272 PRZEGLĄD ELEKTROTECHNICZNY (Electrical Review), ISSN 0033-2097, R. 86 NR 12/2010 Houcine MILOUDI, Abdelber BENDAOUD, Mohamed MILOUDI, Abdelkader GOURBI, Helima SLIMANI IRECOM Laboratory, University Djillali Liabes, Sidi-Bel-Abbes, Algeria Common mode conducted electromagnetic interference in inverter fed-AC Motor Abstract. The increase of switching speed and frequency in power electronics converters has greatly improved their performances and characteristics. These advantages are accompanied with the increased level of interference, so that EMI consideration is a major task for circuit designers nowadays. In Adjustable Speed Drives (ASD), the (dv/dt) leading to conducted emissions at high frequencies which are propagated both through Common Mode (CM) and Differential Mode (DM) in the system. The circulation of high frequency parasitic currents causes several unexpected problems, such as premature deterioration of motor winding insulation and ball bearings. In this paper an inverter-fed AC motor drive is analyzed in order to predict the path of conducted emissions into Common Mode (CM) configuration, showing that both propagation modes may interfere. The equivalent circuit allows frequency-domain analysis to be performed with standard circuit simulators. The proposed circuit model allows the prediction of the main common-mode HF current components. Abstract. The increase of switching speed and frequency in power electronics converters has greatly improved their performances and characteristics. These advantages are accompanied with the increased level of interference, so that EMI consideration is a major task for circuit designers nowadays. In Adjustable Speed Drives (ASD), the (dv/dt) leading to conducted emissions at high frequencies which are propagated both through Common Mode (CM) and Differential Mode (DM) in the system. The circulation of high frequency parasitic currents causes several unexpected problems, such as premature deterioration of motor winding insulation and ball bearings. In this paper an inverter-fed AC motor drive is analyzed in order to predict the path of conducted emissions into Common Mode (CM) configuration, showing that both propagation modes may interfere. The equivalent circuit allows frequency-domain analysis to be performed with standard circuit simulators. The proposed circuit model allows the prediction of the main common-mode HF current components. Keywords: EMI, EMC, Common Mode, high frequency, induction motor, cable Słowa kluczowe: in this line the Editor inserts Polish translation of keywords. Introduction Environmental electromagnetic pollution has been a serious problem for electronic and electrical equipment for years. Any electrical or electronic device is a potential noise source to its environment. High-level electromagnetic disturbances may cause electrical and electronic devices and systems to malfunction in a common electromagnetic environment [1, 11]. A piece of equipment is considered electromagnetically compatible only if its effects are tolerable to all other equipment operating in its environment. To ensure this compatibility, electromagnetic compatibility (EMC) becomes an important engineering discipline. In order to achieve EMC, disturbances should be considered from two distinct points of view: electromagnetic emission (EME) and electromagnetic susceptibility (EMS) [1, 4]. Electromagnetic interference (EMI) is a major concern in inverter motor drive systems. The sources of EMI have been commonly identified as high switching dv/dt and di/dt rates interacting with inverter parasitic components [5]. The conducted electromagnetic interference (EMI) is classified into two types of differential-mode (DM) and common-mode (CM). Differential mode propagation takes place between two conductors and common-mode propagation takes place between a group of conductors and ground [1, 6]. The usual configuration of an inverter-fed motor drive is shown in Fig. 1. Fig. 1. Common-mode and differential-mode current paths in a typical PWM drive In this paper, the EMI in inverter fed-AC motor generation are discussed. The EMI sources of a hard- switching single-phase PWM inverter are identified with separation of common-mode and differential-mode noises. The modelling of the cables connecting an electronic power converter to an ac-motor is necessary to calculate the amplitude of the disturbances induced by the transistor switchings, Fundamentals of E.M.I EMI, or electromagnetic interference, is undesirable electromagnetic noise from a device or system that interferes with the normal operation of the other devices or systems. The motivation of studying EMI is to achieve electromagnetic compatibility (EMC) for a certain device or system [1, 2, 3]. Conducted EMI emission is often defined as undesirable electromagnetic energy coupled out of an emitter or into a receptor via any of its respective connecting wires or cables, as shown in Figure 1-1. The source generates the EMI noise, and a coupling path transfers the noise to a receiver through cables or wires. There are three basic ways to prevent interference: • Suppress the emission at its source. • Make the coupling path as inefficient as possible • Make the receptor less susceptible to the emissions. With the continually increasing use of power converters, the resulting electromagnetic inference (EMI) noise is a concern for both power converter designers and consumers. The EMI noise management of converters should be done in order to comply with stringent electromagnetic compatibility (EMC) regulations. Conducted EMI is often defined as electromagnetic energy undesirable coupled out of an emitter or into a receptor via any of its respective connecting wires or cables. There are three essential elements in EMI problem: source, coupling path and receiver, as illustrated in Fig. 2. A source (culprit) generates the emission, and a coupling path (transfer), transfers the emission energy to a receiver (victim) [1, 6, 10].