Random Carrier Frequency Modulation Research Articles

Sideband Vibro-Acoustics Suppression and Numerical Prediction of Permanent Magnet Synchronous Motor Based on Markov Chain Random Carrier Frequency Modulation

This paper presents a Markov chain random carrier frequency modulation (MRCFM) technique for suppressing sideband vibro-acoustic responses caused by discontinuous pulse-width modulation (DPWM) in permanent magnet synchronous motors (PMSMs) for new energy vehicles. Firstly, the spectral and order distributions of the sideband current harmonics and radial electromagnetic forces introduced by DPWM are characterized and identified. Then, the principle and implementation method of three-state Markov chain random number generation are proposed, and particle swarm optimization (PSO) algorithm is chosen to quickly find the key parameters of transition probability and random gain. A Simulink and JMAG multi-physics field co-simulation model is built to simulate and predict the suppression effect of the MRCFM method on the sideband vibro-acoustic response. Finally, a 12-slot-10-pole PMSM test platform is built for experimental testing. The results show that the sideband current harmonics and vibro-acoustic response are effectively suppressed after the optimization of Markov chain algorithm. The constructed multi-physics field co-simulation model can accurately predict the amplitude characteristics of the sideband current harmonics and vibro-acoustic response.

Conducted electromagnetic interference mitigation in super-lift Luo-converter for electric vehicle applications

In this article, a digital chaotic pulse width modulation (DCPWM)-dependent electromagnetic interference (EMI) noise attenuating procedure has been implemented. With the aid of a field programmable gate array (FPGA), a randomized carrier frequency modulation with a fixed duty cycle has been generated through chaotic carrier frequency, and this process is called DCPWM. Conducted EMI suppression is achieved in a 200 kHz, 40 W elementary positive output super lift Luo (EPOSLL) converter using the DCPWM technique. The results are compared and validated with periodic PWM over DCPWM in simulation and hardware with electromagnetic compatibility (EMC) standards. Besides, 9 dBV (2.81 V) of conducted EMI noise has been minimized in the DCPWM approach against periodic pulse width modulation method for the EPOSLL converter in electric vehicles applications.

POWER SPECTRAL DENSITY OF DUAL RANDOMIZED DISCONTINUOUS PULSE WIDTH MODULATION

This paper addresses the spectral characteristics of a carrier-based dual randomized discontinuous pulse width modulation (DRDPWM) technique for reducing conducted EMI and switching losses in three-phase voltage source inverters. It combines two simple random schemes, random carrier frequency modulation (RCF-DPWM) and random pulse position modulation (RPP-DPWM). First, the modulating principle of the DRDPWM is presented. Then, the analytical expressions of power spectral density (PSD) that characterize the output voltage of the three-phase inverter are derived. Analytical and simulation results show the effectiveness of PSD spreading of the DRDPWM. Finally, experimental results verify the analytical and simulation results and prove the effectiveness of the DRDPWM scheme in spreading the spectrum compared to simple schemes (RPP-DPWM and RCF-DPWM) and conventional scheme DPWM.

Effects of Random Switching Schemes on the EMI Levels of Conventional and Interleaved Buck Converters for Mobile Devices

This study presents a comprehensive detailed analysis of the effect of five different random modulation switching schemes and their randomness levels on the elector magnetic interference (EMI) of designed simple and interleaved DC-DC buck converters for smartphone applications. 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 experimental analysis is performed for all aforementioned switching modulation schemes at the switching frequency of 20 kHz and different randomness levels (RL) (30% to 85%). For a fixed RL of 40%, the switching current harmonics/conducted emission (CE) levels are 5–10 dB/11 dBμV and 17 dB/14 dBμV lower for the RCFMVD case when compared to conventional PWM for both simple and interleaved buck-converters, respectively. The observed switching current harmonics and CE levels for interleaved schemes are around 23 dB and 12 dBμV lower when compared to the conventional simple buck converter scheme for the analyzed circuit configurations. The EMI levels decrease with the increase in the randomness levels from 30% to 85% with less variations in the output voltage level. The findings suggest that a interleaved buck converter circuit with the least-independent switching mechanisms and higher randomness is more appropriate for the reduction of both current spikes and CE levels with RCFMFD as the switching modulation scheme.

Electromagnetic Interference of Spread-Spectrum Modulated Power Converters in G3-PLC Power Line Communication Systems

The impact of spread-spectrum techniques used to mitigate EMI from power converters on Power Line Communication (PLC) systems is studied in this paper. A buck converter, utilizing a Random Carrier Frequency Modulation with Fixed Duty cycle (RCFMFD) based control is considered as a source of conducted EMI and a narrowband G3-PLC as the victim. It is shown that, although considered to be an EMI mitigating technique, the spread spectrum technique has a detrimental effect on the communication channel, which can be explained in the framework of Shannon’s information theory. Conventional emission evaluation methods are therefore incompatible with modern day’s technology.

Spectral analysis of switch voltage for dual randomized PWM DC-DC converters operating in DCM

ABSTRACT This paper addresses the spectral characteristics of a dual randomised pulse width modulation scheme (RCFM-RPPM) for reducing conducted EMI in the basic DC-DC converters (buck, boost, and buck-boost) operating in discontinuous conduction mode (DCM). It combines two simple schemes, random carrier frequency modulation (RCFM), and a random pulse position (RPPM). First, the modulating principle of the dual randomised PWM is presented. Then, a mathematical model of power spectral density (PSD) that characterises the switch voltage of the three basic DC-DC converters is derived. The mathematical model is validated by simulation of a buck converter operating in DCM. Analytical and simulation results show the effectiveness of PSD spreading of the dual randomised scheme compare to the simple randomised schemes. Moreover, the PSD analysis is confirmed by FFT (Fast Fourier Transform) analysis of the switch voltage. Finally, the effect of randomness levels on the PSD spreading is studied.

A Random Modulation Spread-Spectrum Digital PWM for a Low System Clock Digital Buck Converter

The need for a high-efficiency power system has emerged since many IoT devices are mainly operated by batteries. A power system with analog control can have a high control bandwidth, but it is relatively vulnerable to noise disturbances and may suffer from control problems. On the other hand, a digitally controlled power system has high reliability and great controllability at the expense of switching noise and EMI issues. To implement a digitally controlled PWM with high resolution and low EMI, this study proposes a random carrier frequency modulation with dithered duty cycle method, where wide spectrum dithering and random modulation of spread spectrum PWM are tightly integrated. The proposed system was not only able to suppress voltage ripples, but also possible to minimize the occurrence of dependent frequencies due to the fixed dithering pattern. The spectrum of the output voltage showed that the switching frequency component was reduced by about 6.1dB and the output voltage ripples was also reduced compared to the existing PWM techniques.

Implementation of different randomized PWM schemes using Atmega328p microcontroller for EMI reduction in boost converter

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.

Conducted Electromagnetic Interference Spectral Peak Mitigation in Luo-Converter Using FPGA-Based Chaotic PWM Technique

Chaotic switching is a newly evolve randomization method which suppress the conducted electromagnetic interference generated within the DC-DC converter. It can also suppress the spectral peaks present in the frequency band effectively by spread spectrum technique and spread it over the wide range of frequency band implying electromagnetic interference (EMI) suppression. In this article, a chaotic pulse width modulation technique based on randomized carrier frequency modulation with fixed duty ratio is generated through field programable gate array for suppressing the conducted electromagnetic interference generated within the Luo-converter. A hardware prototype of Luo-converter is developed in order to analyze EMI reduction through power spectral density analysis by comparing both traditional periodic PWM switching and chaotic PWM switching. The results obtained from the hardware setup shows significant reduction of EMI with chaotic switching as compared to traditional pulse width modulation switching under both boost and buck operation of Luo-converter.

Effective Suppression of Conducted Electro Magnetic Interference in DC-DC Boost Converter Using Field Programmable Gate Array Based Chaotic Pulse Width Modulation Switching

—In recent years, electro-magnetic interference on DC-DC converters is seen as serious problem as it limits the capability of the DC-DC converter. It is popular to use analog circuits to suppress electro-magnetic interference; however, a cheap analog circuit suffers from numerous drawbacks, including inaccurate pulse generation, carrier frequency limitation, and degraded performance due to aging. Conversely, high-performance digital circuits are capable of providing accurate pulses compared to analog circuits. In this article, a field-programmable gate array is used to generate accurate chaotic pulse-width modulation pulses for DC-DC converters. A spread spectrum technique based on randomized carrier frequency modulation with fixed duty ratio is proposed for gating pulse generation, implemented using a field-programmable gate array for electro-magnetic interference suppression. A hardware prototype is built in the laboratory for the proposed method and tested. The performance of the proposed method estimated through simulation study is validated via experimental results.

An advanced monolithic digitalized random carrier frequency spread-spectrum clock generator for EMI suppression

A novel monolithic digitalized random carrier frequency modulation spread-spectrum clock generator (RCF-SSCG) is proposed. In this design, the output frequency of the proposed RCF-SSCG changes with the intensity of the capacitive charge and discharge current. Its analytical model is induced and the effect of the modulation parameters on the spread spectrum is numerically simulated and discussed. Compared with other works, this design has the advantages of small size, low power consumption and good robustness. The circuit has been fabricated in a 0.5 μm CMOS process and applied to a class D amplifier in which the proposed RCF-SSCG occupies an area of 0.112 mm2 and consumes 9 mW. The experimental results confirm the theoretical analyses.

A comparative study of carrier-frequency modulation techniques for conducted EMI suppression in PWM converters

A rigorous mathematical analysis and a comparative study of carrier-frequency modulation (CFM) techniques for the conducted electromagnetic interference (EMI) suppression in pulsewidth-modulated converters is presented. CFM techniques dither the switching period with a small amplitude variation around the nominal value, so that the harmonic power is redistributed over the spectrum of concern. Two types of dithering signals, including the periodic and random signals, are investigated in this paper. The operational characteristics as well as the input and output power spectra of the converters with the two modulating signals are compared. In particular, their characteristics in the low- and high-frequency harmonic power redistribution will be depicted. It is shown that random CFM (RCFM) gives a more effective way to disperse the harmonics around the switching frequency than the periodic CFM (PCFM) with the same frequency deviation. However, RCFM introduces higher low-frequency harmonics than the PCFM at the converter output. Furthermore, effects of the resolution filter bandwidth in the electromagnetic compatibility analyzer on conducted EMI measurement is discussed. The validity of the analyses is confirmed experimentally by using a dc/dc buck converter operating in continuous conduction mode.

A comparative investigation on the use of random modulation schemes for DC/DC converters

A comparative investigation on the use of random modulation schemes for DC/DC power converters is presented. The modulation schemes under consideration include randomized pulse position modulation, randomized pulsewidth modulation (PWM) and randomized carrier-frequency modulation with fixed and variable duty cycle. The paper emphasizes the suitability and applicability of each scheme in DC/DC power converters. Issues addressed include the effectiveness of randomness level on spreading the dominating frequencies that normally exist in constant-frequency PWM schemes, and the low-frequency power spectral density (PSD) of each scheme. The validity of the analyses is confirmed experimentally by using a DC/DC buck converter operating in the continuous conduction mode. The PSD of the output under each scheme is presented and compared.

Spectral characteristics of randomly switched PWM DC/DC converters operating in discontinuous conduction mode

This paper addresses a comparative study of the spectral characteristics of four random-switching schemes that apply to the basic pulsewidth-modulation (PWM) DC/DC converters operating in discontinuous conduction mode (DCM). They include randomized pulse position modulation, randomized pulsewidth modulation, and randomized carrier frequency modulation with fixed duty cycle and with fixed duty time, respectively. Mathematical models that characterize the input current and output voltage of the three basic PWM converters operating in DCM are derived. In particular, the effectiveness of spreading the dominant switching harmonics in the input current that normally exist in the standard PWM scheme and the introduction of low-frequency harmonics in the output voltage with respect to the randomness level are investigated. The validity of the models and analyses are confirmed experimentally by using a DC/DC buck converter.