Torque Producing Components Research Articles

Evaluation of intelligent PPI controller for the performance enhancement of speed control of induction motor

Induction motor control for high dynamic performance industrial applications is often difficult due to parameters sensitivity and its non-linearity. Through independent manipulation of the flux and torque producing components, Field Oriented Control (FOC) methodologies have been used to improve dynamic performance, widen speed range, and torque/flux quality. Studies have shown that the Parallel Proportional Integral (PPI) compensation method produces responses of higher quality than the traditional cascaded Proportional Integral (PI) type though tuning gains for PPI controller is time consuming and inaccurate. In this research work, modeling of control strategy for Induction motor and tuning of four parameters (Ki, Ki1, Kp, Kp1) of PPI controller at the outer speed control loop have been conducted using GA and PSO algorithms. The speed and torque responses' performances of the proposed controller, PPI-PSO and PPI-GA, have been contrasted with each other. For simulation, SIMULINK and a programming environment of a MATLAB software were employed. The simulation result illustrated that PSO based tuning out performs the GA based tuning in terms of dynamic speed response, torque quality and disturbance rejection capability in the newly control mechanism. Although the speed trajectory tracking performance of both the controllers presented in this study is comparable, comparatively low dynamic performance was found for PPI-GA controller at both high and low speed tests inside the same search space. The PPI-PSO controller yields an optimal result having 0.270 % overshoot, a settling time of 8.185 s, and a rise time of 8.037 s in comparison with PPI-GA controller which exhibits overshoot of 0.640 %, a settling time of 9.596 s, and a rise time of 8.615 s with high-speed trajectory tracking test.

Design and Analysis of Novel Three-Phase PFC for IM Drives

Induction motor drives (IMDs) can achieve high performance levels comparable to dc motor drives. A major problem in getting high dynamic performance in an IMD is the coupling between the flux and torque producing components of stator current. This is successfully overcome in FOC (Field-Oriented Control) IM, making it to the industry standard control. The performance of an IMD with an improved power quality converter at the front end is presented in this study. In the IMD, boost converter is employed to reduce power quality difficulties at the utility interface. As the boost converter contains only one switch, it results in a low processing time and cost. To ensure sinusoidal supply currents with high PF (Power Factor) and minimal THD (Total Harmonic Distortion), a novel PFC (Power Factor Corrector) control technique is proposed. To enhance the performance of the converter and to lower distortions at the motor side, PI (Proportional Integral) controller is incorporated at the PFC side. Thus it controls the DC bus voltage. The proposed boost converter improves power quality by lowering overall harmonic distortion of AC mains current, improving power factor correction, and regulating dc-link voltage. It is designed, modelled, and simulated in the MATLAB/simulink platform. Using a DSP (Digital Signal Processor), the suggested system’s performance is experimentally validated. The system’s performance is evaluated for speed and load torque, and the power quality indices are determined to meet IEEE-519 standards under all operating conditions. From the obtained results, it is evident that the proposed system mitigates the power quality issues effectively.

Inertialess gyrating engines.

A typical model for a gyrating engine consists of an inertial wheel powered by an energy source that generates an angle-dependent torque. Examples of such engines include a pendulum with an externally applied torque, Stirling engines, and the Brownian gyrating engine. Variations in the torque are averaged out by the inertia of the system to produce limit cycle oscillations. While torque generating mechanisms are also ubiquitous in the biological world, where they typically feed on chemical gradients, inertia is not a property that one naturally associates with such processes. In the present work, seeking ways to dispense of the need for inertial effects, we study an inertia-less concept where the combined effect of coupled torque-producing components averages out variations in the ambient potential and helps overcome dissipative forces to allow sustained operation for vanishingly small inertia. We exemplify this inertia-less concept through analysis of two of the aforementioned engines, the Stirling engine, and the Brownian gyrating engine. An analogous principle may be sought in biomolecular processes as well as in modern-day technological engines, where for the latter, the coupled torque-producing components reduce vibrations that stem from the variability of the generated torque.

Space-Shifted Wye–Delta Winding to Minimize Space Harmonics of Fractional-Slot Winding

A space-shifted wye–delta winding for fractional-slot concentrated winding (FSCW) is proposed that can simultaneously cancel both sub- and super-order harmonics of its stator MMF. The new winding concept proposes two sets of three-phase windings by doubling the number of stator slots connected in the wye–delta configuration. These two winding sets are shifted in space with respect to each other and are connected in series. The wye–delta configuration eliminates subharmonics and enhances the torque-producing component, whereas their relative shifting angle eliminates the dominant higher order harmonics to provide a cleaner and enhanced MMF spectrum. In FSCW motors, dominant space harmonics other than the torque-producing component give rise to undesirable losses in the magnet and rotor core. The efficacy of the proposed method is demonstrated through its stator MMF, harmonic spectrum, and motor performance using finite-element analysis. The application of the proposed winding to a permanent magnet (PM) machine showed dominant sub- and super-order harmonics cancellation, total harmonic distortion reduction, and magnetic loss reduction along with torque density and power factor improvements. A prototype PM machine is built, and the performance of the proposed concept is verified experimentally.

Robust and High-Dynamic-Performance Control of Induction Motor Drive Using Transient Vector Estimator

The two most commonly used induction motor control methods are the scalar ( $V/f$ ) and vector (field-oriented) control techniques. $V/f$ control has good steady-state response and robustness against the variation in machine parameters, but the resulting torque dynamics are poorer. Vector control achieves better dynamic performance by decoupling the flux- and torque-producing components of the stator current. Vector-controlled techniques are heavily dependent on the machine parameters and are sensitive to the variation in machine parameters. This paper proposes a novel control technique, which integrates the robustness features of scalar control and good dynamic performance of vector control. Estimation of the transient vector is responsible for improving dynamics in the proposed control. The proposed control technique uses an optimal controller with an output feedback law. The operation of the proposed control is validated experimentally under both steady-state and transient conditions. Finally, the proposed control is compared with both the $V/f$ and vector control strategies in terms of dynamic performance and parameter sensitivity.

Reactive power allocation for loss minimisation in a stand alone variable speed constant frequency double output induction generator

Vector control algorithms reported so far for stand alone operation of variable speed constant frequency double output induction generators propose to supply the full magnetisation current of the machine in addition to the torque producing component from the rotor side converter. As the rotor of a normal induction machine is not designed for this additional load this approach leads to underutilisation of the machine torque capacity. Moreover, supplying the entire magnetisation current from the rotor side is not optimal from the point of view of the machine losses. Since the load voltage is regulated by manipulating the magnetising current through a slow acting flux control loop undesirable fluctuations in the load voltage waveforms are observed during fast load transients. An improved stator flux oriented control strategy for this type of generators, proposed in this study, eliminates undesirable load voltage transients by directly regulating the stator flux through the stator side converter. The total reactive power demand of the system is dynamically distributed between the two converters according to an optimum allocation program so as to minimise the losses without disturbing the stator flux. The effectiveness of the proposed algorithms is verified experimentally on a laboratory prototype.

Effects of flux level on a CSI-fed field-oriented induction motor

A definite relation exists between the flux level, torque and slip speed of a vector controlled induction motor. An untuned vector controller generates an inappropriate slip frequency that changes the operating flux of the machine. This affects the electromagnetic torque linearity and dynamic performance of the drive system. For an induction motor with magnetic saturation, the ratio of flux and torque-producing components of stator current differs from unity for the maximum electromagnetic torque. With a linear model this ratio is unity. The dependence of this ratio for maximum torque output is explained for linear and nonlinear models of the machine. The torque characteristic is analysed with three aspects of magnetic state: true saturation curve, hard-limit saturation curve, and constant inductance model. Degradation in dynamic performance due to saturation for a CSI-fed system is presented.

Real-time detection of intermittent misfiring in a voltage-fed PWM inverter induction-motor drive

This paper develops a real-time condition-monitoring algorithm for pulsewidth modulation (PWM) inverter induction-motor drives. It is designed to detect the intermittent loss of firing pulses of an individual switching device within the inverter. The mathematical model of the induction machine is linearized in the field-torque coordinates, and the misfiring of the inverter is represented by pulse functions, which have effects in both the field and torque directions. Since the fault considered is of an intermittent nature, the time-domain response of the magnetizing and the torque-producing components of the motor stator current is used to form the condition-monitoring signal. The method is adaptive to changes in the operating point during variable-speed operation. Digital simulation and laboratory experiment are utilized to illustrate the method and to evaluate the computational effort required.

Derivation of Linearized Model of Induction Motor on The Basis of Magnetic Energy and Control by PWM Inverter Drive.

Induction motor is expressed as a nonlinear system on a synchronously rotating reference frame. In applying linear control theory, we have usually derived a linear approximated model with a specific operating point. However, the model obtained by this method is not much accurate.In this paper, we derive a linearized model for induction motor from a magnetic energy point of view. In this linearized model, the torque and the stored energies in the rotor field are choosen as state variables, and these magnetic energies are decoupled. This suggests that torque-producing component current and flux-producing conponent current become decoupled. Availability of a control system used the linearized model is illustrated by simulation and experiment results.

Increasing the dynamic torque per ampere capability of induction machines

The objective of this paper is to present a novel means of increasing the dynamic torque per ampere capability of induction machines. The method developed is based on use of an indirect field oriented controller (IFOC) for the induction machine. It is well known that IFOC allows the rotor flux amplitude to be controlled by the d-axis component of stator current. It is also well established that the flux-producing component of the stator current may be controlled independent of the torque-producing component of the stator current. The principal constraint, however, is that the amplitude of the peak current (the vector amplitude) is limited by the power electronic switch ratings. This constraint implies that optimal partitioning of the current components should be possible. Previously used methods have optimized steady state efficiency or steady state torque per ampere. This paper identifies a dynamic method which achieves transient torques over 35% greater than the prior methods. The limitations of the method and its sensitivity to detuning is also examined. >

A power method of measuring the torque-producing output of a magnetic amplifier driving one phase of a two-phase servo motor

The purpose of this paper is to describe a ?power? method of measuring the useful, torque-producing component of the a-c output voltage from magnetic amplifiers used in applications wherein the output phase angle is important, and wherein the ideal phase angle, with respect to the amplifier's excitation, is either zero degree or 90 degrees. Typical of such applications is a single-phase amplifier used to drive one phase of a 2-phase servo motor.