Compensation Control Technique Research Articles

A CFRP/steel hybrid rotating shaft for a high-speed motorized spindle

Most key industry machines have a rotating structure for power transmission, which plays a crucial role in diverse engineering practices. In machine tools, a spindle is the heart of machining centers, and the quality of the spindle has a critical influence on overall machining errors across different manufacturing processes. Especially, axial growth due to thermal displacement of the shaft directly adds depth accuracy error of the tool. While additional compensation control techniques have been developed to cover such errors of spindles in practice, fewer efforts have been made to improve the actual amount of error in the spindle. This study introduces a new carbon fiber-reinforced composite (CFRP) fabricated hybrid design in a rotating shaft for a high-speed motorized spindle. With superior material characteristics of CFRP, it aimed to improve thermal displacement as well as light-weighting of the shaft. The developed spindle with composite shaft was tested in comparison with an equivalent spindle with a conventional single material shaft, and it achieved 18 % shaft weight reduction and 22 % improvement in shaft thermal growth. Furthermore, it was successfully tested in vertical face grinding of silicon carbide (SiC), providing accuracies over 99 %. Machining precision achieved conspicuous difference with 45.4 % enhancement at 3000 rpm and 27.3 % at 5000 rpm grinding. The significance of this study lies in that it suggests the first generalized method of adopting carbon fiber composite in rotating systems, including high-speed motorized spindles, which also proves its feasibility in actual machining.

A Comprehensive Review of Compensation Control Techniques Suitable for Cascaded H-Bridge Multilevel Inverter Operation with Unequal DC Sources or Faulty Cells

A cascaded H-bridge multilevel converter topology is the ultimate solution for energy conversion in various industrial applications due to its exceptional features, such as high modularity and fault-tolerant capability. However, two circumstances can lead to unbalanced operation of the inverter, potentially causing a decrease in its reliability and survivability: unequal DC voltage sources and faulty cells. In recent decades, scientists and engineers have conducted intensive research and meaningful studies to propose control solutions capable of maintaining the stable and continuous operation of the inverter under these operational concerns. Typically, each challenge is addressed separately using a distinct compensation control scheme in the existing literature. The paper aims to offer a comprehensive review of the existing compensation control schemes appropriate for CHBMIs operating under unbalanced conditions. It overviews the most popular control schemes and summarizes their usefulness in such scenarios. The theoretical foundations of each control scheme are presented and discussed, including their operating principles, implementation schemes, advantages, and disadvantages. The paper concludes with suggested future trends that require further research for CHBMIs’ continued growth and adoption in various industrial applications.

Frequency and Voltage Control Techniques through Inverter-Interfaced Distributed Energy Resources in Microgrids: A Review

Microgrids (MG) are small-scale electric grids with local voltage control and power management systems to facilitate the high penetration and grid integration of renewable energy resources (RES). The distributed generation units (DGs), including RESs, are connected to (micro) grids through power electronics-based inverters. Therefore, new paradigms are required for voltage and frequency regulation by inverter-interfaced DGs (IIDGs). Notably, employing effective voltage and frequency regulation methods for establishing power-sharing among parallel inverters in MGs is the most critical issue. This paper provides a comprehensive study, comparison, and classification of control methods including communication-based, decentralized, and construction and compensation control techniques. The development of inverter-dominated MGs has caused limitations in employing classical control techniques due to their defective performance in handling non-linear models of IIDGs. To this end, this article reviews and illustrates advanced controllers that can deal with the challenges that are created due to the uncertain and arbitrary impedance characteristics of IIDGs in dynamics/transients.

The synchronization of discrete quantum chaotic maps with uncertainty via compensated control technique

In this work, a two-dimensional discrete map model based on quantum game is introduced, and its dynamics are investigated. Moreover, the stability condition of Nash equilibrium is also analyzed. In addition, the synchronization control of discrete chaotic maps with uncertainties is studied, and a new dynamical compensation control (DCC) technique is presented by constructing a dynamical compensator. At a result, the influence of the uncertain term can be suppressed effectively. Compared with the previous synchronous control approaches, the proposed method avoids the complex derivation and amplification operation, because it does not use Lyapunov function, and the controller design is simple and the proposed scheme is well verified.

A rate-dependent KP modeling and direct compensation control technique for hysteresis in piezo-nanopositioning stages

This paper first presents a rate-dependent Krasnosel’skii-Pokrovskii (RKP) model to capture the hysteresis of piezo-nanopositioning stages. The dynamic density function of the RKP model is obtained via neural network with frequency behavior input signal. Under the persistently exciting condition, the convergence of the neural network with Krasnosel’skii-Pokrovskii (KP) operators is proved rigorously. In order to address the hysteresis issue, a direct compensation control (DCC) approach with the KP compensation operator is proposed, where its dynamic density function is same as that of the RKP model. Some experiments with different reference signals are conducted to verify the effectiveness of the proposed modeling and DCC method on piezo-nanopositioning stages.

Real-time simulation and performance of DSTATCOM using an improved load current detection-based control technique for compensation of current harmonics and load transients

ABSTRACT Current harmonics are introduced in a distribution system due to the increasing utilization of nonlinear loads. Therefore, elimination of harmonics from supply current is an inevitable task to do. In this paper, an adaptive control technique called I-cos-theta (Icosθ) control algorithm along with a Kernel-based training method is proposed in a fuel cell-based Distributed STATic COMpensator (DSTATCOM) simulation for harmonic compensation. Specifically, the direct and quadrature components of the load current are extracted and retrained using the Kernel-based Icosθ control algorithm. The control algorithm is implemented to generate reference currents, and then the appropriate switching pulses for the Voltage Source Inverter (VSI) of the DSTATCOM. The fuel cell is intended to maintain the DC-link voltage of the DSTATCOM during different loading conditions for power quality improvement. Further, the DC-link voltage is maintained constant at 530 V with an acceptable voltage regulation of <±16%, even under load transients and temporary supply failure conditions. Moreover, the simulation of the fuel cell-based DSTATCOM has been performed in Sim Power System (SPS)/MATLAB Simulink software. Also, a low power rated prototype is developed to verify the proposed simulation model, incorporating with the dSPACE1104 real-time environment.

Adaptive Frequency-Based Reference Compensation Current Control Strategy of Shunt Active Power Filter for Unbalanced Nonlinear Loads

The shunt active power filter (SAPF) is an effective means for the modification of power quality. However, the compensation performance of SAPF would be deteriorated when the unbalanced nonlinear loads are present in the power system. To enhance the compensation performance of SAPF, the adaptive frequency-based reference compensation current control strategy is proposed in this paper. The proposed solution procedure can be divided into three stages including adaptive frequency detection, phase synchronization, and adaptive compensation. With the tracking of power system frequency, the phase synchronization for the SAPF compensation can be effectively modified under the power variation of unbalanced nonlinear loads. Based on the correct synchronization phase angle, the reference compensation current of SAPF can be accurately obtained with the adaptive linear neural network (ALNN) in the stage of adaptive compensation. In addition, the direct current (DC)-link voltage of SAPF can also be effectively regulated to maintain the compensation performance. To verify the effectiveness of the proposed adaptive frequency-based reference compensation current control strategy, the comprehensive case studies implemented with the hardware-in-the-loop (HIL) mechanism are performed to examine the compliance with the specification limits of IEEE Standard 519-2014. The experimental results reveal that the performance of proposed SAPF control strategy is superior to that of the traditional instantaneous reactive power compensation control technique (p-q method) and sliding discrete Fourier transform (DFT).

Position Signal Compensation Control Technique of Hall Sensor Generated by Uneven Magnetic Flux Density

Generally, brushless dc (BLDC) motor control uses a 120° conduction method that utilizes a low-cost Hall sensor as a position sensor. However, because of the mounting position error of the Hall sensor and the uneven magnetic flux density of the rotor, an erroneous position signal may be output, which will adversely affect the BLDC motor control. Therefore, this paper analyzes the abnormal electric current section that occurs due to the position error of the Hall sensor and the uneven magnetic flux density. Subsequently, the error is derived from the analyzed phenomenon as a formula. The compensation control algorithm to overcome the control problem due to this error is studied, and a method to maintain an accurate energization interval is suggested. Further, it is shown through experiments that the quantitative analysis of the error using the proposed compensation control algorithm is valid.

Takagi-Sugeno Fuzzy Model-Based Control of Spacecraft with Flexible Appendage

This paper presents a Takagi-Sugeno (T-S) fuzzy model-based approach to model and control a rigid spacecraft with flexible antenna. First, the equations of motion of the flexible spacecraft, which are based on Lagrange equations and given in terms of quasi-coordinates and the Rayleigh-Ritz method, are briefly reviewed. Then, the T-S fuzzy modeling and the parallel distributed compensation control technique are introduced. We utilize full state-feedback and optimal H∞ robustness performance via a T-S fuzzy model to achieve position and attitude stabilization, vibration suppression, and disturbance rejection objectives. Finally, this technique is applied to the flexible spacecraft equations of motion resulting in a nonlinear controller. The controller produces an asymptotically stable closed-loop system which is robust to external disturbances and has a simple structure for straightforward implementation. Numerical simulation is provided for performance evaluation of the proposed controller design.

A Novel Method of Phase Current Compensation for Switched Reluctance Motor System Based on Finite Element

Torque ripple is a major problem of switched reluctance motor drive system, which causes undesirable vibration and acoustic noise. In this paper, a novel method of torque closed-loop and fuzzy compensation control for the switched reluctance motor drive system based on finite element model is described. In terms of the simulation results and the special characteristics of static torquecurrent-angle which are calculated by finite element method, the phase current can be treated just as the nonlinear function of phase torque. With the proposed control concept, a compensating signal is added to the phase current, the current shape can vary with the fuzzy control ruler to minimize the torque ripple. In the end, an example of 8/6 poles switched reluctance motor is simulated. Simulation results show that the torque ripple coefficient Ti can be reduced about fifty percent and the total torque also can be advanced, which verifies the effects of the proposed fuzzy compensation control technique.

A novel fuzzy friction compensation approach to improve the performance of a DC motor control system

The compensation of friction nonlinearities for servomotor control has received much attention due to undesirable and disturbing effects that the friction often has on conventional control systems. Compensation methods have generally involved selecting a friction model and then using model parameters to cancel the effects of the nonlinearity. In this paper, a method using fuzzy logic for the compensation of nonlinear friction is developed for the control of a DC motor. The method is unique in that a single fuzzy rule is used to compensate directly for the nonlinearity of the physical system. As a result, the method introduces fewer adjustable parameters than a typical fuzzy logic approach while still incorporating many advantages of using fuzzy logic such as the incorporation of heuristic knowledge, ease of implementation and the lack of a need for an accurate mathematical model. The general approach, analysis and experimental results obtained for an actual DC motor system with nonlinear friction characteristics are presented and the effectiveness of the fuzzy friction compensation control technique is discussed. The smoothness of response, response times and disturbance rejection of a PI control system with and without the proposed fuzzy compensator are analyzed and discussed to illustrate the effectiveness of the proposed method.