Several techniques to mitigate conducted electromagnetic interference (EMI) in switch-mode power supplies (SMPS) have been reported in literature. Of these, this paper reviews those techniques that are primarily meant for ac-dc and dc-dc power converters. The techniques are broadly classified based on two criteria-1) reduction of the noise after generation and 2) reduction of the noise at the generation stage itself. A detailed classification and review of various noise mitigation techniques currently available in literature are presented. It is believed that the classification and review of the conducted EMI mitigation techniques presented in this paper would be useful to SMPS researchers and designers.

Conducted EMI Mitigation Techniques for Switch-Mode Power Converters: A Survey

After the successful solid state implementation of memristors, a lot of attention has been drawn to the study of memristor based chaotic circuits. In this paper, a systematic study of chaotic behavior in such system is performed with the help of nonlinear tools such as bifurcation diagrams, power spectrum analysis, and Lyapunov exponents. In particular, a Twin-T notch filter feedback controller is designed and employed to control the chaotic behavior in the memristor based chaotic circuit. Both simulation and experiment results validate the proposed control method.

Controlling Chaos in a Memristor Based Circuit Using a Twin-T Notch Filter

Harmonics and interharmonics may introduce operational problems in electrical and electronic equipment. Therefore, monitoring harmonics/interharmonics for improving the power quality is of importance for both electric utilities and their customers. In this paper, a cascaded two-stage adaptive linear element (ADALINE) structure for both harmonics and interharmonics measurement is proposed. In addition, a simple laboratory setup implemented by MATLAB and the dedicated hardware for measuring power signals is built to verify the performance of proposed method. Results are compared with those obtained by short-time Fourier transform and two other conventional ADALINE-based methods. It shows that the proposed method is with a better accuracy, even if the power frequency deviation and interharmonic components are present in the measured signal. The proposed method also can be adopted for harmonic/interharmonic compensation devices in real time.

A Two-Stage ADALINE for Harmonics and Interharmonics Measurement

Since James Clerk Maxwell established the electromagnetic field theory in 1865, multifarious electrical and electronic products have been invented, designed, produced, and widely deployed, such as wireless communication devices, electrical machines and motors. This has profoundly changed our world and our lives. Now we cannot live without electrical products anymore and, thus, we are surrounded with electromagnetic fields generated. On the other side, especially in the past few decades, the rapid development and wide deployment of electrical products have caused lots of troubles, among which the most prominent one is electromagnetic interference (EMI), which may impact other devices' performance and harm human beings' health. Therefore, fighting EMI has become a stringent, difficult problem faced by engineers and scientists. The sources of EMI include natural sources, like atmospheric charge/discharge phenomena and extraterrestrial radiation, and man-made sources, like power lines, auto ignition, radio frequency interference, and radiation hazards, to name just a few. As important components, direct current (DC-DC) converters are embedded and employed in various electrical devices, thus forming main sources of EMI. Some measures, such as filters and electromagnetic shielding, have been taken to suppress EMI, but these methods have various drawbacks with respect to cost, volume, weight, and efficiency. Therefore, new theories and methodologies are desired to cope with the EMI problem, and chaos theory is a candidate due to the continuous spectrum feature of chaos. This paper aims to provide an overview on the state of the art of traditional EMI suppression technologies, and to introduce the use of chaos theory and chaos control to reduce EMI, as well as to motivate more efforts in theoretical research and engineering practice.

Suppressing electromagnetic interference in direct current converters

Spread-spectrum (SS)-based pulsewidth modulation (PWM) techniques play an important role when tackling the electromagnetic interference (EMI) problem in the switch-mode power supply (SMPS) domain. They achieve the best EMI noise reduction and emerge as a promising and very effective solution to comply with electromagnetic standards. The current work provides an insight into the SS techniques: its history, its types, and mainly its ability to mitigate the EMI problem in the SMPS domain. Moreover, it gives a short review of the different SS-based PWM techniques going from the most basic and simple, i.e., the periodic modulation, to the most developed and complex, i.e., the random and chaotic modulations. Besides, a short review of the different implementation methods was addressed and they were categorized into analog and digital implementation techniques where its pros and cons were provided. Finally, a new fast digital implementation method based on a dsPIC33F microcontroller is presented. Its effectiveness was proved and its advantages over the reviewed implementation techniques were recognized. It reached a 20 dBuV EMI level reduction when the digital chaotic and periodic profiles were embedded into a boost converter prototype.

A Review of Spread-Spectrum-Based PWM Techniques—A Novel Fast Digital Implementation

This paper concerns applying probability analysis to chaotic mapping in DC-DC converters. A computation method for the invariant density of a chaotic mapping is proposed by using eigenvector method. Moreover, the power spectral density of the input to the DC-DC converter and the average frequency of switching are deduced. Further, the invariant density is used for an accurate design of the DC-DC converter parameters. Finally, some examples are given to illustrate the effectiveness of the proposed method.

Hong Li

Papers

Calculation of the invariant density of the chaotic mapping in a DC-DC converter and its applications

Suppressing Interference in Direct Current Converters