Third Harmonic Injection Pulse Width Modulation Research Articles

New control scheme for a dynamic voltage restorer based on selective harmonic injection technique with repetitive controller

Repetitive controller and selective harmonic injection technique (SHI) in medium and low voltage distribution networks improve dynamic voltage restorer (DVR) DC bus voltages as well as nullify power quality (PQ) problems. DVRs use sinusoidal pulse width modulation (SPWM) firing control, but DC bus use seems to be limited, affecting density, cost, and power packaging. By adding 1/6th of the 3rd harmonic waveform to the basic waveform, SPWM yields the developed model. According to the findings, 15% of DC bus usage improves and produces high voltage AC. Nevertheless, just control systems perturb PQ. The proposed controller uses feed forward and feedback to enhance transient response and justify stable zero error. 3rd third harmonic injection pulse width modulation (THIPWM) improves total harmonic distortion (THD) in the proposed scheme. Power system computer aided design (PSCAD) simulation produced high accuracy for THIPWM and repetitive controllers.

Comparative Evaluation of Harmonic Injection Techniques for a Phase-Modular Three-Phase Six-Switch Buck-Boost Y-Inverter

Phase-modular buck–boost dc/ac inverters extend the voltage conversion range of conventional buck-type inverter topologies, and accordingly offer significant advantages for variable-speed motor drives powered from dc sources with wide-voltage-ranges like fuel cells or batteries. In this letter, two new modulation schemes are applied to the six-switch buck–boost Y-inverter (6YI) topology, with an analysis of the efficiency improvement for the proposed third harmonic injection pulsewidth modulation (TPWM) and discontinuous PWM (DPWM) schemes relative to conventional sinusoidal PWM (SPWM). Third harmonic injection PWM (TPWM) substantially reduces conduction losses and discontinuous PWM (DPWM) extends this gain by eliminating high-frequency switching for one-third of the fundamental period. These gains are validated on a 1 kW hardware demonstrator across a dc input voltage from 80 to 240 V, with DPWM reducing total converter losses by 31% over SPWM for a peak efficiency at nominal load of 95.6% with a power density of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$62.3\ {\rm W/in^3}$</tex-math></inline-formula> .

Modeling and Validation of the Switching Techniques Applied to Back-to-Back Power Converter Connected to a DFIG-Based Wind Turbine for Harmonic Analysis

Most power quality problems for electrical grids connected to Doubly-Fed Induction Generators (DFIGs) include flicker, variations of the RMS voltage profile, and injected harmonics because of switching in power converters. These converters have different topologies with the back-to-back (B2B) topology being the most exploited in high-powered three-phase systems. Therefore, in this article a model of a DFIG connected to the B2B power converter is proposed to which different switching techniques are implemented for interharmonic propagation studies. The switching techniques that are implemented include the Sinusoidal PWM (SPWM), the third harmonic injection PWM (THIPWM), and the space vector PWM (SVPWM), to reduce the Total Harmonic Distortion (THD) index of voltage and current in both windings of the machine. MATLAB-Simulink® software is used for modeling and simulating the B2B power converter and the switching techniques. The proposed model is validated with an experimental prototype that includes a 3-kW DFIG, a 10 HP motor, a gear-box with a transmission ratio of 4.5: 1, a B2B power converter, and a three-phase transformer connecting the system to the electrical grid. Finally, it is shown that the results obtained from the experimental tests corroborate the correct operation of the proposed model.

Harmonic elimination by SPWM and THIPWM techniques applied in photovoltaic inverters

With advances in solid-state power electronic devices, control techniques (PWM) have been devised to obtain high dynamics responses from a multilevel power conditioning converter-Photovoltaic. This work discusses the advantages and drawbacks of two different PWM techniques, the sinusoidal (SPWM) technique and the Third harmonic injection PWM (THIPWM) technique. These two methods are compared by discussing their ease of implementation and by analyzing the output harmonic spectra of various output voltage and their total harmonic distortion (THD). The focus of this paper is the simulation study of single-phase inverter, three phases, two levels and three levels inverter for application photovoltaic. Firstly, single phase is modeled with inductive load and their waveforms are observed. Secondly, a two levels inverter, and three levels inverter are leading to the high industrial performances of the drives synchronous, especially, if a high-power quality is requested.

Control Techniques for the Cascaded and Cross-switched Multilevel Inverter - A Comparison

Nowadays, the multilevel inverter has gained huge attention and has become more popularized in high voltage and high-power applications with low harmonics. As the number of output voltage increases, the harmonic content of the output voltage waveform decreases. In this paper, a comparison of cascaded H-bridge and cross-switched multilevel inverters for 7, 9, 15, 21 levels will be carried out. The different control techniques that will be used for carrying out comparisons are space vector pulse width modulation (SPVPWM), sinusoidal pulse width modulation (SPWM), and third harmonic injection pulse width modulation (THI-PWM) respectively. Here, the seven-level inverter is discussed mainly and can be extended to any number of levels.

Voltage boosting capability of three phase current source inverter for standalone system

This paper presents a three-phase current source inverter (CSI) topology with voltage boosting capability for standalone system. Current source inverter (CSI) and voltage source inverter (VSI) are two competitive options to be used as an interfacing unit between variable dc input resource and ac output fed into on-grid, off-grid and industrial used. Among the two topologies, VSI is widely used due to its variable controllable output voltage and ability to operate steadily with open loop V/Hz control. Yet, it suffers circuit complexity due to the need of extra converter stage to meet the required output. On the other hand, CSI has an advantage of voltage boosting capability and better quality of output waveshape, thus no extra converter stage is needed. Most of research works were focusing on studying the suitability and practicality of CSI, along with the advancement using silicon carbide-based power switches and improved modulation techniques to minimize the harmonics suffer by CSI. There is lack of research in investigating the boosting capability particularly on how high CSI able to boost the fundamental output and its impact to overall performance in both open and closedloop standalone system. Thus, this work is intended to highlight in detail the boosting capability of CSI and compare with VSI based on the several circuity and operational features. To support the work, three modulators are implemented namely sinusoidal pulse width modulation (SPWM), third harmonic injection PWM (THIPWM) and space vector modulation (SVM). A dedicated synchronous frame proportional-integral (PI) control in used in closed-loop condition. Result shows that CSI topology able to boost the fundamental output voltage by 52% to 58% by using smaller modulation index as compared to VSI. Interestingly, CSI able to achieve comparable quality and harmonic minimization of output voltage and current as in VSI but with smaller PI control gain. All works are analyzed and verified using MATLAB/Simulink platform.

Review on Multi Level Inverter Topologies and Control Strategies for Solar Power Conversion

Nowadays solar power has become an alternate method of power generation for standalone systems for both urban and rural electrification. The Power Electronics converters used for the power conversion should provide quality AC output to have near sinusoidal voltage. The inverter topology and the PWM technique of the inverter play a vital role in providing quality output. This paper reviews recent contribution to establish the current status and development of the technology to provide reader with an insightful review of multilevel inverters and its control strategy. A brief overview of Multi Level Inverters (MLI) topology and advantages of Cascaded H-Bridge Multi Level Inverter (CHBMLI) for solar power conversion is presented and the various control strategies for CHBMLI are discussed with view point of quality output. Among the different PWM techniques discussed, the Elliptical Multi Carrier PWM (EMC PWM) control strategy is the new modulation technique which successfully improves the DC bus utilization without over-modulation and without adding third harmonic to fundamental frequency. Also, the technique is successful in reducing the %THD at the output voltage. The control strategy is simple even with increased level of output voltage, which is not possible in SVPWM technique. Hence, the EMC PWM technique is having better performance when compared to Multi Carrier PWM (MCPWM) technique, Space Vector PWM (SVPWM) technique and Third Harmonic Injection PWM (THIPWM) technique.

Third harmonic injection pulse-width modulation technique for a five-phase voltage source inverter

&lt;span&gt;Nowadays application of advanced power electronic technology enables producing an AC supply with a phase number higher than three-phase. Five-phase voltage source inverters (5ph-VSI) have been used in advanced power electronic drives to improve the reliability of the drive system and to boost the power capability of the converter as well as to their other inherent merits. This paper shows the mathematical analysis and simulation of the third harmonic injection pulse width modulation (THI-PWM) 5ph-VSI connected with inductive load in three scenarios i.e. star, Pentagon and pentacle. The presented THI-PWM technique for 5ph-VSI aims to increase the inverter fundamental voltage and hence to maximize the utilization of the DC bus without causing over-modulation. The simulation results are compared with typical sinusoidal pulse width modulation (SPWM) and the 10-step mode operation. The proposed scheme may be considered as a compromise case between the two reference cases; as low harmonic components compared with 10-step mode operation and a high utilization factor compared with SPWM.&lt;/span&gt;

Operation of grid‐connected DFIG using SPWM‐ and THIPWM‐based diode‐clamped multilevel inverters

This paper proposes a WECS based on a back to back diode-clamped multilevel inverter systems (DCMLI) fired comparatively by sinusoidal pulse width modulation (SPWM) and third harmonic injection pulse width modulation (THIPWM) techniques. DFIG performance is compared using these technologies for different wind speed under normal operation condition. The proposed approach shows that the DCMLI systems generate a nearly sinusoidal voltage with reduced total harmonic distortion (THD) thus upgrading the power quality of that produced by DFIG. As SPWM and THIPWM MLI are most common usage techniques in research, we applied them in the system to discuss a comparison of using those techniques to determine the number of levels that achieve the IEEE 519 criteria of THD which is less than 5% for both techniques (5th level for SPWM and 4th level for THIPWM) in all operation wind speed. Compared with simple PWM, and THIPWM have many advantages as lower THD, minimal number of switching to decrease switching losses and the output fundamental voltage is increased. Lastly, the paper investigates the variation of the frequency of induced rotor voltage and the active power flow due to the wind speed change when the rotor speed changes from super-synchronous to sub-synchronous speeds.

Comparative Harmonic Analysis of Various PWM Techniques for Diode Clamped Multi-Level Inverter in MATLAB/Simulink

Advances in solid state power electronic devices and microprocessors has led to the development of various pulse-width-modulation (PWM) techniques for industrial applications. For example, PWM based 3-phase voltage source inverters (VSI) convert Solar cell DC power to AC power with variable voltage magnitude and variable frequency. To analyze the applications and advantages of three different PWM techniques over one another, inverter with different techniques have been modelled in the MATLAB/ Simulink environment. The Techniques compared in the paper are: the sinusoidal PWM (SPWM) technique, the third-harmonic-injection PWM (THIPWM) technique, and the bus-clamped PWM (BCPWM) technique. These three methods are compared by discussing their ease of implementation and by analyzing the output harmonic spectrum of various output voltages (poles voltages, line-to-neutral voltages, and line-to-line voltages) and their total harmonic distortion (THD).

Comparative Study on Performance Improvement of SPWM/THIPWM based DCMLI Grid Connected DFIG

Multi-level voltage source converter is integrated in various fields in renewable energy power generation technologies such as wind and solar sources for applications that need higher voltage and higher power. In wind power generation market, doubly fed induction generator (DFIG) based on wind power generation is now the leading technology as they are economically feasible, they do offer a variable speed and efficient substitute to the fossil fuel. This paper proposes a DFIG based on a back to back diode clamped multilevel converter systems (DCMLI) fired comparatively by sinusoidal pulse width modulation (SPWM) and third harmonic injection pulse width modulation (THIPWM) techniques. By using these technologies, the DFIG performance is compared for different wind speeds under normal operation condition. The proposed approach shows that the DCMLI systems generate a near sinusoidal voltage with lower values in total harmonic distortion (THD) thus, upgrading the power quality that is produced by DFIG. Lastly, the variation of frequency of induced rotor voltage and the active power flow due to the wind speed changes when the rotor speed changes from super synchronous to sub synchronous speeds is investigated.

Reliability-Oriented Selection for Grid-Connected Converters: A Low Voltage Direct Current Microgrid Case Study

As the grid-connected AC-DC converter is the key equipment that links the low voltage direct current (LVDC) microgrids and the utility grid, the safe and stable operation of the converter is of great significance to improve the reliability of the LVDC microgirds. Since the converter's reliability is affected by the converter's topological structure and modulation strategy, a civil LVDC microgrid case study is analyzed, and the power losses, thermal stresses, lifetimes and reliability of components in the AC-DC converters with different topologies and modulation strategies are evaluated in this paper. The influence of these two factors on the reliability and efficiency of the converter is discussed, and the normalized weighted total harmonic distortion (NWTHD) with different modulation strategies is analytically determined and compared. The results show that when the converter operates with unity power factor in this application scenario, among the two-level converter, flying capacitor converter, neutral point clamped (NPC) converter and T-type converter, the T-type converter has the highest reliability. The effects of the converter's topology and modulation strategy on the capacitor reliability are relatively small. In view of reliability and power quality, third harmonic injection pulse width modulation (THIPWM) or space vector pulse width modulation (SVPWM) is more suitable for the converter in this microgrid.

Minimizing Total Harmonic Distortion of a Two-Level Voltage Source Inverter Using Optimal Third Harmonic Injection

Full time-domain analysis of the impact of third-harmonic injection (THI) on the output phase voltage waveform of a two-level voltage source inverter is presented, and the total harmonic distortion (THD) performance of different pulsewidth modulation (PWM) methods is provided. Two well-known third harmonic injection PWM (THIPWM) schemes are adopted from the literature: THIPWM6 and THIPWM4, where the THI amplitude is one-sixth and one-fourth the amplitude of the sine-wave, respectively. In this article, three analysis-derived developments are provided. Global optimal THIPWM ensures minimum THD in all linear region, unlike other THIPWM schemes. A unique THI-level is selected for each modulation index from the proposed curve or the compacted lookup table. The best suboptimal THIPWM method is provided that employs a linear injection applied over the linear modulation. To achieve better THD performance and to satisfy different operation criteria, several suboptimal THIPWM methods are proposed. Comparisons between these schemes must define performance indices, and this is carried out using various objective functions, such as the sum of squared error and area under the curve. The impact on extending the linear region is also presented. This study examines when THIPWM is useful and which injection level is best. Experimental verifications support the presented analysis.

Modulation Effects on Power-Loss and Leakage Current in Three-Phase Solar Inverters

Three-phase solar inverters can be operated with different modulation strategies such as sinusoidal pulsewidth modulation (SPWM), space vector modulation (SVM), and third-harmonic injection PWM (THIPWM). The selection of the modulation strategy can significantly affect photovoltaic (PV) leakage currents and power losses and compromise the inverter performance. This paper presents a detailed analysis of traditional and modified modulation effects on power semiconductor losses and PV leakage current. The research focuses on a three-phase three-level T-type neutral point clamped (3L-TNPC) solar inverter. A detailed exploration of traditional SPWM and SVM is presented, and a new modified modulation strategy referred to as two-triplen harmonic injection PWM (2THIPWM) is proposed, which can substitute the SVM scheme. Analytical expressions are derived for the proposed 2THIPWM strategy, which can be used for the SVM power-loss approximation. The comparison between 2THIPWM and SPWM shows a conduction-loss difference greater than the 5% normalized range. The modulation strategies are discussed with respect to the PV common mode current signature, and specific design techniques in modulation lead to reduced leakage currents for safety compliance. The theoretical and experimental results obtained using a 3L-TNPC solar inverter are presented to evaluate the modulation strategies and their impact on performance.

Single-Phase Bridgeless Rectifier Based System With Enhanced Capability of Reactive Power Compensation

Aiming at enhancing reactive power compensation (RPC) capability of the traditional single-phase bridgeless rectifier, a 2.5kVA circuit topology composed of a single-phase bridgeless rectifier and a third-order tuned LC series branch in parallel connection is proposed. The corresponding control strategy using the third harmonic injection pulse width modulation (THIPWM) technique is also presented, which enables the proposed single-phase bridgeless rectifier to operate under varied power factor with the near-sinusoidal current at the point of common coupling (PCC). The principle of the proposed topology is discussed in detail and reactive power compensation capability of the proposed single-phase bridgeless rectifier under a certain amount of active power to be transmitted to the load is studied. Simulation and experiment results are given to validate the feasibility of the proposed circuit topology and the correctness of the theoretical analysis.

Analytical Design of Passive LCL Filter for Three-Phase Two-Level Power Factor Correction Rectifiers

This paper proposes a comprehensive analytical LCL filter design method for three-phase two-level power factor correction rectifiers (PFCs). The high-frequency converter current ripple generates the high-frequency current harmonics that need to be attenuated with respect to the grid standards. Studying the high-frequency current of each element proposes a noniterative solution for designing an LCL filter. In this paper, the converter current ripple is thoroughly analyzed to generalize the current ripple behavior and find the maximum current ripple for sinusoidal pulse width modulation (PWM) and third-harmonic injection PWM. Consequently, the current ripple is used to accurately determine the required filter capacitance based on the maximum charge of the filter capacitor. To choose the grid-side inductance, two methods are investigated. First method uses the structure of the damping to express the grid-side filter inductance as a function of the converter current ripple. Reducing the power loss in the filter and optimizing the grid-side filter inductance is the main focus of the second method which is achieved by employing line impedance stabilization network (LISN). Accordingly, two LCL filters are designed for a 5 kW silicon-carbide-based three-phase PFC. Various experimental scenarios are performed to verify the filters attenuation and performance.

Harmonic Analysis of Various SPWM Techniques for three Phase Diode Clamped Multi-Level Inverter in MATLAB/Simulink Environment

With advances in solid-state power electronic devices and microprocessors, various pulse-width-modulation (PWM) techniques have been developed for industrial applications. For example, PWM-based three-phase voltage source inverters (VSI) convert DC power to AC power with variable voltage magnitude and variable frequency. This paper discusses the advantages and drawbacks of three different PWM techniques: the sinusoidal PWM(SPWM) technique, the third-harmonic-injection PWM(THIPWM) technique, and the bus-clamped PWM (BCPWM) technique. These three methods are compared by discussing their ease of implementation and by analyzing the output harmonic spectra of various output voltages (poles voltages, line-to-neutral voltages, and line-to-line voltages) and their total harmonic distortion (THD).

Cascaded H-bridge Asymmetrical Seven-level Inverter Using THIPWM for High Power Induction Motor

Multilevel inverters are well used in high power electronic applications because of their ability to generate a very good quality of waveforms, reducing switching frequency, and their low voltage stress across the power devices. This paper presents the Third Harmonic Injection Pulse Width Modulation (THIPWM) strategy of a Seven-level Uniform Step Cascaded H-bridge Asymmetrical Inverter (7-level USCHBAI). The THIPWM approach is compared to the well-known Sinusoidal PWM (SPWM) strategy. Simulation results demonstrate the better performances and technical advantages of the THIPWM controller in feeding a High Power Induction Motor (HPIM).

Performance analysis of a stand alone PV system with reduced switch cascaded multilevel inverter

In this paper, a photovoltaic (PV) system fed single phase multilevel inverter (MLI) aimed at feeding standalone loads is proposed. The proposed system consists of PV array, DC-DC boost converter with maximum power point tracking (MPPT) controller and a reduced switch cascaded inverter. The proposed MLI is advantageous in terms of performance and efficiency as it minimises switching losses which are prevalent in the conventional cascaded one. This work also aims at increasing the DC utilisation of the inverter by adopting third harmonic injection pulse width modulation (THIPWM) technique instead of sinusoidal pulse width modulation (SPWM). The non-linear nature of the PV array is combated by a DC-DC converter which is controlled by perturb and observe (P&O) MPPT algorithm. The performance of the proposed system is verified through a simulation study in MATLAB/simulink and also by developing a prototype of 200 watts. The simulation and hardware results demonstrate minimal switching losses, low THD value with increased DC utilisation suitable for various standalone household loads.

One-Dimensional Spectral Analysis of Complex PWM Waveforms Using Superposition

This paper takes a new look at the mechanisms underlying the double-edge pulse-width modulation (PWM) process. It presents a novel way of deriving equations for the spectrum of double-edge PWM using basic mathematical techniques. In the process the underlying nonlinearities that generate the PWM sidebands are identified. Unlike the classical double Fourier series approach, the proposed method of deriving the PWM spectrum does not require the construction of the so-called unit cell. The interaction between this new model of the pulse-width modulator and the regular sampling process is studied, and generalized equations for the Fourier transforms of regularly sampled PWM waveforms are derived. A general solution to the important question of what happens to the PWM spectrum when the PWM reference consists of a summation of signals is presented. It is shown that the addition of reference signals in the time domain results in a double convolution of the PWM sidebands in the frequency domain. As an application of this result, it is shown how new analytic equations for the harmonics of third-harmonic injection PWM and space vector modulation can easily be derived. Finally, the new theoretical results are benchmarked against results from the well-established double Fourier series method.