Efficiency Loss Model for Asynchronous Motor Vector Control

Better to meet the high performance AC speed adjustable speed control strategies and advanced control algorithms in the application of asynchronous motor, Introduced the hardware and software design of asynchronous motor control system development platform based on TMS320F2812. Discussed the vector control system for three-phase Asynchronous motor which use this platform as the control core, described the vector control principle and system structure, then simulate using SIMULINK, give the simulation results and analyse them to verify the feasibility of the design.

A200 an important industrial equipment in the field of industrial production, the problem of operating efficiency of asynchronous motor has drawn wide attention with the increasing severity of environmental problems in recent years. Intended to this problem, this paper takes the retarder test bed motor control system as the research object, deduces the motor efficiency optimization control algorithm, and uses the Simulilnk module in Matlab to establish the asynchronous motor loss model. Based on the vector control of asynchronous motor, a simulation model of efficiency optimization control based on loss model is established, and the efficiency optimization control of induction motor based on loss model is realized. At the same time, this paper compares the efficiency optimization control algorithm with the traditional vector control to test the effect of the efficiency optimization algorithm. The experimental results show that the efficiency optimization algorithm used in this paper responds rapidly and the mutation of the load torque fluctuates slightly, but it can be quickly re-stabilized. At the same time, compared with the traditional vector control, efficiency optimization algorithm can significantly improve the test bed operating efficiency. The simulation experiment provides the theoretical support and reference for the future application of the motor control system on the retarder test bench.

Iron loss, as a source of detuned operation of rotor flux oriented induction machines, has attracted much attention. Appropriate mathematical expressions, that enable evaluation of detuning, have become available and performance deterioration due to iron loss has been evaluated for rated speed operation in the constant flux region. The available studies are based on the measurement of iron loss with sinusoidal supply of rated frequency. This paper at first describes an experimental procedure for determination of iron loss and hence an equivalent iron loss resistance over the frequency range of interest. The procedure is based on no-load tests with PWM inverter supply and it can be executed during commissioning of the drive. The second part of the paper evaluates detuning introduced by iron loss in a rotor flux oriented induction machine, utilising the experimentally determined values of equivalent iron loss resistance. The emphasis is placed on operation in the braking region and on operation in the field weakening region. It is shown that detuning characteristics in the braking region differ from those valid in the motoring region. Detuning in the field-weakening region is found to significantly exceed the one at rated flux, rated speed operation, especially if the machine runs at high speeds with light loads. Finally, a modified rotor flux estimator, that enables compensation of the iron loss, is introduced and verified by simulation.

The present work proposed a methodology to estimate the iron and copper losses of a three - phase, squirrel cage induction motor for both sinusoidal and inverter-fed power supply, based on a two - dimensional finite element analysis software (Maxwell 2D - V16). The three-dimensional effect of stator end winding, rotor end ring, and rotor bars skewing were included by coupling with RMxprt software. The inverter simulation was done by Simulink. The modeling was done based on the design documents of a 2.2 kW, 2 pole test motor. The values of iron and copper losses estimated by Maxwell 2D at full load condition, sinusoidal power supply was compared with that extracted from solving the motor equivalent circuit parameters, and that taken from RMxprt with a good agreement. Both copper and iron losses were increased when motor operated with an inverter-fed power supply with respect to sinusoidal power supply. Also, these losses were decreased with increasing of inverter carrier frequency. The loss results will make a good roadmap for the motor designers, and operators to achieve the goal of an efficient inverter-fed induction motor operation.

Modeling and analysis of variable speed single phase induction motors with iron loss

The application of vector control to a conventional synchronous reluctance motor (VCSynRM) is presented with emphasis on the effects of saturation and iron losses. It is shown experimentally that these parasitic effects can significantly influence the performance of a VCSynRM. A simplified d-q model that includes saturation and iron losses is presented, and experimental results concerning optimal torque/ampere and optimal efficiency operation are shown to be in general agreement with the predictions of the model.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

This paper presents the solution of the energy optimal control of three-phase induction motor (IM) by balancing of torque and flux dependent losses. First, we build formula of total losses of motor (iron losses, copper losses and additional losses). Next, we will be group by isd current (flux dependent) and isq current (torque dependent). Then, we use the PI (Proportional-Integral) regulator to control so that the components two of this losses are equal. Output of PI regulator will obtain optimum rotor flux. Motor operates with this flux will make total losses of motor is the smallest. A comparative study in efficiency and tracking performances is given between the proposed optimal control and the classical Field Oriented Control that operates with constant rotor flux norm.

In recent years, the speed-sensorless vector control of asynchronous motor has become a research focus in modern alternating current machine control. In order to further improve the performance of the speed-sensorless vector control of asynchronous motor, the speed estimation method of the speed-sensorless should have a high accuracy. In this dissertation, the estimation method of the model reference adaptive system is used to identify the actual speed of asynchronous motor and the voltage model and the current model are respectively used as the reference model and the adjustable model of the adaptive system, the self closed loop can be better achieved and the actual speed of asynchronous motor can be more accurately identified with the model reference adaptive system. Finally, speed-sensorless vector control system based on the model reference adaptive system is simulated and the actual speed of motor can be accurately detected. Therefore, this method has certain feasibility.

This paper offers practical guidance about the nature of design and application engineering trade-offs that may be used to optimize motor efficiency to match a low load output shaft power condition and thereby achieve power savings by reducing the losses in squirrel cage induction motors (SCIM). This opportunity is the result of motor efficiency dropping off significantly at low load factors of mechanical output shaft power and can be explained by analyzing the balance between various components of the electric and magnetic power flows in the motor with respect to motor loading. This paper analyzes the possibility of obtaining minimum power losses at low motor loading and explains how iron losses, which usually are considered constant, can be made variable and optimized for power savings. The study was done using a typical 20 HP (15 kW), TEFC, 4 poles, 480 V, energy-efficient motor. This motor type is a common squirrel cage induction motor used in various industry applications and sometimes found operating at low loads for long periods of time. A squirrel cage induction motor design program was used to simulate the motor performance characteristics for low values of motor loading under various supply voltages. The study found that for this particular motor design, power savings of up to 2% and up to 20% of the total input power at motor loadings of 0.5 and 0.1 respectively can be achieved by varying the supply voltage. Minimizing motor losses by reducing the supply voltage could be realized with the advances and emerging technologies in power electronics. The findings of this study suggest a method of evaluating possible power savings for any SCIM prior to installing a specific control device.

This paper investigates the efficiency optimization problem in the drive system of Permanent Magnet Synchronous Motors (PMSM) based on the iron loss resistance model. Initially, an efficiency calculation method is proposed, utilizing the direct current (DC) side power based on the iron loss motor model as the input power. This approach determines the system’s input power by measuring DC side voltage and current, accounting for the impacts of temperature, magnetic saturation, and inverter nonlinearity. It avoids the need for intricate nonlinear loss modeling of the inverter, thereby simplifying the computational requirements for system efficiency. Simultaneously, the d-q axis equivalent equations based on the iron loss motor model are employed to calculate the system’s output power, enhancing the accuracy of the system efficiency calculation. An improved discrete gradient descent algorithm is presented based on this system efficiency calculation model, accelerating the search for the optimal current angle and improving its accuracy. In comparison to existing methods, this approach exhibits adaptive step size and provides more precise and higher efficiency calculations, resulting in faster search speeds. Experimental and simulation evaluations are conducted to assess the effectiveness of the proposed methods.

In today's world, where technology is developing rapidly, electric drive systems play a key role in a huge range of applications: from industrial production lines to vehicles and household appliances. These systems require high efficiency, accuracy and reliability. It is here that there is a need to improve and optimize the processes of controlling electric drives.In recent decades, neural network controllers, or neuroregulators, have won their place in the world of automatic control. Their unique ability to model complex nonlinear dependencies makes them an ideal tool for applications in electric drive systems. Neuro-regulators can adapt to changing operating conditions, learn from data and optimize the control process depending on specific requirements and conditions.This work is devoted to the possibility of using a neuroregulator in the traction asynchronous electric drive system. In the Matlab/Simulink environment, a simulation model of the AD914-U traction asynchronous electric motor vector control system described in the d,q rotating coordinate system was developed. The synthesis of the NARMA-L2 neuroregulator was performed, which combines the principles of the autoregressive model and the moving average model to provide prediction and control of complex processes. The main idea of this controller is to build a nonlinear transformation of input data that can predict the future states of the system. To demonstrate the capabilities of neuroregulators in traction electric motor control systems, comparative modeling of the NARMA-L2 neuroregulator and the classical proportional-integral regulator was conducted.The results of simulation modeling show that the system with a neuro-regulator shows the best indicators of regulation of the given parameters in transient processes and is a promising tool in the development of high-performance and energy-efficient traction electric drives.

The paper presents a comparison between analytical model, the finite elements method (FEM) simulations and measurements for a brushless DC motor used in a solar airplane project. In the preliminary conception phase, an optimization using an analytical model is performed. The motor efficiency and its weight are the key parameters. According to the obtained theoretical optimal configuration, a prototype is built. Airgap flux density, back-emf, iron losses and cogging torque are measured to validate the analytical model. Using a customized test bench, a special emphasis is made on the iron losses in the whole motor (stator and rotor).

Multiphase electric drives have been developed due to numerous advantages offered by those machines when it compared with the conventional three-phase machines. Multiphase motor drives are considered for applications, where the reduction of power per phase for both motor and inverter and high reliability are required. High performance control techniques are developed for multi-phase drives. The performances of the high performance controller and flux observers may be degraded during the operation. Since the parameters of Induction Motor (IM) varies continuously due to temperature variation and heating. Thus it is significantly important that the value of rotor resistance is continuously observed online and adapted by the control algorithm in order to avoid detuning effects. The efficiency and performance of an induction motor drive system can be improved by online observation of the critical parameters, such as the rotor resistance and stator resistance. Among the parameters of IM, rotor resistance is a decisive one for flux estimation, and also the stator resistance becomes critical in the low-speed operation condition. This paper presents a new online estimation method for the rotor resistance of the IM for sliding mode observer. This method generally based on theories of variable structure and is useful in order to adjust online unknown parameters (load torque and rotor resistance). The presented non-linear compensator afford a voltage inputs on the articulation of stator current and rotor speed measurements, and engender an estimates for the unknown parameters simultaneously, the non-measurable state variables (rotor flux and derivatives of the stator current and voltage) that converge to the corresponding true values. Under the persistent excitation condition, the proposed method estimates the actual value of rotor resistance, which guarantees the exact estimation of the rotor flux. Non-linear Backstepping control and adaptive sliding mode observer of a five-phase induction motor drive is presented. The accuracy and validity of the method is verified by MATLAB simulation model.

The fine analysis of rotor losses of induction motors requires separation of the slip- and high-frequency electromagnetic quantities under load conditions. However, the conventional method involves a full slip-cycle finite element simulation, which is very expensive in terms of CPU time and memory usage. To obtain a precise iron loss prediction with reduced time consumption, this paper proposes three methods for fast separation of the slip- and high-frequency electromagnetic quantities at rotor side of an induction motor. The first method (Method A) eliminates the influence of the slip-frequency component by calculating the derivative of the rotor flux density that is obtained by Time-Stepping Finite Element Method (T-S FEM). The second method (Method B) extracts the magnitude of slip-frequency flux density from the spatial distribution of the flux density wave within one supply cycle, and the major high-frequency components are extracted from the wave after subtraction of the full slip-frequency wave determined by Least Square Fitting (LST) the curve in time domain. The third method (Method C) reproduces the full slip-cycle waves by incorporating the wave segments at different positions in rotor teeth, and then separates the slip- and high-frequency components by Discrete Fourier Transform (DFT). The three methods are implemented to separate the slip- and high-frequency rotor flux densities in a 5.5kW induction motor. The accuracy of the results and the CPU time of the three methods are compared with those by the conventional method. The predicted rotor iron losses are also validated by experiments to verify the effectiveness of the presented methods.

Conventional Maximum Torque-Per-Ampere (MTPA) control was derived from the three-phase induction machine model ignoring iron loss. A new MTPA control is proposed in this digest, whose accuracy is improved by considering machine iron loss using a newly published induction machine iron-loss model. The detailed derivation of the proposed MTPA control and possible enhancement of torque-per-ampere capability are provided. Moreover, a new MTPA controller is designed and implemented in MATLAB/Simulink. The proposed MTPA control is compared with the conventional MTPA control and the indirect field-oriented control (IFOC) of rated flux in simulation. It shows that the proposed MTPA control can provide significantly higher torque than the conventional MTPA control and IFOC at the same current level before saturation, or require significantly less current to support the same load torque. At low-load conditions, the proposed MTPA control shows higher efficiency with minor extra cost of dynamic performance compared to the IFOC. Since the advantages of the proposed MTPA control are more significant for certain combination of machine's iron-loss resistance and the operating frequency, possible targets of the proposed MTPA control are high-speed induction machines and induction machines of relatively large iron loss.