Hiroki Funato

Motor modeling for EMC simulation by 3-D electromagnetic field analysis

A building technique of high-frequency motor models by 3-D electromagnetic field analysis has been developed to establish the simulation technology for EMC estimation in the design stage of motor drive systems. Stray capacitance of each part of a motor was calculated by static electric field analysis, while inductance and resistance of its stator windings were calculated by magnetic field analysis. A motor equivalent circuit was then built with these circuit constants to compute frequency characteristics of motor impedance. In order to take eddy current in laminated iron core into account precisely, we analyzed a 3-D model of half thickness of one laminated steel sheet, and a simplified 3-D model of coil end of a motor. We also took the difference between magnetic field distribution of common mode and that of differential mode into account by setting different coil current and boundary conditions in the analyses. The frequency dependence of calculated inductance and resistance was introduced into circuit simulations. As a result, we have obtained frequency characteristics of motor impedance, whose basic features are similar to those of measured data. Possible causes of the discrepancy have also been discussed.

Magnetic near-field probe for GHz band and spatial resolution improvement technique

This paper reports magnetic near-field probe for high frequency band up to 10 GHz and novel measurement technique for improvement of spatial resolution. We fabricated two types of magnetic near-field probe and evaluated frequency characteristics for magnetic and electric near-field in isolation. For the measurement results, we proposed accurate equivalent circuit of probes and evaluated each value of lumped parameter to study the difference of probes. Theoretical results accorded with measurement results. With the use of a fabricated probe, a measurement technique for the improvement of spatial resolution was proposed. This technique allows improving and easy modification of spatial resolution without redesign of probe

Integrated simulation and analysis of resolver sub-system for HEV electric drive

Resolver is widely used in electric drive system especially for hybrid electric vehicles (HEV). A resolver system includes not only a variable-reluctance resolver but also an excitation circuit, shielding cables and a resolver-to-digital (R/D) IC as a multi-physics system with electrical, magnetic, mechanical and control characteristics. This paper studies a resolver for HEV electric motor, and proposes an integrated systematic approach using co-simulation between several commercial simulation tools to simulate the resolverpsilas electromagnetism using transient solver of the finite element method, the excitation and termination circuits, and the behavior model of Type II tracking closed loop algorithm used by the R/D IC. This systematic approach paves way for a high accuracy system level simulation, fault analysis and trouble shooting, etc., which can be used to develop component design, DFMEAs and system integration that match performance in the field and not just a simplified model. A bench test of the presented resolver system is completed to make correlation to validate the model, and the analysis of some fault conditions is provided to make concept proof of this method.

A Study on Correlation Between the PCB Layout and EMI from Chassis

Investigations of radiated emission from a conductive chassis connected to the GND of a PCB with ICs showed higher emissions from a PCB mounted to a chassis than PCB without chassis. The results also showed that the location of the ground connection between the GND plane on the PCB and the chassis can affect emission levels by up to 9 dB. To determine the path of the noise current from the PCB to the chassis, we measured the current at their junction with a thin-current-probe. The position dependence of the junction current frequency spectra correlated with that of radiated emission spectra. Moreover, EMI levels correlated with distance from the screw to the nearest bypass-capacitor.

Application of a Cavity Resonator Model for Characterization and Estimation of Radiation From a PCB–Chassis System

The electric far-field radiated from a printed circuit board (PCB)-chassis system is characterized using a cavity resonator model employing the far field calculated using an equivalent magnetic current loop. The inductive network method with measured current flowing through screws as a stimulus is used to calculate the frequency spectra of the electric field strength along the edge of the PCB with various locations of screws that connect the PCB ground to the chassis. Electric far fields from the equivalent magnetic current loop were derived using correction coefficients that incorporate the asymmetric dimensions of a parallel pair of PCB planes and the chassis. The calculation results reveal that the horizontal far field exceeds the vertical far field due to the asymmetric size coefficients and exhibit good agreement with the measurement results.

Double position-signal-difference method for electric near-field measurements

A position/signal difference method for electric near-field measurements has been investigated and extended to a double position/signal difference method in order to independently extract the normal and tangential electric near-field components using two measurements at slightly different heights above the test object. A printed monopole probe was fabricated and used for electric near-field measurements above a microstrip line using the proposed method. In addition, full-wave electromagnetic simulations were carried out and the measured normal and tangential components were found to be in good agreement with the simulation results at 1 GHz.

Overview of component level EMC characteristics for HEV application

This article presents the power point presentation on the overview of component level testing for HEV products and simulating actual vehicle condition at component-level that would be the most important. A fundamental study of the emission from HV system was calculated and characterized with consideration of effects from HV related typical parameters. The noise source and effects of low voltage system was investigated, with the necessary consideration of coupling between LV and HV system.

An investigation on the reduction technique of radiated emission from chassis with PCB

Correlation between radiated emission from chassis with PCB and the junction current which is the current flowing through screws connecting PCB GND to chassis GND was investigated, and new technique to reduce the junction current was proposed. The measurement results of the junction current frequency spectra showed strong correlation with the emission from chassis with PCB. Also investigation using meshed LCR network SPICE model of PCB and chassis was performed. The calculation results of the junction current showed good correlation with measurement results for frequency spectrum and it suggested that the closer to screw bypass capacitor is placed, the lesser current flows through junction. That new concept was validated by actual measurement and the results of radiated emission showed 19 dB improvements at 320 MHz.

Model-based analysis of screw locations to reduce radiation from a PCB-chassis structure

The effect of the location of screws that connect PCB ground with the chassis has been studied using a SPICE circuit simulation model created by the multilayered finite difference method (MFDM). The model includes the power and ground planes of the PCB and the chassis. By using the created model, the impedance between the ground of the PCB and chassis at every location and the current flowing through the screw when it is placed to connect the ground with the chassis was calculated. The investigation results suggest that the node at which the higher impedance can be observed provides a lower screw current. Furthermore, it revealed that even just two screws connecting the ground with the chassis can provide a lower current than a single screw connection. Far-field measurements were performed to validate the investigation results.

Application of a magnetic near-field probe to the differentiation of defective connections

A new type of probe for the differentiation of defective connections from fully functioning ones between metal plates such as the frame ground has been designed, prototyped, and evaluated. The probe utilizes a dual loop near-field antenna to detect the magnetic near-field due to the current at the connecting point, and an oscillation circuit has been integrated as a stimulus. The prototype probe has been designed and made using a FR-4 PCB. The actual measurements were performed by using a prototyped probe with two metal plates connected at a certain point. The measured results revealed that the peak of the induced voltage could indicate the connecting point of the plates after observing high frequency behavior. A 3D electromagnetic simulation has also been performed, suggesting the results are reasonable.