Random Pulse Width Modulation Technique Research Articles

Development of performance characterization in VSI fed induction motor drives using random PWM

Any industrial or power sector application requires a pulse width modulation (PWM) inverter. Industrial drives in particular are highly concerned with industrial standards. To satisfy the voltage source inverter (VSI) drives objects, a variety of PWM approaches are used, including inverter DC input voltage utilizations, suppression of higher and lower order of harmonics, as well as spreading harmonics, acoustic noise reduction, among others PWMs. One of the better approaches for minimizing noise on voltage source threephase inverter fed drives is random pulse width modulation PWM random palse width modulation (RPWM). Despite the fact that these described RPWM approaches are superior in terms of harmonic spreading and mitigation, these methods are unable to achieve the target DC-link utilizations. As a result, the focus of this paper is on combining multicarrier RPWM principles with space vector PWM space vector pulse width modulation (SVPWM) to produce multi-carrier random SVPWM (MCRSVPWM). The suggested PWM generates random unsystematic triangle carrier (5 kHz, 2.5 kHz, 1.25 kHz, 1 kHz) based pulses, whereas the traditional random PWM techniques are uses a fixed frequency triangular carrier to generate random pulse positions. Asynchronous induction motor driving simulation is carried out using MATLAB/Simulink. The proposed MCRSVPWM is put to the test with a 2kW six-switch VSI-fed induction motor drive system.

Development of performance characterization in VSI-fed induction motor drives using random PWM

Any industrial or power sector application requires a pulse width modulation (PWM) inverter. Industrial drives, in particular, are highly concerned with industrial standards. To satisfy the voltage source inverter (VSI) drives objects, a variety of PWM approaches are used, including inverter DC input voltage utilizations, suppression of higher and lower order of harmonics, as well as spreading harmonics acoustic noise reduction, among others PWMs. One of the better approaches for minimizing noise on voltage source three-phase inverter fed drives is random pulse width modulation (RPWM). Despite the fact that these described RPWM approaches are superior in terms of harmonic spreading and mitigation, these methods are unable to achieve the target DC-link utilizations. As a result, the focus of this paper is on combining multicarrier RPWM principles with space vector PWM (SVPWM) to produce multi-carrier random SVPWM (MCRSVPWM). The suggested PWM generates random unsystematic triangle carrier (5 kHz, 2.5 kHz, 1.25 kHz, 1 kHz) based pulses, whereas the traditional random PWM techniques are uses a fixed frequency triangular carrier to generate random pulse positions. Asynchronous induction motor driving simulation is carried out using MATLAB/Simulink. The proposed MCRSVPWM is put to the test with a 2-kW six-switch VSI-fed induction motor drive system.

36-5-4] 전력전자변환기에 적용된 Chaos PWM 기법의 스펙트럼 확산에 관한 연구

In this study, the power spectrum of the random PWM technique using the Linear Congruential Generator (LCG) and the PWM technique with chaotic logistic, tent and double tent map characteristics were compared with the fixed frequency switching PWM technique. The random technique generates random numbers using LCG, and the chaos number is generated using each chaos map, and a bifurcation tree with a=4.0 and λ=0.99 conditions in which a complete chaos state exists in the ranges of 0 and 1 is used. In order to prove the validity of this study, a DSP-based power electronics converter for driving a three-phase induction motor was manufactured. As a result, the chaos logistic map and tent map were limited in the spread of broadband in the spectrum of power electronics converters. However, the advanced chaos double tent map was similar to the excellent spectrum spread performance of the Random PWM technique by LCG. Harmonic Spread Factor(HSF) of the output voltages of each technique were measured according to the increase in the modulation index, and the chaos double tent map and random technique were very advantageous from the viewpoint of HSF.

Electromagnetic Interference of Power Converter with Random Modulation on the Power Line Communication System

Random Pulse Width Modulation (RPWM) allows controlling the switching signal of power converters in order to reduce the harmonic peaks by spreading the noise spectrum. Currently, many manufacturers of power converters are deploying this modulation scheme in order to comply with Electromagnetic Compatibility (EMC) test requirements. However, when the converters coexist with Power Line Communication (PLC) systems, such as in Smart Grid (SG) applications, resorting to RPWM needs further investigations since it potentially affects the communication channel by increasing the bit error rate. This possible detrimental effect is investigated in this work, by considering a PLC system for automatic meter reading (AMR) implemented in a SG application. To this end, the model of a complete PLC system is implemented in SIMULINK, and Quadrature Phase Shift Keying (QPSK) modulation is used to model the PLC modems in the communication channel. Results show that, even if the deployment of RPWM techniques may lead to an appreciable reduction/spreading of the peaks in the noise spectrum, it may also lead to an increase of the bit error rate on the PLC system.

Constant and variable switching frequency random PWM strategies for open-end winding induction motor drive

High amounts of harmonics cause noise and electromagnetic interference to nearby systems. Pulsewidth modulation (PWM) techniques are used to reduce the amount of harmonics near the multiples of switching frequencies. To trim down the noise and electromagnetic interference and improve the quality of the output voltages, different types of constant and variable switching frequency random PWM techniques for dual inverter-fed open-end winding induction motor drive configuration are discussed in this study. Moreover, the vector control technique is used along with random PWM techniques to improve the transient response of the dual inverter.

A random carrier frequency PWM technique with a narrowband for a grid-connected solar inverter

The quality of power is always a concern for the high penetration of a grid-connected solar photovoltaic (PV) system due to the variation in solar irradiation and the temperature change of solar output, which in turn varies the fundamental component of power delivered to the grid. A solar source requires an inverter interface to supply the AC load as well as for the grid interconnection. Any reduction in the fundamental component generated by solar PV at a lower irradiation level or at high- temperature results in increasing %THD at the output of inverter for a given fixed switching frequency since harmonics due to PWM technique is comparable with the fundamental component. The selection of high-fixed-switching-frequency PWM reduces harmonics but increases the stress on switches and switching losses. It also suffers from issues of harmonics at carrier frequency and its sideband at multiples of switching frequency that causes acoustic noise and EMI. The random frequency PWM (Random PWM) method overcomes these issues presented by the fixed-frequency PWM method. However, a wide band of Random PWM makes the inverter filter design difficult and causes resonance in the distribution system. In addition, asymmetry in the carrier wave introduces even-order harmonics in the line current. Hence, this paper proposes a narrowband random frequency PWM method to reduce sideband harmonics, lower-order harmonics, even-order harmonics and a total harmonic distortion (THD) for a solar-based grid-connected inverter. Simulation results present a satisfactory performance of the proposed control technique for a steady-state and transient results. Experimental validation of the same is carried out on the OPAL-RT OP4500-based laboratory prototype of a 2-kVA inverter which depicts reduction in harmonics and hence improvement in power quality.

A Novel Application of Harmonics Spread Spectrum Technique for Acoustic Noise and Vibration Reduction of PMSM Drive

This paper presents experimental investigation study of Acoustic Noise and Vibration (ANV) reduction in Permanent Magnet Synchronous Motor (PMSM) drives with a novel application of `harmonics spread spectrum technique'. In order to reduce the ANV of PMSM drives, the Random Pulse Width Modulation (RPWM) method is applied which distributes the power of harmonic noise in a wide range of discrete frequency spectrum. Furthermore, in-depth theoretical analysis is presented about the way RPWM improves torque ripples, vibration and acoustic noise in PMSM drives. The theoretical and experimental results obtained are used to draw the operational concept of the power electronics converters to reduce ANV; which is produced by PMSM drive. Time and frequency-domain analysis are carried out to examine the effects of change in the operating parameters such as pulse-width, etc. of the power electronics converters on the ANV. A small-scale laboratory set-up was developed for PMSM drive with low cost acoustic chamber for experimental investigations. Experimental results show significant reduction in ANV and torque ripples of the PMSM drive with the application of RPWM technique.

Predictive Control of IM Drive Acoustic Noise

Acoustic behavior of electric drives is an important factor for their application in areas where humans expect certain comfort, such as in electric vehicles. The main problem addressed in this article is high tonality of noise emitted by conventional pulsewidth modulation (PWM) controlled drives. We propose to use an explicit model of the transfer function from the electric variables to the sound pressure with experimentally identified parameters. This model is then used to include acoustic quality into the cost function of the finite control set model predictive control (FCS-MPC). Specifically, we propose to penalize the sound pressure resonant frequencies in the spectrum of the direct flux component of the stator current vector. We study the impact of this penalization on acoustic properties of the drive measured by the sound pressure level and spectral flatness measure on three experimental induction machine (IM) drives of different power and acoustic environment. In comparison with the conventional PWM, random PWM, and FCS-MPC techniques, the proposed approach improves the tonality of the noise in terms of spectral flatness and in high-speed regimes it also improves total sound pressure level by several decibel.

Power quality improvement in wind energy conversion system using hybrid SVPWM inverter control technique for THD reduction

Wind energy is an abundant and naturally occurring source of energy that is being widely researched and implemented in recent times on a global scale. Quality of power generated from these renewable energy systems greatly determines the efficiency of such implementations. This research paper investigates and proposes a hybrid control scheme for reducing the total harmonic distortion which severely degrades the quality of power from energy conversion systems. The proposed hybrid space vector modulation scheme is a variant and improvement of the conventional PWM schemes. The produce more fundamental components with least harmonics by combining the merits of sinusoidal PWM and triangular carrier signal. The proposed modulation scheme is implemented in a closed loop PI controller scheme and results have been compared against three variants of PWM techniques namely sinusoidal, random and space vector PWM techniques and a drastic reduction in THD and power spectral density is observed justifying the superior performance of the proposed hybrid control scheme.

Coupled random PWM technique for dual inverter fed induction motor drive

Dual inverter fed induction motor drives provide more advantages in contrast with other multilevel inverter drives. Coupled PWM techniques provide good standard of output voltage than the decoupled PWM techniques for dual inverter configuration. In this paper analysis of open end winding induction motor by coupled random PWM signals and decoupled SVPWM signals was carried out. Induction motor by random PWM technique generate low acoustic noise and electromagnetic interference to near by systems. The performance evaluation of the drive wss implemented in MATLAB/simulink and the results were presented.

Space vector based random pwm algorithms for acoustic noise and harmonics reduction for voltage source inverter fed ac drive

Conventional Space vector based Pulse Width Modulation (PWM) method is superior to Sinusoidal PWM technique in terms of its better DC bus utilization as well as harmonic reduction. But it doesn’t give solution to reduce acoustic noise which is more annoyance to the driver and the passenger or the human beings in certain applications such as electric propulsion or accessory drives. This paper presents space vector based random PWM techniques - a solution to reduce the acoustic noise as well spread spectrum resulting in low harmonic distortion as suppression of peak sound pressure levels. The techniques employed for a VSI fed Induction motor drive are 1) Random Zero vector PWM 2) Dual Zero Random PWM and 3) Variable Delay Random PWM. The spectrum plots of stator current demonstrate the effectiveness of the proposed PWM techniques. The feasibility of the proposed PWM techniques has been confirmed in terms of acoustical noise and harmonic distortion is presented in this paper.

Response to Discussion on “A Variable Switching Frequency PWM Technique for Induction Motor Drive to Spread Acoustic Noise Spectrum With Reduced Current Ripple”

In random pulse width modulation (RPWM) category, a wide variety of schemes is seen as described in the paper. The discussion part is mainly focused on the randomized carrier frequency approach, where the switching periods are selected randomly, irrespective of the ripple voltage. For prediction of rms current ripple over a switching cycle as well as rms current ripple over the line cycle, precise knowledge of the switching period is required; this is not possible with random PWM techniques, though these methods are following a probability distribution function. However, accurate prediction of current total harmonic distortion (THD) is possible with the variable frequency PWM (VFPWM) method, as the switching period is a function of the fundamental angle. The procedure followed for current THD prediction is explained in [1].

Selective Voltage Noise Cancellation in Three-Phase Inverter Using Random SVPWM

This study has focused on the noise elimination at a selected frequency from the line voltage of a two-level three-phase inverter, when it is driven by random space-vector pulse-width modulation. Distribution of noise power in a wide range of frequencies in the conventional random pulse-width modulation (RPWM) methods may cause system resonant frequency excitation. Therefore, it can increase the acoustic noise and vibration in loads of inverters, especially ac motors. Thus, for the effective utilization of RPWM techniques, it is necessary to cancel noise at a specified frequency. The proposed method is able to create a gap in the spectrum of the line voltage at a selective frequency in the human hearing range. Therefore, unlike conventional RPWM techniques, switching periods are determined based on the position of the rotary reference vector. The presented relation between switching periods and the reference vector is used for the conventional space-vector pulse-width modulation (SVPWM) and two-phase SVPWM. The simulation and experimental results confirm that the proposed method effectively creates a gap at the selected frequency in power spectrum density of the line voltage of the three-phase inverter using random SVPWM.

An Investigation on the Performance of Random PWM Controlled Converters

This paper provides an insight on various random pulse width modulation techniques and their effect on spreading the harmonic spectrum for various applications like drives, hybrid electric vehicles and renewable energy sources, for two level as well as three level inverter. Acoustic noise reduction, electromagnetic interference conducted and torque ripple are obvious advantages of random pulse width modulation (PWM). PWM converters with multilevel topology can meet with global quality standards for power supplies. The random PWM technique provides additional advantages. Among others, it may be implemented to achieve switching loss equalization in power switches for cascaded H-Bridge multilevel inverters. This paper provides in depth understanding for different random PWM techniques and their applications.

Random PWM Technique for Dual-Inverter-Fed Vector-Controlled Induction Motor Drive

From the analysis of harmonic spectrum of conventional PWM techniques, it is observed that a high amount of energy is concentrated around the harmonics of switching frequencies as side bands resulting in acoustic noise, vibration and electromagnetic interference. These effects can be mitigated by spreading the spectrum and reducing the magnitude of harmonics around switching frequencies. This can be achieved by introducing the randomness in control signals. In this paper a simplified and more generalized carrier-based random pulse width modulation (RPWM) technique is presented for asymmetrical dual-inverter-fed vector-controlled induction motor drive. In the proposed RPWM technique a zero sequence signal is added to the commended reference signal to obtain the required modulating signal. The randomness is introduced in generating the zero-sequence signal. To validate the proposed RPWM technique, simulation and experimental studies are carried out and the results are presented.

Vibration and Noise Analysis of 4Ф Switched Reluctance Motor Drive

The Switched Reluctance Motor (SRM) is getting large attention for industry application due to their simple construction, high starting capabilities, high reliability, and high efficiency and also rotor carries no windings, no slip-rings there is no brushes, it requires less maintenance. In spite of the merits, it had some demerits like acoustic noise and vibration is one of major issues in SRM. The DSP-TMS320F28335 processor were implemented due to their high performance for the control applications.In this work the Random Pulse Width Modulation (RPWM) technique is used to reduce the acoustic noise and vibration by varying random turn on and turn off angle control.The acoustic noise and vibration signals are measured using accelerometer and sound level meter in 1HP, 8/6poles of SRM drive. The experimental analysis of vibration signals are measured using Lab VIEW at different speeds and load conditions. The acoustic noise signals are measured using Sound level meter .Both the Acoustic and vibrations are analyzed experimentally for different speeds and load conditions. The experimental results show that the noise and vibration analysis and also compare the sinusoidal PWM is better than Random PWM techniques. DOI: http://dx.doi.org/10.11591/telkomnika.v14i3.7965

A New Random PWM Technique for Conducted-EMI Mitigation on Cuk Converter

Electromagnetic Interference (EMI) is a system to system or environment to system phenomenon. The literature survey proved that the Randomized Pulse Width Modulation (RPWM) technique is a promising technique to reduce EMI. A new Constant Trailing Edge, Randomized Pulse Width Modulation (CTERPWM) technique is proposed in this paper. The effect of the proposed RPWM technique for mitigation of conducted-EMI on Cuk converter operating in Continuous Conduction Mode (CCM) is simulated and tested. In this paper, the analytical expressions for the Power Spectral Density (PSD) are derived for the proposed RPWM technique and are validated by experimental measurements. The effectiveness of the proposed RPWM technique on the mitigation of conducted-EMI is verified comparing simulation and experimental results and it is identified that both the results are almost similar with allowable experimental deviations. The comparative investigation proves that the proposed RPWM technique can mitigate and spread the dominant peaks of conducted-EMI over the complete spectrum for the Cuk converter. Based on the investigation the CTERPWM technique is recommended for adoption.

Strategy for switching period selection in random pulse width modulation to shape the noise spectrum

In this study a new random pulse width modulation (RPWM) has been proposed. The aim of this method is to create a gap at selective frequency in voltage spectrum to prevent the resonant frequencies excitation. This gap can be placed in human hearing band. Hence, the proposed method can reduce acoustic noise in loads supplied by power electronic converters. Unlike conventional RPWM techniques, in this method the switching period is dependent on the duty ratio. In other words, in each switching cycle the switching period is determined as a function of duty ratio and switching periods in pervious switching cycles. The experimental results confirm the ability of the proposed method for reducing noise power at a selected frequency in voltage spectrum.

Performance evaluation of photovoltaic grid connected shunt active power filter

This paper describes the performance of photovoltaic (PV) Generator connected to a grid with shunt active power filter (APF). The PV system utilises perturb and observe maximum power point tracking algorithm to extract maximum power from the sun and injecting the same to the grid. Shunt active power filter (SAPF) is used to reduce the harmonics present in the photovoltaic generation based on PQ modified theory. The control algorithm and regulation of voltage source multilevel inverter (MLI) functioning as a harmonic filter uses the pulse width modulation (PWM) technique. PQ theory identifies the currents of references, which provides possibility for controlling the currents injected at the point of common coupling (PCC). Regulator is used to determine DC link voltage of PWM control inverter. Two switching schemes namely; Sinusoidal PWM and pseudo random carrier PWM have been applied and the performance results of both techniques have been studied. The simulations have been completed using MATLAB/Simulink software and the result shows that improvement in power quality and power factor for the pseudo random PWM technique is quite large than sinusoidal PWM.

New Random PWM Technique for a Full-Bridge DC/DC Converter With Harmonics Intensity Reduction and Considering Efficiency

PWM techniques for a full-bridge dc/dc converter are investigated and a new random PWM technique is proposed in this paper. Three PWM techniques with constant switching frequency are discussed and the related random PWM techniques which spread the harmonic clusters and give constant average inductor current to reduce the output voltage ripple are discussed. The pros and cons of three constant switching frequency PWM techniques and the related random counterparts are investigated. Experimental results show that there is a significant efficiency drop of the random PWM technique due to significant increase of switching counts. Therefore, this paper presents a new random PWM technique to significantly reduce the harmonic intensity while not causing relevant impact on the efficiency. An FPGA-based digital-controlled isolated full-bridge dc/dc converter prototype is built to verify the performance of conventional and proposed PWM techniques. The specifications of the converter include the following: input voltage = 400 V, output voltage = 12 V, output power = 528 W, and switching frequency = 100 kHz. Measured efficiency and harmonic spread factor will be used for the evaluation of these PWM techniques.