Load Torque Perturbations Research Articles

Speed synchronization of two DC motors with independent loads based on the higher load torque

Dual-motor and multi-motor electric drive systems have been used in many industrial applications, and speed synchronization of the motors can always get worse by system parameter uncertainties and load torque perturbations. This work focuses on the application of adjustable speed double-direct current (DC) motor drive control systems. In this paper, a system of two DC motors with armature control at different load conditions has been built. The synchronization of these motors was set basing on the higher torque of the two motor shafts. When two DC motors operate at different shafts a challenge appears in synchronization of their speeds, particularly with the existence of load difference allocated on their shafts. This work paid special attention to this problem. It presents a dynamic simulation of speed control and synchronization of dual DC motor drive. The results show the advantages of the used technique in terms of steady-state and transient performance.

Robust Cascaded Deadbeat Predictive Control for Dual Three-Phase Variable-Flux PMSM Considering Intrinsic Delay in Speed Loop

In this article, a robust cascaded deadbeat predictive speed control method (PSC) is proposed with speed and disturbance observer for the dual three-phase variable-flux permanent-magnet synchronous motor (VF-PMSM) drives. Considering the intrinsic delay in speed loop, an improved predictive speed model has been derived in discrete domain. In turn, a speed observer is proposed for the cascaded PSC to mitigate the issue of this intrinsic delay. In order to improve the system robustness, the torque disturbance observer including the generalized proportional integral observer and the sliding-mode observer has been proposed for parameter variation and load torque perturbation. Furthermore, the stability analysis indicates that the margin of parameter mismatch is determined by the coefficient in the speed observer, which can be expressed as the equivalent gain in discrete domain. The performance comparison between the conventional PSC method and the proposed PSC method has been investigated for parameter robustness. The experimental results are presented to verify the improvements of the proposed PSC method for the dual three-phase VF-PMSM drives under model uncertainty and magnetization manipulation conditions.

Three-Phase Induction Motor Controller Design Based on Hysteresis Voltage Control

This paper describes a controller for Three-Phase Induction Motor. Induction motor is an electromechanical actuator widely used due to its reliability and relatively low maintenance cost. However, the control problem of an induction motor is complex due to nonlinearities, load torque perturbation, and parameter uncertainties. An element included in this study is voltage source control, which is to control the voltage fed from three-phase inverter to Three-Phase Induction Motor. Hysteresis Controller was proposed in this paper to minimize voltage error. Hysteresis controller is seen as an input – output phase lag corrector. The implementation of the designed hysteresis controller is performed in simulation using MATLAB/Simulink. The result proved that the proposed controller design can minimize the line voltage error of the induction motor, preventing the line voltage from being kept low hence avoiding excess current at low speeds.

Performance of synchronized master-slave closed-loop control of AC electric drives using real time motion over ethernet (RTMoE)

Multi-motor driving servomechanisms are widely used in modern industry for high-performance applications involving synchronized control of position, speed, acceleration and deceleration. Several synchronous control schemes have been developed to achieve good speed or position tracking regardless of various uncertainties and load torque perturbations. However, these solutions have some disadvantages, namely the costs associated with the necessary interfaces to transmit hardware synchronization signals between multiple drives and difficulty to integrate other tools and communication networks. Recently, Industrial Ethernet network-based control systems are becoming increasingly popular for industrial applications and factory automation. To overcome some of these disadvantages this paper proposes an approach that uses a real-time Ethernet applied to a dual-motor master-slave synchronization system, without introducing significant degradation of speed or position in the application performance. With this solution the position reference from the master encoder is transmitted by the real-time Ethernet instead of the classic hardware interface. This allows the integration of different tools and the explore of other functionalities of electric drives. The performance of the proposed solution was tested using industrial equipment through several practical experiments. It was also compared with an existing solution based on hardware interfaces, to identify advantages, limitations and cost savings of using real-time Ethernet networks solutions in synchronized AC electric drives.

Disturbance Observer Based Robust Sliding Mode Control of Permanent Magnet Synchronous Motor

This paper addresses speed control of permanent magnet synchronous motor under load torque perturbations. The mathematical model is derived using park’s transformation. The load torque disturbance is considered unknown bounded, and states variables are available in feedback. In order to achieve robust speed performance, sliding mode control (SMC) is introduced. However, it is noted that conventional SMC does not provide satisfactory performance under load torque disturbances. To end this, a novel control strategy called disturbance observer SMC (DOSMC) is formulated. It includes an observer that offers a tool to vanish the effect of load torque. The DOSMC technique has two distinguished characteristics: first, the design gains are needed to be greater than the maximum limit of disturbance estimation error instead of disturbances, second; the proposed observer estimates load disturbances and provide a compensator to update sliding surface and control input. The stability analysis of overall control system is verified using Lyapunov theorem. Simulations in MATLAB/Simulink proves efficacy of the proposed scheme.

Speed Tracking and Synchronization of a Dual-Motor System via Second Order Sliding Mode Control

Dual-motor systems have been widely used in industrial applications, and speed synchronization of the motors can always be deteriorated by system parameter uncertainties and load torque perturbations. In this paper, a new robust control strategy for the dual-motor systems is developed by incorporating second order sliding mode control (2-SMC) techniques. The strategy is to design chatting-free control laws to stabilize speed tracking of each motor while synchronizing their velocity. In the proposed scheme, firstly, speed controller for a single motor is designed to eliminate the effects of system parameter variations and load torque perturbations. Secondly, a cross-coupled architecture based synchronous controller is designed to reduce speed error of the motors caused by characteristic inconsistency and unbalanced load torque. Stability of the closed loop system is analyzed by Lyapunov theory; it is proven that both speed tracking errors and synchronous error can converge to zero. Finally, experiments are performed to examine the effectiveness of the developed controllers. Experimental results will show the good performance of the proposed control scheme.

Induction motors variable speed drives diagnosis through rotor resistance monitoring

Induction motor driven by vector control method makes high performance control of torque and speed possible. The decoupling of flux and electromagnetic torque obtained by field orientation depends on the precision and the accuracy of the estimated states. Rotor asymmetries lead to perturbations of air gap flux patterns in induction machines. These perturbations in flux components affect the electromagnetic torque, as well as stator currents and voltages. This paper first investigates the control of the induction motor using an extended Kalman filter (EKF) for a direct field-oriented control. It then studies the broken rotor bars (BRBs) fault by the monitoring the rotor resistance. The hypothesis on which the detection is based is that the apparent rotor resistance of the motor will increase when a rotor bar breaks. The rotor resistance is estimated and compared with its nominal value to detect BRBs fault. The EKF estimates the rotor flux, speed and rotor resistance on line by using only measurements of the stator voltages and currents. Simulation results show the effectiveness of the proposed method in the cases of load torque perturbation and speed reversion.

Load Torque Estimation and Passivity-Based Control of a Boost-Converter/DC-Motor Combination

An algebraic approach is presented for the fast feed-forward adaptation of the angular velocity trajectory tracking task in a Boost-converter driven dc-motor system. For the adaptation, the load torque perturbations are assumed piecewise constant and are, nonasymptotically, online estimated using the available noisy measurements of the state variables. The controller is a linear controller based on the exact tracking error dynamics passive output feedback (ETEDPOF) controller design methodology including suitable adaptive feed-forward precompensation depending explicitly on the precisely estimated torque. The performance of the adaptation, which is achieved by means of the algebraic online-estimation of the current unknown load torque, is successfully validated in an experimental laboratory setup.

A Third-Order Sliding-Mode Controller for a Stepper Motor

This paper deals with the robust control problem of a stepper motor subject to parameter uncertainties and load torque perturbation. The developed algorithm is based on third-order sliding-mode control such that a desired angular motor position is accurately tracked. The proposed scheme requires the measurement or the estimation of the motor speed and acceleration for feedback. To avoid the use of tachometers and accelerometers which add cost and energy consumption, a robust second-order sliding-mode observer is presented. Experimental results illustrate the performance and the advantages of the proposed controller.

Observer-based second order sliding mode control laws for stepper motors

This paper deals with the design of an observer-based second order sliding mode control law for the stepper motor. The control objective is to perform accurate tracking of the motor position. The motor velocity is obtained via a second order sliding mode observer. The second order sliding mode controller is shown to be robust with respect to time-varying load torque perturbation and parametric uncertainties. Experimental results illustrate the efficiency of the proposed approach.

Sensorless direct torque control of an induction motor by a TLS-based MRAS observer with adaptive integration

This article presents a new speed and flux estimation algorithm for high-performance direct torque control (DTC) induction motor drives based on model reference adaptive systems (MRAS) observers using linear artificial neural networks (ANNs). Two completely new improvements of MRAS speed and flux observers are presented here: the first is a solution to the open-loop integration problem in the reference model, based on the voltage model of the induction machine, by means of a new adaptive neural integrator, the second is the employment of a new adaptation law in the ANN adaptive model, based on the total least-squares (TLS) technique. In particular, the adaptive neural integrator is based on two adaptive noise filters which completely cancel any DC drift present in the voltage or current signals to be integrated. This neural integrator does not need any a priori training of its two only neurons, adapting itself on-line. With regard to the ANN-based adaptive model, since the most suitable least-square technique to be used for training is the TLS technique, here the neuron is trained on-line by means of a TLS EXIN algorithm which is the only neural network able to solve a TLS problem recursively. Also the TLS EXIN algorithm does not require any a priori training, since it adapts itself recursively on-line. Moreover, to improve the dynamical performances of the speed loop of the drive, the adaptive model has been used as predictor, i.e. without any feed-back between its outputs and its inputs. The sensorless algorithm has been verified experimentally both on the classic DTC technique and on the DTC-SVM (space vector modulation), by adopting a proper test set-up. The speed observer has been tested in the most challenging operating conditions. The experimental results show that the dynamical performances of the sensorless drive are comparable or even better than those obtained with the corresponding DTC drives with encoders as for the medium to high-speed ranges. As for low-speed ranges, the presented sensorless DTC algorithm outcomes the performance presented in the literature for MRAS systems, thus permitting to have an accurate estimation equal or better than that obtainable with more complex observers. Finally, experimental results show that the MRAS speed observer is robust to load torque perturbations and permits zero-speed operation at no-load conditions.

A Trajectory Planning Approach for the Regulation of the Induction Motor

An output feedback passivity based controller is suitably combined with an off-line trajectory planning for the equilibrium to equilibrium regulation of the nonlinear induction motor. As obtained from computer simulations, the proposed dynamic feedback controller naturally sustains the presence of un-modelled constant load torque perturbations and it is robust with respect to discontinuous variations of the rotor resistance parameter.

A speed control method for a PM motor using a speed observer and a low‐resolution encoder

AbstractThis paper proposes a new speed control method for a PM motor using a low‐resolution encoder and a speed observer. The servo system should be economical and simple. For this purpose, this paper realizes the high‐performance speed control system using a low‐resolution encoder, whose performance is nearly equal to the performance of speed servo system using a conventional optical encoder. The speed observer uses the information of motor current and motor voltage. The rotor position is calculated by the estimated value of speed observer. This observer has the influence of electrical parameter variation. This paper proposes the correction algorithm of both the voltage error of PWM inverter and the electrical parameter variation. The experimental results and numerical simulation results point out that the proposed speed control system has the desired speed response with respect to parameter variations and load torque perturbation. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 143(1): 66–75, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10121

Speed Control Method for PM Motor using Speed Observer and Low Resolution Encoder

This paper proposes a new speed control method for PM motor using a low resolution encoder and a speed observer. The servo system should be economical and simple. For this purpose, this paper realizes the high performance speed control system using a low resolution encoder, whose performance is nearly equal to the performance of speed servo system using a conventional optical encoder. The speed observer uses the information of motor current and motor voltage. The rotor position is calculated by the estimated value of speed observer. This observer has the influence of electrical parameter variation. This paper proposes the correction algorithm of both the voltage error of PWM Inverter and the electrical parameter variation. The experimental results and numerical simulation results point out that the proposed speed control system has the desired speed response, on condition of parameter variations and load torque perturbation.

A PASSIVITY PLUS FLATNESS CONTROLLER FOR THE PERMANENT MAGNET STEPPER MOTOR

ABSTRACTA passivity based controller, in suitable combination with the flatness property of the system, is proposed for the effective feedback equilibrium to equilibrium regulation, via planned trajectory tracking, of the angular position in a permanent magnet (PM) stepper motor. The control scheme is shown to be easily modifiable as to include traditional proportional‐integral‐derivative (PID) feedback control actions which efficiently account for unmodeled load torque perturbations.

Maximum slew-rate governor control for impulse turbines

A deflector bang-bang and speed derivative methodology for controlling impulse turbine transients is developed. The control was implemented in a linear simulation to demonstrate its effectiveness in controlling load torque perturbations. The proposed controller strategy is implemented in a nonlinear simulation. The design was found to significantly reduce turbine off-speeds and nominal operating point settling times in both simulations. >