Squirrel-cage Motor Research Articles

Thermal-electromagnetic coupling simulation study of high efficiency and energy saving application of induction motor for offshore oil platform

The load of the offshore oil platform is mostly pump unit, Asynchronous motor with cage rotor has simple structure, reliable operation, and inexpensive. But it has a huge shortcoming of its low efficiency. When the output power is constant, improving efficiency is to decrease loss of the motor. This paper discusses some methods of energy saving and low consumption of the pump unit to improve the efficiency. Direct drive pump can completely eliminate transmission loss, eliminate bearing of centrifugal pump impeller pump, reduce friction, and thus reduce mechanical loss. The rotor copper loss and stator copper loss will be reduced by using copper squirrel cage and multi-wound motor, so the efficiency of the motor will be improved. If all the pump unit of the offshore oil platform is turned into this low consumption motor, it will save a lot of energy and greatly improve the efficiency of the load. Today, motors are widely found in various devices and their analysis involves the coupling of multiple physical fields. One of the most serious problems for some large motors is the heating problem, which generates various losses during motor operation, and these losses are eventually converted into thermal energy and emitted in the form of heat. The operating temperature of the motor has a great influence on the insulating material of the motor. Afterwards, a method of thermal-electromagnetic coupling simulation of the motor is carried out with a pump unit in the offshore oil platform as an example, and the magnetic line distribution, magnetic field density distribution cloud diagram and water pump temperature distribution of the motor are obtained, which are the basis of the electromagnetic design of the water pump and the design of the heat dissipation system.

Modelling of induction motor incorporating magnetic saturation

The paper studies the need to take into account the magnetic saturation of a squirrel-cage induction motor (IM). A mathematical description of an IM with linear and nonlinear magnetic characteristics is given. The simulation of motor’s direct start, as well as the field oriented control (FOC) system in Simulink Matlab environment is presented. The results of simulation are presented: time diagrams and mechanical characteristics of the motor. The conclusion is made whether it is necessary to take into account saturation in the study of transients in an asynchronous squirrel-cage motor.

Sustainable operation analysis of the mining industry power supply system

The paper presents an analysis of operating currents and torques during self-starting of motors with a voltage of 6 kV for cases of short circuit in the head feeders from the main step-down substation and in the feeders to the most distant substations of mining enterprises. For the network under consideration, the characteristic modes are: short circuit on the buses of shop substations. For the mining industry when selfstarting asynchronous motors with a squirrel-cage rotor and synchronous motors with asynchronous startup, the current multiplicity will be determined by the duration of the power failure (run-down duration). It has been established that the acceleration of motors during self-start will be somewhat slower than the usual start, since self-start begins at a speed of 0.89–0.94 of the synchronous speed and a resistance torque is equal to 0.65–0.75 of the maximum motor torque. The self-starting time of the motors is from 9 s to 42 s. To ensure self-starting conditions in the most severe modes in mountain conditions, it is necessary to make changes to the protection settings presented in the work.

Діагностування обмоток статора асинхронного двигуна з використанням моделювання на основі годографа вектора Парка

Despite the large number of methods for monitoring the condition of the stator windings of squirrel-cage induction motors, the issue of improving and developing diagnostic equipment with a high degree of reliability that meets modern operational requirements remains unresolved. The available methods take into account only the limiting or permissible states of the winding parameters, which do not allow us to evaluate defects at an early stage of their development. An especially hard-to-diagnose damage requiring further research is the interturn short circuit in the phase of the stator winding. The paper considers a method for diagnosing interturn closure of a stator winding using mathematical modeling based on the hodograph of the Park vector. For this purpose, a mathematical model of an induction motor with established adequacy to real processes was chosen, with which the computing unit of the Park vector was used. As a result of modeling, using an example of an asynchronous motor model AIR with a power of 11 kW, the hodographs of the Park vector for a stator without defects in nominal mode were obtained; as a result of interturn closure with complex phase resistance reduced to 80% in nominal mode and in idle mode. It is established that the considered method of applying the simulation model of a squirrel-cage asynchronous motor based on the hodograph of the Park vector allows modeling defects in the stator windings, studying their effect on motor operation, and also diagnosing the degree of defects that occur in the stator. When applying the method of spectral analysis of the hodograph of the Park vector to diagnose interturn closure faults of the stator winding, it is necessary to take into account the influence on the result of the parameters of the supply network, the nature of the load, the influence of external electromagnetic fields, transient processes in the motor, etc., accounting for which requires additional research. The possibility of using method of the hodograph of the Park vector for diagnostics of windings of induction motors remotely, without stopping the operation of the motor and when used in fully automated diagnostic systems, makes this method the most promising for further development and use.

Various Rotor Topologies of Line-Start Synchronous Motor for Efficiency Improvement

Abstract Line-start synchronous permanent magnet motor (LSSPMM) is being considered as a replacement or alternative to asynchronous squirrel-cage motor (AM) in constant speed applications. This is due to the better efficiency and power factor than the asynchronous motor. There are various rotor topologies of LSSPMM concerning the magnets placement and their dimensions. The paper analyses six different rotor topologies in terms of achieving the best efficiency and power factor for the same output power of the motor with minimal consumption of permanent magnet material. All other motor design parameters remain unchanged, i.e. all motor topologies are analysed for the same stator laminations and the same motor windings. The numerical finite element method (FEM) models and dynamic models for obtaining transient characteristics of speed, torque and current verify the proposed design of various motor models. The results from all motor models are compared and adequate conclusions are derived regarding the optimal rotor topology in terms of obtaining the best efficiency and power factor with minimal consumption of permanent magnet material, for the same output power of the motor.

Effect of Symmetrical Voltage Sag on Induction Motor Considering Phase-Angle Factors Based on a New 2-D Multi-Slice Time-Stepping Finite Element Method

Voltage sag is one of the most common power quality disturbance in industry, which causes huge inrush current and inrush torque of induction motors, and has serious impacts on the safe and stable operation of induction motor. To further study the detailed transient characteristics of induction motors during sag events, an improved 2-D multi-slice field-circuit-motion coupling time-stepping finite element method (FEM) is proposed. Then, taking a 5.5 kW, a 55 kW and a 135 kW induction motors as examples, the influence of phase-angle jumps and initial point-on-wave on the stator current peak, torque peak, speed loss and critical clearing time of the induction motor are discussed by using the proposed model. The simulation results show that stator current peak and torque peak increase obviously, while speed and critical clearing time decrease apparently, when considering the phase angle jump. And different initial points have little influence on these operation indicators. Finally, the proposed method is verified by comparing the measured and calculation data of the 5.5 kW three-phase squirrel-cage motor, respectively. The results show that the proposed method can reach higher precision with considering nonlinear characteristics.

Techno-economic analysis of slip ring motor replaced by standard squirrel cage induction motor with VSD

Induction motor slip ring-type technology has been widely used in industrial as one of the crucial electrical components to convert energy mechanically. The construction of this motor is more complex than other standardized induction motors such as squirrel cage. The complexity lies in the connection between the rings and brushes which requires more maintenance. Meanwhile, Squirrel cage motor that is supported by a Variable Speed Drive allows its user to start motor smoothly and adjusts the speed more efficiently. In this study, we exclusively investigate the possibility of the outdated technology replacement by using squirrel cage standardized induction motor based on its compatibility and the financial perspective as well. To prevent any coming up problems, the selections of new motor and VSD must fulfil the requirement of the existing system. Technical data were collected from customer’s SCADA and nameplates. While the financial calculation was made based on the payback period. In this case, the payback period is projected within two years and the energy saving could reach 69% that basically depends on operation patterns. According to our perspective, standard squirrel cage motor potentially replaces the slip ring motor in which it is not only having a simple operation but also less maintenance and energy cost.

Technology trends for LNG compression using innovative electric solutions

During the last 30 years, there has been a significant evolution and innovation of electric driven compressors in replacement of steam or gas turbines. Technology trends are highlighted in this paper with a focus on LNG Compression, covering standalone and integrated compression fed by Variable Frequency Drives (VFDs), and the emergence of the induction squirrel cage motor up to 120MW.

Full-Scale Physical Simulator of All SiC Traction Motor Drive With Onboard Supercapacitor ESS for Light-Rail Public Transportation

This article deals with the design and laboratory implementation of a full-scale physical simulator of an all-silicon carbide (SiC) traction motor drive for light-rail transit systems (LRTS) with onboard supercapacitor energy storage system (ESS). It consists of a pulsewidth modulation (PWM) rectifier representing the 750 V dc catenary line, a three-phase two-level PWM traction inverter to drive a three-phase squirrel-cage traction motor, a flywheel coupled to the motor shaft to represent the dynamic behavior of the transportation vehicle, a loading generator connected to the grid via a dc-link converter with active front-end, and a supercapacitor ESS containing a bidirectional dc–dc converter supplied from the common dc link. The PWM rectifier, a traction inverter, and a bidirectional dc–dc converter are all SiC power MOSFET-based converters for high efficiency and high power density. A physical simulator is a valuable tool in the design and testing of all SiC converters. It is equipped with software programs for a catenary model, rail track model, and vehicle model, and permits the performance verification of various control, modulation, and energy-saving strategies. The physical simulator system developed in this article also allows the performance verification of a vehicle formation on a prespecified real track and evaluation of benefits of the onboard supercapacitor ESS in real time.

Squirrel-Cage Rotor Design and Manufacturing for High-Speed Applications

A high-speed squirrel-cage induction machine requires a totally different design compared to the traditional squirrel-cage industrial motor because of the mechanical limitations caused by the high speed. This results in a more complicated rotor construction and expensive material selection, and sets higher standards for the manufacturing precision. The objective of this paper is to demonstrate the design aspects, material selection, and manufacturing of a squirrel-cage rotor for high-speed applications. In this paper, the rotor dimensioning approach based on equations and data analysis is presented. Rotor material selection and construction topology influence on the electrical machine design are discussed. The results are illustrated with the design of a 6-kW, 120 000-r/min induction machine for a turbo circulator. The influence of rotor parameters on the electromagnetic performance of the designed machine is demonstrated. Mechanical stresses for different topologies are studied with finite-element method analysis. Several manufacturing methods for producing a high-precision rotor are described and compared. The presented rotor design approach, which enables high electromagnetic performance and robust construction, is verified by the testing of a prototype.

Design and analysis of a novel wound rotor for a bearingless induction motor

ABSTRACTThe traditional squirrel-type bearingless induction motor (BIM) suspension winding generates induced current in its squirrel-cage rotor and affects the phase and amplitude of the suspension force. Based on the analysis of the spatial distribution of torque winding magnetic field and suspension winding magnetic field, a new type of wound rotor BIM is designed. Different from the squirrel-cage rotor, the wound rotor uses a special method of embedding a set of coils at any symmetrical four rotor slot positions, so as to only induce the torque winding magnetic field. The induced current, air-gap magnetic density, magnetic field line distribution, suspension force as well as electromagnetic torque of the traditional squirrel-cage motor and the new wound motor are analysed by Maxwell finite element calculation. The results show that the designed new wound BIM can not only effectively suppress the induced current of suspension winding, eliminating its influence on the suspension force, but also has a better starting performance.

FE analysis of coupled electromagnetic-thermal phenomena in the squirrel cage motor working at high ambient temperature

PurposeThis paper aims to elaborate the method and algorithm for the analysis of the influence of high temperature on electric and thermal properties of the materials, as well as thermal phenomena process.Design/methodology/approachThe paper presents specially author’s software for the transient finite element analysis of coupled electromagnetic-thermal problems in a squirrel cage induction motor. The numerical implementation is based on finite element method and step-by-step algorithm. The nonlinearity of a magnetic circuit, the dependence of electric and thermal parameters on temperature, the movement of a rotor and skewed rotor bars have been taken into account. To verify the developed algorithm and software, the influence of high ambient temperature on selected electromagnetic and thermal parameters of the induction motor was examined.FindingsThe results of simulations compared with measurements confirm the adequacy of this approach to the analysis of coupled electromagnetic-thermal problems.Research limitations/implications3D effects have only been taken into account when using quasi-3D techniques (e.g. the multi-slice for skewed rotor slots).Practical implicationsThe author’s software developed can be useful in the analysis and design of squirrel cage motors, especially motors working in high ambient temperature.Originality/valueThe paper offers appropriate author’s software for the transient and steady-state analysis of coupled electromagnetic and thermal problems in squirrel cage motors with skewed slots.

Induction Motor Faults Diagnosis when Considering Bars Skew and Saturation Effects

The objective of the work presented in this paper is the diagnosis of the three-phase induction machine with secondary effects such as the rotor bars skewing and the saturation phenomenon. To enable reliable diagnosis of an induction machine, a mathematical model is required to simulate the machine behavior. Among the existing mathematical models, the approach of the winding function is the most promising because it takes into account the actual distribution of the windings in the stator slots. Nevertheless, the major drawback of this model is the non-consideration of the skewing effect of the bars and the non-linear evolution of the FMM between the ends of the slots. The aim of this paper is to use the modified winding function approach (MWFA) with 2D extension to take into account the rotor bars skewing and saturation effects in the presence of faults such as the rotor broken bars, the short-circuit between stator turns and the eccentricity. A series of simulations is conducted to study the spectral contents of the stator current of the induction squirrel cage motor in the various operating cases.

Modeling of the Combined Electric Drive

In the article the possibility of application of the combined electric drive on the basis of the electromechanical transducer of the alternating current squirrel-cage motors. A comparative analysis of the characteristics of drive mechanisms of different types is given. The main task of the study is to increase the traction force of the drive mechanism at a constant power. The possibility of using an automated design system T-Flex CAD to create a 3D-model of the device is shown. The dependence of the traction characteristics of the drive on the power and speed of the basic asynchronous motor is established. The results of comparison of calculated and experimental characteristics of the designed electric drive are presented.

Operational reliability of low-voltage asynchronous motors at asymmetrical supply voltage

Issues of operating modes of 4A series asynchronous squirrel-cage motors and AI serried motors at asymmetrical supply voltage for different values of motor shaft load are considered on the basis of simulation using Matlab software package and Simulink package. In the simulation, currents in asynchronous motor phases were evaluated as a function of K2U, KZ, and based on these results, permissible operation parameters were evaluated for induction motors. The results obtained are the basis for technical solutions aimed at improving operational reliability of asynchronous motors, they will allow taking into account permissible operating parameters of asynchronous motors not only in the design, but also in operation in power supply systems of various facilities.

CPU-FPGA based real-time simulation of fuel cell electric vehicle

Proton exchange membrane fuel cell (PEMFC) has been considered as one of the promising renewable power technologies for the vehicular application. This paper proposes a fuel cell electric vehicle (FCEV) power system model that can be implemented in the hardware-in-the-loop (HIL) emulation for real-time execution on field-programmable gate arrays (FPGAs). The FCEV model comprises three parts: a PEMFC, a Z-source inverter and a squirrel cage motor. To achieve an accurate and efficient FPGA resources’ utilization, the PEMFC model is implemented by CPU whereas the models of the DC-AC inverter and the electrical motor are built in FPGA. For the validation of the proposed power system, the real-time simulation tests are conducted with a high accuracy. The developed hybrid system model can reach a simulation time step of 100 ns for FPGA and 500 μs for CPU under the co-simulation mode. Moreover, the simulation under various system operating conditions indicates that the high performance can be reached by the hybrid system computed in real-time. The proposed real-time model can be used to design the on-line diagnostic and model predictive control method, which can help to test the FCEV before the commercial applications.

Integral‐series Fourier analysis of chaotic PWM patterns for common mode voltage stresses

In this study, the theory of pulse width modulation (PWM) is developed for both sine-wave PWM (SPWM) and chaotic sine-wave PWM (CSPWM). In SPWM, power spectra are analysed by an analytical method such as double Fourier series (DFS) technique, and the integral-series Fourier method is fully devised and analytically theorised for CSPWM. It is shown that the root-mean-square value of inverter's zero-sequence voltage does not rely on carrier and reference frequency in fixed-frequency SPWM, while in CSPWM, this depends on frequency modulating gain and chaotic sequence of numbers. Also, the computation time of purely numerical harmonic analysis can be much heavier than analytical ones. Furthermore, the DFS and integral-series Fourier methods are applied to SPWM and CSPWM with two different frame sizes of squirrel cage motors for the shaft voltage and the electro-magnetic interference (EMI). The numerical and experimental results show that CSPWM can have positive effect on the shaft voltage while it definitely weakens the EMI problems.

Maximizing the Efficiency of 3-Phase Induction Motors (Squirrel Cage Motor)

Maximizing the Efficiency of 3-Phase Induction Motors (Squirrel Cage Motor)

A Low cost modelling of the variable frequency drive optimum in industrial applications

A single or three phase asynchronous motors, or known a squirrel cage motors (SCMs) are represent one of generally using in many industrial applications. They are consuming further than half-percent of the total generated electrical energy. This motor is working at its full speed when it is attached to the main AC- supply. Therefore, speed control of asynchronous motor is necessary to industrial applications that require changeable flow control of fluid (air, water and chemical liquid streaming). There are many methods to control the speed of motors, such as changing the stator number of poles, controlling supply voltage, addition series reactor or resistances. The modern method is Volt per Hertz, or scalar control this method applied by changing voltage and frequency of three-phase supply, or by making a V/f equal to a constant value in this method a large amount of energy can be saved. In this study, analysis and practical implemented to variable voltage Variable Frequency Drive or called a VFD. The model enables an exception of a large amount of energy, when connected to control speed of Induction motor. A new simplified method for implemented of an AC Drive system with a moderate price for components was proposed. This method totally based on assembling overall components of AC-Drive. The advantage of this design is simplicity, robustness and ease of tuning as well as manufacturing due to these advantages. This design is very suitable for real time applications as motor speed controller. The experimental results obtained show that design helps to preserve a large amount of energy to the power grid, by a limited starting current of the motor as well, eliminating a voltage flicker at starting and reducing dissipating power during running in long period. Results verified experimentally.

The Analysis of the Digital AC Motor Speed Control System Operation

Abstract The article presents the analysis of the automatic alternate current motor control system, carried out by the author. The automatic control system has been implemented on the existing laboratory stand, containing: the squirrel-cage asynchronous motor and the frequency inverter. The existing stand imposed one of the available speed control methods for the motor and the necessity of the appropriate elements selection for the automatic control system [1]. The automatic control system has been designed and created as the constant value follow-up digital controller. To designate the parameters of the control object the unit step method of was used. After registering the output changes caused by the unit step, the characteristic curve was received that allowed to determine the alternative transmittance of the control object which, in turn, has made possible to find the appropriate controller settings.