The circuit-field coupling techniques, which could take the nonlinearity, time and space harmonics, core losses, and mechanical movement into consideration, have been widely applied in modern power ...system simulation. However, existing coupling schemes can deal with only one finite-element (FE) model connected to the external circuit. A new coupling method in which the generic machine model is established by the multiloop method and the parameters are extracted from FE analysis in real time is proposed in this paper. The introduced method allows one more transient FE model; adding to the arbitrary schematic with robust and reliable simulation results. The comparisons from the simulation results of the proposed method with strong coupling cosimulation and experimental results have verified the effectiveness of the new method. Furthermore, experimental tests of a three-stage generator system are carried out to validate the results from the coupling simulation with the proposed method.
This brief presents a generic model to emulate distortion circuits using operational amplifiers and diodes. Distortion circuits are widely used for enhancing the sound of guitars and other musical ...instruments. This brief introduces a new model for an ideal operational amplifier that does not include implicit equations and is thus suitable for implementation using wave digital filters (WDFs). Furthermore, a novel WDF model for a diode is proposed using the Lambert W function. A comparison of output signals of the proposed models to those obtained from a reference simulation using SPICE shows that the distortion characteristics are accurately reproduced over a wide frequency range. Additionally, the proposed model enables real-time emulation of distortion circuits using ten multiplications, 22 additions, and two interpolations from a lookup table per output sample.
We present analysis and modeling of a new innovative nanoelectromechanical switch (NEMS) with virtually zero leakage current, 1-3-V operation voltage, 1-10-ns switching time, and small footprint. In ...addition to acting as a simple switch, the physical structure of NEMS enables positioning of multiple contacts to realize functional logic gates in a single device. The implementation of basic two (or more) input logic gates using a single device improves reliability and reduces charging delay time. The reduction in the number of devices also improves yield and power while simplifying implementation. To evaluate NEMS design, we present an accurate NEMS SPICE circuit simulation model which enables the measurement of NEMS timing and power requirement. Based on the model and the device fabrication data, we show that NEMS ISCAS-85 circuit shows significant improvement over CMOS technology counterpart (using 65- and 45-nm technology).
Process variations (PV), including global variation (GV) and local variation (LV), have become one of the major issues in advanced technologies, which is crucial for circuit performance and yield. ...However, developing a mature and physics-based model is challenging and time-consuming. Thus, in this work, we propose a machine learning (ML) based method for device modeling with PV and implement the corresponding circuit simulation, which is demonstrated on advanced Nanosheet FETs (NSFET). Verified by TCAD simulations, the artificial neural network (ANN)-based ML algorithm enables to capture PV, e.g., dimension and work function variations (WFV), with high accuracy and improved efficiency. For GV, the ANN surrogated NSFET-based ring oscillator (RO) simulation results show that the larger width (Wsh) or height (Hsh) of the Nanosheet leads to the higher RO frequency and lower circuit delay. For LV, the respective impacts of grain size and WF on circuit performance can be distinguished. The proposed workflow, from ANN model training to circuit simulation based on the generated Verilog-A model, is fully automatic, promising to shorten the procedure of device modeling and accelerate the development of advanced technologies.
FastSpice techniques are considered in this paper and in particular partitioning methods that split a large circuit in a set of smaller sub-circuits to quickly and accurately compute a dcsolution. ...Each sub-circuit contributes to a set of Jacobian matrices with reduced dimensions that are more efficiently LU-factorised during the iterations of the solving methods. As a matter of fact, the numerical effort required by factorisation is a non linear (polynomial) function of the matrix dimension. We describe the use of voltage and current probes that can be inserted to “virtually” tear nodes and branches of the original circuit to further improve circuit splitting. The proposed techniques do not alter the accuracy of the simulation and thus we obtain FastSpice performances while keeping Spice accuracy. This can be a key issue in simulating circuits designed with deep-submicron technologies. Simulation performances of the proposed approach are compared with those of modern commercial full-chip FastSpiceand Spice-like simulators.
A parameterised wideband equivalent circuit model capturing the per-unit-length (p.u.l.) frequency-dependent resistance and inductance of on-chip coplanar waveguides (CPWs) is presented. The ...parameterised model for on-chip CPWs is suitable for various process nodes and over a large geometry range with signal line width-to-thickness ratios $w_{\rm s}/t$ws/t between 1 and 15 and spacing-to-thickness ratios $s/t$s/t between 0.25 and 15. The model has been validated by both EM simulation and measurements of fabricated test chips. The model is accurate to within 10% over the normalised geometry range. The model can easily be implemented into standard circuit simulators.
Doubly salient permanent-magnet (DSPM) motors offer the advantages of high power density and high efficiency. In this paper, it is examined that the DSPM motor is a new class of fault-tolerant ...machines, a potential candidate for many applications where reliability and power density are of importance. Fault analysis is performed in a DSPM motor drive, including internal and external faults. Due to the fact that the experimentation on a true motor drive for such a purpose is impractical because of its high cost and difficulty to make, a new cosimulation model of a DSPM motor drive is developed using coupled magnetic and electric circuit solvers. Last, to improve the performance of a DSPM motor drive with an open-circuited fault, a fault compensation strategy is proposed. Simulation and experimental results are presented, showing the effectiveness of the proposed cosimulation method and the high performance of the fault-tolerant characteristic of DSPM motor drives.
The diode-grounded scheme for stray-current collection in some systems, such as the Taipei rapid transit systems (TRTS), has been constructed to gather the stray current leaking from the running ...rails and avoid corrosion damage to the system as well as the surrounding metallic objects. During operation of the TRTS, a high potential between the negative return bus and system earth bus at traction substations, referred to as rail potential, has been observed on the Blue line between BL13 and BL16. Since the Blue and Red-Green lines have their running rails and stray-current collector mats in junction at the G11 station, the TRTS suspects that the impedance bond at G11 is the cause of rail potential rise. This paper presents the results of field tests for studying whether the impedance bond at G11 of the tie line has an impact on rail potential and stray currents in TRTS. The results show the rail potential can be reduced by disconnecting the impedance bond at G11 of the tie line so that the negative return current of the Blue line cannot flow to the rails of the Red-Green Line, and vice-versa. In addition, rail potential and stray currents occurring at a station of the Blue line are numerically simulated by using a distributed two-layer ladder circuit model. The simulation results are compared with the field-test results and they are consistent with each other.
A grinding circuit simulation combined with ball weal law was used to determine the optimum composition of the make-up ball sizes in tumbling ball mills. It was found that the optimum composition ...depends on various factors, including the feed size, the product size, the mill diameter and the breakage parameters. In all cases, binary mixtures of two ball sizes (50.8mm and 25.4mm) performed better than a mixture of the three ball sizes. An equation therefore could be developed for calculating the optimum composition of the make-up balls as a function of various parameters.
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•The optimum composition of the make-up ball sizes in ball mills is presented.•The effect of various factors was investigated via a grinding circuit simulation.•Binary mixtures of two ball sizes always perform better than other mixtures.•An equation is proposed for calculating the optimum composition of the make-up balls.
Monopole HVDC systems create dc current flow in the earth, which can cause the grounding location potential to rise relative to infinite spot and alters the working point of the transformer core. ...Because of the nonlinearity of the transformer core, the exciting current produces the amount of harmonics under dc bias. Past research has focused almost on simulation and testing dc bias problems of single-phase transformers. However, due to the complicated magnetic circuit structure in a three-phase five-limb transformer, there are some difficulties in studying its dc bias problem. In this paper, a new model and algorithm are proposed to find the nonlinear characteristics for the three-phase five-limb transformer under dc bias. Maxwell's equations are used to replace the magnetic circuit model of the transformer. By combining an electrical circuit with the nonlinear characteristic curve of the core, dc bias problems for a three-phase five-limb transformer are studied. Results show that the waveform of the no-load current and magnetic field intensity of the transformer are distorted under dc current inrush, and low-order harmonics increase with increasing dc current. Finally the interior and exterior nonlinear curve characteristics under dc bias are discussed.
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