Multiple PWM Research Articles

A comprehensive review on recent trends and future prospects of PWM techniques for harmonic suppression in renewable energies based power converters

Research has concentrated on promoting the development of environmentally friendly energies since air pollution, energy crises, and global warming are main challenges in modern era. One effective way to reduce environmental damage is to use Renewable Energy Resources (RER). The prominence of RER is increasing due to escalating global energy challenges. Power converter development and application are closely associated to the deployment of RER. One major problem with these power converters is the presence of extremely high harmonic components in their output voltage. Various PWM techniques are employed to suppress harmonics and no singular PWM technique is universally applicable to all circumstances. Firstly, this review paper provides readers with in-depth explanation of the significance of harmonic suppression as well as presentation of several important PWM strategies. Then, the advantages and disadvantages are explored, and the methods are compared in terms of the number of harmonics suppressed by each PWM technique. Further, this review also discusses and describes harmonics suppression, PWM categorization, Single PWM, Multiple PWM, Sinusoidal PWM, Modified Sinusoidal PWM, SVPWM, Hysteresis PWM, Selective Harmonic Elimination PWM, and Multiple Carrier PWM, as well as their benefits and drawbacks. Tables with comparative assessment based on various parameters are provided for each PWM technique. Lastly, conclusion with a thorough presentation of future tendencies is provided.

A Standard Two Stage On-Board Charger With Single Controlled PWM and Minimum Switch Count

A novel two-stage standard battery charger having minimum switch count using a single controlled PWM signal is presented in this paper for Electric Vehicle (EV) charging application. The first stage is responsible for AC to DC conversion with power factor correction (PFC) operation that consists of two switches and two diodes. The second stage is a DC-DC converter having a half bridge LLC resonant configuration along with an isolation transformer. The complete charger consists of only four switches and four diodes, which is minimum among the reported literatures. Moreover, unlike a conventional control strategy that requires multiple separate controlled PWM signals for different switches, the new control scheme manages both the PFC operation as well as constant current–constant voltage (CC-CV) optimal battery charging with a single controlled PWM signal. The detailed operation and its modeling are presented in this paper. A 470 W scaled down laboratory prototype is built to validate the proof of concept. The proposed charger is tested to charge a battery set of 24 V, 30 Ah using CC-CV logic with a maximum efficiency of 97.6%. The prototype is also tested with resistive load at its rated power and dynamics results are captured. A TMS320F28335 DSP board from Texas Instrument is used for implementing the control technique.

Vibration Analysis of Pulse-Width-Modulated Nozzles in Vineyard Blast Sprayers

Spraying systems to protect crops against pests are still necessary to maintain food production at the rates demanded by the current population. However, today, it is crucial to use precision agriculture to reduce the negative effects of pesticides and other agrochemicals such as fungicides. In particular, pressure fluctuations related to transient states when using pulse-width-modulated nozzles (PMW) have been reported to decrease the accuracy of preset flow rates in air-assisted orchard sprayers. The objective of this paper is to analyze the vibrations induced in the spraying system of a vineyard blast sprayer controlled by pulse-width-modulated nozzles, considering the instantaneous duty cycle (DC) as the control variable. An air-assisted vineyard sprayer was modified to host 24 solenoid shutoff valves with hollow disc–cone nozzles. A triaxial accelerometer was mounted to track the effect of duty cycle (20%, 30%, 50%, and 70%). In addition to accelerations, high-speed images were recorded, and the pressure according to time and the flow were estimated. The hydraulic system of the sprayer, when controlled in real time by the PWM solenoids, created pulsating impacts at the nozzle level with the same frequency of 10 Hz of the PMW system. The impact effect was significantly higher for low duty cycles under 40% DC. In addition, to demonstrate the inaccuracy of opening and closing the valves at a precisely specified time, this study also confirmed the divergence between the theoretical duty cycles commanded by the sprayer’s control unit and the actual ones measured in real time. The results of the analysis showed the difficulty of opening and closing the valves with precision to obtain accurate duty cycles in the practical implementation of smart sprayers and the importance of understanding the vibration effects of pulses in arrangements of multiple PWM nozzles working simultaneously.

3-Phase multi-inverter with cascaded H-bridge inverter designing and implementation for renewable system

Several applications of Distributed Generation networks uses Multilevel inverters, specifically photo voltaicsystems. Few major benefits of the Multilevel inverters are its power quality and the output voltages generated from the small PV voltage sources are high.Furthermore, AC output voltage is low for these inverters and it is nearly 400 V (phase to phase voltage). This research developed a compact three-phase modular multilevel inverter with symmetrical decomposition and asymmetrical of input multi-terminal for various PV system’s ratings. The 3-phase inverter proposed uses lower number of components. The design incorporates multiple carrier PWM for reduction of THD. The PV panels are related at every 3 phase VSI (Voltage Source inverter’s) DC side. The 3-phase isolation transformer with primary open-end windings, connects 3-phase VSIs AC sides in which multilevel operation are ensured. Three half-bridge cells for each phase for 7-level output voltage generation are combined. Proposed inverter is evaluated by comparing with existing methods such as Neutral-Point-Clampedthree-phase Multi Level Inverter (NPC-MLI), Multi Level Inverter with Linear Discriminate Notation Reactor (MLI with LDNR) and Cascaded H-bridge Multi Level Inverter (CHBMLI). Hence the proposed TPM-CHI achieves 2.1 V and 2.2amps of THD under symmetric disposition, 2.2 V and 2.4amps of THD under asymmetric disposition.

Low Switching Frequency Operation Control of Line Voltage Cascade Triple Converter

With the increasing power level of wind power generation system, the traditional topology of power converters can no longer meets the demand of high-power wind power generation systems due to the limitation of device performance. The line voltage cascade type multiple PWM converter (LVC-VSC) is a kind of converter that uses the traditional two-level and six-switch voltage source converter as the basic component unit, and each unit is combined with the line voltage cascade method. This type of converter is suitable for medium-voltage and high-power applications such as wind power generation and metallurgical drives because of its easy modularization, strong scalability and low number of isolated power supplies required. However, for medium-voltage and high-power applications, the switching frequency of power devices in the converter is low, usually limited to a few hundred hertz. The traditional modulation method of line voltage cascade converter has a large number of redundant states, and simply reducing the carrier ratio will cause serious degradation of control performance and system instability. To address this problem, this paper proposes a modulation strategy and a corresponding control method for low switching frequency. The modulation strategy is based on the vector relationship of finite switching states, and the optimal switching sequence is selected according to the modulation system by removing redundant states, thus ensuring the application of different modulation sequences under different modulation depths and ensuring the current quality on the basis of the minimum switching frequency, which effectively solves the control problems at low switching frequency. The experimental results show the correctness and effectiveness of the proposed modulation strategy and control method.

Multi-input and multi-output bi-directional power converter for solar photovoltaic system

This paper presents the development of a multi-input multi-output bi-directional power converter (MIMO-BDPC) with a digital pulse-width modulation (DPWM) controller for solar photovoltaic (SVP) application. The converter is operated in three modes such as buck, boost, and inverter. The converter uses a minimum number of active components and the DPWM controller controls the switching frequency or pulse period which are reconfigurable for effective synchronous and autonomous operation. The autonomous mode is selected by the controller based on the availability of the power source. The combination of high performance, low cost, and high reliability in a single controller is achieved via this intelligent digital approach. The controller is based on the power and load changes in multiple PWM modes. The Intel Altera Cyclone IV FPGA control will be used for digital PWM. The FPGA is scheduled for parallel data processing with multiple resource blocks. During control, this controller can be reprogrammed dynamically again. This makes the system extremely efficient in the check aspect, reducing time and cost. The proposed MIMO-BDPC is tested with the above-mentioned modes of operation using MATLAB software and also through hardware results.

Синтез двухчастотного тока параллельно-последовательным резонансным LCLC-преобразователем с многократной широтно-импульсной модуляцией

The methods to form a two-frequency inductor current in a resonant converter with multiple pulse-width modulation for systems of induction heating of complex surface shape bodies are considered. The study of the methods used to form and to regulate the frequency components of the inductor current is carried out. The approaches to assess the energy efficiency of two frequency converters are proposed and its assessment is carried out for multiple PWM by the values of power factors and overall power. It is shown that the high-frequency harmonic is formed by two components: the one that is generated by multiple modulation and the one contained in the rectangular voltage of low frequency, the latter significantly affects the energy characteristics. The advantages in terms of energy of bipolar PWM over unipolar PWM are shown

Design of Four Rotor Unmanned Aerial Vehicle Based on Open CV

This design is based on the OpenCV technology of the four rotor UAV, mainly by the control module and image module of two parts. The control module contains a STM32 micro controller, it can generate multiple PWM to control the motor to produce basic movements, while the body is equipped with three axis acceleration of three axis gyroscope MPU-6050 module, electronic compass, barometer and wireless communication module, and use STM32 to read sensor data for gesture calculation and control motor action; The image module is equipped with a ARM Cortex-A53 processor, running the Python-OpenCV operating system in the embedded Linux environment, OpenCV implementation of the UAV aerial features, in addition, the onboard Wifi module can be accessed by SSH remote desktop to obtain detection images, which can be widely used in security monitoring, exploration engineering, home security and other fields.

Design of Control System for Multi-joint Robot Based on STM32

The motion of Bionic Hexapod spider robot is relatively flexible. It has high comprehensive performance and research value whether it is the stability of motion, the load capacity of fuselage, or the difficulty of control. In this project, a Bionic Hexapod spider robot with STM32 chip as the core control is designed. Combined with the actuator control board design action, the STM32 chip built-in timer is used to generate multiple PWM signals to drive the steering gear motion, so that the robot can achieve different posture. At the same time, a wireless remote controller based on NRF24L01 wireless module is designed to expand the usability of the project. On the basis of the simulation, the actual operation principle of the robot is verified, which lays a good theoretical foundation for the continuous improvement of the robot in the future.

Design and implementation of cascaded H-Bridge multilevel inverter using FPGA with multiple carrier phase disposition modulation scheme

The paper deals with design of Cascaded H-Bridge Multilevel Inverter (CHB-MLI) with separate DC source to each inverter using multiple carrier Phase Disposition PWM such as symmetric disposition, phase opposition disposition and alternative phase opposition disposition to reduce the Total Harmonic Distortion (THD) and to improve the power quality of the supply voltage and current. In early days, the multilevel inverters are controlled with high frequency PWM method. This is not suitable for high power applications due to the high switching losses. With the help of multiple carrier PWM switching losses in the inverter circuit are reduced, so it can be used for high switchi ng frequency applications. The simulation of proposed system is developed using MATLAB Simulink software. The Performance simulation results are validated through experimental test setup using SPARTAN - 6 FPGA. Simulation results and effectiveness of the proposed method is proved and validated by experimental data.

DSP based Controller with Switching Loss Reduction Technique for Brushless DC Motor Drive System

PMBLDC motor finds its application in various fields which includes hybrid electric vehicles, robotic applications with high precision control, fans and industries. This paper presents DSP based control with switching loss reduction technique for Permanent Magnet Brushless DC motor. Firing pulses for power switches are generated using DSP TMS320C2407 based on hall sensor feed-back. The algorithm is written in C using code composer studio to generate single mode PWM pulses and multiple PWM pulses. To reduce the switching losses three switches are turn on and turn off with single pulse and the remaining three switches are with multiple PWM pulses. The hardware is implemented and the trapezoidal stator voltage and corresponding gating signals are measured for various speed. The experimental results validate the performance of proposed system.

Cascaded half-full-bridge PWM multilevel inverter configuration

inverter topology. It is made up of a main inverting H-bridge legs and level-clamping half-bridge circuits, each having its own dc source. The single-carrier, multilevel PWM scheme is employed to generate gating signals for the power switches. The modulation scheme is hybridized to enable the output voltage of the proposed inverter configuration to inherit the features of switching-loss reduction from fundamental PWM and good harmonic performance from multiple sinusoidal PWM. Moreover, a simple base PWM circulation scheme is also introduced in this work to obtain a resultant sequential switching hybrid PWM (SSHPWM) circulation that balances power dissipation among the four power switches of the main H-bridge module. Operational principles with switching functions are given. For a modulation index of 0.9, the proposed inverter configuration was subjected to an R-L load and the respective numbers of output voltage level were synthesized. FFT analyses of the output voltage waveforms were carried out and the corresponding THD value of 13.16{\%} was obtained. To verify the performance of the proposed inverter architecture, simulations and experiments were carried out on a 2.95 kW rated prototype of the proposed inverter for an R-L load and adequate results were obtained.

Design and Implementation of Modified Buck Boost Converter Fed B4 Inverter for Brushless Dc motor Drive using Low Cost DSPIC Controller

The Research deals with the speed control of Brushless DC Motor drive by low cost dsPIC controller and B4 Inverter with new converter design (Four Switch Inverter) rather than conventional inverter (Six Switch Inverter) is proposed. The conventional Six switch Inverter is modified into B4 Inverter in order to reduce the switch leg failure, and Total Harmonic Distortion. This facilitates the operation of voltage source Inverter at fundamental frequency switching by using the Electronic commutation technique rather than Mechanical commutation. In addition we propose single phase Rectifier and Three phase voltage source Inverter, dsPIC controller to generate the multiple carrier PWM pulses for B4 Inverter which is fed to the Permanent Magnet Brushless DC Motor to obtain the desired motor speed. The proposed Research mainly focused on the new topology of Buck boost converter design for B4 inverter, By this new modified buck boost Enhancement converter design motor speed are controlled and voltage imbalance in the capacitors are avoided the capacitor voltage is similar voltage level is obtained during the buck and the boost mode operation of the converter side, So results with improved quality of Boosted up output DC Power is obtained. Simulation Modeling Results are carried out by Matlab/Simulink environment and Portable Experimental Hardware is developed Results are carried out Sucessfully and Validated for various operating parameter conditions.

A Comparative Harmonic Analysis of Single Level and Two Level Matrix Converter with various Load Condition

This paper presents the electrical harmonic analysis of a single-phase single level matrix converter and a single phase two-level matrix converter for various load condition. The matrix converter eliminates the rectifier and dc link due to direct ac-ac conversion. Multiple PWM for multilevel (Two level) and normal sinusoidal PWM signal generation for single level have been used here. Simulation is performed for both single level and multi-level matrix converter. The results obtained here demonstrate a high performance matrix converter.

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.

Finite set model predictive control to a shunt multilevel active filter

Purpose – The purpose of this paper is to implement a finite set model predictive control algorithm to a shunt (or parallel), multilevel (cascaded H-bridge) active power filter (APF). Specifically, the purpose is to get a controller that could compensate the mains current and, at the same time, to control the voltages of its capacitors. This strategy avoids the use of multiple PWM carriers or another type of special modulator, and requires a relatively low processing power. Design/methodology/approach – This paper is focussed in the application of the predictive controller to a single-phase parallel APF composed for two H-bridges connected in series. The same methodology can be applied to a three-phase APF. In the DC buses of each H-bridge, a floating capacitor was connected, whose voltage is regulated by the predictive controller. The controller is composed by, first, a model for the charge/discharge dynamics for each floating capacitor and a model for the output current of the APF; second, a cost function; and third, an optimization algorithm that is able to control all these variables at the same time, choosing in each sample period the best combination of firing pulses. Findings – The controller can track the voltage references, compensate the current harmonics and compensate reactive power with an algorithm that evaluates only the three nearest voltage levels to the last voltage level applied in the inverter. This strategy decreases the number of calculations required by the predictive algorithm. This controller can be applied to the general case of a single-phase multilevel APF of N-levels and extend it to the three-phase case without major problems. Research limitations/implications – The implemented controller, when the authors consider a constant sample time, gives a mains current with a Total Harmonic Distortion (THD-I) slightly greater in comparison with the base algorithm (that evaluates all the voltage levels). However, when the authors consider the processing times under the same processor, the implemented algorithm requires less time to get the optimal values, can get lower sampling times and then a best performance in terms of THD-I. To implement the controller in a three-phase APF, a faster Digital Signal Processor would be required. Originality/value – The implemented solution uses a model for the charge/discharge of the capacitors and for the filter current that enable to operate the cascaded multilevel inverter with asymmetrical voltages while compensates the mains currents, with a predictive algorithm that requires a relatively low amount of calculations.

Experiment and Simulation of a Modular Push–Pull PWM Converter for a Battery Energy Storage System

This paper presents a modular push-pull PWM converter (MPC) for a battery energy storage system, which is intended for grid connections to medium- or high-voltage power systems. The converter per phase consists of a center-tapped transformer and two arms based on a cascade connection of multiple bidirectional PWM chopper-cells with floating dc capacitors. This paper discusses the operating performance and control method of the MPC, focusing on voltage balancing of all the floating dc capacitors. Moreover, a comparison is made between the MPC and a modular multilevel converter (MMC), under an assumption that both are used as the same battery energy storage system. The validity of the operating performance and control method is confirmed by both computer simulation using the “PSCAD/EMTDC” software package and experiment using a three-phase, 200-V, 5-kW downscaled model.

Multiple low frequency dual reference PWM control of a grid connected photovoltaic three phase NPC inverter with DC/DC boost converter

In recent years, power demand of industrial applications has increased significantly reaching some megawatts. The use of multilevel converters for applications of medium and high powers is proposed as a solution to drawback semiconductor technology. A multilevel converter not only achieves high power ratings, but also enables the use of renewable energy sources. Renewable energy sources such as photovoltaic can be easily interfaced to a multilevel converter system for a high power application. This paper presents the simulation study in Matlab/Simulink of a grid connected photovoltaic three phase Neutral Point Clamped (NPC) inverter with DC/DC boost converter for constant and variable solar radiation.

Control and Verification of a Modular Push-Pull PWM Converter for a Battery Energy Storage System

This paper presents a modular push-pull PWM converter (MPC) for a battery energy storage system, which is intended for grid connections to medium-voltage or high-voltage power systems. The converter per phase consists of a center-tapped transformer and two arms consisting of a cascade connection of multiple bidirectional PWM chopper-cells with floating dc capacitors. This paper discusses the operating performance and control method of the MPC, focusing on voltage balancing of all the floating capacitors. Moreover, a comparison is made between the MPC and a modular multilevel cascade converter (MMCC-DSCC), both of which are used as the same battery energy storage system. The validity of the operating performance and control method is confirmed by both computer simulation using the “PSCAD/EMTDC” software package and experiment using a three-phase, 200-V, and 5-kW downscaled model.

Comparison of Multiple Carrier Disposition PWM Techniques Applied for Multi-Level Shunt Active Filter

Comparison of Multiple Carrier Disposition PWM Techniques Applied for Multi-Level Shunt Active FilterThis work presents the simulation of a shunt active filter using seven-level cascaded inverter. The ultimate objective is to bring out the influence of multiple carrier level shifted PWM techniques on the performance of a shunt active filter. Classical disposition PWM techniques such as PD, POD and APOD have been used to generate the gating signals for the inverter active switches. A comparison is presented to substantiate the effect of these techniques in filtering. The comparison is made from the perspective of reduction in THD of source currents after filtering. For compensation current extraction synchronous detection method has been used. The harmonic reduction is achieved in source currents as well as source voltages.