Load Torque Research Articles

Fault Diagnosis of PMSM Stator Winding Based on Continuous Wavelet Transform Analysis of Stator Phase Current Signal and Selected Artificial Intelligence Techniques

High efficiency, high reliability and excellent dynamic performance have been key aspects considered in recent years when selecting motors for modern drive systems. These features characterize permanent magnet synchronous motors (PMSMs). This paper presents the application of continuous wavelet transform (CWT) and artificial intelligence (AI) techniques to the detection and classification of PMSM stator winding faults. The complex generalized Morse wavelet used for CWT analysis of three different diagnostic signals—the stator phase current, its envelope and the space vector module—is used to extract the symptoms most sensitive to the interturn short circuits (ITSCs) at the incipient stage of the damage. The effectiveness of automatic stator winding fault classification is compared for three selected ML algorithms: multilayer perceptron, support vector machine and k-nearest neighbors. The effect of the ML models’ hyperparameters on their accuracy is also verified. The high effectiveness of the proposed methodology is confirmed by the results of the experimental verification carried out for different load torque levels and supply voltage frequency values.

Study on the Engagement Characteristics and Control Strategy of High Speed Difference Dry Friction Clutch

In the short/vertical take-off and landing aircraft propulsion system, the vertical take-off/landing and rapid flight are switched through the engagement and disconnection of the dry friction clutch. The smooth and rapid connection of the friction clutch is crucial for the mobility and reliability of this type of aircraft. However, the friction clutch vibrates and generates a large amount of heat at high speed, which affects the engagement performance of the clutch. In practice, when the engagement pressure rises quickly, the clutch engagement time is short, and the temperature rise is small, but the impact torque is large, and vice versa. In view of this problem, with a short/vertical take-off aircraft dry friction clutch as the research object, considering the nonlinear variation of friction coefficient and lift fan load torque, the dynamics model and temperature field model of the high speed difference dry friction clutch are established to analyze the clutch engagement time, impact torque, and temperature change. The engagement test at the high speed of the clutch shows that the simulation results of the kinetic model and temperature field model are consistent with the test results. To realize low temperature rise, low impact torque, and short engagement time, the variable slope engagement pressure control method is proposed. Compared with the traditional fixed slope engagement pressure, the proposed variable slope engagement pressure can reduce the engagement time, impact torque and temperature rise simultaneously. The research results can provide a reference for the friction clutch engagement control of short-range take-off and landing aircraft, reduce the development cost of such aircraft, and improve the reliability of the design.

TRUSTS: A novel treadmill-based multifunctional testing system for performance evaluation of wheeled planetary exploration rover

This paper presents a novel treadmill-based multifunctional testing system (TRUSTS) to execute ground testing for wheeled planetary exploration rover (WPER) in both regular and extreme physical conditions before launching. The TRUSTS with specially-made components featuring compact structure and multifunctional testing items comprises a traction loading subsystem (TLS) and a treadmill-based resistance torque loading subsystem (TRTLS). The former offers the working modes including traction loading, position holding, and range limiting. The latter offers working modes including resistance torque loading and leader–follower tracking. By appropriately allocating the working modes of two subsystems, the TRUSTS is capable of conducting diverse testing items. The customized controllers for the TLS and the TRTLS are proposed to guarantee the operation performance of the TRUSTS in all testing items. Extensive experimental results on a Mars rover prototype in both regular and extreme physical conditions demonstrate that the devised TRUSTS could effectively executing trafficability and maneuverability as well as adaptability tests with reliable scenarios and satisfactory precisions of motion tracking and traction/torque loading, which makes the TRUSTS a favorable choice for comprehensive performance assessment of rover in simulant extraterrestrial environment.

Robust synergetic control of electric vehicle equipped with an improved load torque observer

Abstract For environmental reasons, a great effort was focused on the improvement of the steady-state performance and dynamic performance of electric vehicles (EV). The EV is one of the cleanest and most ecological transport solutions. Accurate knowledge of EV load torque signals is important information for controlling and improving EV active safety. The estimation of load torque in EV drive contributes to cost reduction and solves many of the implementation problems encountered: lack of space, and severe environment. On this basis, in this research, our contribution contains two parts. The first part is the conception of a new scheme of control based on synergetic control (SC) for the speed of an EV propelled by a Six-Phase Permanent Magnet Synchronous Motor (PMSMs) is developed. This control technique offers a fast response, decreases the size of modeled system, and asymptotic stability of the closed-loop system in a vast domain. The second part deals with the synthesis of the sliding mode observer (SMO) to estimate load torque, compensate for strong disturbances and achieve high servo precisions. Moreover, reducing the chattering is inherent in the conventional SMO, we have proposed to replace the switching observer term Ksign with a smooth function and super twisting algorithm. The obtained simulation results proved the high performance assured by the synergetic control such as robustness and dynamic performance, and good estimation accuracy with free chattering even in strong noises.

Matlab-based simulations of a three-phase induction motor for dynamic studies

The aim of this paper is to develop a generalized MATLAB program to study the dynamic behavior of a three-phase induction motor. The d-q axis transformation theory is applied in rotor reference frame to study the motor dynamics. A general-purpose MATLAB program is developed and used for the dynamic simulation of a 5HP, 460V, 60Hz, 4-poles induction motor. The developed program is used to study the effect of variation of Stator Resistance (Rs), Moment of Inertia (J), and Load Torque (TL) at t=0.7sec during transient state. The results obtained show that, the torque-speed characteristic curve and mechanical rotor speed-time characteristics of induction motor depend upon the rotor resistance and the moment of inertia. Also, during the simulation of the motor under loaded torque at t=0.7sec, the results showed an increase in the initial starting torque and it reduces from 2000Nm – 0Nm as the operating time progressed. A sudden residual increase occurred in the torque from 0-1000Nm at the loaded time t=0.7sec, and the mechanical rotor speed increased at starting time from 0-1800rpm with respect to operating time and suddenly experienced a drop from 1800rpm to about 1700rpm at the loaded time of t=0.7 sec. The developed program is particularly useful for machine designers in the manufacture of various types of induction machines.

Research on complex vector quasi-resonant control methods for permanent magnet synchronous motor

A complex vector quasi-resonant controller is proposed to solve the current controller’s dynamic coupling problem and static harmonics. Although current feedforward decoupling has been widely used, the calculation relies on the motor parameters. When the motor works at high speed and high torque load, the parameters change greatly, failing to decouple. In the static conditions, due to the inverter nonlinearity, the PMSM stator current contains lots of high harmonics, which causes the motor produces a specific frequency torque ripple. Therefore, complex vector quasi-resonance is proposed. The complex vector transfer function contains a virtual axis zero point, which varies with speed so that the zero point of the controller and the pole of the controlled object are eliminated. The quasi-resonant controllers are connected in parallel with the main controller and suppress harmonics at fixed frequencies of the system. The method is based on the resonant controller with infinite gain at the resonant frequency point, which can achieve zero steady-state error tracking, achieving the purpose of torque pulsation suppression. In this paper, through theoretical derivation and algorithm structure design, the algorithm’s effectiveness is verified in the simulation. The proposed algorithm has a fast response in the dynamic state and smaller current harmonics in the steady state.

Investigation of a Cup-Rotor Permanent-Magnet Doubly Fed Machine for Extended-Range Electric Vehicles

This paper investigates a cup-rotor permanent-magnet doubly fed machine (CRPM-DFM) for extended-range electric vehicles (EREVs). The topology and operating principle of the powertrain system based on CRPM-DFM are introduced. Then, the mathematical model of CRPM-DFM is established and the feedback linearization control of CRPM-DFM is given to realize the decoupling control of flux and torque. Moreover, the torque characteristic of CRPM-DFM is analyzed and the load torque boundaries with sinusoidal steady-state solution of CRPM-DFM is deduced. In addition, the MTPA control is derived to improve the efficiency of CRPM-DFM, and the efficiency of CRPM-DFM regarding various operating modes is investigated. Furthermore, the speed optimization strategy of ICE is proposed to reduce fuel consumption. Finally, the driving performance and fuel economy of the powertrain system are verified by simulation.

Autonomous Electric-Vehicle Control Using Speed Planning Algorithm and Back-Stepping Approach

Autonomous electric vehicles (AEVs) have garnered increasing attention in recent years as they hold significant promise for transforming the transportation sector. However, despite advances in the field, effective vehicle drive control remains a critical challenge that must be addressed to realize the full potential of AEVs. This study presents a novel approach to AEV drive control for concurrently generating a suitable speed profile and controlling the vehicle drive speed along a planned path that takes into account various driving circumstances that mimic real-world driving. The designed strategy is divided into two parts: The first part presents a proposed speed planning algorithm (SPA) that works on developing an adequate speed profile for vehicle navigation; first, the algorithm uses an approach for identifying sharp curves on the predefined trajectory; secondly, based on the dynamic properties of these curves, it generates an appropriate speed profile to ensure smooth vehicle travel across the entire trajectory with varying velocities. The second part proposes a new back-stepping control technique with a space vector modulation (SVM) strategy to control the speed of an induction motor (IM) as a traction part of the AEV. A load torque observer has been designed to enhance the speed-tracking task, while the system stability has been proven using Lyapunov theory. Through a series of experiments and simulations using MATLAB/Simulink software and the dSPACE 1104 real-time interface, we demonstrate the effectiveness of the SPA combined with the back-stepping control technique and highlight its potential to advance the field of AEV technology. Our findings have important implications for the design and implementation of AEVs and provide a foundation for future research in this exciting area of study.

Advanced PMSM speed control using fuzzy PI method for hybrid power control technique

In mobile electric drive systems, the Permanent Magnet Synchronous Motors (PMSM) drive system is preferred for development because of its high efficiency, power density, and low maintenance cost advantages. The PMSM speed control method based on the active and reactive power control of the inverter eliminates the division of the control area based on the reference speed. In order to improve the ability to respond quickly to PMSM speed changes caused by load torque changes or reference speed changes, the article proposes a control method using an advanced Fuzzy PI controller instead of a traditional PI control in the speed control loop. The results obtained by simulation on MATLAB/Simulink demonstrate that the tracking control quality robustly remains at the working point in the steady state and simultaneously reduces the tracking error to the new reference speed and load torque values.

Experimental study of the VFD's speed stabilization processes under torque disturbances

<span lang="EN-US">Maintaining speed with various jumps and changes in load torque is one of the main tasks of variable frequency drives (VFD). The article considers the operation of the VFD under the influence of periodic perturbations of variable frequency and amplitude. The dependence of the transient function of the VFD and the family of frequency characteristics associated with it on the frequency of the stator voltage and slip underlies the methodology for experimental studies of such drives. The traditional method is based on the response to harmonic stimulation and works well for a non-linear system. In the course of the work, it was found that the introduction of dynamic positive feedback (DPF) allows to compensate for disturbances of varying frequency and amplitude. Experiments with a sinusoidal change in the load torque have shown the effectiveness of introducing the DPF in front of conventional sensorless control systems (vector and scalar).</span>

Encoderless Five-phase PMa-SynRM Drive System Based on Robust Torque-speed Estimator with Super-twisting Sliding Mode Control

In this paper, a robust torque speed estimator (RTSE) for linear parameter changing (LPC) system is proposed and designed for an encoderless five-phase permanent magnet assisted synchronous reluctance motor (5-phase PMa-SynRM). This estimator is utilized for estimating the rotor speed and the load torque as well as can solve the speed sensor fault problem, as the feedback speed information is obtained directly from the virtual sensor. In addition, this technique is able to enhance the 5-phase PMa-SynRM performance by estimating the load torque for the real time compensation. The stability analysis of the proposed estimator is performed via Schur complement along with Lyapunov analysis. Furthermore, for improving the 5-phase PMa-SynRM performance, five super-twisting sliding mode controllers (ST-SMCs) are employed with providing a robust response without the impacts of high chattering problem. A super-twisting sliding mode speed controller (ST-SMSC) is employed for controlling the PMa-SynRM rotor speed, and four super-twisting sliding mode current controllers (ST-SMCCs) are employed for controlling the 5-phase PMa-SynRM currents. The stability analysis and the experimental results indicate the effectiveness along with feasibility of the proposed RTSE and the ST-SMSC with ST-SMCCs approach for a 750-W 5-phase PMa-SynRM under load disturbance, parameters variations, single open-phase fault, and adjacent two-phase open circuit fault conditions.

Influence of drivetrain efficiency determination on the torque control of wind turbines

Decreasing the levelized cost of energy is a major design objective for wind turbines. Accordingly, the control is generally optimized to achieve a high energy production and a high-power coefficient. In partial load range, speed and torque are controlled via the generator torque but the rotor torque determines the power coefficient of the turbine. High uncertainties for the uncalibrated low-speed shaft torque measurement and varying drivetrain efficiencies which depend on the speed, load and temperature lead to a torque control error that reduces the power coefficient of the wind turbine. In this paper the rotor torque control error and the impact on the power coefficient of wind turbines is quantified. For this purpose, the variation of drivetrain efficiency is analyzed. An efficiency model for the wind turbine drivetrain is build and validated on the test bench. Then, the influence of the drivetrain speed, torque loads, non-torque loads, and temperature on the efficiency is quantified. Finally, the influence of the rotor torque control error on the power coefficient was simulated with an aerodynamic model. The results show that of all examined influences only torque and temperature significantly impacting the efficiency leading to rotor torque control errors that reduce the power coefficient and consequently increase the levelized cost of energy. Improved efficiency measurement on WT test benches or drivetrain efficiency modelling can reduce the rotor torque control error and therefore decrease the LCOE.

Validation of a wind turbine gearbox strain simulation model in service to virtual sensing

Over the last decades, the use of wind power as a source of renewable power has increased, while the Levelized Cost of Electricity (LCoE) of wind power has fallen. In order to further drive down the LCoE, there is an increasing interest to monitor key turbine quantities in order to improve maintenance procedures and decrease downtime. In this paper, we focus on the indirect detection of one such key quantity, the torque load on the gearbox. In order to avoid expensive direct torque sensors, we study the potential of strain gauges installed on the gearbox housing as virtual torque sensors. Our results verify that the strain response is repeatable, torque-driven and predictable; which are the most important conditions for using the sensors in virtual load sensing. Next, we compare the measured strain response to simulated strain results obtained from a physics-based model. The model consists of a static FE model of the gearbox housing and a torsional model of the shafts and gears in the drivetrain. An optimisation approach selects the FE model node where the simulated strain best matches the measured strain. We conclude that the studied strain gauges are promising for model-based virtual sensing of the torque on the gearbox.

Direct measurement of input loads for the wind turbine drivetrain under test on a nacelle test bench

Modern wind turbines have some of the highest levels of torque and non-torque loads of all industrial sectors. These high loads present a great challenge for the design of wind turbines. On a nacelle test bench, the wind turbine drivetrain can be tested and validated against the design. It is therefore important to measure the correct level of each load and all its dynamic behaviors during the test. The best way to achieve this is to measure the loads directly in front of the drivetrain. This paper presents a method of direct load measurement on the shaft adapter which connects the drivetrain to the test bench. The technical solution and some important details about the instrumentation on the adapter are also presented. Methods of signal nulling as well as signal conversion from raw signals to the loads are compared as well. The measurements obtained are then compared with the applied loads from the test bench which show good agreement. As a special case, the torque measurement is validated and calibrated up to 5 MN m by means of a state-of-the-art torque transducer.

High-Precision Finite-Time Positioning Control for an Inertial Reference Unit With Asymmetric Loads and Mover Sideslip

In this article, a finite-time controller is designed on high-precision positioning for an inertial reference unit (IRU) with asymmetric loads and mover sideslip based on a finite-time extended state observer (ESO). The asymmetric loads caused by centroid deviation from central axis are a negative factor, which results in a negative load torque for IRUs. The mover sideslip is another negative factor that brings about output forces errors between actual output forces and theoretical output forces for voice coil motors. The finite-time ESO is designed to estimate and compensate the asymmetric loads and mover sideslip. The finite-time controller is proposed with high convergence rate for the IRU. Experimental results are presented to show effectiveness of the proposed finite-time control method in high-precision positioning under asymmetric loads and mover sideslip.

Torque Disturbance Compensation Method Based on Adaptive Fourier-Transform for Permanent Magnet Compressor Drives

The large fluctuating torque disturbance of the single-rotor permanent magnet compressor has a significant impact on the drive system. An adaptive Fourier-transform-based torque disturbance compensation method is proposed to improve the control performance in this article. Based on the analysis of compressor load torque characteristics, a self-adjusting strategy is proposed to reduce the compensation error of the traditional open-loop Fourier-transform scheme. The compensation current is adaptively generated by adopting an indirect iterative learning mechanism that can obtain the multifrequency torque disturbances information in real-time. The proposed method does not require the accurate compressor parameters and the discrimination of harmonic disturbances, which has satisfactory suppression ability for the multifrequency torque disturbance. The convergence and parameter sensitivity of the proposed method are analyzed theoretically. The effectiveness of this method is verified by experiments on a 1.5-kW permanent magnet compressor drive platform.

Low cost high performance self-starting sensorless single phase induction motor drive

<p><span lang="EN-US">The present paper is directed to achieve a low-cost high-performance self-starting single phase induction motor (SPIM) drive system. A phase shifted pulse width modulation (PWM) trains feeding the motor will replace the starting and running capacitors. Adaptive sliding mode control, enhance with model reference adaptive control (MRAC), is implemented to achieve high performance sensorless SPIM drive. The obtained results confirm the feasibility of the proposed system in starting and fast tracking the reference speed with nearly zero percentage overshoot and zero steady-state error. Moreover, the proposed SPIM drive system is robust to external load torque disturbances and insensitive to system parameter variations. Extensive simulations have been conducted to confirm the validity of the proposed system.</span></p>

Adaptive Neural Network Control Using Nonlinear Information Gain for Permanent Magnet Synchronous Motors.

In this study, an adaptive neural network (NN) control using nonlinear information (NI) gain for permanent magnet synchronous motors (PMSMs) is proposed to improve control and estimation performance. The proposed method consists of a nonlinear controller, a three-layer NN approximator, and NI gain. The nonlinear controller is designed via a backstepping procedure for position tracking. The commutation scheme is designed to implement the PMSM control without the direct-quadrature (DQ) transform. The three-layer NN approximator is designed to estimate the unknown complex function generated by the recursive backstepping process. The NI gains are designed to enhance the control and estimation performance according to the increased tracking errors owing to the load torque and the desired position variations. All of signals in the closed-loop system guarantee the semiglobal uniformly ultimately boundness (UUB) using the Lyapunov stability theorem and the input-to-state stability (ISS) property. The performance of the proposed method was validated by experiments performed using a PMSM testbed.

Cascaded Modular Multilevel Converter and Cycloconverter Based Machine Drive System

Low-speed drive is one of the challenges for modular multilevel converters (MMCs) due to large capacitor voltage fluctuation. In this article, a cascaded MMC and cycloconverter (CCV) based machine drive system is proposed to ensure stable operation of medium-voltage and low-speed machine. The MMC provides medium-frequency ac voltage for the CCV, and the CCV converts the medium-frequency ac input to low-frequency ac output required by the machine. Detailed analysis about MMC's operation frequency, device current stress, and submodule (SM) capacitance are given in this article. Proposed drive system can operate at zero/low frequency under rated load torque, while the SM capacitance is much smaller than that in existing methods. Simulation and experimental studies are conducted, and the results verify the effectiveness of the proposed system.

Comparison and Experimental Verification of Different Approaches to Suppress Torque Ripple and Vibrations of Interior Permanent Magnet Synchronous Motor for EV

Interior permanentmagnet (IPM) motors have been the most promising solutions for electric vehicles (EV) drives in terms of torque/power density, compactness, and efficiency. However, IPM motors are vulnerable to large torque ripple and high-level electromagnetic vibrations due to the differences of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d-&amp;q</i> -axis inductance and abundant spectrum of exciting forces. This article presents an intensive comparison of IPM motors with three design approaches to reduce cogging torque, torque ripple, and electromagnetic vibration. The design approaches compared cover skewing slot and segmented rotor approaches commonly used in industry, as well as a new asymmetric pole approach. A commercial 10 kW 8-pole/ 48-slots V-shaped IPM motor for EV traction is taken as the reference base. Extensive performance comparisons, including cogging torque, back-EMF, load current, load torque profiles, PM reliability, and torsional force were carried out. Besides, vibration aspects in terms of exciting force, modal property, and electromagnetic vibration response were also analyzed and compared. Finally, the prototypes with the mentioned three design approaches are produced, respectively, and intensive experimental tests were done to verify the analysis and comparison.