Pulse Width Modulation Control Technique Research Articles

A novel PWM technique to eliminate common-mode voltage for single-phase three-level T-NPC inverter

This paper presents a new pulse width modulation (PWM) technique in order to eliminate common mode voltage for a single-phase full H-bridge T-NPC inverter. Three-level NPC inverters are commonly used in grid connected applications or as UPS backup power for industry. In addition to abilities such as to withstand high voltage, and reach output voltage and current with low harmonic distortion, three-level NPC inverter is advantageous for mitigating common mode voltage and leakage current. The new proposed PWM technique is based on the switching state table of the three-level H-bridge T-NPC inverter that containing many switching states with zero common mode voltage. Furthermore, implementation of PWM control for single-phase three-level T-NPC inverter configuration can decrease voltage stress on the output and reduce output voltage distortion compared with bipolar PWM control technique for two-level H-bridge inverter. In this paper, the sine wave carrier PWM technique is analyzed, designed and modelled based on the switching table. The analytical analysis will be evaluated using MATLAB/SIMULINK. Simulation results of the proposed PWM technique for three-level T-NPC inverter are compared with conventional techniques without common mode voltage elimination; the quality of the three-level T-NPC inverter is also compared to that of traditional two-level inverter. The power loss content is evaluated using PLECS software. The obtained results confirm the advantages of the eliminated common mode voltage PWM technique in the three-level T-NPC inverter configuration.

Position control of a pneumatic cylinder actuator using modified PWM algorithm

Pneumatic cylinders are used as actuators for modern automatedsystems in many industries applications for their numerous advantages.Basically, those applications are implemented using components suchas proportional and servo pneumatic control valves that are relativelyexpensive because of their high accuracy even in applications thatdo not require such high accuracy. Recently, binary (on/off) solenoiddirectional control valves (DCVs) have been used to replace many ofthe expensive components and consequently reduce the system costwith achieving acceptable accuracy. This paper presents a controltechnique for a positioning system of a pneumatic double acting cylindercontrolled by pair of on/off solenoid DCVs. The control technique hasbeen developed based on a parametric study presented previously by theauthors[1]. The control technique depends on operating the DCVs usinga pulse width modulation (PWM) algorithm that is modified to employa valve dead-zone compensator (DZC) along with using optimumpneumatic parameters gained from the performed parametric study. Anexperimental test bed for a pneumatic double acting cylinder positioningsystem that uses a pair of on/off solenoid DCVs has been installed to testthe accuracy of the presented control technique. A comparison betweenthe performance of the positioning control technique using the modifiedPWM control algorithm and the traditional one has been carried outto experimentally show the enhancement of the positioning accuracywith acceptable maximum steady state error less than 0.7 mm whenusing the modified PWM control technique due to reducing the systemnonlinearity associated with its dynamics.

Comparative Study of FCS-MPC and PWM Control Techniques for Autonomous Four-Leg VSI

Finite control set model predictive control (FCS-MPC) is considered as a new control technique in the power electronics fields which do not require modulation stage. The absence of modulation stage results in operating under variable switching frequency which can affect the harmonic distortion of the output signal, the switching losses, filters design and so on. On the other hand, the linear controllers control the power converters with constant switching frequency by using modulators. In this paper, the overall performance of FCS-MPC is assessed by performing a comparative study with a linear controller based on scalar pulse width modulation (PWM). The control systems are applied on an autonomous four-leg voltage source inverter (VSI) with LC filter as part of an autonomous power supply system. The main purpose of the two control techniques is to control four-leg VSI to provide balanced load voltage with lower total harmonic distortion. The steady state performance of the two control techniques is tested under balanced, unbalanced, linear and nonlinear load conditions. Moreover, the effect of the load variations on the switching frequency of the FCS-MPC is discussed. Finally, the performances of the two control methods in tracking the reference voltage under transient conditions are analysed.

Analysis of Switching Sequence Operation for Reduced Switch Multilevel Inverter With Various Pulse Width Modulation Methods

Pulse Width Modulation (PWM) methods are used to control the switching sequence operations of conventional Multilevel Inverter (MLI) and Reduced Switch Multilevel Inverters (RSMLI). Many researchers proposed various RSMLIs with their switching sequence operation and PWM control techniques. But, the switching operations of RSMLIs are not similar to conventional MLIs which are major problem of switch control. Logical equations are proposed for the operation of RSMLIs with the multi carrier pulse width modulation methods like, Alternative Phase Opposition Disposition (APOD), Phase Opposition Disposition (POD) and Phase Disposition (PD). To operate the individual switch in RSMLI, logical operators are used to produce required pulse sequence from the sequence of PWM method and their analysis is not present in previous works. The proposed methodology and binary representation of PWM method are analyzed on various RSMLIs for 7 level output voltage. Control of individual switching sequence and the operation of RSMLIs are simulated using MATLAB/Simulink. THD comparison is presented for RSMLIs with various PWM methods.

Fast Switching Valve Utilization to Control Pneumatic Cylinder Speed

The position and speed of the piston of pneumatic cylinder are very important parameters in evaluating the pneumatic system performance. Utilization of Pulse Width Modulation (PWM) technique to control the Fast Switching Valve (FSV) usually causes fluctuation in the piston motion and accordingly, the system performance deteriorates. The objective of this work is to introduce a novel PWM control technique considering the suitable duty cycles according to the switching frequency in order to improve the FSV characteristics and reduce piston speed fluctuation. A test rig for a simple pneumatic circuit with an FSV as a control element has been designed and realized. The displacement of the piston is measured using a Linear Wire Potentiometer Transducer (LWPT), while its derivative is used to estimate the speed considering a low pass filter to reduce the effect of piston position signal noise. A nonlinear mathematical model is introduced and experimentally validated. The results of both computer simulation and experimental measurements show that the integration between fast switching valve and PWM control signal leads to a quasi-linear relationship between duty cycle and piston speed. Moreover; results proved the successful control of piston speed based on the correct duty cycle and valve switching frequency.

High Voltage Gain Quasi-Switched Boost Inverters With Low Input Current Ripple

Two high voltage gain quasi-switched boost inverters (HG-qSBIs) are introduced in this paper. The proposed HG-qSBIs has the following characteristics: 1) continuous input current with low ripple; 2) reduced voltage stress on the capacitor, switch, and diodes; 3) shoot-through immunity; 4) achieved high voltage gain with single-stage conversion; and 5) improve the output voltage capability with using high modulation index. A novel pulse-width modulationcontrol technique is proposed for the introduced HG-qSBI. Operating principle, circuit analysis, and passive component design guideline of the HG-qSBI are addressed. Comparison analysis between the introduced HG-qSBI and other Z-source-based high voltage gain inverters is presented. A prototype is made to test the introduced HG-qSBI. Simulation and experimental verifications are shown to prove the accuracy of the theoretical analysis.

Variable switching frequency modulation scheme for PWM converter integrating series‐resonant voltage multiplier‐based voltage equalizer for photovoltaic strings under partial shading

Conventional photovoltaic (PV) systems require not only a converter for string control but also preferably a voltage equalizer to preclude partial shading issues, which increases the system complexity because two separate converters are necessary. A single‐switch, single‐magnetic pulse width modulation (PWM) converter integrating a series‐resonant voltage multiplier (SRVM) as a voltage equalizer has been proposed in previous work to simplify PV systems by reducing the converter count. The equalization performance of the integrated converter employing a traditional PWM control scheme, however, is unavoidably impaired because the effective operation period of the SRVM in a switching cycle is relatively short at a fixed switching frequency fS. This paper proposes a variable‐fS PWM control technique to improve the voltage equalization performance of the SRVM. The proposed modulation scheme adjusts fS according to the duty cycle variation so that the SRVM's effective operation period is extended. Detailed mathematical analysis revealed that the proposed modulation scheme could improve the equalization performance of the integrated converter. The experimental equalization tests for three PV modules connected in series were performed emulating a partial shading condition. With the proposed modulation scheme, the extractable maximum power from the partially shaded string increased by up to 7%, demonstrating the improved equalization performance of the SRVM. © 2018 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Implementation of Cascaded based Reversing Voltage Multilevel Inverter using Multi Carrier Modulation Strategies

In this paper, a cascaded based reversing voltage (CBRV) multilevel inverter structure is proposed inorder to compensate the major drawbacks in the conventional multilevel inverters. The proposed topology requires less number of components, less carrier signals and gate drives when compared to existing multilevel inverters particularly at higher levels. Therefore, the complexity and overall cost are greatly reduced particularly for higher output voltage levels. This paper also presents the most relevant control and modulation methods by a triangular based multi carrier pulse width modulation (PWM) scheme for the proposed CBRV inverter topology. This paper presents a comparison between different modulation strategies for CBRV inverter topology based on sinusoidal and space vector references with multi triangular carrier waves. The work strive hard to present the scrutiny that has been made between various PWM control techniques for 1–Ф seven level CBRV inverter structure. The comparison is made in terms of Total Harmonic Distortion (THD) and fundamental RMS voltage. Finally, the simulation results are included to verify the effectiveness of the proposed CBRV inverter topology and validate the proposed theory. A hardware set up was developed for a 1–Ф seven level CBRV inverter topology using FPGA based pulse generation.

Photovoltaic Based Series Z-source Inverter fed Induction Motor Drive with Improved Shoot through Technique

This paper explores the series Z-source inverter (SZSI) topology for induction motor (IM) with solar photovoltaic (SPV) as source in drive application. Series Z-source inverter has single stage power conversion with buck-boost capability. Shoot through ratio is used for boosting dc link voltage in series Z- source inverter. In this paper, for enhancing the performance of SZSI improved shoot through envelop technique along with sinusoidal pulse width modulation control technique for solar PV based series Z-source inverter fed drive, is presented. The major benefits of modified boost control technique are current reduction and harmonics reduction in output voltage as compared to simple boost control scheme. The validity and feasibility of modified boost control technique for shoot through envelop to control SZSI fed induction motor is verified by simulation and experimental results.

Thermal analysis and reliability evaluation of cascaded H‐bridge MLPVI for grid‐connected applications

Nowadays, great progress has been made in the development of multilevel inverters (MLIs) in grid-connected photovoltaic (PV) energy systems, because of the advantages such as reduced voltage stress on the power semiconductor switches and having higher efficiency. Since the multilevel PV inverter (MLPVI) has been a critical part within the failures of a PV energy system, so it becomes important to predict the lifetime of the components and the MLPVI system. In this paper, a five-level modular cascaded H-bridge MLI is analyzed based on grid-connected application for PV energy system, and an independent dc-link voltage controller for each H-bridge is implemented by taking the reference value generated from the maximum power point tracking algorithm of each PV module. The loss and thermal distributions of the different power devices in the MLPVI system are investigated and illustrated for various pulse-width modulation (PWM) controllers. The junction temperature and power losses of the components in the MLPVI are simulated by MATLAB/Simulink and Piecewise Linear Electrical Circuit Simulation (PLECS) blockset, which validate the theoretical analysis. The reliability of the MLPVI is evaluated using parts stress method. It shows that the MLPVI has a good reliability when phase shift PWM control technique is used.

Adaptive neural network–based synchronized control of dual-axis linear actuators

Synchronized motion control with high accuracy becomes very essential part in industry. Due to some possible effect such as unknown disturbance or unmatched system model, it is difficult to obtain the precision of synchronous control using the conventional proportional–integral control method with parallel architecture. The adaptive compensator must be employed to eliminate tracking errors. The objective of this research is to propose the modified cross-coupling architecture using single-neuron proportional–integral controller and a synchronous compensator for dual-axis linear actuator. The single-neuron proportional–integral control strategy with delta learning algorithm can adjust the weighting coefficients of controllers to provide the robustness for each single-axis DC linear actuator system. A back-propagation neural network compensator is designed to adaptively reduce position and velocity errors between the two-axis servo systems. Both simulation and experimental results are developed to demonstrate that the synchronous position tracking performances in terms of root mean square error and sum of absolute error can be substantially improved, and the robustness to linear actuator uncertainties can be obtained as well. The proposed coupling strategy which uses the microchip platform and pulse–width modulation control technique is realized and implemented, and the synchronization performances to external disturbance load are illustrated by several experimental results.

A Overlapping Carrier Based SPWM for a 5-Level Cascaded H-bridge Multilevel Inverter

This paper proposes a switching control for a cascaded H-bridge inverter structure with reduced switches which is used to improve the THD performance of a single phase five level CHB MLI. The multi level inverter is simulated for the conventional carrier overlapping APOD and the proposed carrier overlapping APOD Pulse Width Modulation (PWM) switching control technique. The total harmonic distortion (THD) of the output voltages are observed for both PWM control techniques. The performance of the symmetric CHB MLI is simulated using MATLAB-SIMULINK. It is observed that the proposed carrier overlapping APODPWM provides output with relatively low THD as compared to the conventional carrier overlapping APODPWM.

A Overlapping Carrier Based SPWM for a 5-Level Cascaded H-bridge Multilevel Inverter

<p>This paper proposes a switching control for a cascaded H-bridge inverter structure with reduced switches which is used to improve the THD performance of a single phase five level CHB MLI. The multi level inverter is simulated for the conventional carrier overlapping APOD and the proposed carrier overlapping APOD Pulse Width Modulation (PWM) switching control technique. The total harmonic distortion (THD) of the output voltages are observed for both PWM control techniques. The performance of the symmetric CHB MLI is simulated using MATLAB-SIMULINK. It is observed that the proposed carrier overlapping APODPWM provides output with relatively low THD as compared to the conventional carrier overlapping APODPWM.</p>

THD Analysis of an Overlapping Carrier Based SPWM For a 5-Level Cascaded H-bridge Multilevel Inverter

This paper analyzes the Total Harmonic Distortion (THD) performance of a single phase 5-level CHB MLI. The multi level inverter is simulated using the carrier overlapping APOD Pulse Width Modulation (PWM) switching control technique. The total harmonic distortion (THD) of the output voltage is observed for the PWM control technique at varying modulation index of 0.7-1.0. The performance of a 5-level CHB MLI is simulated using MATLAB/SIMULINK. It is observed that the carrier overlapping APODPWM provides output with relatively low THD.

Analysis of Three Phase Reduced Switch Nine Level Inverter with Various PWM Strategies

This paper proposes a three phase nine level inverter with various three phase star (Y) connected loads of R (Resistive) load, RL (Resistive Inductive) load and IM (Induction Motor) load. The various PWM (Pulse Width Modulation) control techniques were proposed. Motor load provides rated speed N (rpm) and its corresponding electromagnetic torque T (N-m). Pulse Disposition (PD) technique provides better Total Harmonic Distortion (THD) and rated speed for this proposed topology. Performance factors are like VRMS, VPEAK, IRMS, IPEAK (fundamental), THD were obtained and its FFT plots are analyzed and presented. Simulations were performed using MATLAB – SIMULINK. Simulation results such as output voltage, output current and speed torque characteristics are shown. Carrier Overlapping (CO) PWM is found to execute relatively higher fundamental RMS component.

Comparative Study and Design Analysis of Several Pulse Width Modulation Control Techniques

Various PWM techniques are used for controlling the different loads such as R, R L, and RLE. In the existing system the control technique like, TSPWM, Single pulse PWM and Multiple Pulse PWM is Used to control the load, which has Acoustic noise and harmonic distortion .The proposed system reveals the reduction of losses by comparing TSPWM, SVPWM and RPWM .The highest possible peak phase fundamental is higher for SVPWM than TSPWM, and the RPWM technique offers significant benefits over deterministic PWM when implementing motor drive system.

Implementation of PWM control strategy for torque ripples reduction in brushless DC motors

The generated torque ripples from the BLDC motor is the main issue that affects the drive performance of the BLDC drive system. In this paper, a new switching technique to minimize the torque ripples due to current commutation is proposed. The presented scheme has been implemented using a commercial and low-cost mid-range PIC microcontroller to generate the modified pulse width modulation (PWM) control signals. An analysis of phase current during commutation time is carried out. Experimental results verify the effectiveness of proposed method. Results had shown a smoother output torque and current produced in comparison with that using conventional PWM control technique with an average of 50 % reduction in the generated torque ripples.

Comparison of Hybrid Modulation Techniques for a Single Phase Rectifier

The objective of this paper is to control a single phase power rectifier using Hybrid PWM (Pulse Width Modulation) to get a required output. Nowadays PWM control technique has become an integral part of the most power electronics system. This technique is the most suitable one for controlling the output voltage of a power rectifier. In this paper the performance of the proposed module is analyzed for various Hybrid modulation techniques and the most suitable technique is identified on the basis of Total Harmonic Distortion present in the supply current waveform. Hybrid PWM technique is used to control Gate signal of power switches of single phase power rectifier. By this way, ON and OFF time of circuit MOSFETs can be controlled to obtain the desired DC output voltage. The performance of the power rectifier with the Hybrid PWM technique is promising and attractive for harmonics free power supply applications.

A novel control scheme for buck power converters using duty-cycle modulation

A novel duty-cycle modulation control scheme for buck power converters is studied in this paper. Compared to the widely used pulse width modulation technique encountered in power electronics, the proposed control scheme offers under the same operating conditions a variety of merits, including a greater hardware simplicity, a lower modulation frequency and a better transient response. In addition, while offering new characteristics, it provides under load disturbances the same level of robustness than the standard pulse width modulation control technique. The characteristics of both control techniques are validated and compared on a well tested prototyping buck converter, using a mix of analytical reasoning, virtual simulations, and real tests on a laboratory workbench.

Space Vector PWM Technique for a Three-to-Five-Phase Matrix Converter

Variable-speed multiphase (more than three phases) drive systems are seen as serious contenders to the existing three-phase drives due to their distinct advantages. Supply to the multiphase drives is invariably given from a voltage source inverter. However, this paper proposes an alternative solution for supplying multiphase drive system using a direct ac-ac converter called a matrix converter. This paper proposes the pulsewidth modulation (PWM) algorithm for the matrix converter topology with three-phase grid input and five-phase variable-voltage and variable-frequency output. The PWM control technique developed and presented in this paper is based on space vector approach. This paper presents the complete space vector model of the three-to-five-phase matrix converter topology. The space vector model yield 2 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">15</sup> total switching combinations which reduce to 243 states considering the imposed constraints, out of which 240 are active and 3 are zero vectors. However, for space vector PWM (SVPWM) implementation, only 90 active and 3 zero vectors can be used. The SVPWM algorithm is presented in this paper. The viability of the proposed solution is proved using analytical, simulation, and experimental approaches.