Cross-coupling Phenomenon Research Articles

Enhanced Linear ADRC Strategy for Sensorless Control of IPMSM Considering Cross-Coupling Factors

Estimation of rotor coordinate system by high-frequency (HF) signal injection is an effective sensorless control strategy, which can solve the decoupling problem of position information of interior permanent magnet synchronous motor (IPMSM) in the low-speed range. However, the inductance cross-coupling phenomenon caused by magnetic saturation will lead to a decline in the accuracy of rotor angle extraction, resulting in a serious deterioration of the sensorless control performance. To solve this problem, an HF signal injection method considering <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d-q</i> axis coupling inductance is proposed to estimate HF inductance and the rotor angle. The estimated HF inductor combined with the current loop enhanced linear active disturbance rejection control (ELADRC) is used in the current loop control to estimate the disturbance and improve the current regulation quality of the current control system. Furthermore, the stability and the tracking performance of the enhanced LADRC are analyzed theoretically. Finally, the stability of a closed-loop IPMSM drives system based on ELADRC considering HF inductance is analyzed. The experimental results of a salient pole IPMSMs driver verify the effectiveness and practicability of the scheme.

Complex Vector Analysis and 2DOF Internal Model Decoupling Control for Toroidal Motor

The planets in toroidal motor rotate while revolving, which causes the cross-coupling phenomenon between d -axis and q -axis, and it affects the dynamic response performance of toroidal motor. To improve the output performance of toroidal motor, the internal model decoupling control is adopted with combination of two degree of freedom (2DOF) control. Based on complex vector theory, complex vector model of toroidal motor with two inputs and two outputs is established. Two degree of freedom internal model decoupling controller is designed. The response performances under the proposed control strategy are simulated and analyzed. The simulation results show that the controller reduces the influence of cross-coupling on the output performance of toroidal drive system greatly, and improves the anti-load disturbance and robust performance of toroidal motor drive system.

Precision tracking of a 2-DOF stick-slip positioner using modeling-free inversion-based iterative control and modified inverse hysteresis compensator

This paper presents the precision control of a 2-DOF stick-slip positioning stage that exhibits friction nonlinearity, hysteresis nonlinearity, creep nonlinearity and cross-coupling phenomenon. Considering the complexity of friction nonlinearity model, the controller was established based on modeling-free inversion-based iterative control (MIIC), which could improve the tracking performance of repetitive trajectory. In order to reduce the influence of hysteresis and cross-coupling for data-based controller, the hysteresis compensator was added based on a modified inverse Prandtl-Ishlinkskii model, and the decoupling control strategy was utilized to eliminate the coupling error. In addition, the proportion-integration-differentiation (PID) controller was adopted to form the feedforward/feedback controller and guarantee the robustness. The developed controller was applied to a 2-DOF stick-slip positioner with comparative experiments. Experimental results indicate that the performance of proposed controller is superior to pure PID controller and even PID controller combined with hysteresis compensator. And comparing with conventional MIIC controller, the influence of nonlinear disturbance could be effectively reduced.

Origin of destruction of multiferroicity in Tb2BaNiO5 by Sr doping and its implications

The orthorhombic Haldane-spin chain compound Tb2BaNiO5 (Néel order, TN1= 63 K) has been shown to be an exotic multiferroic system below (TN2=) 25 K due to various fascinating features, pointing to a strong potential for the advancement of concepts in this field. In particular, the rare-earth ions play a direct decisive role unlike in many other well-known multiferroic materials and there appears to be a critical canting angle, developing below TN2, subtended by Tb 4 f and Ni 3d moments to trigger this cross-coupling phenomenon. However, for a small replacement of Sr for Ba, viz. in Tb2Ba0.9Sr0.1NiO5, ferroelectricity was reported to get destroyed, but retaining magnetic features at (TN1=) 55 K and (TN2 =) 14 K. In this article, we address the origin of suppression of multiferrocity in this Sr-doped system through neutron diffraction studies and density functional theory calculations. We find that, unlike in Tb2BaNiO5, there is no pronounced change in the relative canting angle of the magnetic moments around TN2 and that the absolute value of this parameter down to 2 K fails to exceed the critical value noted for the parent, thereby explaining the origin of destruction of magnetoelectric coupling in the Sr-doped material. This finding renders strong support to the proposal of possible existence of ‘critical canting angle’ – at least in some cases – to induce multiferroicity, apart from serving as a route to engineer multiferroic materials for applications.

Calculation of Cross-Coupling Inductance and Electromagnetic Torque in Wound-Rotor Synchronous Starter/Generator

In this paper, the cross-coupling phenomenon in the wound-rotor synchronous starter/generator system is studied. Due to the armature reaction, the excitation field is dragged away from the d -axis by the armature magnetic field and the cross-coupling inductance ${L_{dq}}$ exists. What is more, the cross-coupling phenomenon also occurs in the excitation field, it means not only the mutual inductance ${M_{df}}$ between the d -axis and excitation field exists, but also mutual inductance ${M_{qf}}$ between the q -axis and excitation field exists. If this ${M_{qf}}$ component is ignored, this will result in a torque calculated error, especially facing an intense armature reaction, the error can be more than 20%. The mathematical expressions of cross-coupling inductance ${L_{dq}}$ , ${M_{qf}}$ are derived. Based on these expressions, a more accurate torque equation is proposed. The validity of the proposed analysis is proved by showing the agreement with experimental results and maximum torque per ampere (MTPA) loci.

A Comprehensive Investigation of a Microfabricated U-Bend Polymer Waveguide With Analyte Micro-Reservoir for Versatile On-Chip Sensing Applications

In our earlier designed, embedded U-shaped-waveguides, due to lower area of analyte interaction, there was always a scope to simplify and modify the device design to improve its evanescent-absorbance sensitivity. To achieve this objective, a simple designed micro-analysis chips consisting of a U-bend waveguide probes coupled microreservoir structure were theoretically and experimentally investigated in this paper. For the fabrication of these microstructures along with fiber-to-waveguide-coupler structures, a single-step micro-fabrication procedure was performed using SU-8 photoresist. Initially, in this paper, using suitable numerical-calculations, we have also focused on the analyzing various physical parameters, which contribute to their sensitivity, which further corroborated with the experimental results. Furthermore, we recognized the effect of cross-coupling phenomenon (between their two straight-arms) to be a reason for lower RI-sensitivity, as well as linear and higher evanescent-absorption-based detection sensitivity for lower bending-diameter (<0.5 mm) waveguide. Compared with embedded U-bend waveguides, the overall evanescent-absorption sensitivity of U-bend waveguides was found improved by approximately three times. Finally, it proved to be a useful flexible sensing-probe for any physical, chemical, and biological sensing application, provided appropriate surface modification is made to this waveguide probe. [2016-0285]

MIMO $$H_{\infty }$$ H ∞ Integral Control Design for 2D Tunneling Current Measurement System: STM Application

Ultrahigh measurement precision of the tunneling current (which is a quantum mechanical phenomenon and of the order of nano-amperes) is one of the key requirements in many of its applications like in STM (Scanning Tunneling Microscope). STM is used to generate the image of any conducting sample surface with atomic scale resolution, and the image quality highly depends on the precision of the tunneling current. Multi-axis piezoelectric actuator is attached with the tip of STM to move it precisely over the sample surface in vertical as well as in horizontal directions. The desired precision of the tunneling current is adversely affected not only because of the sample surface variations and the measurement noise, but also because of the cross-couplings of multi-axis piezoelectric actuator. In this paper, a dynamic modeling of MIMO (multi-input-multi-output) plant having vertical tunneling current measurement system with horizontal scanning system in the presence of cross-coupling phenomenon is proposed. Then, a robust MIMO \(H_{\infty }\) integral controller is analyzed in order to achieve the desired measurement precision of the tunneling current. Results are compared with SISO (single-input-single-output) \(H_{\infty }\) integral controller and the conventionally used classical PI (proportional-integral) controller. The simulation results achieved with proposed MIMO \(H_{\infty }\) integral controller show improved performances than those obtained with SISO \(H_{\infty }\) integral controller and classical PI controller.

Research and Modeling of Mechanical Crosstalk in Linear Arrays of Ultrasonic Transducers

Abstract Linear arrays of ultrasonic transducers are commonly used as ultrasonic probes in medical diagnostics for imaging the interior of a human body in vivo. The crosstalk phenomenon occurs during the operation of transducers in which electrical voltages and mechanical vibrations are transmitted to adjacent components. As a result of such additional excitation of the transducers in the array, the directivity characteristics of the aperture used changes, and consequently there is interference with properoperation of a given array and the emergence of distortions in the obtained ultra sound image that reduce its quality. This paper studies the manner of propagation of mechanical crosstalk in the designed model of a linear array of ultrasonic transducers on the basis of unwanted signals, which appeared on elementary piezo-electric transducers when power is supplied to the selected transducer in the array. The universal model of linear array of ultrasonic transducers, which has been developed, allowed the simulation of mechanical crosstalk, taking in to account the cross-coupling phenomenon in all of its structure with the use of finite elements method (FEM) implemented in COMSOL Multiphysics software. The analysis of crosstalk signals showed that they consist of aggregated pulses propagating with different speeds and frequencies. This signifies the formation of different vibration modes transmitted simultaneously via different paths. The paper is an original approach which enables to identify different vibration modes and estimate their participation in the crosstalk signal and their ways of propagation. Conclusions from the research allow predicting specific design changes which are significant due to the minimization of mechanical crosstalk in linear arrays of ultrasonic transducers.

Effect of Enlarging the Aircraft Vertical Tail on State Variables of Stability Response during Dynamic Coupling

In this paper the variables of high performance aircraft including the modification of vertical tail during the roll inertia cross coupling phenomenon is presented. To demonstrate the effects of the enlarging the area of vertical tail on stability of aircraft, the longitudinal-lateral equations of aircraft motion at steady roll rate are solved. The results indicate that damping of the modified system is increased and the longitudinal-lateral state variables response of the aircraft is improved. The increase in the area of the vertical fin is a necessary feature in the development of the aircraft to improve stability during roll and decrease the possibility of cross coupling occurrence. Also the results indicated that the critical value of roll rate in case 1,at Mach no.=0.6, takes the range of ,while the values of critical roll rates in case 2,3 and 4 are , , ,Respectively. The numerical results shows 19% , 15.5% , and 15% gain in rolling margin for cases 2, 3, and 4 respectively, when compared with original (case 1) .

Application of linear thermodynamics to the atmospheric system. Part II: exemplification of linear phenomenological relations in the atmospheric system

The linear phenomenological relations in the atmospheric boundary layer are proved indirectly using observational facts to combine linear thermodynamic theory and similarity theory in the boundary layer. Furthermore, it is proved that the turbulent transport coefficients are in proportion to the corresponding linear phenomenological coefficients. But the experimental facts show that the linear phenomenological relations are not tenable in the atmospheric mixing layer because the turbulent transport process is an intense non—linear process in the mixing layer. Hence the convection boundary layer is a thermodynamic state in a non—linear region far from the equilibrium state. The geostrophic wind is a special cross—coupling phenomenon between the dynamic process and the thermodynamic process in the atmospheric system. It is a practical exemplification of a cross—coupling phenomenon in the atmospheric system.

Surface plasmon cross coupling in molecular fluorescence near a corrugated thin metal film.

Surface plasmons on opposite sides of a thin metal film can cross couple in the presence of a surface corrugation, or grating. We report the observation of this cross-coupling phenomenon as a radiative-decay mechanism for molecules near a corrugated thin metal film.