Iet Generation Transmission & Distribution | 2019
Generic frequency-domain model for the emission of PWM-based power converters in the frequency range from 2 to 150 kHz
Abstract
With an increasing number of power converters using fast switching technologies, more cases of interference between devices in the frequency range from 2 to 150\u2005kHz occur. The most widely used technique in such devices is pulse-width modulation (PWM) [e.g. in photovoltaic inverters (PVIs), active harmonic filters, battery storage systems and some types of electric vehicle chargers]. Only little is known about the behaviour of those sources, the factors influencing their emission and the interaction with other devices and the propagation in the network. To extend such knowledge, reliable and accurate models are required. In this study, a quantitative model for the prediction of voltages and currents in this frequency range is developed and verified. Since in most cases no information about internal circuits and controls of the devices is available, a measurement-based black-box approach is used. The emission around the switching frequency of single-phase voltage-source power converters is combined into a single emission source represented by a Thevenin equivalent. The general method to parameterise the model is presented and exemplarily applied for two PVIs and one battery-electric vehicle charger. Moreover, the interaction of two devices at a joint point of connection is simulated and compared with real measurements.