Jan Hansen

Generation of physical equivalent circuits using 3D simulations

Physical equivalent circuits are powerful tools for EMC analysis of electronic devices, however their generation is in general cumbersome. In this paper, a procedure to generate physical equivalent circuits using 3D simulations is described. The method is based on a numerical computation of Z parameters using 3D simulations. Equivalent circuit tpoplogy and parameters are extracted from the simulated Z parameter matrix. Maxwells equations are used in a reduced form to eliminate all effects that cannot be modelled by equivalent circuits.

Transfer Function Method for Predicting the Emissions in a CISPR-25 Test-Setup

The CISPR-25 standard is used in the automotive industry to characterize the electromagnetic radiation of electronic components. The setup is comprised of an electronic device, a cable harness, a metallic table, and an antenna. Dimensions stretch from a couple of meters for the setup to fractions of a millimeter for printed circuit board features. Numerical prediction of radiated emissions (RE) is of great usefulness for prediction of potential electromagnetic compatibility nonconformities in the early design process, but extremely difficult to be done for this setup as a whole. In this paper, we demonstrate how RE can efficiently be computed based on a setup as commonly used to model conducted emissions only, i.e., electric control unit and harness on infinite-ground plane. Applying Huygens principle and using it to generate a fixed transfer function between a particularly chosen Huygens surface and the antenna, we arrive at a novel computing scheme for RE. The scheme is applied for the antenna model and antenna factor-based calculations and demonstrates agreement with measurements within 5 dB range.

Advanced simulations of automotive EMC measurement setups using stochastic cable bundle models

This paper deals with modeling and simulation of cable bundles for automotive EMC tests. A new stochastic cable bundle model is presented. The parameters of the model are grouped into parameters for geometry, simulation, and disorder. Using a particularly developed cable bundle testbench, the model is validated against measurements and the parameter dependencies are investigated. The parameter study shows that the model is governed by one universal constant which describes the stochastics of the cable bundle and a characteristic density which is directly related to the cable bundle geometry. Finally, the model is used in an exemplary EMC setup whose device under test is a partially populated printed circuit board of an automotive electronic control unit. The simulation agrees very well with the according real life measurement setup.

Eigenmodes of electrical components and their relation to equivalent electrical circuits

Physical equivalent electrical circuits facilitate root-cause analysis of resonance phenomena in electromagnetic components. We extend an existing formalism for the generation of physical equivalent circuits by linking the resonant behaviour of the equivalent circuit with 3D electromagnetic eigenmodes of the component. We define a figure of merit, which we call quality, describing the frequency range of validity and the accuracy of equivalent circuit descriptions of 3D components. We validate our approach by analyzing practical examples.

Simulation of automotive EMC emission test procedures based on cable bundle measurements

Two time efficient simulation methods for the prediction of the conducted and radiated automotive EMC emission tests, respectively, are presented. To verify the correct prediction of the cable bundle model, a novel cable bundle test bench has been developed. It allows a fully automated network analysis with up to 32 ports. Several types of cable bundles are experimentally characterized under stochastic considerations. The system simulation for the conducted emission setup is partitioned into four parts connected on circuit level. The statistically analyzed voltage at the output of the line impedance stabilization network is in very good agreement to respective measurements. To simulate the radiated emission a novel method is presented, where the setup is partitioned by the use of Huygens principle. The simulated prediction of the antenna voltage is in good agreement with respective measurements. The presented approaches are very time efficient and therefore can be used effectively during product development.

Capacity extraction in physical equivalent networks

Physical Equivalent Circuits of electronic devices are very useful for EMC root-cause analysis, because they boil down complex coupling paths into rather simple circuit schematics, displaying only relevant inductive and capacitive structures. However, their derivation can be extremely time-consuming and requires thorough understanding of the device under test. Recently, a method was proposed to derive such a circuit with the aid of a computer. Whereas the design of an inductive network is relatively straight forward, correct placement of only the relevant capacities is difficult. In frequency range of interest, there are often too few resonances to determine capacitances uniquely, revealing that capacity placement has typical properties of an ill-posed problem. Engineering intuition states that often, only few capacitances dominate the root-causes of an EMC spectrum. We present a regularization method that allows to quickly determine the C matrix with fewest number of entries via an iterative least squares minimization. We are thus able to compute a unique physically meaningful capacitance matrix of a physical equivalent circuit.

A Novel Segmentation Approach for Modeling of Radiated Emission and Immunity Test Setups

A novel procedure is developed to simulate radiated emission (RE) and immunity scenarios using a common approach for electronic control unit with complex wiring harness and terminations. This is possible by applying Huygens principle and Reciprocity theorem to the problem. A segmented approach is proposed to split the device under test into multiple segments, which converts the radiation problem to circuit simulation, in addition to reducing the requirement of computing resources. The proposed method is validated using measurements and also full-wave three-dimensional simulations for both RE and immunity test setups.

EMI system model for a gearbox electronic control unit

A system simulation approach to model conducted emissions of a gearbox electronic control unit (ECU) is presented. The system is partitioned in ECU, cable harness, and load. The ECU itself is modeled using 3D electromagnetic simulation. For the cable harness and loads analytic models are employed, so that the incorporation of these parts into the model can be done without any increase in simulation time. The model is used to investigate resonances between PCB and housing, and common and differential mode currents on the cable harness. Also, optimal positions of critical subassemblies on the printed circuit board inside the ECU have been investigated.