Fuzzy based random pulse width modulation technique for performance improvement of induction motor

Pulse Width Modulation (PWM) techniques are vital for voltage source inverters (VSIs) to deliver high-quality, controlled outputs. The output voltage harmonic spectrum reveals the distinct performance of different PWM algorithms. Conventional PWM methods focus on enhancing performance parameters such as increasing the fundamental component, reducing total harmonic distortion (THD), minimizing switching losses, and selectively eliminating harmonics. In modern applications, additional challenges such as harmonic power dispersion and electromagnetic interference mitigation are also critical. This paper primarily addresses the enhancement of harmonic power dispersion through random PWM (RPWM) techniques. Unlike traditional deterministic PWM strategies, RPWM generates non-deterministic harmonic profiles, effectively spreading harmonic energy across a wider frequency range and thereby reducing acoustic noise in drive applications. A set of carrier-based RPWM techniques is proposed to improve VSI performance. These are implemented on a field-programmable gate array (FPGA) platform, confirming high-speed operation, less power dissipation, and efficient hardware utilization. The effectiveness of the FPGA implementation is validated through MATLAB–Simulink co-simulation, demonstrating the proposed RPWM methods' superiority in harmonic power dispersion and system performance.

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.

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.

PWM techniques for full-bridge DC/DC converter are investigated and a new multi-dimension random PWM technique is proposed in this paper. Three PWM techniques with constant switching frequency are discussed and the related random PWM techniques are 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 there is significant efficiency drop of the random PWM technique due to significant increase of switching counts. Therefore, this paper presents a two-dimensional 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: input voltage = 400 V, output voltage = 12 V, output power = 120 W and switching frequency = 100 kHz. Measured efficiency and Harmonic Spread Factor will be used for the evaluation of these PWM techniques.

An improved random SVPWM for zero voltage switching three phase inverter

A new two-dimensional random switching PWM technique is proposed to reduce the dominant harmonic clusters while retaining constant average inductor current and constant sampling frequency. The special feature of constant average inductor current can reduce the output voltage ripple. And the controller parameters of digital-controlled power converter are not required to change which is quite essential to digital-controlled system. Current random PWM methods are discussed and compared with the proposed method in this paper. It will be shown that the presented method is with the merits of randomly changes switching frequency while keeping constant sampling frequency and average inductor current. An FPGA-based digital-controlled buck converter experimental system has been set up. The specifications of the converter includes: input voltage = 5 V, output voltage = 1.5 V and switching frequency = 200 kHz. The proposed random switching pattern is implemented by software. Experimental results demonstrate the effectiveness of the proposed random switching pattern.

Random pulse width modulation (RPWM) is a switching technique used to spread voltage and current harmonics over a wide frequency range. By using a randomly changing inverter switching frequency, the power spectrum of the electromagnetic acoustic noise can be spread to the wideband area. Wideband noise is much more comfortable and less annoying than narrowband noise. Thus, RPWM has been attracting interest as an excellent method for the reduction of acoustic noise in inverter drive systems. A new RPPWM (random position space vector PWM) is proposed and implemented. Each of three phase pulses is located randomly in each switching interval. Along with randomisation of the PWM pulses, space vector modulation is also executed in a C167 microcontroller. Simulation and experimental results show that the voltage and current harmonics are spread to the wideband area and that the audible switching noise is reduced by using the proposed RPPWM method.

FPGA based Random Pulse width modulation (RPWM) technique is adopted to trigger the Single Input Dual Output (SIDO) DC Chopper configuration. Comparison between conventional Pulse width Modulation (PWM) and proposed switching technique is made through simulation results. The configuration and switching techniques proposed can suppress the conducted Electromagnetic Interference (EMI) better than the conventional switching schemes. Experimental results obtained validate the proposed configuration.

This paper addresses improved electromagnetic compatibility (EMC) in switched-mode power converters (SMPCs), without using electromagnetic interference (EMI) filters. A practical solution is proposed for minimizing conductive EMI in a pulsewidth modulated (PWM), and random PWM dc-dc power converters. A comparative investigation is performed into the use of different random modulation schemes (driven by the DSP-2 board with the TMS320C32) as against the normal PWM. The effectiveness of randomization on spreading those dominating frequencies that normally exist in constant frequency PWM schemes is evaluated by power spectral density (PSD) estimations in the low-frequency range. Some parasitical- and topology-based EMI sources in devices are presented and frequency analysis is shown by using the discrete Fourier transform (DFT). SPICE simulations are also used to verify practical solutions for eliminating negative EMI sources and achieving EMC improvements. Finally, levels of conductive EMI are estimated with DFT, and experimentally verified to comply with the CISPR 25 (or EN 55025) regulations. Moreover, it is clearly shown, that limited speed PWM driving of the power switches with appropriate snubber circuits guarantees reduced conductive EMI. When considering the price and high EMC, in the final solution the power converter is driven by the mu-controller PIC16F876 with limited numerical and peripheral capabilities, where only normal PWM and randomized PWM can be implemented

Randomized modulation technology can effectively suppress high frequency noise in motor drive application. This paper is devoted to issues in synthesis of randomized modulation schemes and proposes a dual random PWM technology based on two-state Markov chain and pseudo-random binary sequence (PRBS). This combined type of randomized modulation can make the switching cycle more evenly distributed and significantly suppress the high frequency noise focused on the switching frequency and its integer multiples. We focus on the power spectra of certain associated waveforms. Furthermore, the DTP-PMSM model with random PWM has been built to evaluate the effect with random PWM modulations based on four methods including conventional method, Markov chains, PRBS and the method combining Markov chain with PRBS. The simulation results prove that proposed PWM strategy possesses excellent harmonic power spreading ability and high frequency noise suppression capability.

In the system of permanent magnet synchronous motor (PMSM) driven by indirect matrix converter (IMC), SVPWM technology is used in the inverter stage, which causes that the output current generates high-frequency harmonics around the integral multiples carrier frequency, thus generating high-frequency noise and electromagnetic interference. In order to suppress the high-frequency harmonics of output current in IMC-PMSM, a Markov chain random asymmetrical SVPWM (MRA-SVPWM) method is proposed in this paper. Although random PWM (RPWM) technology have some effect to reduce the harmonic amplitude. There are still some inherent defects. Markov chain with non-aftereffect is applied to random switching frequency PWM in order to improve the performance of RPWM. Meanwhile, MRA-SVPWM changes the switching state by adjusting the vectors order and thus changes the coefficient of the harmonic. A better suppression performance around the integer multiples carrier frequency is achieved. Meanwhile, the principle of harmonic suppression is analyzed by using three-dimensional Fourier. Finally, the effectiveness of the proposed algorithm is verified by experiments.

Low frequency harmonics injection into AC power supply and small power factor are the main disadvantages of conventional rectifiers. By using the high power factor correction circuits (HPFCC) the input current has a sinusoidal form and is in phase with the power supply voltage. By solving the problem of power factor with high frequency switching current mode control, another problem arises-that of high frequency harmonics generated in radio-frequency (RF) range by the converter. Therefore the problem of electromagnetic interference (EMI) must be appropriately treated as well. This paper deals with randomized pulse width modulation (RPWM) strategy for the boost rectifier. The randomized modulation principle is introduced in an ordinary PWM control unit which is widely used in unity power factor correction circuits. Introduction of the RPWM results in smaller increases of the total harmonic distortion (THD) in the input current and consequently neglected decreasing of the power factor. On the other hand, this approach causes the high-order harmonics spectral components to be significantly reduced and dispersed around ordinary spectral lines, which means reduced conducted EMI as well.

As an alternative to the existing deterministic pulse-width modulation methods, a random pulse-width modulation technique for voltage-controlled power inverters is proposed. Advantages of the technique include non-repetitiveness of the switching pattern, simplicity of the hardware, and uncommonly high limits of switching frequency. A prototype random pulse-width modulator is described and experimental results are presented.

This paper presents an electromagnetic interference analysis of the random modulation switching schemes based on the switching current harmonics and conducted emission (CE) levels of a buck converter. The analyzed switching schemes are pulse width modulation (PWM), random pulse width modulation (RPWM), random pulse position modulation (RPPM), random carrier frequency modulation various duty (RCFMVD), and random carrier frequency modulation fixed duty (RCFMFD). The conducted experimental analysis suggests that the utilization of the RCFMFD did not only reduces the harmonics and CE levels but also produces the desired output voltage value of the buck converter.

The use of a bi-directional buck-boost cascade converter in electric vehicles allows the suitable control of both motoring and regenerative braking operations. Based on the bidirectional buck-boost cascade converter, the random pulse width modulation (RPWM) scheme is implemented to reduce the conducted electromagnetic interference (EMI). Compared with the fixed frequency PWM (FPWM), the proposed RPWM scheme can suppress the peaky EMI as well as provide the bidirectional power transfer capability. Simulation and experimental results are given to support the validity.