Steady-state Circuit Research Articles

Parametric estimation in three-phase induction motors using torque data via the generalized normal distribution optimizer

This research addresses the parametric estimation problem in three-phase induction motors by applying a recently developed metaheuristic method known as the generalized normal distribution optimizer (GNDO). A nonlinear programming model based on the steady-state circuit of the induction motor, which uses its Thevenin equivalent, is employed to model the estimation problem. Estimation is carried out by minimizing the mean square error between torque data (obtained from measurements or provided by the manufacturer) and the values calculated with the model. The main advantage of using the GNDO is its effective balance between the exploration and exploitation of the solution space via Gaussian distributions. Numerical tests in two three-phase induction machines confirm the effectiveness of this approach in comparison with the classical genetic algorithm, the particle swarm optimizer, and the sine cosine algorithm. The GNDO approach reports objective function values of about 9.7834×10−14 and 2.6500×10−14, while the sine cosine algorithm reaches solutions of about 4.6327×10−10 and 1.2400×10−6 in both tested motors. All numerical simulations were performed in the MATLAB software, version 2022b.

Self-Rotation of Electrothermally Responsive Liquid Crystal Elastomer-Based Turntable in Steady-State Circuits.

Self-excited motions, characterized by their ability to harness energy from a consistent environment and self-regulate, exhibit significant potential in micro-devices, autonomous robotics, sensor technology, and energy generation. This study introduces an innovative turntable system based on an electrothermally responsive liquid crystal elastomer (LCE). This system facilitates self-rotation within a steady-state circuit. Employing an electrothermal LCE model, we have modeled and numerically analyzed the nonlinear dynamics of an LCE-rope within steady-state circuits, utilizing the four-order Runge-Kutta method for calculations. The numerical results reveal the emergence of two distinct motion patterns in the turntable system under steady-state conditions: a self-rotation pattern and a static pattern. The self-rotation is initiated when the system's absorbed energy surpasses the energy lost due to damping effects. Furthermore, this paper delves into the critical conditions necessary for initiating self-rotation and examines the influence of various key dimensionless parameters on the system's rotation amplitude and frequency. These parameters include gravitational acceleration, the initial position of the mass ball, elastic stiffness of the LCE and spring, limiting temperature, heating zone angle, thermal shrinkage coefficient, and damping factor. Our computational findings establish that these parameters exert a modulatory impact on the rotation amplitude and period. This research enhances the understanding of self-excited motions and offers promising avenues for applications in energy harvesting, monitoring, soft robotics, medical devices, and micro- and nano-devices.

Generalized Circuit Representation for a Synchronous Machine

In this letter, a generalized circuit representation for a synchronous machine is presented. This circuit represents voltage and current relationship and can be used for dynamic and harmonic analysis. A distinct feature of the circuit is the use of Laplace transform variable <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$s$</tex-math></inline-formula> , which simplifies both calculus and frame conversion. Two derivation approaches are presented. The first approach starts from a steady-state circuit representation, while the second approach starts from the dq-frame dynamic model of a synchronous generator. Both arrive at the same representation.

Self-Sustained Oscillation of Electrothermally Responsive Liquid Crystal Elastomer Film in Steady-State Circuits.

Self-excited oscillations have the advantages of absorbing energy from a stable environment and Self-control; therefore, Self-excited motion patterns have broader applications in micro devices, autonomous robots, sensors and energy-generating devices. In this paper, a Self-sustained curling liquid crystal elastomer (LCE) film-mass system is proposed on the basis of electrothermally responsive materials, which can realize Self-oscillation under a steady-state current. Based on the contact model and dynamic LCE model, a nonlinear dynamics model of LCE film in steady-state circuits is developed and numerical calculations are carried out using the Runge-Kutta method. Through numerical calculations, it is demonstrated that LCE film-mass systems have two motion patterns in steady-state circuits: namely, a Self-oscillation pattern and a stationary pattern. Self-sustained curling of LCE film originates from the fact that the energy absorbed by the system exceeds the energy dissipated due to the damping effect. In addition, the critical conditions for triggering Self-oscillation and the effects of several key dimensionless system parameters on the amplitude and period of Self-oscillation are investigated in detail. Calculation results show that the height of electrolyte solution, gravitational acceleration, elastic modulus of LCE film, limit temperature, curvature coefficient, thermal shrinkage coefficient and damping factor all have a modulating effect on the amplitude and period of Self-oscillation. This research may deepen the understanding of Self-excited oscillation, with promising applications in energy harvesting, power generation, monitoring, soft robotics, medical devices, and micro and nano devices.

Efficiency-oriented circuit parameter optimization of dual active bridge converter

The power carbon neutrality path is to build a new power system with new energy as the main body. Dual active bridge (DAB) converter is considered as the core topology of new power system mode due to its galvanic isolation, bi-directional power capability, and wide soft-switching range, which is responsible for inter-connection between DC buses of different voltage levels and various DC loads. However, the lack of fast and accurate quantitative circuit parameter optimization design methods in DAB converter affects the improvement of the full working domain efficiency. In this paper, a hierarchical filtering method considering the control parameter is proposed to avoid the full range exhaustive search, and the effectiveness and correctness of the method are verified experimentally. First layer circuit characteristics must fulfill output power and inductor current requirements. The second layer filters poor inductor RMS current and soft-switching parameters. The last layer filters out weak steady-state circuit characteristics and identifies optimal regions. The proposed method improves the efficiency while reducing the area of the circuit parameter region for calculating the loss function by 85% compared with the traditional full-scale search method based on the loss analysis model, thus improving the optimization speed. The optimal circuit parameter solving process provides a graphical representation of the relationship between DAB operating characteristics and the optimal parameter area, ensuring proper optimization. Besides, the idea of hierarchical filtering can be well applied to the optimal design of other converters, and better guide the industrialization of products. • Using hierarchical filtering method can speed up the design. • Visualization of parameters can ensure the correctness of optimization results. • The design of other converters can also use the hierarchical filtering method. • Optimal design of parameters can ensure the normal operation of the device and also improve the steady-state characteristics.

A New and Simple Mathematical Technique to Study the Steady-state Performance of Isolated Asynchronous Generator

Isolated Asynchronous Generator (IAG) is nowadays widely used for renew-able power generation from the sources like wind and small hydro. Tradi-tionally, the steady-state analysis of IAG is carried out by solving a complexhigher order non-linear polynomial equation obtained in a complicated wayfrom the steady-state circuit diagram. In this paper, a simple new mathe-matical procedure has been introduced to obtain two non-linear polynomialequations in much more simplified form which can easily be solved forthe unknown variables i.e., per unit generated frequency (a) and magnetiz-ing reactance (Xm). Between these two equations, one equation comprisesonly one unknown variable‘a’ and hence, easy to solve. Differential SearchAlgorithm (DSA) has been efficiently implemented for solving these non-linear equations. The computational efficacy of DSA has been compared withthat of Newton-Raphson (N-R) method, Linear Search Algorithm (LSA),Binary Search Algorithm (BSA) and Particle Swarm Optimization (PSO) technique. The performance of the IAG has been studied under differentoperating conditions such as variation of speed, capacitance and load. Allthe simulated results have been experimentally verified using a three-phase,415 volts, 2.2 kW, star-connected induction generator and a close agreementhas been found.

A New Interpretation of the Steady-State Two-Reaction Theory of a Salient-Pole Synchronous Machine

This work contributes two improvements to the well-established two-reaction theory of a salient-pole synchronous machine. Namely, a single circuit is proposed that explicitly accounts for the saliency in the machine. By defining new machine reactances and using a current-controlled voltage source, the proposed single circuit proposed provides an alternative to coupled <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</i> - and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">q</i> -axis circuit models. The new reactances are also used in a revised phasor diagram to make apparent the internally developed power of a salient-pole synchronous machine that is similar to a round-rotor synchronous machine. The revised two-reaction theory is illustrated using the mathematical model of a three-phase salient-pole synchronous machine whose equations are derived using complex space vectors instead of traditional matrix transformations. A detailed derivation is presented and the resulting equations can directly be used to solve for the steady-state operating EMF and power angle from the terminal voltages and currents in the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">abc</i> coordinate system. The ease of their application is demonstrated using a numerical example of the steady-state circuit equations and the revised phasor diagrams.

An Explicit Discrete-Time Large- and Small-Signal Modeling of the Dual Active Bridge DC–DC Converter Based on the Time Scale Methodology

The conventional method to model a dc–dc converter is by averaging its state variable over a switching period. However, due to the dc–ac–dc structure of the dual active bridge converter (DABC), the average value of the inductor current over a switching cycle is zero. Therefore, the conventional methodology cannot be applied to the DABC. The time-scale discrete-time modeling of the DABC is proposed to mitigate the zero average state variable problem. The time-scale methodology simplifies the analysis of the DABC by segregating the fast state variable inductor current and slow state variable output voltage. The proposed model has the advantage of the explicit large signal in terms of the circuit parameter, like the average value model. The explicit steady-state circuit expression from the large-signal model helps in the study of the soft-switching range of the DABC. Moreover, the small-signal model from the proposed method results in an explicit small-signal model. The model incorporates semiconductor <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> -resistance, inductor equivalent series resistance, transformer resistance, and leakage inductance. The effect of the converter net equivalent resistance on the small-signal model is thoroughly studied. Finally, the model accuracy in the steady-state, open-loop, and the small-signal are verified in both the switching simulation model and experimental setup.

Fault location of three-core power distribution cables based on lump-parameter model considering conductor couplings

Due to the poor working conditions, the three-core distribution cables are prone to faults. Since most of the cables are laid underground, accurate fault location is difficult. Considering the couplings between the earth screen and core conductors, a lump-parameter model of the three-core cable is constructed in this paper. Through the steady-state circuit analysis, a method for identifying and locating a fault in the three-core cable is proposed. In the method, the information of the grounding line current, core current and voltage phasors at both terminals in normal operation are firstly used to compensate the synchronous measurement error. Then, the fault current is derived by the phase-corrected phasors in fault condition to identify the fault conductor. Finally, the accurate fault distance is computed by employing the fault voltage continuity criterion. A three-core distribution cable model is created by RTDS and various fault simulations are conducted. The results demonstrate the effectiveness of the method under different fault conditions.

A Dual Active Bridge Derived Hybrid Switched Capacitor Converter Based Two-Stage 48 V VRM

This article proposes a two-stage 48-V voltage regulator module using a hybrid switched-capacitor converter in the first stage. Apart from being compact in nature, this first-stage converter has several other advantages such as efficient regulation ability and hence scalability, inherent full/partial soft switching for most of the switches, reduced switch voltage and current stresses, and the possibility of wide range variable switching frequency operation. These combined features together help to obtain a flat high-efficiency curve for the first stage. The second-stage multiphase buck converter also exhibits flat high-efficiency characteristics through phase shedding. Steady-state circuit operation and analysis of the first-stage converter is presented in this article. An accurate discrete-time model of the first-stage converter is also developed. Thereafter, a design guideline for the two-stage converter is discussed. Finally, experimental results from an 80-W laboratory prototype show that the proposed converter possesses a relatively flat high-efficiency profile and exhibits a faster load transient response compared to that of the state-of-the-art solutions.

Аналіз процесів у перетворювачі з дванадцятизонним регулюванням напруги і електромеханічним навантаженням

The article focuses on electromagnetic processes in the electric circuits withsemiconductor switches. The mathematical model of the converter with twelve-zone regulation of output voltage has been developed to analyse electromagnetic processes in semiconductor converters with pulse-width regulation. The graphs representing electromagnetic processes in electric circuits are given. The mathematical model of the semiconductor converter is also used to research transients in semiconductor converters with active inductive load. The method of multiparameter functions, which are the parts of algorithmic equations of the analysis of steady-state and transient processes inbranchy electric circuits with semiconductor switches and reactive elements, has been developed in terms of considering the features of using phase and linear voltages of the power supply network. The authors have created a new mathematical model of steadystate and transient processes in electric circuits of modulating semiconductor converters with multichannel zonal usage of phase voltages in three-phase power supply without taking into account electric power losses in switches to evaluate rapidly the influence of load parameters on the characteristics of regulated sinusoidal and DC voltages. The results of this work can be used to improve the method of multiparameter modulatingfunctions to simplify the analysis of transient processes in electric circuits without taking into account the losses in key elements. Ref. 4, pic. 3

Dissipation in Non-Steady State Regulatory Circuits

In order to respond to environmental signals, cells often use small molecular circuits to transmit information about their surroundings. Recently, motivated by specific examples in signaling and gene regulation, a body of work has focused on the properties of circuits that function out of equilibrium and dissipate energy. We briefly review the probabilistic measures of information and dissipation and use simple models to discuss and illustrate trade-offs between information and dissipation in biological circuits. We find that circuits with non-steady state initial conditions can transmit more information at small readout delays than steady state circuits. The dissipative cost of this additional information proves marginal compared to the steady state dissipation. Feedback does not significantly increase the transmitted information for out of steady state circuits but does decrease dissipative costs. Lastly, we discuss the case of bursty gene regulatory circuits that, even in the fast switching limit, function out of equilibrium.

Polarization in electrostatics and circuits: Computing and visualizing surface charge distributions

In electrostatic situations and in steady-state circuits, charges on the surface of a conductor contribute significantly to the net electric field inside the conductor. These charges build up quickly due to transient currents that are initiated by the presence of external charged objects or objects such as batteries that maintain a charge separation. We describe an algorithm for computing the detailed surface charge distributions in equilibrium electrostatic situations and in steady-state DC circuits, and discuss the results of our computations of surface charge distributions for several systems. The results show that in simple DC circuit geometries a roughly constant gradient of surface charge plays a dominant role in establishing the net field inside circuit elements. Three-dimensional visualization contributes to new insights into surface charge distributions on circuit elements.

Effect of DC-Link Voltage Limitation on Postfault Steady-State Performance of Asymmetrical Six-Phase Induction Machines

The asymmetrical six-phase induction machine represents the most common multiphase machine type used in many high-power industrial applications. While a body of research covering control of the machine under fault conditions has been published in the literature, corresponding studies to investigate the dc-link voltage design requirements under postfault operation in a simple and efficient manner have not met the same interest. To this end, this paper first introduces the machine steady-state equivalent circuit under one open-phase fault, which simplifies the estimation of different machine characteristic curves instead of using tedious mathematical techniques. As far as the machine parameters are concerned in this paper, a modified locked-rotor test based on the derived equivalent circuit is also proposed to fully estimate the parameters of different subspaces using a simple technique without the need for additional tests. The proposed steady-state circuit is also used to understand the effect of the secondary subspace impedance, neutral configuration, and the postfault control strategy on the maximum achievable torque for a limited dc-bus voltage. The minimum dc-link voltage magnitude to provide rated output under postfault operation is also given. The proposed concepts have been experimentally verified using a prototype asymmetrical six-phase machine.

Unified Equivalent Steady-State Circuit Model and Comprehensive Design of the LCC Resonant Converter for HV Generation Architectures

In this paper, a unified equivalent circuit model which can simplify the design and analysis of a family of high-voltage (HV) generation architectures based on the series–parallel ( LCC ) resonant converter is proposed. First, four HV generation architectures are reviewed in terms of the modularization level of HV transformers and rectifiers. Next, the steady-state, unified equivalent resistor and capacitor ( RC ) model that can be easily embedded into the resonant tank to replace the complex HV transformers and rectifiers is derived. The generic model can be applied to the HV generators with different architectures, different voltage multiplier topologies, stage, and polarities number. Further analysis of the power factor of the resonant tank, the voltage gain of HV generators, and electrical stresses of power components is achieved with the derived equivalent circuit model. The analysis reveals the inherent circuit properties among HV generators with different configurations. Subsequently, a comprehensive design methodology considering the power factor, conduction angle, and quality factor is presented, which leads to low electrical stresses on the components and high efficiency. Furthermore, the parameter selection constraint based on the power factor, conduction angle, and quality factor is derived, which can ensure the effective design outputs. Finally, the proposed unified equivalent model and comprehensive design methodology are validated by the experimental results of a 250 V input, 20 kV output 500 W HV generator hardware prototype with distributed transformers and voltage multipliers.

Design and Implementation of a High Efficiency, Low Component Voltage Stress, Single-Switch High Step-Up Voltage Converter for Vehicular Green Energy Systems

In this study, a novel, non-isolated, cascade-type, single-switch, high step-up DC/DC converter was developed for green energy systems. An integrated coupled inductor and voltage lift circuit were applied to simplify the converter structure and satisfy the requirements of high efficiency and high voltage gain ratios. In addition, the proposed structure is controllable with a single switch, which effectively reduces the circuit cost and simplifies the control circuit. With the leakage inductor energy recovery function and active voltage clamp characteristics being present, the circuit yields optimizable conversion efficiency and low component voltage stress. After the operating principles of the proposed structure and characteristics of a steady-state circuit were analyzed, a converter prototype with 450 W, 40 V of input voltage, 400 V of output voltage, and 95% operating efficiency was fabricated. The Renesas MCU RX62T was employed to control the circuits. Experimental results were analyzed to validate the feasibility and effectiveness of the proposed system.

A Thermal Energy Harvesting Power Supply With an Internal Startup Circuit for Pacemakers

A complete thermal energy harvesting power supply for implantable pacemakers is presented in this paper. The designed power supply includes an internal startup and does not need any external reference voltage. The startup circuit includes a prestartup charge pump (CP) and a startup boost converter. The prestartup CP consists of an ultralow-voltage oscillator followed by a high-efficiency modified Dickson. Forward body biasing is used to effectively reduce the MOS threshold voltages as well as the supply voltage in oscillator and CP. The steady-state circuit includes a high-efficiency boost converter that utilizes a modified maximum powerpoint tracking scheme. The system is designed so that no failure occurs under overload conditions. Using this approach, a thermal energy harvesting power supply has been designed using 180-nm CMOS technology. According to HSPICE simulation results, the circuit operates from input voltages as low as 40 mV provided from a thermoelectric generator and generates output voltages up to 3 V. A maximum power of 130 $\mu $ W can be obtained from the output of the boost converter, which means that its efficiency is 60%. A minimum voltage of 60 mV and a maximum time of 400 ms are needed for the circuit to start up.

Effects of homeostatic constraints on associative memory storage and synaptic connectivity of cortical circuits.

The impact of learning and long-term memory storage on synaptic connectivity is not completely understood. In this study, we examine the effects of associative learning on synaptic connectivity in adult cortical circuits by hypothesizing that these circuits function in a steady-state, in which the memory capacity of a circuit is maximal and learning must be accompanied by forgetting. Steady-state circuits should be characterized by unique connectivity features. To uncover such features we developed a biologically constrained, exactly solvable model of associative memory storage. The model is applicable to networks of multiple excitatory and inhibitory neuron classes and can account for homeostatic constraints on the number and the overall weight of functional connections received by each neuron. The results show that in spite of a large number of neuron classes, functional connections between potentially connected cells are realized with less than 50% probability if the presynaptic cell is excitatory and generally a much greater probability if it is inhibitory. We also find that constraining the overall weight of presynaptic connections leads to Gaussian connection weight distributions that are truncated at zero. In contrast, constraining the total number of functional presynaptic connections leads to non-Gaussian distributions, in which weak connections are absent. These theoretical predictions are compared with a large dataset of published experimental studies reporting amplitudes of unitary postsynaptic potentials and probabilities of connections between various classes of excitatory and inhibitory neurons in the cerebellum, neocortex, and hippocampus.

Analysis of the Energy Metering Problem in Dynamic Environment

The traditional electric power metering theory is a kind of no-error metering theory in sinusoidal steady-state circuit. However, the applying condition is too rigor, and the engineering environment is hard to fulfil, the application premise should be extended to dynamic. Ideal linear elements are adopted to build a first-order dynamic circuit. And the analytic expressions of the capacitor cumulative electric energy in the charging process are derived theoretically. It points out that the cumulative electric energy of capacitor in dynamic circuit is a nonzero value. This fully demonstrates that the energy metering principle brings error when it is used in dynamic environment.

Dissemination of the Phasor Method in Electrical Engineering in China

Synchrophasors, widely used in the monitoring and analysis of power systems, evolved from the phasor method presented by Charles Proteus Steinmetz in 1893. The phasor method is a mathematical method for solving linear sinusoidal steady-state circuits and time-varying electromagnetic fields. This paper traces the history and diffusion of the phasor method in the discipline of electrical engineering in China. In 1914, Sidney Roby Sheldon, an American teacher at the Government Institute of Technology of the Communications Ministry, Shanghai, China, introduced the phasor method to his students in his Alternating Currents course. The textbook used was Elements of Electrical Engineering (Volume II) by William Suddards Franklin and William Esty. In 1920, The Electrical Magazine published a paper “Complex number and its application” by Sijiu Shi (editor of the electrical engineering section of this periodical). This is the earliest example found of Chinese literature introducing the phasor method. In the 1930s, Principles of Alternating Currents, an American electrical engineering textbook that includes the phasor method, was translated by Chinese scholars; this Chinese version promoted the use of the phasor method in China's electrical engineering field. Alternating Current Circuits, authored by the Chinese university professor Pen Tung Sah and published in 1948, may be the earliest example of the phasor method being included in a Chinese electrical engineering textbook; it played an important role in popularizing the phasor method in China.