Variable Speed Induction Motor Research Articles

A Variable Speed Induction Motor Drive With 24-Stepped Voltage Waveform Throughout Modulation Range

Multi-level inverters produce low order harmonics in over-modulation region, which can be eliminated by generating polygonal space vector structure. A variable speed induction motor drive to generate 24-stepped voltage waveform throughout modulation range is proposed in this article. An open-end winding configuration induction motor (OEIM) is fed with primary and secondary inverter from both the ends of OEIM and generates a 24-stepped phase voltage. The proposed scheme also produces 96-stepped phase voltage waveform at extreme modulation index with highly suppressed higher order harmonics and excellent quality phase voltage. The motor terminal sees a 24-stepped waveform at all speeds, devoid of low order harmonics up to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$19^{th}$</tex-math></inline-formula> order. The scheme does not require vector timing calculation due to availability of highly dense 24-sided polygonal structure. Primary and secondary inverters are derived by cascading flying capacitor and CHB cells. Experimental verifications are performed on in-house developed laboratory prototype. Motor phase voltage and phase current waveforms during steady state and transient conditions justifies performance of the proposed scheme. Dynamic performance and floating capacitors voltage balancing method are verified by experimental results.

Improved Control Strategy for Water Pumping System Fed by Intermittent Renewable Source

This paper focuses on a water pumping system fed by a hybrid (PV–Wind) generator. The water pumping system uses centrifugal pumps driven by variable speed Induction Motors (IM) controlled by a Field Oriented Control (FOC). The absence of battery storage to decouple sources and power demand is the main originality of the contribution, together with the typical adaptation of the FOC strategy. Furthermore, the absence of battery storage will consequently lead to fixing the system operating point at a steady state which is imposed both by the intermittent renewable energy sources and by the hydraulic load characteristics. The basic idea is then to adapt the system impedance by using the two degrees of freedom offered by the power source inverter in order to control, firstly, the DC bus voltage and, secondly, the rotor flux of the induction machine; the adaptation of the FOC strategy is based on this idea. Simulation results clearly confirmed by experimental investigations show the satisfying performance of the system even with variable powers of the intermittent renewable source.

Model reference adaptive system speed estimator based on type-1 and type-2 fuzzy logic sensorless control of electrical vehicle with electrical differential

Introduction. In this paper, a new approach for estimating the speed of in-wheel electric vehicles with two independent rear drives is presented. Currently, the variable-speed induction motor replaces the DC motor drive in a wide range of applications, including electric vehicles where quick dynamic response is required. This is now possible as a result of significant improvements in the dynamic performance of electrical drives brought about by technological advancements and development in the fields of power commutation devices, digital signal processing, and, more recently, intelligent control systems. The system’s reliability and robustness are improved, and the cost, size, and upkeep requirements of the induction motor drive are reduced through control strategies without a speed sensor. Successful uses of the induction motor without a sensor have been made for medium- and high-speed operations. However, low speed instability and instability under various charge perturbation conditions continue to be serious issues in this field of study and have not yet been effectively resolved. Some application such as traction drives and cranes are required to maintain the desired level of torque down to low speed levels with uncertain load torque disturbance conditions. Speed and torque control is more important particularly in motor-in-wheel traction drive train configuration where vehicle wheel rim is directly connected to the motor shaft to control the speed and torque. Novelty of the proposed work is to improve the dynamic performance of conventional controller used of model reference adaptive system speed observer using both type-1 and type-2 fuzzy logic controllers. Purpose. In proposed scheme, the performance of the engine is being controlled, fuzzy logic controller is controlling the estimate rotor speed, and results are then compared using type-1 and type-2. Method. For a two-wheeled motorized electric vehicle, a high-performance sensorless wheel motor drive based on both type-2 and type-1 fuzzy logic controllers of the model reference adaptive control system is developed. Results. Proved that, using fuzzy logic type-2 controller the sensorless speed control of the electrical differential of electric vehicle EV observer, much better results are achieved. Practical value. The main possibility of realizing reliable and efficient electric propulsion systems based on intelligent observers (type-2 fuzzy logic) is demonstrated. The research methodology has been designed to facilitate the future experimental implementation on a digital signal processor.

Robust Nonlinear Predictive Control Applied to Induction Motors

In this paper, a nonlinear predictive controller is proposed for a variable-speed induction motor. The research work is directed towards improving the trajectory tracking capability, stability guarantee, robustness to parameter variations, and disturbance rejection. The Generalized Predictive Control (GPC) without constraint and output-constrained controller to induction motor drive is illustrated. The variables to be controlled are rotor speed and flux trajectory. The load torque is considered an unknown disturbance. Finally, the tuning parameter of GPC is automatically determined. The simulation results show a good performance for the nonlinear dynamic system.

Harmonic generation of variable speed drive under complex-voltage unbalance conditions

Efficiency in the industrial sector is a priority when seeking to minimize production costs and reduction in losses. Harmonic generation and associated losses need to be treated carefully with broad implementation of variable speed induction motor applications. The effect of these induced losses can add up to a significant loss. This study uses statistical tools alongside synthesized models to deduce and compare outcomes from regulated and unregulated converters in which harmonics may be triggered by switching algorithm of modern switch-mode power supplies and other inductive loads attached to supply bus system. These harmonics accumulate over time due to losses propagating through connected equipment when changes occur on the bus system. In this regard, results obtained from investigating and comparing three original equipment manufacturer variable speed drives that were exposed to voltage unbalance and complex harmonic conditions are presented in this study. A conclusion accomplished from the investigation and comparison suggests that generation of 6-pulse uncontrolled rectifier losses is negligible. Experimental validation confirms that unregulated 6-pulse converter produces on average more harmonics compared to the regulated converter of standard as recommended in guideline to permissible harmonic tolerance.

Variable speed induction motors’ fault detection based on transient motor current signatures analysis: A review

Induction motor is a major component in the industrial sector. It is experiencing great development concerning size, market share, and technological design. Any sudden failure in this element may lead to great damage. Condition monitoring is a fast emerging technology for the online detection of induction motor incipient faults. It avoids unexpected failure of a critical system, by increasing the life expectancy of the concerning elements while reducing operation and maintenance costs. This paper presents the condition monitoring techniques used with these machines, focusing on the Transient Motor Current Signatures Analysis method that has proven its effectiveness in diagnosing faults of electrical rotating machines, gathering a review on the most important applications that can be used with this technology, and how to process these signals to find out the type and cause of the fault. What distinguishes this paper is that it focuses on applications with variable speeds, so two promising techniques that will be effective in non-stationary signals frequency estimation are presented, which are the Adaptive Notch Filtering method and the Adaptive-Observer approach. Challenges and future goals are also discussed to guide researchers wishing to delve into this field.

Closed-Loop Adaptive High-Starting Torque Scalar Control Scheme for Induction Motor Variable Speed Drives

This article proposes a closed-loop (CL) high-starting torque (HST) scalar control scheme (SCS) for induction motors (IM). It endows the recently proposed HST-SCS with high-output torque capability beyond starting after using an outer speed control loop feeding an inner current control loop with adaptive controllers. Presenting a cascade normalized adaptive passivity-based controller (N-APBC) for nonlinear systems encompassing the IM allows obtaining this result. It extends the normalized adaptive controller for the cascade case. As a result, it keeps the HST-SCS simple control scheme without needing variable observers or parameter estimators and employing tuning information only from the motor nameplate and datasheet. Test bench experiments with a 10 HP motor validate the proposal’s effectiveness. Comparative experimental results show that the CL HST-SCS has a required stator phase voltage lower than HST-SCS. The CL HST-SCS applies the adaptive starting voltage curve for a more extended time than HST-SCS, from the start to 1.9 s versus 1.2 s, respectively. Hence, CL HST-SCS assures HST not only for starting but almost up to 600 rpm, resulting in a smoother transient behavior than HST-SCS under this speed.

New Adaptive Starting Scalar Control Scheme for Induction Motor Variable Speed Drives

This article proposes a new scalar control scheme for variable speed drives of induction motors with an adaptive starting control. Besides centrifugal pumps, blowers, and fans, it expands the scalar control application field to move, for instance, a class of conveyor belts with nominal torque loading. An adaptive passivity-based controller designed for a class of nonlinear systems encompassing the dynamical machine model keeps a constant stator starting current. The proposed methodology uses information from the motor nameplate. Hence, it keeps a simple control scheme, not needing parameter estimates, neither adjusting controllers nor variable observers depending on them. Experimental results with a 10 HP downscaled laboratory prototype validate the proposed control strategy effectiveness. It shows rated-starting torque capabilities and fast speed response. Moreover, it shows lower stator current consumption than previous scalar control schemes.

Simulation Analysis and Experimental Evaluation of Improved Field-Oriented Controlled Induction Motors Incorporating Intelligent Controllers

This work discusses the simulation and experimental demonstration of a genetic algorithm hybrid fuzzy-fuzzy controller (GA-HFFC) system to achieve speed control of a variable-speed induction motor (IM) drive based on a space vector pulse width modulation (SVPWM) technique by means of an eZdspF28335 digital signal processing (DSP) experiment board. Two features of field-oriented control (FOC) were used to design the GA-HFFC, namely, the current and frequency. To overcome the limitations of the FOC technique, the principles of the GA-HFFC were introduced through the acceleration-deceleration stages to regulate the speed of the rotor with the help of a fuzzy frequency controller, while a fuzzy stator current amplitude controller was involved during the steady-state stage. The results revealed that the proposed control approach could deliver a practical control solution in the presence of diverse operating conditions.

SENSORLESS VECTOR CONTROLLED THREE-PHASE PWM INVERTER-FED INDUCTION MOTOR DRIVE SYSTEM WITH AUTO-TUNING ESTIMATION OF MACHINE PARAMETER APPROACH

This paper deal with a practical development technology on a highly accurate faster response adjustable speed drive implementation for the three-phase sinewave fed general purpose induction motor system which is based upon sensorless slip frequency type vector control scheme with an automatic auto-tuning machine parameter estimation strategy. The essential procedure and considerations to measure and estimate the exact stator and cage rotor circuit parameters of the induction motor treated here are discussed under its operating conditions. The speed regulation characteristics of the induction motor is illustrated and evaluated for the induction machine parameter variations under the actual operating conditions ranging from a low frequency to a high frequency for various specified load torque setting. The variable speed induction motor drive system employing sensorless slip frequency-based vector control scheme which incorporates the current controlled three-phase high frequency carrier PWM switching inverter with automatic auto-tuning estimation strategy on the temperature-dependent and -independent machine circuit parameters is practically implemented using DSP-based vector controller. The dynamic speed response performances under essentially changed load torque disturbances as well as steady state speed against torque characteristics of the proposed variable speed drive control and implementations are illustrated and discussed from an experimental point of view.

A Novel Solution to Eliminate Frequency Intermittency by Adding Spinning Reserve to the Micro-Hydro Turbine Generator using Real-Time Control of Induction Motor through AC-DC-AC Power Converters

Small micro-hydro has a variable output in terms of frequency and voltage. Formerly Electronic Load Controller has been used to stabilize the output frequency of micro-hydro in which these ELCs wasted extra generated energy as heat. In this paper, a novel approach to handle these frequency variations by designing a Variable Frequency Drive (VFD) is proposed. Besides, the electronic governor of micro-hydro turbine generator is designed by incorporating a variable speed induction motor. Thus, the spinning reserve of the motor could be used for irrigation or water storage purposes by consuming extra generated power. Further, the DC bus of VFD enables the system to integrate with other Distributed Energy Sources (DES), which will be helpful in the future extension of the microgrid.

Implementation of a V/f Controlled Variable Speed Induction Motor Drive

DSP implementation of speed control of three phase induction motor drive is presented in this paper. A closed loop speed control has been achieved using constant V/f technique which is a simple scalar control method used to control the magnitude of the control quantities. In this study, a fourth order polynomial drived from V/f curve is constructed instead of using look up table which takes much time for determination of voltage from frequency value. A PI controller is used in speed control. dSPACE DS-1103 controller board is used for the implementation with Matlab/Simulink, which has a simple real time interface. Steady-state speed characteristics and transient responses with various reference speed commands are presented by experimental system. The simulation and experimental results provide a smooth speed response and good performance under various dynamic operations. Real time speed control has been implemented and some results are presented.

Fast Frequency Response From Smart Induction Motor Variable Speed Drives

Using their fast power reduction capabilities, the induction motor variable speed drives can successfully participate in the power system primary frequency control. A new control strategy for fast frequency support from the diode front-end induction motor variable speed drive is presented in this paper. By this, practical restrictions are considered. In this context, an existing conventional scheme presented in literature is firstly modified by deploying an estimated motor's power losses for a more exactly control design. Next, a novel control scheme is proposed. It attains the fastest frequency support from the drive and simultaneously restricts its minimum power consumption to a given positive value to prevent regeneration mode during the frequency support process. The frequency of applied voltage to the motor is adjusted through a proportional-integrator compensator with deviation of the drive's consumption power from its reference power as input. The reference power is synthesized by permanent and temporary components, which are determined based on deviation and time derivative of the power system's frequency, respectively. The effectiveness of the proposed smart drive for the primary frequency control is investigated using the New England 39 bus and a more realistic Great Britain 36 zone test networks. It improves system frequency response in terms of the rate of change of frequency and the frequency nadir. Furthermore, the new control scheme can contribute to quickly damping inter-area oscillations in multi-machine power systems.

Weighting Factors Optimization of Predictive Torque Control of Induction Motor by Multiobjective Genetic Algorithm

This study investigates the application of a multiobjective genetic algorithm for the obtaining of a set of weighting factors suitable for use in the model predictive torque control (MPTC) of an induction motor variable speed drive. The MPTC approach aims at minimizing a cost function at each step and has been highlighted for its fast torque response, easy incorporation of system constraints, and absence of voltage modulators. Nevertheless, its structure contains weighting factors in the cost function, which lacks an analytical design procedure. The nondominated sorting genetic algorithm II (NSGA-II) was designed for a tradeoff between torque and flux performances and average switching frequency of the system. Experimental results showed NSGA-II offered a Pareto set of feasible solutions, so that torque ripple, flux ripple, or average switching frequency can be minimized, depending on the solution chosen. Its application constitutes a project tool for MPTC weighting factors that adjusts several factors concomitantly and incorporates desired restrictions.

A Simplified Predictive Torque Control Scheme for Open-End Winding Induction Motor Drive

Variable speed induction motor (IM) drives with predictive torque control (PTC) technique is an advancing technology nowadays. The PTC technique is introduced for dual-inverter fed open-end winding IM (OEWIM) configuration owing to its benefits. The conventional PTC requires flux weighting factor assignment because of two different control objectives (torque and flux) in single cost function. This weighting factor selection plays a key role in selecting optimal voltage vector for better torque and flux response. Several analytical and empirical methods are introduced for optimal selection of weighting factor, which demands more computation time. This paper aims to develop modified PTC, eliminating flux weighting factor. The flux control objective is replaced by an equivalent reactive torque control. Thus making two control objectives of the same units and eliminating the requirement of flux weighting factor in cost function. Furthermore, nearest voltage vector selection strategy is introduced to limit the number of prediction voltage vectors in each sampling period. Thus, overall computational burden is reduced achieving minimum torque and flux ripples. The performance of the proposed PTC for multilevel inversion fed OEWIM is evaluated through MATLAB/Simulink simulations and experimental analysis. To highlight its benefits, these results are compared with those of the conventional and recent PTC techniques.

Impact of Core Material Grades on the Performance of Variable Speed Induction Motors Fed by Inverters

In this paper, we investigate the variation in performance of variable speed induction motors fed by inverters with grades of core materials used for stators and rotors from both results of measurement and finite element analysis. Identical shaped stator/rotor cores are manufactured by using several kinds of electrical steel sheets from low to high grades. Then, the characteristics of these motors are measured. Finite element analysis is applied to these motors to understand the measured results by separating losses and torques according to origins. The measured motor characteristics are found to be in good agreement with the results of the analysis. The analysis reveals the variation in each loss component with electrical steel sheets. Finally, the strong and weak points of the application of high-grade electrical steel sheets to the variable speed induction motors are discussed.

Prediction of the mass unbalance of a variable speed induction motor by stator current multiple approaches

Generally, rotor mass unbalance is one of the most probable causes of the majority of degradations suffered by electric drives in an industrial environment (current pumping, rolling problem, misalignment, etc.), especially those with high power and variable speed. This document is an experimental contribution to the reliable detection of mass unbalance and changes in its severity if, by necessity of service, the system is subjected to a speed variation. The implementation of the technical orbits Park, strengthened by the application of the Fourier transforms (FFT, STFT) to the Park vector of the stator current allowed the identification of the unbalance defect at low frequency. The sequence of current analytical approaches favors the convergence towards an unambiguous reading of the mass unbalance defect. A comparative table has been drawn up in order to observe the evolution of the gravity of this mechanical defect in the case of a speed variation of the induction motor. The results obtained by this multifaceted approach are very satisfying and can contribute to a self-diagnostic with the assistance of a decision-making technique.

Medium-Voltage Vector Control Induction Motor Drive at Zero Frequency Using Modular Multilevel Converter

Conventional modular multilevel converter (MMC) has severe limitation to operate at low frequency for the application of variable-speed induction motor drive. Fluctuation of submodule (SM) capacitor voltage increases rapidly as the motor speed decreases with rated torque. Finally, it becomes impractical to operate the motor at zero frequency. Recently, MMC-based medium voltage induction motor drive has been proposed to tackle this problem without additional circulating current. However, it does not solve the problem near zero frequency with nonzero motor torque. This paper proposes new method to solve this problem of high peak-to-peak voltage ripple of SM capacitor at all frequencies including zero frequency. Vector control strategy for induction motor is adopted here to have accurate control of torque near zero frequency. First, the problem of low-frequency operation is analyzed. Then, the solution is proposed analytically. The proposed control technique and overall performance of the drive have been verified through experimental results.

誘導電動機のインバータ可変速システムの 基礎と留意点（その４）

誘導電動機のインバータ可変速システムの 基礎と留意点（その４）

Fault Eccentricity Diagnosis in Variable Speed Induction Motor Drive Using DWT

Fault Eccentricity Diagnosis in Variable Speed Induction Motor Drive Using DWT