High-frequency interferences produced in systems consisting of PWM inverter, long cable and induction motor

The operation of inverter-fed asynchronous motor drives is inherently accompanied by high-frequency interferences caused particularly by parasitic currents of the common and differential modes. These emissions propagated by conduction and radiation may unfavourably affect the operation of nearby telecommunication and signal cables and various low-current devices. The paper deals with an analysis of these phenomena based on theoretical considerations and results of special measurements of the common and differential mode disturbances. Evaluated are mainly the frequency characteristics of selected parts of the system and their contributions to the resultant harmonic spectra.