2456 IEEE TRANSACTIONS ON POWER ELECTRONICS, VOL. 24, NO. 11, NOVEMBER 2009 Common-Mode Emissions Measurements and Simulation in Variable-Speed Drive Systems Chaiyan Jettanasen, Franc ¸ois Costa, Member, IEEE, and Christian Vollaire, Member, IEEE Abstract—In order to efficiently reduce electromagnetic inter- ference emissions, especially common-mode (CM)-conducted noise emissions, which are the most disturbing in any variable-speed drive systems, the understanding of behavior and the knowledge of propagation path of parasitic currents in the system are essential. In this paper, a simple CM disturbances modeling is proposed to predict or estimate the CM noise currents. The modeling principle is based on specific experimental characterizations and the model- ing of the complete CM circuit considered as a chain of quadripo- lar matrices. Each part of the system is represented by a two-port network associated in cascade using matrix [T]. The comparison between calculations and experiments in a variable-speed drive system effectively confirms the validity of the proposed approach. Parametric studies carried out herein using this valid model will show the way in which CM currents could be reduced or eliminated in a considered existing system. Index Terms—Common-mode (CM) emissions, electromag- netic compatibility (EMC)/electromagnetic interference (EMI), pulsewidth modulation (PWM) inverter, two-port network mod- eling, variable-speed drive. I. INTRODUCTION I N RECENT years, the switching frequency of voltage- source pulsewidth modulation (PWM) inverters has strik- ingly increased due to the great progress in electric power and semiconductor elements [i.e., insulated gate bipolar transistor (IGBT)]. This has brought significant improvements in control- lability of voltage, current, and torque of variable-speed motor drive systems [1]. Power losses and acoustic noise are also de- creased considerably. Nevertheless, it causes a number of major electromagnetic interference (EMI) problems in electrical sys- tems [1], [2], industrial applications, and aircraft [3]. These impediments [4], [5] include: 1) High frequency (HF) leakage current flowing to the ground through the stray capacitance between the motor windings and the frame, and that between power transistors and heat sink; 2) deterioration of motor winding insulation; 3) shaft voltage and bearing current in motor; 4) radiation of cables. Manuscript received February 27, 2009; revised May 20, 2009. Current version published December 4, 2009. Recommended for publication by Associate Editor R. Burgos. C. Jettanasen and C. Vollaire are with the Ampere Laboratory, Unit´ e Mixte de Recherche Centre National de la Recherche Scientifique 5005, Ecole Centrale de Lyon, Ecully Cedex 69131, France (e-mail: chaiyan.jettanasen@hotmail.fr; christian.vollaire@ec-lyon.fr). F. Costa is with the System and Application of Technology for the Informa- tion and the Energy Laboratory, Unit´ e Mixte de Recherche Centre National de la Recherche Scientifique 8029, Ecole Normale Sup´ erieure de Cachan, Cachan 94235, France (e-mail: francois.costa@satie.ens-cachan.fr). Color versions of one or more of the figures in this paper are available online at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/TPEL.2009.2031493 Consequently, it is necessary to know the different propaga- tion paths of the common-mode (CM) noise emissions, which are the most disturbing in the system, in order to apply an ap- propriate method to minimize or eliminate them in any variable- speed drive system. In aeronautics, these problems are extremely important because for the new-generation “more electric” air- plane, the pneumatic and hydraulic machines will be replaced by electrical actuators (e.g., steering deflection, braking sys- tems, landing gear, etc.) in order to reduce the costs as well as the weight of the embedded systems. The use of electric materials in these systems, which has to take into account the constraints of aeronautical environments, such as vibrations, temperature, weight, etc., imposes reliability constraints and very strong restrictions in terms of electromagnetic compatibil- ity (EMC). CM-conducted emissions produced by such systems can generate radiated emissions that could create malfunctions in sensitive avionic surrounding equipment, in particular the embedded electronics. Modeling of such a system is generally difficult because of its complexity. Many models have been created in a circuit- type simulation environment, usually used to design ac motor drive systems. To validate this kind of complex system in EMI analysis, simulated temporal signals have to be converted into spectral signals using fast Fourier transform (FFT) command in the simulators. Computing time of this process strongly de- pends on the maximum frequency desired and the system com- plexity. Normally, it is limited approximately at some kilohertz. The simulation could be impossible if the considered system is too complex. Thus, the approach proposed herein [6] is an interesting solution to avoid these previously stated restrictions because it directly provides the results in frequency domain. Besides, this attractive modeling, which is based on specific ex- perimental measurements of the different parts of the system, is efficient and simple. The modeling principle is to represent the CM circuit by a chain of two-port networks corresponding to each component of the system (i.e., line impedance stabilization network (LISN), diode rectifier, voltage inverter, shielded cable, and induction motor). Measuring of CM impedance of each el- ement and CM voltage generated by the PWM inverter is the essential step to make the quadripolar impedance matrix model available. This approach can also be used efficiently to optimize EMI filters or as the means of EMI reduction because it enables us to calculate or evaluate the CM current at every node of the system. Moreover, when the components (cable, motor, etc.) are reused in another system, this model could allow us to effec- tively predict CM disturbances without measurement testing. In this paper, the experimental bench used in the study is presented first. Second, the CM modeling and specific characterizations of each part in the system are described. Third, experimental and 0885-8993/$26.00 © 2009 IEEE Authorized licensed use limited to: Francois Costa. Downloaded on February 2, 2010 at 12:36 from IEEE Xplore. Restrictions apply.