
Pulse Width Modulation ◽  
Induction Machine ◽  
Single Pulse ◽  
Torque Ripple ◽  
Switching Frequency ◽  
Pulse Modulation ◽  
Medium Voltage ◽  
Harmonic Elimination ◽  
Power Switches

Multiphase induction machines are used extensively in low and medium voltage (MV) drives. In MV drives, power switches have a limitation associated with switching frequency. This paper is a comparative study of the eleven-phase induction machine’s performance when used as a prototype and fed sinusoidal pulse-width-modulation (SPWM) with a low switching frequency, selective harmonic elimination (SHE), and single pulse modulation (SPM) techniques. The comparison depends on voltage/frequency controls for the same phase of voltage applied on the machine terminals for all previous techniques. The comparative study covers torque ripple, stator and harmonic currents, and motor efficiency. 

scholarly journals Constant-Current, Constant-Voltage Operation of a Dual-Bridge Resonant Converter: Modulation, Design and Experimental Results

2021 ◽  
Vol 11 (24) ◽  
pp. 12143
Author(s):  
Jiaqi Wu ◽  
Xiaodong Li ◽  
Sheng-Zhi Zhou ◽  
Song Hu ◽  
Hao Chen
Keyword(s):  
High Efficiency ◽  
Experimental Tests ◽  
Rechargeable Batteries ◽  
Constant Current ◽  
Switching Frequency ◽  
Resonant Converter ◽  
Constant Voltage ◽  
Switching Loss ◽  
Wide Range ◽  
Modulation Methods

To meet the requirements of charging the mainstream rechargeable batteries, in this work, a dual-bridge resonant converter (DBRC) is operated as a battery charger. Thanks to the features of this topology, the required high efficiency can be achieved with a wide range of battery voltage and current by using different modulation variables. Firstly, a typical charging process including constant-voltage stage and constant-current stage is indicated. Then, two different modulation methods of the DBRC are proposed, both of which can realize constant-voltage charging and constant-current charging. Method I adopts phase-shift modulation with constant switching frequency while Method II adopts varying frequency modulation. Furthermore, as guidance for practical application, the design principles and detailed design procedures of the DBRC are customized for the two modulation methods respectively in order to reduce the switching loss and conduction loss. Consequently, the full soft-switching operation with low rms tank current is achieved under the two modulation methods, which contributes to the high efficiency of the whole charging process. At last extensive simulation and experimental tests on a lab prototype converter are performed, which prove the feasibility and effectiveness of the proposed modulation strategies.

scholarly journals Modeling and Compensation for Dead-Time Effect in High Power IGBT/IGCT Converters with SHE-PWM Modulation

Energies ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 4348 ◽  
Author(s):  
Jingling Cheng ◽  
Dongdong Chen ◽  
Guozhu Chen
Keyword(s):  
High Power ◽  
Pulse Width Modulation ◽  
Power Converters ◽  
Dead Time ◽  
Open Loop ◽  
Time Effect ◽  
Operating Conditions ◽  
Switching Frequency ◽  
Harmonic Elimination ◽  
The Dead

Research on applying selective harmonic elimination pulse width modulation (SHE-PWM) to high power converters has drawn tremendous interest, due to the advantages of low switching frequency and high output harmonic performance. In the fields of high power converters such as variable speed traction motor drives and static synchronous compensators (STATCOM), the adoption of high voltage but slow speed semiconductor devices, i.e., IGBT/IGCT, results in a longer dead time of several microseconds, which leads to a motor vibration in the former case or the distortion of grid current in the latter case. This paper analyzes in detail the mechanism of the dead-time effect on 3-level SHE-PWM with different operating conditions considered. For the first time, a general mathematical model describing the relationship between the dead time and harmonic distribution of SHE-PWM wave is established. Based on which an open-loop compensation method by inserting a margin time into the effective switching angles is proposed. Furthermore, a closed-loop controller that implements online adaptive adjustment of the margin time is designed in case of a variable frequency application. The effectiveness of the proposed method in different scenarios is verified through simulation results.

scholarly journals 4-level capacitor-clamped boost converter with hard-switching and soft-switching implementations

2019 ◽  
Vol 10 (1) ◽  
pp. 288
Author(s):  
A.N. Kasiran ◽  
Asmarashid Ponniran ◽  
A.A. Bakar ◽  
M.H. Yatim
Keyword(s):  
Pulse Width Modulation ◽  
Boost Converter ◽  
Soft Switching ◽  
Switching Frequency ◽  
Switching Loss ◽  
Snubber Circuit ◽  
High Switching Frequency ◽  
Parameters Analysis ◽  
Very High ◽  
Current Ripple

This paper presents parameters analysis of 4-level capacitor-clamped boost converter with hard-switching and soft-switching implementation. Principally, by considering the selected circuit structure of the 4-level capacitor-clamped boost converter and appropriate pulse width modulation (PWM) switching strategy, the overall converter volume able to be reduced. Specifically, phase-shifted of 120° of each switching signal is applied in the 4-level capacitor-clamped boost converter in order to increase the inductor current ripple frequency, thus the charging and discharging times of the inductor is reduced. Besides, volume of converters is greatly reduced if very high switching frequency is considered. However, it causes increasing of semiconductor losses and consequently the converter efficiency is affected. The results show that the efficiency of 2-level conventional boost converter and 4-level capacitor-clamped boost converter are 98.59% and 97.67%, respectively in hard-switching technique, and 99.31% and 98.15%, respectively in soft-switching technique. Therefore, by applying soft-switching technique, switching loss of the semiconductor devices is greatly minimized although high switching frequency is applied. In this study, passive lossless snubber circuit is selected for the soft-switching implementation in the 4-level capacitor-clamped boost converter. Based on the simulation results, the switching loss is approximately eliminated by applying soft-switching technique compared to the hard-switching technique implementation.

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