Features extraction of conducted disturbance below 150 kHz from rectifier for ICT equipment

Power conversion equipment, such as a rectifier, uses pulse width modulation (PWM), and/or pulse frequency modulation (PFM). The International Electric Commission (IEC) published an international standard for conducted immunity tests below 150 kHz that uses a continuous wave (CW) or a CW with pulse modulation as test waves, but does not specify that the test waves should simulate features of conducted disturbances from rectifiers with PWM/PFM control, so as to evaluate the immunity characteristics of ICT equipment in an actual use environment. For creating new test waves that can more precisely evaluate the immunity characteristics of ICT equipment against conducted disturbances below 150 kHz from rectifier, this paper presents a features extraction method that uses short-time Fourier analysis (STFT). For feature extraction by circuit simulation, the features of the disturbances from rectifiers with PWM/PFM control have been determined as time fluctuations in the peak voltage and its frequency. When this feature extraction method was used to measure conducted disturbances from these two types of rectifiers, features originating in the PWM and PFM controls were found.