A. Müsing

3-D Electromagnetic Modeling of Parasitics and Mutual Coupling in EMI Filters

The electromagnetic compatibility (EMC) analysis of electromagnetic interference (EMI) filter circuits using 3-D numerical modeling by the partial element equivalent circuit (PEEC) method represents the central topic of this paper. The PEEC-based modeling method is introduced as a useful tool for the prediction of the high frequency performance of EMI input filters, which is affected by PCB component placement and self- and mutual-parasitic effects. Since the measuring of all these effects is rather difficult and time consuming, the modeling and simulation approach represents a valuable design aid before building the final hardware prototypes. The parasitic cancellation techniques proposed in the literature are modeled by the developed PEEC-boundary integral method (PEEC-BIM) and then verified by the transfer function and impedance measurements of the L-C and C-L-C filter circuits. Good agreement between the PEEC-BIM simulation and the measurements is achieved in a wide frequency range. The PEEC-BIM method is implemented in an EMC simulation tool GeckoEMC. The main task of the presented research is the exploration of building an EMC modeling environment for virtual prototyping of EMI input filters and power converter systems.

Computationally Efficient Integration of Complex Thernal Multi-Chip Power Module Models into Circuit Simulators

For analyzing reliability or short-term overload conditions of power electronic systems, it is necessary to know transient temperatures of the power semiconductors. Directly coupling thermal and circuit simulators increases the simulation time by orders of magnitude, therefore making such an approach impractical. A well-known solution to this problem is to extract thermal equivalent circuits from 3D-field simulations and to insert them directly into the circuit simulator. In this paper we discuss the poor scaling performance of this state-of-the-art approach. There is an enormous increase in simulation time if there are more than just a few chips thermally modeled. We propose a general procedure at the circuit simulator solver level to increase the calculation speed of such a coupled simulation significantly.

Efficient Calculation of Non-Orthogonal Partial Elements for the PEEC Method

For various electrical interconnect and EMC problems, the partial element equivalent circuit (PEEC) method has proven to be a valid and fast solution method of the electrical field integral equation in the time as well as the frequency domain. Therefore, PEEC has become a multipurpose full-wave method, especially suited for the solution of combined circuit and EM problems, as found, for instance, on printed circuit board layouts, power electronics devices or EMC filters. Recent research introduced various extensions to the basic PEEC approach, for example a non-orthogonal cell geometry formulation. This paper presents a fast, flexible and accurate computational method for determining the matrix entries of partial inductances and the coefficients of potential for general non-orthogonal PEEC cell geometries. The presented computation method utilizes analytical filament formulas to reduce the integration order and therefore to reduce computation time. The validity, accuracy, and speed of the proposed method is compared with a standard integration routine on example cell geometries where the numeric results of the new method show improved accuracy, coming along with reduced computation time.

Steps Towards Prediction of Conducted Emission Levels of an RB-IGBT Indirect Matrix Converter

Numerical prediction of conducted emissions has the potential to become an important utility in power converter design. Advance knowledge of the conducted emission and simulations of the EMC performance can help to reduce cost and time in the design process. This paper presents a detailed time-domain simulation of an Indirect Matrix Converter (IMC) for predicting common and differential mode conducted emissions. The simulation model includes the parasitic inductances and capacitances of the PCB layout, whose values are obtained using the Partial Element Equivalent Circuit (PEEC) method. The simulation also includes the EMC filter, the mains connection cable and a load model for which parameters and parasitics are obtained from measurements. The results of the simulation are compared with conducted emissions measurements of an existing IMC Index prototype.

Voltage-dependent capacitors in power electronic multi-domain simulations

We discuss multi-domain simulation of power electronic systems where non-linear capacitors have a significant impact on the system behaviour, e.g. employing the MOSFET output capacitor Coss for soft switching or employing nonlinear thermal models in coupled electrical-thermal simulations. It is shown which errors can result from approximating non-linear capacitors with simple linear ones as proposed e.g. for Coss in datasheets. Furthermore a highly efficient implementation of non-linear capacitors in numerical circuit simulators is proposed.

Optimization of the current distribution in press-pack high power IGBT modules

Todays IGBT modules achieve high current ratings by paralleling several semiconductor switches. For high power and high voltage applications, the press-pack IGBT design is a technology of increasing importance, since it is designed for a low inductance series connection in a module stack. This work examines the module-internal current distribution in a press-pack configuration during switching transients by means of the PEEC simulation method. Parasitic effects which result in current unbalances between the paralleled switches are determined and quantified, where special emphasis is put on the power module external interconnection wiring and its influence on the current distribution and power loss in the distinct switches. A hardware test setup is discussed in detail, and a layout design optimization is which balances the loss distribution among the switches.

Full PEEC Modeling of EMI Filter Inductors in the Frequency Domain

In this paper, the performance of a new method based on the coupling of the partial element equivalent circuit method and boundary integral method (the PEEC-BIM method) for 3D modeling of toroidal inductors, which are typically used in electromagnetic interference (EMI) filter applications, is presented. The presence of magnetic materials is modeled by replacing the surface of magnetic regions with an equivalent distribution of fictitious current loops. It is shown that the influence of the magnetic core on the impedance and the stray field of EMI filter inductors can be modeled and explained in detail by PEEC-BIM simulation results. The developed PEEC-BIM approach is verified by both 3D finite-element method (FEM) simulations and near-field measurements for different winding configurations and magnetic cores. Regarding computational complexity, the developed PEEC-BIM method applied to toroidal inductors performs extremely well. The PEEC-BIM simulation is at least twice faster than the corresponding FEM-based analysis. The PEEC-BIM method has been implemented in a PEEC-based simulation tool, which facilitates the simulation of entire EMI filter structures.

PEEC modelling of toroidal magnetic inductor in frequency domain

In this paper, a detailed 3D Partial Element Equivalent Circuit (PEEC) model of a toroidal coil with a magnetic core is developed. The PEEC problem in the presence of magnetic materials is solved in the frequency domain via a magnetic current/charge approach, i.e. replacing the magnetized objects by a distribution of equivalent fictitious magnetic currents/charges in free space. The simulation parameters are the winding and magnetic core properties. The permeability is either taken from datasheets or determined by measuring the series equivalent impedance. To verify the proposed 3D PEEC model, calculated and measured impedance values are compared for several winding arrangements and core materials. A good agreement between simulation and measurements is presented up to the first resonant frequency. For higher frequencies, a more accurate specification of the permeability is required, as well as the core dielectric property has to be considered.

Novel online simulator for education of power electronics and electrical engineering

In this paper a novel online simulator is introduced that is integrated into the educational project iPES which is a free collection of Java applets for educational purpose. iPES has been translated into 12 languages and has currently more than 10, 000 visits per month. The novel online simulator is optimized for power electronics, easy to use, and allows unlimited simulation of converter topologies. The concept of embedding a circuit simulator in the form of a Java applet into a webpage allows the creation of power electronic and electrical engineering courses that are easy for students to access, highly flexible and require a low administrative effort. The paper will discuss the status of the iPES project in detail including all shortcomings and will show how the integration of the online simulator significantly improves the educational value.

New circuit simulation applets for online education in power electronics

This paper presents new online simulation applets based on Java technology. The applets are integrated into a series of student exercises which accompany the introductory and advanced lecture courses in power electronics at the Swiss Federal Institute of Technology Zurich. Furthermore, the new applets are available via the educational project iPES which is a free collection of Java applets for educational purposes. iPES has been translated into 12 languages and has currently more than 10,000 visits per month. The novel online simulation applets are easy to use and allow an unlimited simulation of converter topologies. The concept of embedding a circuit simulator in the form of a Java applet into a public accessible homepage allows the creation of power electronic and electrical engineering courses that are easy for students to access, highly flexible and require small administrative efforts for the lecturer. The paper will discuss the technical details of the online simulation project and will show how the integration of the online simulator significantly improves the educational value.