Current Controlled Voltage Source Research Articles

An efficient multidisciplinary design research for the integrated low speed permanent magnet motor system based on analytical and numerical hybrid analysis

This paper proposed an efficient high-accuracy multidisciplinary design process for the integrated system of low speed permanent magnet synchronous motor (PMSM). The method combined the analytical models and numerical models together to get an efficient way to design the integrated motor. In the proposed method, a magnetic equivalent circuit (MEC) model of the motor is established first based on one modular structure of the motor, and the finite element analysis (FEA) numerical model is used to correct the results of the analytical model next. Then the iron loss, copper loss, and switching loss from the results of the electromagnetic model are loaded to a proposed simplified lumped parameter fluid-thermal model. This fluid-thermal coupled analytical model cuts the fluid flow into several parts depends on the parameters of the cooling path, each parts act as a current controlled voltage source coupled with these parameters. And because this coupled model has controlled sources, the conventional node voltage method is not suitable anymore, so a more universal list parameter calculation method is proposed for this coupled model. Finally, the computational fluid dynamics (CFD) model is used to correct the results of the analytical model as well. The aim of the above analytical models is to quickly get the suitable multidisciplinary pre-design or design trends, and this pre-work or trends will reduce the design process time of the high-accuracy numerical models.

A 7.6-ns Delay Subthreshold Level-Shifter Leveraging a Composite Transistor and a Voltage-Controlled Current Source

A novel level shifter (LS) circuit that uses a new low-power approach based on a parasitic capacitance voltage controlled current source is presented to minimize the propagation delay (PD) and maximize the voltage conversion range. This new scheme uses a simplified circuit including a dependent current source, a composite transistor made of three interconnected n-channel MOSFETs (TnM), one CMOS input inverter, and one CMOS output buffer to provide a fast response time. The circuit utilizes the combined action of the equivalent parasitic capacitance of the TnM, the value of which changes dynamically according to the transient value of the input voltage, and the dependent current source to shift the input signal level up from subthreshold voltage levels to +3.0 V, with minimal delay and power consumption. The LS circuit fabricated in 0.35 μm CMOS technology occupies a silicon area of only 25 μm×25 μm. The LS shows measured rising and falling PDs of, respectively, 4 and 11.2 ns. The measured results show that the presented circuit outperforms other solutions over a wide frequency range of 1 to 130 MHz. The fabricated circuit consumes a static power 31.5 pW and a dynamic power of 3.4 pJ per transition at 1 kHz, V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DDL</sub> =0.8 V, and a capacitive load of C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</sub> =0.1 pF.

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.

Novel Self-Excited Brush-Less Wound Field Vernier Machine Topology

To realize the brush-less operation for wound field vernier machines (WFVMs), a novel self-excited topology is proposed in this paper which involves a four-pole main armature winding and a two-pole excitation winding connected in series using an uncontrolled rectifier. Upon supplying current from a single current-controlled voltage source inverter (VSI), this procedure results in four-pole and two-pole magnetomotive force (MMF) components in the airgap. The four-pole MMF produces the main stator field while the two-pole MMF component develops a sub-harmonic field in the airgap. The rotor is altered to house a forty-four-pole rotor field and two-pole harmonic windings. The two-pole harmonic field is employed to induce a current in the harmonic winding, which is rectified by means of a full-bridge diode rectifier to energize the rotor field winding and realize brush-less operation for WFVM. Two-dimensional finite element analysis (2-D FEA) is implemented in JMAG-Designer to confirm the operation of the proposed WFVM topology and attain the electromagnetic performance for a four-pole, twenty-four-slot outer-rotor vernier machine.

An Online Parameter Estimation Using Current Injection with Intelligent Current-Loop Control for IPMSM Drives

An online parameter estimation methodology using the d-axis current injection, which can estimate the distorted voltage of the current-controlled voltage source inverter (CCVSI), the varying dq-axis inductances, and the rotor flux, is proposed in this study for interior permanent magnet synchronous motor (IPMSM) drives in the constant torque region. First, a d-axis current injection-based parameter estimation methodology considering the nonlinearity of a CCVSI is proposed. Then, during current injection, a simple linear model is developed to model the cross- and self-saturation of the dq-axis inductances. Since the d-axis unsaturated inductance is difficult to obtain by merely using the recursive least square (RLS) method, a novel tuning method for the d-axis unsaturated inductance is proposed by using the theory of the maximum torque per ampere (MTPA) with the combination of the RLS method. Moreover, to improve the bandwidth of the current loop, an intelligent proportional-integral-derivative (PID) neural network controller with improved online learning algorithm is adopted to replace the traditional PI controller. The estimated the dq-axis inductances and the rotor flux are adopted in the decoupled control of the current loops. Finally, the experimental results at various operating conditions of the IPMSM in the constant torque region are given.

A Comparison of Instantaneous and Extension p-q Methods for Current Controlled Voltage Source Inverter in Microgrid

ABSTRACT With the advancement in technology and population growth, the motivation of integrating utility grid with the microgrid through power electronic converters increases. This paper presents the control of power electronic converter connected at the grid side. This converter regulates the power flow between renewable energy system (RES), load and grid in addition to the compensation of harmonic and reactive power. The reference currents are generated to decide the power flow from RES to the load and to suppress the harmonic and reactive power in the grid making grid current sinusoidal. In this paper, the reference current generation techniques like instantaneous p-q method and extension p-q method are implemented and compared. Linear Quadratic Regulator (LQR) is used to track the reference current. The control law of LQR is designed in a simple way using simplified equivalent circuit of a three-phase grid integrated renewable energy system. The system is tested experimentally under balanced and unbalanced conditions in two different modes such as insufficient renewable power and excess renewable power. The supremacy of extension p-q method over instantaneous p-q method is proved by getting low total harmonic distortion and better power factor under balanced and unbalanced conditions experimentally.

MOSFET-C current mode filter for secure communication applications

In this paper, a dual output current-mode biquad filter with band-pass and low-pass outputs using MOS transistors and capacitors is presented. In these type of filters MOSFETs operating in saturation mode are used instead of standard active elements and transconductances of these transistors are utilized instead of resistors. In the study a voltage controlled current source (VCCS) based core filter circuit is presented. This circuit is used as a starting point for the complete filter design. After VCCSs are replaced by MOSFETs biased for operating in saturation region, a resistorless MOSFET-C type filter circuit is obtained with only seven transistors and two grounded capacitors. Also, an agile filter application for secure communication is given to illustrate the functionality.

A Highly Robust Binary Neural Network Inference Accelerator Based on Binary Memristors

Since memristor was found, it has shown great application potential in neuromorphic computing. Currently, most neural networks based on memristors deploy the special analog characteristics of memristor. However, owing to the limitation of manufacturing process, non-ideal characteristics such as non-linearity, asymmetry, and inconsistent device periodicity appear frequently and definitely, therefore, it is a challenge to employ memristor in a massive way. On the contrary, a binary neural network (BNN) requires its weights to be either +1 or −1, which can be mapped by digital memristors with high technical maturity. Upon this, a highly robust BNN inference accelerator with binary sigmoid activation function is proposed. In the accelerator, the inputs of each network layer are either +1 or 0, which can facilitate feature encoding and reduce the peripheral circuit complexity of memristor hardware. The proposed two-column reference memristor structure together with current controlled voltage source (CCVS) circuit not only solves the problem of mapping positive and negative weights on memristor array, but also eliminates the sneak current effect under the minimum conductance status. Being compared to the traditional differential pair structure of BNN, the proposed two-column reference scheme can reduce both the number of memristors and the latency to refresh the memristor array by nearly 50%. The influence of non-ideal factors of memristor array such as memristor array yield, memristor conductance fluctuation, and reading noise on the accuracy of BNN is investigated in detail based on a newly memristor circuit model with non-ideal characteristics. The experimental results demonstrate that when the array yield α ≥ 5%, or the reading noise σ ≤ 0.25, a recognition accuracy greater than 97% on the MNIST data set is achieved.

PERFORMANCE ASSESSMENT OF IMPROVED CURRENT CONTROL STRATEGY BASED SHUNT ACTIVE POWER FILTER: A REVIEW

The most powerful solution to current harmonics is a shunt active power filter (SAPF). Because of its simple implementation features, the Synchronous Reference Frame (SRF) concept has been commonly used in current harmonics extraction algorithms in its controller. The traditional SRF algorithm, on the other hand, has a significant time delay due to its heavy dependency on slow numerical filters. Furthermore, the algorithm is still thought to have unnecessary features that place an undue computational burden on the controller. Active control filters are commonly used in the power system to reduce harmonics induced by nonlinear loads. The Shunt Active Power Filter (SAPF) injects a suitable compensating current at a line point known as the point of common coupling (PCC) to cancel out the line's harmonics and restore the sinusoidal existence of voltage and current waveforms. As an active filter, a three-phase current-controlled voltage source inverter (VSI) with a DC connection capacitor across it is used. Shunt active power filter (SAPF) is the best solution that minimises the harmonic problems in power systems, but how fast and how effective it is. This paper describes a detailed study about the various types of power quality disturbances and their mitigation techniques and their comparative details.

Performance analysis and implementation of a scanning tunneling potentiometry setup: Toward low-noise and high-sensitivity measurements of the electrochemical potential.

Scanning tunneling potentiometry allows for studying charge transport on the nanoscale to relate the local electrochemical potential to morphological features of thin films or two-dimensional materials. To resolve the influence of atomic-scale defects on the charge transport, sub-µV sensitivity for the electrochemical potential is required. Here, we present a complete analysis of the noise in scanning tunneling potentiometry for different modes of operation. We discuss the role of various noise sources in the measurements and technical issues for both dc and ac detection schemes. The influence of the feedback controller in the determination of the local electrochemical potential is taken into account. Furthermore, we present a software-based implementation of the potentiometry technique in both dc and ac modes in a commercial scanning tunneling microscopy setup with only the addition of a voltage-controlled current source. We directly compare the ac and dc modes on a model resistor circuit and on epitaxial graphene and draw conclusions on the advantages and disadvantages of each mode. The effects of sample heating and the occurrence of thermal voltages are discussed.

Numerical Simulation of Heat Transport Problems in Porous Media Coupled with Water Flow Using the Network Method

In the present work, a network model for the numerical resolution of the heat transport problem in porous media coupled with a water flow is presented. Starting from the governing equations, both for 1D and 2D geometries, an equivalent electrical circuit is obtained after their spatial discretization, so that each term or addend of the differential equation is represented by an electrical device: voltage source, capacitor, resistor or voltage-controlled current source. To make this possible, it is necessary to establish an analogy between the real physical variables of the problem and the electrical ones, that is: temperature of the medium and voltage at the nodes of the network model. The resolution of the electrical circuit, by means of the different circuit resolution codes available today, provides, in a fast, simple and precise way, the exact solution of the temperature field in the medium, which is usually represented by abaci with temperature-depth profiles. At the end of the article, a series of applications allow, on the one hand, to verify the precision of the numerical tool by comparison with existing analytical solutions and, on the other, to show the power of calculation and representation of solutions of the network models presented, both for problems in 1D domains, typical of scenarios with vertical flows, and for 2D scenarios with regional flow.

Pulsewidth-Modulator-Based Transfer Function Measurement Method for Variable Frequency-Controlled Half- and Full-Bridge Converters

Variable frequency control is widely used in half-bridge and full-bridge converters. Measuring the switching-frequency-to-output-voltage transfer function is critical to verify a derived model and guide the design of closed-loop parameters. The existing voltage-controlled-oscillator-based measurement method is complicated in circuit implementation and the accuracy could be affected by the bandwidth of the voltage-controlled current source. In this letter, a pulsewidth-modulator-based measurement method is proposed, which is much simpler in the circuit and more accurate. The principle of this method is analyzed in detail. Finally, the experimental results of a half-bridge and a full-bridge series-series compensated wireless power transfer systems are presented to verify the proposed method.

Performance enhancement of shunt active power filter using soft computing techniques

Nowadays, active power filter (APF) is the most popular device for harmonic compensation. This paper presents the soft computing techniques for compensation of currents harmonics using a shunt active power filter (SAPF). The method includes a 3-phase supply system with a current-controlled voltage source converter (CC-VSC) having an input coupling inductor and output tank capacitor for a self-supported DC bus. The performance of the active power filter can be enhanced by using soft computing techniques such as artificial neural network (ANN) controller and gravitational search algorithm (GSA) for generating control signals of the SAPF. The current reference is calculated to compensate source current THD with synchronous reference frame (SRF) technique with proportional integrator (PI) controller. From the result, it is evident that both the soft computing techniques reduce the computational time &amp;amp; fast convergence which improves the filter performance during the transient period and makes it self-tuned. The proposed structure is simulated using MATLAB/Simulink and subsequently experimentally verified. The presentation of the system is originated to be suitable for numerous features of power quality enhancement structure.

Novel Single Inverter-Controlled Brushless Wound Field Synchronous Machine Topology

This paper proposes a novel brushless excitation topology for a three-phase synchronous machine based on a customary current-controlled voltage source inverter (VSI). The inverter employs a simple hysteresis-controller-based current control scheme that enables it to inject a three-phase armature current to the stator winding which contains a dc offset. This dc offset generates an additional air gap magneto-motive force (MMF). On the rotor side, an additional harmonic winding is mounted to harness the harmonic power from the air gap flux. Since a third harmonic flux is generated in this type of topology, the machine structure is also modified to accommodate the third harmonic rotor winding to have a voltage induced as the rotor rotates at synchronous speed. Specifically, four-pole armature and field winding patterns are used, whereas the harmonic winding is configured for a twelve-pole pattern. A diode rectifier is also mounted on the rotor between the harmonic and field windings. Therefore, the generated voltage on the harmonic winding feeds the current to the field winding for excitation. A 2D-finite element analysis (FEA) in JMAG-Designer was carried out for performance evaluation and verification of the topology. The simulation results are consistent with the proposed theory. The topology could reduce the cost and stator winding volume compared to a conventional brushless machine, with good potential for various applications.

Design of electrical impedance tomography for biomedicine

Electrical Impedance Tomography (EIT) has an advantage than another imaging systems in the medical field, they are safe, fast, and simple. The role of EIT is promising, so that it is necessary to develop electrical impedance tomography devices, especially in the biomedical field. we have successfully constructed a multi-frequency EIT system for biomedicine consisting of an oscillator, buffer, VCCS (voltage controlled current source), mux-demux, differential amplifiers based on Arduino Mega. The system succesfully has been tested to produce an image of conductors, insulators, and animal organs so that suitable for biomedical field.

Structural Modifications of Headphone Front Chamber for Better Frequency Response: Experimental and Simulation Studies

The supra-aural headphone concentrates the sound in the listener’s ears, so the loudspeaker sound is confined to the cavity between the pinna and the headphone casing. It is then directed toward the tympanic membrane through the ear-canal. The high-quality sound requirement of supra-aural headphone on one side and space limitation on the other prompted this research. Similarly, inherent sound leakages from headphone on one side and a need for loud sound on the other also impelled this research. This research proposes headphone design modifications for interaction between sound from the diaphragm’s rear and front side for improved frequency response. The changes attempt to stop the sound from the diaphragm’s rear side to leak to the external surrounding, and it is routed to interact with the sound from the front side of the diaphragm in two distinct ways due to the geometrical/structural modifications of the headphone front cover. Prototypes of three headphones (one traditional and two modified) have been modeled by computer-aided drafting software and fabricated by 3D printing. In parallel, equivalent circuits have been formed for the simulation as per the proposed headphone testing setup. The frequency response measurements of headphones have been done in an anechoic chamber using B&K HATS Type 4128. The simulated and measured responses of headphones demand modification of the equivalent circuit by adding the current-controlled voltage source. The optimum simulated performances of all three headphones with a modified equivalent circuit show an improved agreement with respective measured performances.

Design of digital regulated power supply based on feedback control

This paper studies and designs a multi-functional digital regulated power supply, which can realize the switch between the two functions of numerical control current source and numerical control voltage source, and can set the relevant current parameters and voltage parameters through the keyboard. The idea of feedback control is fully adopted to establish the internal and external double negative feedback structures, so as to improve the precision of the regulated power supply. The digital regulator has the advantages of convenient control, large amount of display data, stable performance and so on. It is suitable for various applications of small capacity power supply.

A General Mutual Coupling Model of MIMO Capacitive Coupling Interface With Arbitrary Number of Ports

A general mutual coupling model of multiple input and/or multiple output (MIMO) capacitive coupling interface with an arbitrary number of ports is proposed. In the model proposed in this letter, all the capacitances between the metal plates are taken into account. The self-capacitance of each port and mutual capacitances between the two ports are defined, and a simple equivalent circuit composed of self capacitances and current-controlled voltage sources is obtained. The proposed model helps to reduce the complexity of the MIMO capacitive coupling interface and can be used to simplify the analysis of the power transfer performance of MIMO capacitive power transfer systems. An example capacitive coupling interface setup with two input ports and two output ports is built and tested. The measured and model-based theoretical results of the self and mutual capacitances of the capacitive coupling interface are compared and found to be in good consistency, which verifies the correctness of the proposed model.

An Experimental Measurement and Control of Human Body Stomach Using Electrical Impedance Tomography

A newly proven technique is non-invasive bio-impedance, and also known as Electrical Impedance Tomography (EIT), which is used for medical or non-medical applications. EIT images are based on the internal distributions of the conductivity or resistivity from the boundary data, which depend on the voltage measurement of the stomach attached electrodes of the human body. An experimental study of the EIT system presented here has been used 8/16 surface electrodes configurations for the human body’s stomach. Then, according to the data acquisition methods of the EIT, the surface potentials of the stomach through the current injection were measured. For current pulses, a voltage-controlled current source has been created, and the created current source is a combination of voltage to current converter and current signal generator. Current positions and measuring voltages have been calculated using the designed control unit. However, the imaging algorithm requires sufficient data through the experimental work, which defines the cross-sectional image of resistivity. The cross-sectional image has been based on the Finite Element Method (FEM). It produces 2D/3D images, impedance distribution graphs and Mesh models. The proposed EIT system has been used for non-medical and industrial applications, which have non-invasive, inexpensive, radiation-free and a high potential for imaging modality.

Transient Stability and Current Injection Design of Paralleled Current-Controlled VSCs and Virtual Synchronous Generators

With development of power electronic technology, the paralleled current-controlled voltage source converters (CCSs) and virtual synchronous generators (VSGs) system has advantages in providing power and voltage/frequency regulation at the same time in rural area or remote island. However, the paralleled system faces great challenges in safe and stable operation due to their limited thermal capacity and weak anti-disturbance ability, especially during fault periods. This article focuses on transient stability and stability-oriented control design of the paralleled CCS-VSG system. First, mathematical model of the paralleled system is established and then the effect of two kinds of CCSs' current injection angle (active current and reactive current) on VSG's transient stability has been revealed through extended equal area criterion. Based on the theoretical analysis results, transient stability improvement control is put forward by controlling the CCS to track the VSG's frame. Compared with the conditions that only active- or reactive current is provided by the CCS, the system can achieve the best transient performance when the proposed control is adopted. Moreover, the effect of CCS's capacity on transient stability of the VSG has also been discussed. Finally, both Lyapunov's method and simulation/experimental results are provided to validate the correctness of theoretical analysis.