Hong Li

Bio: Hong Li is an academic researcher from Rolf C. Hagen Group. The author has contributed to research in topics: Chaotic & Electromagnetic interference. The author has an hindex of 3, co-authored 7 publications receiving 73 citations.

Analyzing Chaotic Spectra of DC–DC Converters Using the Prony Method

Abstract: When dc-dc converters operate in chaotic modes, they can generate spread spectra, which are useful for reducing the electromagnetic interference (EMI). Conventionally, the Fast Fourier Transform (FFT) is used to analyze the spectra. However, it is not applicable to the inner-harmonics, the nonintegral multiples of the fundamental frequency, which is a prominent feature of chaotic signals. In this brief, the Prony method is suggested for chaotic spectral estimation of dc-dc converters. Numerical simulations show its advantages over the traditional FFT

A Chaotic Peak Current-Mode Boost Converter for EMI Reduction and Ripple Suppression

Abstract: A novel chaotic peak current-mode boost converter is proposed. By deriving its corresponding current mapping function, a thorough analysis of its chaotic behavior is carried out. As demonstrated both in simulations and experiments, the proposed design can effectively reduce electromagnetic interference and suppress ripples of the converter's output, resulting in a better design for power supplies.

Controlling DC–DC converters by chaos-based pulse width modulation to reduce EMI

Abstract: In this paper, periodic and chaotic behaviors of DC–DC converters under certain parametric conditions are simulated, experimentally verified, and analyzed. Motivated by the work of J.H.B. Deane and D.C. Hamill in 1996, where chaotic phenomena are useful in suppressing electromagnetic interference (EMI) by adjusting the parameters of the DC–DC converter and making it operate in chaos, a chaos-based pulse width modulation (CPWM) is proposed to distribute the harmonics of the DC–DC converters continuously and evenly over a wide frequency range, thereby reducing the EMI. The output waves and spectral properties of the EMI are simulated and analyzed as the carrier frequency or amplitude changes with regard to different chaotic maps. Simulation and experimental results are given to illustrate the effectiveness of the proposed CPWM, which provides a good example of applying chaos theory in engineering practice.

Device for producing carrier signals for suppression of noise pulse and electromagnetic transient emission of hard and soft-switching direct current converter, is provided for producing synchronous chaotic modulation for driving converter

Abstract: The device is provided for producing the synchronous chaotic modulation for driving the converter both digitally and synchronously. The disturbance energy is submitted through pulse width modulation corresponding to the regulation frequency band spectral spreading. The digital carrier signal is distinguished with their mathematical specifications. An independent claim is also included for a method for production of carrier signals for suppression of noise pulses and electromagnetic transient emission of hard and soft-switching direct current converter.

Analyzing chaotic spectra of DC-DC converters using the Prony method

Abstract: When DC-DC converters operate in chaotic modes, they can generate spread spectra, which are useful for reducing the electromagnetic interference (EMI). Conventionally, the fast Fourier transform (FFT) is used to analyze the spectra. However, it is not applicable to the inner-harmonics, which is a prominent feature of chaotic signals. In this paper, the prony method is suggested for chaotic spectral estimation of DC-DC converters. Numerical simulations show its advantages over the traditional FFT

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

Abstract: 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.

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

Abstract: 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.

A Two-Stage ADALINE for Harmonics and Interharmonics Measurement

Abstract: 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.

Suppressing electromagnetic interference in direct current converters

Abstract: 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.

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

Abstract: 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.