Equivalent source corresponding to radiated field of EMC filter components September 16, 2010 Sanâa ZANGUI sanaa.zangui@ec-lyon.fr

Outline Introduction Aims Equivalent model Mutual inductance Validation Measurement method Summary Questions

Power electronic system Introduction In Power electronic => Noises By conduction By radiation Low pass filter => reduce conducted noises (HF) Power electronic system Filter Motor Magnitude (dB) Low pass filter Frequency

The self-parasitics of components Introduction 1MHz 30MHz Mutuals inductances Frequency Magnitude (dB) The self-parasitics of components 1 2 Cy DM EPC EPR L ESR ESL M 3 Magnetic Coupling Analysis (Low voltage/ high current) Near-field Approximation - Distance between components<< wavelength λ - Maximum frequency (100MHz) => λmax= 3meters Parasitic parameters and EMC Filter Performances: - Self-parasitic - Filter components coupling

Aims Taking into account the effects of parasitic parameters in the first step of designer a filter Equivalent Model Components : Model the magnetic near-field produced by filter components Take into account the near electromagnetic environment Integrated in an electrical circuit software Compute Coupling Effects Using the equivalent model of components According to their geometric placement.

Equivalent model ( Multipolar expansion) 3D EM fields : multipolar expansion The field is computed outside the sphere that contains the equivalent source. n=1 m=0 (dipole) n=2 m=0 (quadrupole)

Equivalent model ( Equivalent model) The expression of the magnetic field : Qnm are functions of H Computing H by using 3D numerical model or measurement n: degree, m: azimuthal order, Ynm : The spherical harmonics functions Qnm are parameters which need to be identified => equivalent model of the radiated field component

Mutual inductance Using the equivalent radiated field source model. The spheres which contain each of the sources don’t intersect The expression of the mutual inductance is: The coefficients of the multipolar expansion of sources 1 and 2 must be expressed in the same reference => translation.

Computing method Component 1 Component 2 H1 field by numerical modeling or measurement H2 field by numerical modeling or measurement Q1nm Computation Q2nm Computation Equivalent model 1 Equivalent model 2 Rotation + translation in the reference1 of Q2nm => Q’2nm Computation of the mutual inductance M in function of Q1nm and Q’2nm The translation is based on the “Addition Theorem for Vector Spherical Harmonics”

Numerical modeling H field by FEM method(Flux3D®) To result this case : - Flux3D => 2000 unknows - Multipolar expansion : For n=Nmax=3 =>15unknows For n=Nmax=5 => 35unknows Infinite box Sphere of validity Element to modeling Normal component of H => Qnm => equivalent model => mutual inductance

Validation (case 1) Our result was compared to the numerical result computed by FEM(Flux3D cedrat). Two loops, C1 and C2 with a radius “Rspire” of 10 cm, separated by r At r =0.2m the error is greater for Nmax=3 than Nmax=5 Relative error (%) Mutual inductance(H)

Validation (case 2) For the same previous loops C1 and C2 For a rotation of 45° around the y axis of the loop C2 The results are similar to the previous case Mutual inductance(H) Relative error (%)

Measurement method Coefficient of coupling K Relation valid : L1. > 10*R (R : resistance of coil) This method will be used : measure K in function of the distance between 2 identical loops K: coefficient of coupling, M: mutual inductance, VS: input voltage, VE : output voltage.

Summary The method is validated : Using multipolar expansion => equivalent model of the radiated field of components. Using the equivalent model to compute the coupling (Mutual inductance) between components. Apply this method to more complex components. Measurement system that measures Qnm components . Couple this method with Partial Element Equivalent Circuit (PEEC)=> filter modeling including all coupling (track/track, components/components, components/track). The cylindrical harmonics can be considered for modeling components such as capacitors or cables. Provide component libraries including models of coupling between power electronic components.

Questions