Random Switching Pulse Positioning-Based SVM Techniques for Six-Phase AC Drive to Spread Harmonic Spectrum

It is known that if harmonic spectra are reduced, then acoustic noise also reduced. Hence, this paper proposes a new random switching strategy using DSP TMS320F2812 in order to reduce the harmonic spectra of a single phase 6/6 switched reluctance machine. The proposed method combines random turn-on, turn-off angle technique and random pulse width modulation technique. A Harmonic Spread Factor (HSF) is used to evaluate the random modulation technique. The proposed method is then being simulated in Matlab/ Simulink environment. Furthermore, this algorithm has also been inspected on various switching frequency. The experimental results show that the proposed strategy provides better harmonic spectra performance than conventional strategies, i.e. And a good agreement between experimental and simulation results is obtained.

The paper analyses a random pulse width modulated technique applicable for Z-source inverter. The proposed technique comprises the random pulse position PWM with a randomised frequently triangular carrier having characteristics of both space vector and random lead-lag modulations. This random pulse PWM is produced through the logical comparison of the pseudorandom binary sequence bits with the PWM pulses corresponding to two fixed frequency triangular carriers. Matlab/Simulink was used for modelling and simulation of the proposed method. It has been found that the output harmonic spectra of a Z-source inverter operating under the PWM with randomised frequency are dispersed and continuously distributed that can significantly reduce acoustic noise generated by the inverter and the load.

The randomized pulse width modulation techniques are used to reduce electromagnetic interference in power converters by spreading the harmonic energy. Thus, a wider spectrum with lower amplitudes is obtained. Based on the pulse width modulation signal parameters, three main randomized techniques are achieved: the random carrier frequency modulation, the random pulse width modulation and the random pulse position modulation. This paper presents a short review of the different implementation methods. Then, a detailed implementation of the three considered random techniques using Atmega328p microcontroller is detailed. Finally, an analysis of the experimental conducted electromagnetic noise taken from a boost converter is discussed. These results prove that the random carrier frequency modulation approach is completely better than other techniques in terms of electromagnetic noise reduction.

In order to reduce the vibration and noise of permanent magnet synchronous motors, this paper proposes a control strategy by analyzing the relationship between the vibration and noise of the permanent magnet synchronous motor and the current harmonics of the inverter based on actual project applications. Some methods include random switching frequency modulation technology, random pulse position modulation technology and dead zone compensation technology on current harmonics are analyzed respectively in this paper. Then this paper proposed a mixed control strategy, which combined with random switching frequency-random and pulse position-dead zone compensation methods. Matlab tools are used to simulation and verification the Mixed control strategy. Simulation and experimental results show that this control strategy can effectively reduce the total underwater noise level of permanent magnet synchronous motors.

This paper proposes a new random switching strategy using DSP TMS320F2812 in order to reduce the harmonics spectra of a single phase switched reluctance machine. The proposed method combines random turn-on, turn-off angle technique and random pulse width modulation technique. A harmonic spread factor (HSF) is used to evaluate the random modulation technique. The experimental results show that the harmonic intensity of output voltage for the proposed method is better than that for conventional methods.

The analysis of random pulsewidth modulation (PWM) techniques has matured into a state where analytical expressions have been derived to aid in understanding the frequency domain characteristics. Derivations of the formulae require a lot of algebra, and the expressions must be verified by laboratory measurements. It is shown, however, that factors originating from digital signal processing techniques make the comparison difficult if proper measures against misinterpretation are not taken. A methodology to overcome the problems is presented. Novel expressions for the random lead-lag pulse position technique and the random switching frequency technique are also presented as well as their verifications by laboratory measurements on a full-bridge DC/DC power converter.

The aim of the study was to evaluate the potential colonization of nosocomial bacteria in enteral feeding systems and its effect on early gut colonization of preterm neonates. Mother's own milk, donor milk, and preterm formula samples obtained after passing through the external part of the enteral feeding tubes were cultured. In addition, meconium and fecal samples from 26 preterm infants collected at different time points until discharge were cultured. Random amplification polymorphism DNA and pulse field gel electrophoresis were performed to confirm the presence of specific bacterial strains in milk and infant fecal samples. Approximately 4000 bacterial isolates were identified at the species level. The dominant species in both feces from preterm infants and milk samples were Staphylococcus epidermidis, S aureus, Enterococcus faecalis, E faecium, Serratia marcescens, Klebsiella pneumoniae, and Escherichia coli. All of them were present at high concentrations independently of the feeding mode. Random amplification polymorphism DNA and pulse field gel electrophoresis techniques showed that several bacteria strains were found in both type of samples. Furthermore, scanning electron microscopy revealed the presence of a dense bacterial biofilm in several parts of the feeding tubes and the tube connectors. There is a sharing of bacterial strains between the neonates' gastrointestinal microbiota and the feeding tubes used to feed them.

Noise reduction at the specific frequency of the line voltage of two level three phase voltage source inverter (VSI) fed induction motor (IM) is dealt in this paper, and the paper aims to develop a new PWM called random space vector pulse width modulation technique (RSVPWM) for reducing noise on line voltage and as well is applied for modeling in cloudsystems. The developed Random SVPWM combines RPWM and Space vector modulation (SVPWM) technique, the paper also investigates the three-phase VSI fed IM and its noise behavior along with noise reduction for cloud system. The proposed method includes a gap in the spectrum of line voltage at selective frequency in human hearing range and as well employed in cloud systems. Therefore, unlike conventional RPWM techniques, switching periods are determined based on the position of rotary reference vector. This work on comparison with other PWM techniques such as sine PWM, RPWM and SVPWM, performs in a better manner. Among all PWM method the proposed RSVPWM generate higher voltages with low total harmonic distortion for VSI fed IM and as well for the considered cloud system models. The proposed RSVPWM achieves less line voltage noise (10.4 dB at lower modulation range and 9 dB at higher modulation range), which proves its effectiveness. The simulation and experimentation is carried out for the full range of switching frequency of 1–20 kHz. The modulation method can be used in both open- and closed-loop IM drive such as V/F and vector control. The above method is applied for both IM and considered cloud system problems.

Random pulse width modulation in static power converters results in the partial transfer of power from the discrete spectrum of the output voltage to the continuous spectrum, with advantageous effects on the operation of the supplied electromechanical systems. In this paper, a random PWM technique with randomized pulse position for three-phase voltage-controlled inverters is analyzed. Closed-form equations for the discrete and continuous power spectra of the line-to-line and line-to-neutral voltages of the inverter have been derived and confirmed by experiments. Presented theory opens the way to numerical optimization of the voltage spectra of randomly modulated inverters. >

The power spectral densities of UWB impulse radio systems with pulse position modulation (PPM) consist of both continuous spectra and discrete frequency spikes. These discrete spikes cause interferences to narrowband systems and deny the harmless coexistence of PPM UWB systems and narrowband systems. To suppress these discrete spikes, in this paper, a random pulse carrier phase jitter (PCPJ) technique is presented and applied to PPM UWB signals. Both theoretical analyses and simulations are carried out and the obtained results show that the proposed technique can effectively suppress the frequency spikes, increase the transmitted power, and thus improve the performance of PPM UWB systems.

Power Line Communication (PLC) technologies utilize existing power cables for both power and data transmission which minimizes cost and complexity. However, recent studies show that alternative modulation schemes such as Random Pulse Width Modulation (RPWM), applied to power converter to minimize conducted emissions, have possible side effects on the PLC system. In this work, the effects of the switching frequency of randomly modulated power converter on the G3-PLC system is investigated. To this end, a range of switching frequencies from 10 kHz-100 kHz is applied to a randomly modulated DC-DC converter and its potential effect on the G3-PLC is studied. Experimental results confirmed that switching frequencies near the bandwidth of the G3-PLC caused significant disturbance and possible coexistence issue compared to the frequencies out of this range. Moreover, there is a tradeoff between Electromagnetic Interference (EMI) reduction and coexistence issue that is Random Frequency Modulation, which is very effective for EMI reduction, is found to be very disruptive for G3-PLC, compared to alternative random modulation techniques like Random Pulse Position Modulation.

Power Line Communication (PLC) technologies are being used in many applications and offer the advantage of utilizing existing power cables for both power and data transmission, thus minimizing cost and complexity. Nevertheless, PLC technology requires further investigation to solve possible co-existence issues. Indeed, recent studies confirmed that alternative modulation schemes such as Random Pulse Width Modulation (RPWM), applied to switching-mode power converters to minimize conducted emissions, detrimentally interfere with the PLC system. This paper presents an experimental test campaign aimed at investigating the effects of RPWM on the G3-PLC system, with the final goal of understanding the conditions under which RPWM schemes can be considered as an effective alternative to conventional Pulse Width Modulation (PWM) in applications involving PLC systems. In details, the effects of different RPWM parameters such as switching frequency, modulation index, and Random Number Update Rate (RNUR) on the G3-PLC is investigated. In addition, different RPWM schemes such as Random Frequency Modulation (RFM) and Random Pulse Position Modulation (RPPM) are compared in terms of performance so as to highlight which RPWM is best suited to assure coexistence with PLC systems. The impact of RPWM on the communication channel is evaluated in terms of Frame Error Rate (FER), Channel Capacity, and Channel Capacity Loss metrics. Experimental results confirmed that randomly modulated converters with switching frequencies near the G3-PLC bandwidth cause more significant disturbance and possible coexistence issues than the switching frequencies out of this range. Results also show that the modulation index and the RNUR of RPWM have a direct effect on the communication channel. Moreover, a trade-off between Electromagnetic Interference (EMI) reduction and coexistence issues is observed: RFM, which is very effective for EMI reduction, is found to be very disruptive for G3-PLC, compared to alternative random modulation techniques such as RPPM.

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.

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.

A new random inverter control technique is presented in the paper, which not only reduces the dominant harmonic cluster of PWM voltage, but also dramatically mitigates the common mode voltage of inverter-fed induction motor drives. It is demonstrated that the common mode voltage for the new random switching technique can be mitigated to 50% in comparison with that for conventional random space vector modulation (RSVM) technique. Moreover, the first dominant cluster for the new random technique is also significantly reduced in comparison with that for existing space vector modulation (SVM) technique. Test results derived from experimental induction motor drives are presented confirming the theoretical analysis.