Integrated design of speed-sensorless and adaptive speed controller for a brushless DC motor

The study develops a design of an integrated new speed-sensorless approach that involves a torque observer and an adaptive speed controller for a brushless dc motor (BLDCM). The system is based on the vector control drive strategy. The speed-sensorless approach first employs a load observer to estimate the disturbed load torque, and then the estimated load torque is substituted into the mechanical dynamic equation to determine the rotor speed, and thus develop a speed-sensorless algorithm. Additionally, the mechanical rotor inertia constant and the friction coefficient, which are the inputs of the load observer, are estimated using the recursive least-square rule. Therefore, the proposed speed-sensorless approach is unaffected by the time-variant motor parameters nor is affected by the integrator drift problem. It also has a simpler computing algorithm than the extended Kalman filter for estimating the speed. The modified model reference adaptive system algorithm, an adaptive control algorithm, is adopted as a speed controller of the BLDCM to improve the performance of the speed-sensorless approach. Simulation and experimental results confirm that the performance of the design of a new integrated speed-sensorless approach and the adaptive speed controller is good.     

Magnetising method for speed sensorless controlled induction motordrives

In speed-sensorless controlled standard induction machine drives a start without torque is only possible if the rotor speed of the demagnetised machines is known. A new method is proposed, which allows a fast and accurate identification of the rotor speed of demagnetised machines without a speed or position sensor     

A new scheme for speed-sensorless control of induction motor

Various control algorithms have been proposed for the speed-sensorless control of an induction motor. These sensorless algorithms are mainly based on the speed feedback with the flux and speed estimations. This paper proposes a new scheme for the speed-sensorless control of an induction motor. The proposed scheme is based on the current estimation without the flux and speed estimations, in which the controlled stator voltage is applied to the induction motor so that the difference between stator currents of the mathematical model and motor may be forced to decay to zero. The performance of the proposed scheme is verified through simulation and experiment.     

Four-quadrant position sensorless control in SRM drives over the entire speed range

Proper synchronization of the excitation with respect to the rotor position is essential in optimal control of switched reluctance motor (SRM) drives. To avoid additional cost, size, and unreliability caused by the external position sensors, magnetic status of the SRM can be directly monitored to detect commutation instants. A one-to-one correspondence between magnetic status of the SRM and rotor position removes the need for an explicit access to the rotor position. In order to obtain a good precision over the entire speed range, educated modifications on the structure of the sensorless strategy is necessary. This is due to the impact of the operational regions on dynamic behavior of the SRM. In addition, introduction of SRM technology to industrial and domestic applications has raised the need for four-quadrant operation of the SRM drives. The present paper introduces a range of strategies that are necessary to accommodate this requirement in a sensorless format. Our experimental findings indicate that high-grade sensorless operation in a four-quadrant SRM drive is possible and can be integrated in a variety of applications.     

Design and implementation of sensorless techniques for switched reluctance drive systems

This article proposes two different methods for estimating the shaft position for a switched reluctance motor (SRM). Method 1 uses the self-inductance estimation technique to obtain the rotor position. First, by on-line measuring the slope of the stator current and compensating for the back electromotive force (EMF) effect, the self-inductance of the SRM can be detected. Then, the shaft position of the motor can be estimated according to the self-inductance. Method 2, on the other hand, uses the phase-locked loop technique to generate high-frequency signals. These signals can be used to estimate the shaft position of the SRM. The two proposed methods are compared and discussed in the article. Several experimental results are shown to validate the theoretical analysis. The adjustable speed range of the system is from 10 to 3000 rpm. Additionally, the proposed drive system can automatically start from a standstill to a setting speed.     

Sensorlose Drehzahl- und Lageregelung von Permanentmagnet-Synchronmaschinen auf Basis des INFORM-Verfahrens

This paper deals with the operation of permanent magnet synchronous motors without speed- and position sensors in speed- and position-controlled drive applications. Starting from classical field-oriented control methods, a speed-sensorless drive is presented. The basic idea is to estimate the actual speed and position of the drive by means of the INFORM method (low speed and standstill) and EMF-based models (high speed). Measurements on a position-controlled industrial system verify the high quality of the sensorless system which reduces the hardware costs of the drive and increases the reliability by eliminating mechanical components.     

A sensorless switched reluctance drive system using a self-inductance estimating technique

This paper proposes a new method for estimating the shaft position of a switched reluctance motor (SRM). The shaft position of the SRM is obtained by on-line estimation of the self-inductances of the motor, and a closed-loop drive system can thus be achieved. The drive system performs well in both the pulse-width-modulated (PWM) region and the single pulse region. The adjustable speed range of the system is from 20 rev/min to 2000 rev/min. In addition, the drive system is automatically started from standstill to a required speed and exhibits good transient and load disturbance responses. The detailed theoretical analysis and several experimental results are presented in the paper. First, the basic principle of the proposed method is explained. The self-inductance estimating technique is derived by using the mathematical model of the SRM. Then, the relationship between the self-inductance and the shaft position of the motor is discussed. Next, a starting technique is presented. It is then shown how a 32-bit microprocessor system is used to estimate the position and speed, speed-loop control, and the generation of three-phase current commands. Several simulated and experimental results validate the theoretical analysis.     

Inductance model-based sensorless control of the switched reluctance motor drive at low speed

A sensorless control scheme for the switched reluctance motor (SRM) drive at low speed is presented in this paper. The incremental inductance of each active phase is estimated using the terminal measurement of this phase. The estimated phase incremental inductance is compared to an analytical model, which represents the functional relationships between the phase incremental inductance, phase current, and rotor position, to estimate the rotor position. The presented sensorless control scheme requires neither extra hardware nor huge memory space for implementation. It can provide accurate rotor position information even as the magnetic characteristics of the SRM change due to aging. Combined with other inductance model-based sensorless control techniques, the proposed method can be used to develop an inductance model-based sensorless control scheme to run the SRM from standstill to high-speed. Simulation and experimental results are presented to verify the proposed scheme.     

Speed-sensorless control system of a bearingless induction motor based on iterative central difference Kalman filter

ABSTRACT

In order to obtain speed self-detecting with low cost for a bearingless induction motor (BIM) a speed-sensorless control strategy based on the iterative central difference Kalman filter (ICDKF) is proposed. Firstly, on the basis of the BIM mathematical model, the nonlinear state equation is established and its order is reduced from fifth-order to fourth-order using the stator terminal voltage and current as input. Then, a sterling interpolation formulation is used in the filter to reduce the model error, and an iteration loop link is adopted to improve the filter accuracy. Finally, the online speed of the BIM is identified through the filter rotor speed estimation. Theoretical analysis, simulation and experimental results by UKF and CDKF method have been compared. The results show that the proposed speed-sensorless control system not only has good speed tracking performance and reduce the load disturbance but also improves the BIM suspension performance.     

Making the case for applications of switched reluctance motor technology in automotive products

Switched reluctance machines (SRM) offer attractive attributes for automotive applications. These include robustness to harsh operational conditions, rugged structure, fault resilient performance, and a wide range of speed. The main debate over the adequacy of switched reluctance drives in automotive applications has often focused on efficiency and position sensorless control over the entire speed range, adaptation of control algorithms in the presence of parameter variations, and high levels of acoustic noise and vibration. The present paper demonstrates three key technologies developed over the past few years that have resulted in tangible improvements in the performance of SRM/generators (SRM/G) as related to the above areas of interest. This paper intends to illustrate the new possibilities and remaining challenges in applications of SRM in automotive industry. The proposed technologies have been validated by simulation and experimental results.     

Automatic control of excitation parameters for switched-reluctance motor drives

This paper presents a new approach to the automatic control of the turn-on angle used to excite the switched-reluctance motor (SRM). The control algorithm determines the turn-on angle that supports the most efficient operation of the motor drive system, and consists of two pieces. The first piece of the control technique monitors the position of the first peak of the phase current (/spl theta//sub p/) and seeks to align this position with the angle where the inductance begins to increase (/spl theta//sub m/). The second piece of the controller monitors the peak phase current and advances the turn-on angle if the commanded reference current cannot be produced by the controller. The first piece of the controller tends to be active below base speed of the SRM, where phase currents can be built easily by the inverter and /spl theta//sub p/ is relatively independent of /spl theta//sub m/. The second piece of the controller is active above base speed, where the peak of the phase currents tends to naturally occur at /spl theta//sub m/ regardless of the current amplitude. The two pieces of the controller naturally exchange responsibility as a result of a change in command or operating point. The motor, inverter and control system are modeled in Simulink to demonstrate the operation of the system. The control technique is then applied to an experimental SRM system. Experimental operation documents that the technique provides for efficient operation of the drive.     

Speed-sensorless vector control of an induction motor using neuralnetwork speed estimation

In this paper, a novel speed estimation method of an induction motor using neural networks (NNs) is presented. The NN speed estimator is trained online by using the error backpropagation algorithm, and the training starts simultaneously with the induction motor working. The estimated speed is then fed back in the speed control loop, and the speed-sensorless vector drive is realized. The proposed NN speed estimator has shown good performance in the transient and steady states, and also at either variable-speed operation or load variation. The validity and the usefulness of the proposed algorithm are thoroughly verified with experiments on fully digitalized 2.2 kW induction motor drive systems     

Comparative analysis of experimental performance and stability of sensorless induction motor drives

This paper compares the experimental performance of three flux and speed observers for speed-sensorless induction motor drives and discusses the cause of their differences. The small signal analysis using the linearized model is carried out to analyze stability. Three methods are generally accepted to be representative candidates for high sensorless performance, namely: 1) rotor-flux model reference adaptive system (MRAS); 2) torque-current MRAS; and 3) adaptive nonlinear flux observer. Many other sensorless methods improved these methods. The paper discusses baseline conditions for the experiments and the stability analysis, which include matched load inertia, specified speed estimator dynamics, and sensorless operation within a speed control loop. For the comparison tests in the paper, the speed estimation dynamics of the methods are the same; this is important for parameter sensitivity. The paper concentrates on the low-speed performance, and all results shown are under sensorless speed control.     

An approach for sensorless position estimation for switchedreluctance motors using artifical neural networks

This paper presents a new approach to the sensorless control of the switched-reluctance motor (SRM). The basic premise of the method is that an artificial neural network (ANN) forms a very efficient mapping structure for the nonlinear SRM. Through measurement of the phase flux linkages and phase currents the neural network is able to estimate the rotor position, thereby facilitating elimination of the rotor position sensor. The ANN training data set is comprised of magnetization data for the SRM with flux linkage (λ) and current (i) as inputs and the corresponding position (&thetas;) as output in this set. Given a sufficiently large training data set, the ANN can build up a correlation among λ, i and &thetas; for an appropriate network architecture. This paper presents the development, implementation, and operation of an ANN-based position estimator for a three-phase SRM     

基于DSP无速度传感器的感应电动机控制研究

感应电机高动态控制的困难性在于感应电机是一个高阶、非线性的复杂系统。异步电动机传统方法采用模型为基础的无速度传感器磁场定向控制,高性能矢量控制系统中需采用速度闭环控制。为了提高异步电机无速度传感器矢量控制的控制性能,将其与矢量控制结合起来,组成一种基于TMS320F2812的无速度传感器矢量控制系统。本文主要介绍了硬件实现其软件实现方法,并且通过MATLAB仿真验证了所提出方法的有效性使系统具有良好的动态性能以及稳定性。     

基于MRAS的异步电机无速度传感器矢量控制

异步电机无速度传感器矢量控制系统中的速度辨识方法是目前研究的热点,其中MRAS由于其原理简单、实用性较强等优点,在交流调速系统中得到了广泛应用。本文采用改进的电压型转子磁链估算模型,避免了由纯积分环节造成的积分漂移等问题,采用可变PI型自适应律,结构简单且具有较好的辨识效果,最后给出了转子磁场定向的无速度传感器矢量控制系统的实现,仿真结果表明该系统具有良好的动静态性能,且具有一定的抗干扰能力。     

Robust speed control of a switched reluctance vector drive usingvariable structure approach

The robust speed control of a switched reluctance vector drive is presented in this paper. An approximate sliding-mode input power controller and another feedforward sliding-mode speed controller are combined with space voltage vector modulation. The resultant drive has rapid and robust speed response. In addition, a switched reluctance motor (SRM) drive incorporating the proposed controller requires only one current sensor and can be implemented in a low-cost 8-bit microcomputer and a few discrete integrated circuits. Furthermore, the controller does not require any offline characterization of the motor or load characteristics and could easily be applied to SRMs with any number of phase windings. A 4 kW four-phase SRM drive is constructed to test the performance of the controller. The results show that a step response from 200 to 1980 RPM needs only 2-3 s, even when driving a high-inertia load, and that the speed error can be controlled below 1%, even under unknown and dynamic loads. It is concluded that modified sliding-made controllers are effective in dealing with the highly-nonlinear characteristics of the SRM drive system     

A novel sliding-mode observer for indirect position sensing ofswitched reluctance motor drives

A switched reluctance motor (SRM) drive generally requires a rotor position sensor for commutation and current control. However, the use of this position sensor increases both cost and size of the motor drive and causes limitations for industrial applications. In this paper, a novel indirect position sensing technique, namely, the sliding-mode observer, is proposed for SRM drives. The corresponding design approach and operating performance are provided to illustrate the fast convergence and high robustness of the observer against disturbances and variations     

Elimination of position sensors in switched reluctance motordrives: state of the art and future trends

This paper covers the range of topics related to sensorless control of switched reluctance motor (SRM) drives from their fundamentals to their limitations and state of the art and future trends. This should help the reader to develop a systematic understanding of the sensorless techniques that have been developed over the past two decades. The inherent vulnerability to mechanical failures, extra cost, and size associated with external position sensors such as optical encoders, resolvers, and custom-designed Hall-effect sensors has motivated many researchers to develop sensorless control techniques for SRM drives. Ideally, it is desirable to have a sensorless scheme, which uses only terminal measurements and does not require additional hardware or memory while maintaining a reliable operation over the entire speed and torque range with high resolution and accuracy. Advances in the development of low-cost digital-signal-processor-based microcontrollers have paved the way for the fulfillment of this objective. It is, furthermore, our view that the existing trends in the development of more powerful processors will ultimately replace the concept of sensorless controls with the concept of eliminating the need for position sensing, a concept that will further revolutionize the motor drive technology     

Control characteristics of the SRM drives. I. Operation in thelinear region

The control characteristics of switched reluctance motor (SRM) drives are analyzed for operation of the motor in the linear region of its magnetic characteristics. After reviewing the motor operation, the authors consider the current-fed and voltage SRM drives. For both types of drives, the control variables and the related ranges are identified, the relationships between such variables and the average motor torque are calculated, and the torque capability is found. The basic schemes for the speed control of the SRM drives are also formulated