Nonlinearity Of Circuit Research Articles

Modelling and optimization of TPMLMs with slotted stators based on Bayesian DNN

AbstractThe Permanent Magnet Linear Motor (TPMLM) is widely used in different industrial fields. TPMLMs with slots and iron cores have high power density, but their thrust fluctuations and copper losses are significant. Due to the nonlinearity and saturation of magnetic circuits, their electromagnetic models are complex and the accuracy of numerical methods is very inferior. Substantially accurate modelling is crucial for motor optimisation design. In this paper, a data‐driven modelling method based on Bayesian optimisation deep neural network (DNN) is proposed to improve the accuracy of the electromagnetic field. The finite element (FE) modelling under different structural parameters is analysed and provides a training dataset for DNN. Then, a multi‐objective optimisation problem for the slotted TPMLM is carried out based on the multi‐objective black hole algorithm. Compared to the original design, the average thrust of TPMLM increased by 49.37%, the thrust fluctuation percentage decreased by 9.59%, and the coil copper consumption percentage decreased by 2.64%. The results show that the improved DNN model has very high modelling accuracy, providing a new way for motor design and optimisation.

An analog circuit fault diagnosis method using improved sparrow search algorithm and support vector machine.

In analog circuits, component tolerances and circuit nonlinearity pose obstacles to fault diagnosis. To solve this problem, a soft fault diagnosis method based on Sparrow Search Algorithm (SSA) and Support Vector Machine (SVM) is used. In this study, ISSA is obtained by optimization using four strategies for SSA deficiency. Twenty-three benchmark functions are used for optimization experiments, and ISSA converges faster, more accurately, and with better robustness than other swarm intelligence algorithms. Finally, ISSA is used to optimize the SVM parameters and establish the ISSA-SVM fault diagnosis model. In the Sallen-key test circuit diagnosis experiments, the correct fault diagnosis rates of SSA-SVM and ISSA-SVM are 97.41% and 98.15%, respectively. The results show that the optimized ISSA-SVM model has a good analog circuit fault diagnosis with an increase in diagnostic accuracy.

Dual-polarization MZM-based photonic nonlinear analog self-interference cancellation for in-band full-duplex radios

In this paper, we propose a dual-polarization Mach-Zehnder modulator-based photonic nonlinear analog self-interference cancellation (SIC) technique for in-band full duplex (IBFD) systems. By using the proposed technique, an arbitrary 4th order nonlinear transfer function can be generated, meaning the performance limitation caused by the nonlinearity of the analog SIC circuit can be overcome by imitating the nonlinear transfer function of the analog SIC circuit before cancellation. This paper also presents a performance analysis through simulations and the results of a proof-of-concept demonstration. In the experiment, the proposed nonlinear SIC technique could achieve 29 dB cancellation over 500 MHz bandwidth centered at 1.25 GHz frequency along various degree of distortion caused by nonlinearity. In addition, the performance enhancements achieved by the proposed technique are evaluated in terms of error vector magnitudes (EVMs) and constellations of the signal-of-interest (SOI) in the simulation which is based on the experimental SIC results. More than 3 dB of SOI power gain could be obtained in evaluated EVM performances.

Synthesis of Behavioral Models for Circuits With Nonlinearity Less Than Model Error

A method for the parameter extraction of a nonlinear-dynamical behavioral model is considered. At this method, the model satisfactorily reflects the nonlinear signal distortions, the value of which is less than the model error. As an example, a digitizer was used. It is shown that a model in the form of a third-order nonlinear recursive filter with integrators in the feedbacks is sufficient. The maximum modeling error is 10% and the amplitude of nonlinear distortions is 3-7%. By including the difference between the calculated and measured nonlinear distortion signals in the optimization criteria when extracting of the model parameters, an error of no more than 29% in the representation of the amplitude of nonlinear distortions was achieved at the correct modeling of the distortion waveform. We explain this by the fact that most of the model error relates to the representation of linear dynamical properties. These properties are the same at any level of the test signal and, under the appropriate parameter’s extraction, do not affect to the modeling error for the circuit nonlinearity.

Barrier function-based adaptive terminal sliding mode control of plug-in hybrid electric vehicle with saturated control actions

Plugin hybrid electric vehicles in contrast to traditional hybrid electric vehicles (HEV) are getting enormous attention in the modern electric transportation market as they address the environmental issues, fuel economy crisis, and CO2 emission. Fuel cell-based PHEV with smart charging mechanism is an important application of the clean energy generation and storage system. There are two main subsystems in a PHEV: A hybrid energy storage system (HESS) and an integrated charging unit (ICU). In this study, an effective control strategy for the charger and HESS comprising three power sources: Fuel cell (FC), battery, and a superconducting magnetic energy storage (SMES) connected to the DC bus is presented. Due to the non-linearity of power conditioning circuits in ICU and HESS, designing a robust nonlinear controller is still a challenge. A barrier function-based adaptive terminal sliding mode controller is proposed to ensure the finite-time convergence of the output variable. It also maintains it in a predefined neighborhood of zero without overestimating the control gain and hence exhibits better dynamic performance in the presence of external disturbances of unknown upper bound. The asymptotic stability of the system has been ensured by using the Lyapunov stability criterion. Finally, the energy management algorithm in HESS using the state of charge of the battery and SMES as the decisive factor is incorporated to maintain the stability of the system under varying load conditions. The performance of the proposed controller has been compared with conventional nonlinear control techniques like adaptive terminal sliding mode control (ATSMC) and supertwisting sliding mode control (STSMC) by using MATLAB/Simulink. The performance of the system is further validated by using a C2000 Delfino F28379D MCU dual-core microcontroller with a hardware-in-the-loop (HIL) setup.

Information Energy Capacity Region for SWIPT Systems Over Rayleigh-Fading Channels

In this paper, we study the fundamental limits of simultaneous information and power transfer over a Rayleigh-fading channel, where the channel input is constrained to peak-power (PP) constraints that vary in each channel use by taking into account high-power amplifier (HPA) nonlinearities. In particular, a three-party communication system is considered, where a transmitter aims simultaneously conveying information to an information receiver and delivering energy to an energy harvesting receiver. For the special case of static PP constraints, we study the information-energy capacity region and the associated input distribution under: a) average-power and PP constraints at the transmitter, b) an HPA nonlinearity at the transmitter, and c) nonlinearity of the energy harvesting circuit at the energy receiver. By extending Smith’s mathematical framework, we show that the optimal input distribution under those constraints is discrete with a finite number of mass points. We show that HPA significantly reduces the information energy capacity region. In addition, we derive a closed-form expression of the capacity-achieving distribution for the low PP regime, where there is no trade-off between information and energy transfer. For the case with time-varying PP constraints, we characterize the optimal input distribution of this channel by using Shannon’s coding scheme. Specifically, we numerically study a particular scenario for the time-varing PP constraints, where the PP constraint probabilistically is either zero or equal to a non-zero constant.

Study of Nonlinear Excitation Circuits for Fluxgate Magnetometer.

This paper presents the common methods and corresponding drawbacks concerning nonlinear analysis of fluxgate excitation circuits and emphasizes the importance of nonlinear analysis for these circuits. With regard to the nonlinearity of the excitation circuit, this paper proposes the use of the core-measured hysteresis curve for mathematical analysis and the use of a nonlinear model that considers the coupling effect of the core and winding and influence of the historical magnetic field on the core for simulation analysis. The feasibility of mathematical calculations and simulation for the nonlinear study of fluxgate excitation circuit is verified via experiments. The results demonstrate that, in this regard, the simulation is four times better than a mathematical calculation. The simulation and experimental results of the excitation current and voltage waveforms under different excitation circuit parameters and structures are essentially consistent, with a difference in current of no more than 1 mA, thereby verifying the effectiveness of the nonlinear excitation analysis method.

Chance-constrained resource allocation for cognitive wireless-powered backscatter communication networks

With the rapid development of the Internet of Things (IoT) and the increasing number of wireless nodes, the problems of scare spectrum and energy supply of nodes have become main issues. To achieve green IoT techniques and resolve the challenge of wireless power supply, wireless-powered backscatter communication as a promising transmission paradigm has been concerned by many scholars. In wireless-powered backscatter communication networks, the passive backscatter nodes can harvest the ambient radio frequency signals for the devices’ wireless charging and also reflect some information signals to the information receiver in a low-power-consumption way. To balance the relationship between the amount of energy harvesting and the amount of information rate, resource allocation is a key technique in wireless-powered backscatter communication networks. However, most of the current resource allocation algorithms assume available perfect channel state information and limited spectrum resource, it is impractical for actual backscatter systems due to the impact of channel delays, the nonlinearity of hardware circuits and quantization errors that may increase the possibility of outage probability. To this end, we investigate a robust resource allocation problem to improve system robustness and spectrum efficiency in a cognitive wireless-powered backscatter communication network, where secondary transmitters can work at the backscattering transmission mode and the harvest-then-transmit mode by a time division multiple access manner. The total throughput of the secondary users is maximized by jointly optimizing the transmission time, the transmit power, and the reflection coefficients of secondary transmitters under the constraints on the throughput outage probability of the users. To tackle the non-convex problem, we design a robust resource allocation algorithm to obtain the optimal solution by using the proper variable substitution method and Lagrange dual theory. Simulation results verify the effectiveness of the proposed algorithm in terms of lower outage probabilities.

A Study of Out-of-Band Emission in Digital Transmitters Due to PLL Phase Noise, Circuit Non-Linearity, and Bandwidth Limitation

A Study of Out-of-Band Emission in Digital Transmitters Due to PLL Phase Noise, Circuit Non-Linearity, and Bandwidth Limitation

Spurs in Millimeter-Wave FMCW Radar System-on-Chip

In this article, we present a nonlinear system model to evaluate the impact of circuit nonlinearities on spurs in millimeter-wave frequency-modulated continuous-wave (FMCW) radar system-on-chips. The developed model includes the harmonics of the frequency multiplier, nonlinearity of the power amplifier (PA) and low-noise amplifier (LNA), the switching operation of the receiver (RX) mixer, the limited bandwidth of the PA, LNA, transmitter (TX) and RX antennas, as well as the TX-to-RX leakage. The developed nonlinear model can be used to derive the frequency and amplitude of spurs in the radar IF spectrum. The major insights about the impact of different nonlinearities and their <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">interactions</i> are as follows. 1) The harmonics of the frequency multiplier appear as spurs in the IF spectrum. 2) The PA can be driven in its nonlinear region to mitigate the harmonics generated by the frequency multiplier. 3) Bandwidth of the TX and RX systems should be limited to attenuate the undesired harmonics. 4) The interaction between the TX-to-RX leakage signal and the LNA nonlinearity can lead to spurs close to the target echo in the IF spectrum.

Coupled Field Analysis of Phenomena in Hybrid Excited Magnetorheological Fluid Brake

The paper presents a field model of coupled phenomena occurring in an axisymmetric magnetorheological brake. The coupling between transient fluid dynamics and electromagnetic and thermal fields as well as mechanical equilibrium equations is taken into account. The magnetic field in the studied brake is of an excited hybrid manner, i.e., by the permanent magnets (PMs) and current Is in the excitation winding. The finite element method and a step-by-step algorithm have been implemented in the proposed field model of coupled phenomena in the considered brake. The nonlinearity of the magnetic circuit and rheological properties of a magnetorheological fluid (MR fluid) as well as the influence of temperature on the properties of materials have been taken into account. To solve equations of the obtained field model, the Newton-Raphson method and the coupled block over-relaxation method have been implemented. The elaborated algorithm has been successfully used in the analysis of the phenomena in the considered magnetorheological brake. The accuracy of the developed model and its usefulness have been verified by a comparative analysis of the results of simulation and laboratory tests carried out for the developed prototype of the studied brake.

Prediction of EMI Filter Attenuation in Power-Electronic Converters via Circuit Simulation

This article investigates the conducted-emission (CE) suppression characteristics of electromagnetic interference (EMI) filters used in power-electronic equipment by time-domain circuit simulation. An operational definition of insertion attenuation is introduced by comparing the CE in the absence and in the presence of the EMI filter. For the sake of exemplification, the analysis focuses on switched-mode dc–dc converters. It is shown that the EMI-filter attenuation behaves differently from the standard insertion loss (IL) and exhibits peculiar properties in these circuits. Namely, its response is known at discrete frequencies where the converter generates CE and may strongly depend on the harmonic index so to jump between quite different levels from a harmonic component to the next one, with a pseudoperiodic behavior, which can be related to the duty cycle. This effect is caused by circuit nonlinearity and is partially mitigated if the simulation accounts for two practically relevant aspects: random instability of the duty cycle and resolution bandwidth of the EMI receiver. The dependence of the common-mode (CM) and differential-mode attenuations on the loading conditions and duty cycle is analyzed, and it is shown that linear IL models provide reasonable predictions of CM attenuation only. Finally, experimental evidence of the unveiled phenomena is presented.

Fair Scheduling of Wireless Power Transfer to Nonlinear Energy Harvesters

The performances of two wireless power transfer (WPT) scheduling schemes, time sharing (TS) and spatial multiplexing (SM), in terms of provisioning fairness among energy receivers (ERs), are studied and compared while taking into account the nonlinearity of the harvesting circuits. In the network, the multiple-antenna energy transmitter attempts to maximize the harvested energy by the ER which has accumulated the minimum amount of energy among all single-antenna ERs during the WPT block—hence the max-min fairness criterion. Two network scenarios are studied: homogeneous, where similar channel coefficients are assumed for all the well-apart ERs, and heterogeneous, where the said coefficients can take arbitrary values. For WPT in single-band or multi-band, we analytically prove that the optimal scheduling policy in the homogeneous scenario is to allocate each ER the full transmit power with uniform distribution of charging times among ERs, rather than to allocate the full power transfer block with uniform distribution of the power among ERs. Generalization of the network to the heterogeneous scenario aims to find the optimal beamforming vectors for the SM scheme and the optimal time sharing vector for the TS scheme. We form the max-min fairness optimization problems for both scheduling techniques, in single-and multi-band WPT scenarios. The problems, which are nonlinear and non-convex, are solved through exhaustive search algorithms. It is proven that the TS scheduling outperforms the SM one in terms of max-min fairness as a result of taking into account the inherent non-linearity of the harvesting devices.

Tuning inter-modal energy exchanges of a nonlinear electromechanical beam by a nonlinear circuit

A model of a nonlinear beam with a piezoelectric patch linked to a nonlinear circuit is considered. The physical and mechanical parameters of the system are such that it presents a 1:3 internal resonance. The aim is to study, for different time scales, the effect of the nonlinearity of the electrical circuit on energy exchanges between the resonant modes. In fact, we would like to master energy channelling between two internally resonant modes of a composite beam via a nonlinear circuit. The investigations are carried out on the projected system equations on its internally resonant modes. The system behaviours at different scales of time are studied by coupled methods of complexification and multiple scale. Analytical developments permit to reveal different system dynamics characterized by periodic and/or non-periodic regimes. Finally, the paper is accompanied by comparisons between systems equipped with a resonant circuit (linear) and a nonlinear one.

Fast Design Space Exploration and Multi-Objective Optimization of Wide-Band Noise-Canceling LNAs

Design optimization of RF low-noise amplifiers (LNAs) remains a time-consuming and complex process. Iterations are needed to adjust impedance matching, gain, and noise figure (NF) simultaneously. The process can involve more iterations to adjust the non-linear behavior of the circuit which can be represented by the input-referred third-order intercept (IIP3). In this work, we present a variation-aware automated design and optimization flow for a wide-band noise-canceling LNA. We include the circuit non-linearity in the optimization flow without using a simulator in the loop. By describing the transistors using precomputed lookup tables (LUTs), a design database that contains 200,000 design points is generated in 3 s only without non-linearity computation and 10 s when non-linearity is taken into account. Using a gm/ID-based correct-by-construction design procedure, the generated design points automatically satisfy proper biasing, input matching, and gain matching requirements. The generated database enables the designer to visualize the design space and explore the design trade-offs. Moreover, multi-objective optimization across corners for a given set of specifications is applied to find the Pareto-optimal fronts of the design figures-of-merit. We demonstrate the presented flow using two design examples in a 65 nm process and the results are verified using Cadence Spectre.

Определение потерь в стали бесконтактного двигателя постоянного тока с использованием линейной аппроксимации импульсов напряжения

Analysis of iron loss of a BLDC motor is of particular interest at the design stage or when researching methods to improve energy efficiency. Most of the existing methods for determining losses in steel are based on the analysis of losses for individual harmonic components of induction with their subsequent summation. However, the application of these methods for various forms of voltage obtained at the output of the converter is incorrect due to the non-linearity of magnetic circuits. This paper proposes a method for determining steel losses of BLDC motor using a linear approximation of voltage pulses, which makes it possible to take into account the influence of the voltage shape on the magnitude of magnetic induction directly, without expansion into a Fourier series. The dependences of steel losses on the switching frequency for various values of the duty cycle, and on the rise time of voltage pulses are obtained. Comparison of the simulation results of the 5 kW BLDC Motor with the experimental data of the idling mode given by the manufacturer proved the adequacy of the considered method.

A Novel Time-Multiplexed Fully Differential Interface ASIC With Strong Nonlinear Suppression for MEMS Accelerometers

In this paper, a novel time-multiplexed fully differential (TMFD) interface ASIC with strong non-linear suppression is presented. The interface ASIC adopts the half-bridge measurement method and two single-end charge amplifiers in the novel C-V converter instead of the conventional full-bridge sensing structure. The C-V converter can greatly suppress the influence of the common-mode voltage by declining the gain of virtual ground node for charge transfer. As a result, the non-linearity of the front-end circuit decreases obviously due to the low common-mode disturbance. This research also proposes a TMFD SC PGA with continuous output to suppress the fluctuation caused by discrete signals from conventional SC PGA. The readout circuit chip was implemented in a 1P3M 0.18μm CMOS process. The operating frequency reaches 200kHz with a power consumption of 2.5mA from a 3.3V power supply. Due to the strong non-linear suppression capability of the proposed interface ASIC, the measuring sensitivity of the accelerometer achieved 0.530 V/g with only a DC non-linearity of 0.08%. The experimental results at different operating temperature indicates that the presented readout ASIC performs great temperature stability. The temperature sensitivity ratio reduces to 0.008‰/K. The experimental results indicates that the non-linearity has reduced significantly compared with conventional readout chips.

Experimental and Simulation Studies of Partial Demagnetization Process of Permanent Magnets in Electric Motors

For the analysis of the process of partial demagnetization of permanent magnets (PMs) in electric machines, a field model of coupled electromagnetic and thermal phenomena was proposed. In the proposed approach the non-linearity of the magnetic circuit, the effect of temperature on the magnetic, electrical and thermal properties of the materials as well as the developed method for modeling the process of partial demagnetization of the PMs were taken into account. In order to verify the usefulness and effectiveness of the developed algorithm as well as software for analyzing the impact of temperature and the process of partial demagnetization of the magnets on the operation of a PM motor, the results of calculations were compared with the results of experimental studies. The experimental tests were carried out on a specially designed and constructed measuring test stand. The results of the research on the process of partial demagnetization of magnets in the line start permanent magnet synchronous motor (LSPMSM) are presented and the conclusions resulting therefrom have been formulated.

Comparative Analysis of the Steady-State Model Including Non-Linear Flux Linkage Surfaces and the Simplified Linearized Model when Applied to a Highly-Saturated Permanent Magnet Synchronous Machine—Evaluation Based on the Example of the BMW i3 Traction Motor

This paper presents a finite element method (FEM)-based model, which describes the magnetic circuit of the BMW i3 traction machine. The model has been reconstructed based on data available in the public domain. The reader is provided with numerical data regarding flux linkage surfaces in d- and q-axes, as well as with all the information needed to develop a space-vector model of the machine in steady-state, taking into consideration the non-linearity of the magnetic circuit. Hence, the data of a highly-saturated machine from a renowned product are provided, which can serve as a reference design for research. After that, torque curve and partial load operation points are calculated. Finally, the machine model is linearized and the calculations are repeated with the simplified linearized model. The results from both models are then compared with each other. This comparison is intended to assess the magnitude of the expected inaccuracies, when simplified analytical tools are applied to highly-saturated machines (which are the backbone of automotive electrical drivetrains). It is especially important with regard to preliminary design of electrical drivetrains, as at this stage detailed machine geometry and materials are not known.

Scavenging energy from a vibrating building using distributed electromagnetic energy harvesters with nonlinear circuits

The energy scavenged from a vibrating building installed with distributed electromagnetic energy harvesters under random excitation is analyzed. Each harvester is connected to an energy harvesting circuit made of a full-wave bridge rectifier connecting a resistor in parallel with a capacitor. Statistical linearization is adopted to estimate the stationary response of the harvester-structure system. As an illustrative example, a 20-story building equipped with 16 harvesters on each story is examined. Results show that the scavenged energy mainly concentrates at the higher stories. The vibration mitigation and energy scavenging performance of the harvesters can be enhanced simultaneously with the proper design of harvesters and circuits. Gradient ascent approach with the first-order perturbation approximation is proposed to determine the optimal design of distributed harvesters with nonlinear circuits that maximizes the total mean output power. Results show that output power decreases due to circuit nonlinearity. The maximum total mean output power obtained from the 20-story building under wind excitations with mean speed of 5 m/s is around 1.32–2.17 kW for harvesters having short-circuit damping coefficient ranging 100–300 kNs/m. These results show that scavenging energy from structural vibration is a feasible technology even considering the negative effect of circuit nonlinearity.