Tamar Makharashvili

A Measurement-Based Model of the Electromagnetic Emissions From a Power Inverter

Rapidly switching semiconductors in modern high power inverter/motor-drive systems generate fast changing voltages and currents which may result in unwanted emissions. While models of power inverters have been built in the past to predict emissions, they are typically “black box” models where the cause of and solution to emissions problems is difficult to analyze. To improve inverter system design strategies, a detailed measurement-based SPICE model of a power inverter system was built in which there is a straightforward correlation between system geometry and parasitic circuit elements. This model was validated through measurements. The model was able to predict transfer characteristics between ports of the inverter within 4 dB from 100 kHz to 100 MHz. Once built, this model was used to identify structures responsible for resonances and to determine possible improvements of the power inverter design to reduce emissions. Measurements of S21 and radiated emissions after adding these improvements demonstrated that they were able to reduce emissions by 10-20 dB, thus confirming the accuracy of the model and its ability to improve understanding of emission mechanisms and to guide development of emissions reduction strategies.

Development of Simple Physics-Based Circuit Macromodel From PEEC

The evaluation of electromagnetic parasitics is important for electromagnetic interference within power electronics systems. Simple yet accurate physics-based lumped-circuit models of these parasitics can facilitate fast analysis and better understanding of the system performance. Methods exist to reduce complex electromagnetic models to much simpler representations but, while they speed up calculation, they do not preserve physicality. In this paper, a methodology is developed for obtaining a simplified SPICE circuit from a large-scale partial element equivalent circuit (PEEC) model, where there is a clear correlation between geometry and parasitic circuit elements. To preserve correlation between equivalent circuits and physical geometry, reduction is done first for inductance and resistance; then, reduction is performed for capacitance using nodes from the reduced LR model. The reduced model gives a better insight into the causes of and possible solutions to electromagnetic problems and can be used to improve the design. The method was validated on real power electronics geometries using frequency-dependent behavior of port impedances and admittances. The initial PEEC model for this example contained approximately 10 645 unknowns and was reduced to 195 elements. The calculated and measured impedances agree within 0.1 dB up to 200 MHz.

Inductance Extraction for PCB Prelayout Power Integrity Using PMSR Method

Proper power integrity (PI) analysis is required for printed circuit board (PCB) power distribution network (PDN) design. Top-layer interconnect inductance for PI has always been a vital concern for high-speed industry. Developing a simple physics-based equivalent circuit model for critical structures is essential for understanding the physics of the system and for intelligent designs. In this paper, a physics-based model size reduction (PMSR) method is applied to get the equivalent circuit model for the above-ground geometries. The extracted physics-based models are also based on the partial element equivalent circuit (PEEC) method, and can be used in analyzing the structure in its parts. By applying PMSR method, a physics-based equivalent circuit model can be proposed and this circuit model is related to the geometric features of the design. In this way, PMSR method can provide an intuitive guideline in designing PCB and reducing above inductances, therefore, a low-ripple dc voltage can be delivered through PDN. Taking advantage of PEEC and PMSR methods, the top-layer inductances of three different geometries are calculated and the physics-based circuit models are obtained, respectively.

Study of alien crosstalk to a BroadR-Reach® protocol based system

BroadR-Reach® is a point-to-point Ethernet Physical Layer (PHY) standard, which is used in automotive applications. This technology allows full-duplex communication between two devices over a single, Unshielded Twisted-wire Pair (UTP) cable. Here, alien crosstalk in a 6 UTP bundle is investigated for meeting electromagnetic compatibility requirements. Alien crosstalk refers to crosstalk to the BroadR-Reach® communication channel from an unrelated signal wire. Alien Near-End and Far-End Crosstalk in two different UTPs with and without an inline Circular Plastic Connector (CPC) are compared to standard limits. An inline connector in the middle of a 15 m 6 UTP cable bundle, with a 25 cm untwisted region, fails the Power Sum Alien Near-End Crosstalk (PSANEXT) standard limit by 4 dB at 100 MHz, while the same bundle without the connector passes the standard by a margin of 8 dB at 100 MHz.

Radiated EMI Estimation From DC–DC Converters With Attached Cables Based on Terminal Equivalent Circuit Modeling

An equivalent two terminal model based on the Thevenin equivalents describes the common mode (CM) currents on the input and output side of two widely used types of dc-to-dc power converters—buck and boost. Thus, it describes a nonlinear circuit by a linear equivalent circuit. The maximized spectrum of the CM currents is extracted for converters with stochastic signals using a novel characterization procedure. The extracted Thevenin model is used in co-simulation combined with a full-wave electromagnetic solver to predict the radiated emissions from the system consisting of the shielded dc–dc converters with attached cables and a DC brushless motor as load. The results using the terminal model agree well with the measurements providing that the actual CM loads are within the range of CM loads used while obtaining the Thevenin equivalent circuit.

Top-layer inductance extraction for the pre-layout power integrity using the physics-based model size reduction (PMSR) method

Proper power integrity analysis is required for printed circuit board (PCB) power distribution network (PDN) design. Developing a simple physics-based equivalent circuit model for critical structures is essential for understanding the physics of the system and for intelligent designs. In this paper, a physics-based model size reduction (PMSR) method is applied to get the equivalent circuit model for the above-ground geometries. The extracted physics-based models are also based on PEEC, and can be used in analyzing the structure in its parts. By applying PMSR method, a physics-based equivalent circuit model can be proposed and this circuit model is related to the geometric features of the design. In this way, PMSR method can provide an intuitive guideline in designing PCB and reducing above inductances, therefore, a low-ripple DC voltage can be delivered through PDN. Taking advantage of PEEC and PMSR methods, the top-layer inductances of three different geometries (the shared via design, the doublet design and the shared pad design) are calculated and the physics-based circuit models are obtained, respectively.

Transient simulation for power integrity using physics based circuit modeling

A transient simulation analysis is proposed for printed circuit board (PCB) power distribution network (PDN) by using physics based circuit model. The PCB PDN is divided into different blocks. Different modeling methods are used to provide physics-based circuit models for each block. Then, Hspice simulation is used to do transient simulation for the PCB PDN based on the circuit.

PEEC macromodels for above plane decoupling capacitors

Decoupling capacitors perform an important function in the impedance reduction of power distribution systems. Hence, they are a key part of an electrical model required for the design of such systems. In this paper, we construct circuit models for the capacitors which include the local environment such that the overall PDN model is simplified and it can be considered as decoupled macromodels.