Periodic Carrier Frequency Modulation Research Articles

Suppressing the Maximum EMI Spectral Peak Through Asynchronous Carriers in the Three-Phase Inverter With the Periodic CFM

In inverters, high-frequency switching of pulsewidth modulation is the main source of electromagnetic interference (EMI). The carrier frequency modulation (CFM) technology can effectively reduce the spectral peaks of EMI. This letter proposes an asynchronous carrier scheme. In the scheme, the carrier frequencies of three legs are staggered from each other to avoid the possibility of superposition, which will appear by using the same carrier in the three-phase inverter. Based on the suppression of the spectral peaks in the periodic CFM, the use of the asynchronous carriers will further disperse the EMI peak energy. The case that the maximum EMI spectral peak is suppressed to the lowest is sought out under some given parameters. The feasibility and effectiveness of the asynchronous carrier scheme are verified by the simulations and experimental results in a three-phase inverter.

Suppressing Interference Peak in an Active Power Filter via Periodic Carrier Frequency Modulation Based on a Spectrum Analysis Approach

This paper aims at developing a spectrum analysis approach to suppress the electromagnetic interference (EMI) and the current harmonics in an active power filter (APF) via periodic carrier frequency modulation sinusoidal pulsewidth modulation (PCFMSPWM) control signals based on double Fourier series. The APF EMI concentrated at multiples of switching frequency results from the concentrative current harmonics. A novel spectrum analysis method based on PCFM and double Fourier series is developed to reduce the APF current harmonics. In this scheme, the optimal frequency deviations and waveforms of periodic signals are selected by calculating the spectrum of PCFMSPWM control signals. As a result, the modulation signal which has the best suppression effect on the interference peak is obtained and the quantitative design of PCFM is realized. Simulations and experiments of an APF driven by standard SPWM and triangular PCFMSPWM are implemented. On the basis of the simulations and experiments, effectiveness of triangular PCFM in alleviating APF current harmonics and EMI are validated.

Suppressing Conducted DM EMI in an Active Power Filter via Periodic Carrier Frequency Modulation

Active power filters (APF) aim at solving the harmonic problem originated by the nonlinear load in power systems. However, the high dv/dt and di/dt outputs from power electronic devices in a voltage source converter on APF introduced unwanted conducted electromagnetic interference (EMI) when compensating for the low-frequency harmonic components. Hence, this paper develops a spectrum analysis approach to investigate and quantify the source differential-mode (DM) voltage of a single-phase shunt APF to suppress the DM EMI via periodic carrier frequency modulation (PCFM). In this scheme, the analytical expressions of source DM voltage in the APF using the PCFM scheme are obtained with a double Fourier series. In addition, the influence of PCFM parameters on the source DM voltage spectrum is predicted based on the analytical expression. As a result, the PCFM parameters, which have the best suppression effect on the DM EMI are obtained. The experiment results proved the validity of the sawtooth PCFM APF with the maximum frequency deviation equal to 800 Hz in alleviating the APF DM EMI.

Hybrid periodic carrier frequency modulation technique based on modified SVPWM to reduce the PWM noise

This study proposed a hybrid periodic carrier frequency modulation (HPCFM) technique based on the modified space vector pulse-width modulation (SVPWM) for two-level three-phase voltage source inverters to eliminate the PWM noise. Owing to PWM technique and switching losses considerations, ear-piercing high-frequency acoustic noise from motor is common. The proposed HPCFM technique is able to remove the high-frequency unpleasant acoustic noise more effectively than conventional PCFM with lower switching losses and shorter frequency range. In addition, the PWM harmonics in phase voltage and phase current are reduced significantly. Furthermore, the HPCFM method is simple to implement and does not employ additional circuits in drive system. The effectiveness of the proposed approach has been confirmed by detailed experimental results.

Periodic Carrier Frequency Modulation in Reducing Low-Frequency Electromagnetic Interference of Permanent Magnet Synchronous Motor Drive System

This paper introduces the periodic carrier frequency modulation (PCFM) for permanent magnet synchronous motor (PMSM) drive systems so as to reduce the low-frequency electromagnetic interference (EMI). PMSMs are widely used in many applications and they are usually fed by pulsewidth modulation (PWM) inverters. The EMI of PMSM, which results from the switch of power device, generates undesirable effects on the control system. Therefore, it is of importance to reduce the EMI of PMSM. The common mode (CM) conducted EMI model of the PMSM drive system is constructed to investigate the CM voltage. The simulations and experiments of PMSM fed by the fixed frequency PWM (FFPWM) and PCFM are implemented to analyze the CM conducted EMI. The CM EMI spectra of PMSM fed by the FFPWM and PCFM with different spreading frequency widths are compared to explore the influence of PCFM on the CM conducted EMI. The regular patterns on PCFM in reducing the CM conducted EMI of PMSM drive systems are revealed.

Study on Modulating Carrier Frequency Twice in SPWM Single-Phase Inverter

The electromagnetic interference (EMI) of the inverter output, which is controlled through a sinusoidal pulse width modulation method, is mainly generated at the carrier frequency and its harmonics. The peaks of the interference can be reduced effectively by using carrier-frequency modulation (CFM). The spectrum of the output differential-mode voltage in a SPWM inverter with periodic CFM is analyzed theoretically in this paper. Through changing the maximum frequency deviation, periodic signal's frequency and waveform of CFM, the suppression effects of interference peaks are discussed. A new scheme, in which the carrier frequency is modulated twice, is presented. In this scheme, the frequencies and waveforms of periodic signals are optimized and selected under the condition of the same maximum frequency deviation, and the synthetic modulation signal which has the best suppression effect of the maximum interference peak is obtained. The feasibility and validity of the scheme are proved by simulation and experiment results in a single-phase inverter.

Sinusoidal periodic carrier frequency modulation in reducing electromagnetic noise of permanent magnet synchronous motor

This study introduces a simple method to reduce the electromagnetic noise of permanent magnet synchronous motor (PMSM) fed by pulse-width modulation (PWM) inverter. The analysed relationship between PMSM electromagnetic noise and current harmonic shows that PMSM electromagnetic noise concentrating on integral multiples of switching frequency is produced by the concentrative current harmonic. To spread the current harmonic spectrum, sinusoidal periodic carrier frequency modulation (PCFM) is presented and discussed theoretically. Simulations and experiments of PMSM fed by PWM inverter are conducted to verify the effectiveness of sinusoidal PCFM in reducing PMSM current harmonic and electromagnetic noise. The most efficient sinusoidal PCFM strategy in alleviating PMSM current harmonic and electromagnetic noise is put forward based on the comparison about reductions of PMSM current harmonic and electromagnetic noise by sinusoidal PCFM with different modulation frequency ratios.

Analysis of Triangular Periodic Carrier Frequency Modulation on Reducing Electromagnetic Noise of Permanent Magnet Synchronous Motor

This paper introduces a simple approach to reduce the electromagnetic noise of permanent magnet synchronous motor (PMSM) driven by pulse width modulation (PWM) supply. Alleviating the PMSM electromagnetic noise has become an important demand due to demanding requirement on human life environment. The PMSM electromagnetic noise concentrated at multiples of switching frequency results from the concentrative current harmonic. Triangular periodic carrier frequency modulation (PCFM) is introduced to alleviate the PMSM current harmonic and electromagnetic noise in this paper. The principle of triangular PCFM in reducing PMSM current harmonic and electromagnetic noise is analyzed. The impact of modulation frequency ratio on reducing PMSM electromagnetic noise is investigated. Simulations and experiments of PMSM driven by standard PWM and triangular PCFM are implemented. The simulated and experimental results verify the disciplinarian of triangular PCFM in alleviating PMSM current harmonic and electromagnetic noise.

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.