Nonlinear adaptive control of direct-drive brushless DC motors andapplications to robotic manipulators

Robust adaptive nonlinear control of brushless DC (BLDC) motors is considered. A controller is designed for the plant that is robust to parametric and dynamic uncertainties in the entire electromechanical system. These uncertainties are shown to be bounded by polynomials in the states. In addition, the controller can reject any bounded unmeasurable disturbances entering the system. A model for the motor incorporating magnetic saturation is used to design voltage-level control inputs for the motor. The design methodology is based on our earlier work on adaptive control of nonlinear systems. The overall stability of the system is shown using Lyapunov techniques. The tracking error is shown to be globally uniformly bounded. The design procedure is shown to be also applicable to multilink manipulators actuated by BLDC motors. The performance of the controller is verified through simulations and comparisons with a proportional-integral-derivative-type controller are made     

Development and implementation of an FPGA based fractional order controller for a DC motor

Fractional calculus has been gaining more and more popularity in control engineering in numerous fields, including mechatronic applications. One of the most common applications in all mechatronic domains is the control of DC motors. Several control algorithms have been proposed for such motors, ranging from traditional PID algorithms, to the more sophisticated advanced methods, including fractional order controllers. Nevertheless, very little information regarding the implementation problems of such fractional algorithms exists today. The paper proposes a simple approach for designing a fractional order PI controller for controlling the speed of a DC motor. The resulting controller is implemented on an FPGA target and its performance is compared to other possible benchmarks. The experimental results show the efficiency of the designed fractional order PI controller. Beside the initial DC motor, two other different DC motors are also used in the experiments to demonstrate the robustness of the controller.     

A robust digital position control of brushless DC motor with deadbeat load torque observer

A method for the robust position control of brushless DC (BLDC) motors is presented. The linear quadratic controller plus load torque observer is used to obtain an approximately linearized robust BLDC motor system for an AC servo, using the field-orientation method. The gains are obtained systematically from a discrete state space analysis. The robustness is obtained without affecting the overall system response. The load disturbance is detected by a zero-observer of the unknown and inaccessible input, and is feedforward compensated without requiring noisy current information. The overall system is controlled using a microprocessor, and the performance of each control algorithm is compared with both the simulation and the experimental results for two types of machines, a BLDC motor and a brushless direct drive (BLDD) motor     

Optimal controller design for a matrix converter based surface mounted PMSM drive system

This paper proposes a new control algorithm for a matrix converter permanent magnet synchronous motor (PMSM) drive system. First, a new switching strategy, which applies a backpropagation neural network to adjust a pseudo DC bus voltage, is proposed to reduce the current harmonics of the permanent magnet synchronous motor. Next, a two-degree-of-freedom controller is proposed to improve the system performance. The parameters of this controller are obtained by using a frequency-domain optimization technique. The controller design algorithm can be applied in an adjustable speed control system and a position control system to obtain good transient responses and good load disturbance rejection abilities. The controller design procedures require only algebraic computation. The implementation of this kind of controller is only possible by using a high-speed digital signal processor. In this paper, all the control loops, including current-loop, speed-loop, and position-loop, are implemented by a 32-b TMS320C40 digital signal processor. The hardware, therefore, is very simple. Several experimental results are shown to validate the theoretical analysis.     

Power electronics in German railway propulsion

The state of the art of power electronics is reviewed. Because of the different requirements, such as suburban or long distance traffic and DC or AC supply, various systems are in use and some peculiar configurations, as resistor braking, have become important. With AC supply special line-commutated rectifiers causing low displacement factor and small harmonic content are used for DC motor propulsion. With DC supply choppers allow nondissipative motor control, often combined with special circuits for field weakening and for change of driving/breaking. Particularly important is three-phase propulsion with robust squirrel-cage motors, made possible by the development of suitable variable-frequency inverters. Both current source and voltage source inverters are used in suburban cars as well as for locomotive drives. The most universal but also most complicated system served by the voltage source inverter is described in more detail     

直流电机监控闭环转速系统的实现

直流电动机闭环转速系统的突出优点是在很宽的范围内通过改变PWM的占空比实现调速、快速起停、正反转控制及制动等.其组成的控制系统简单、廉价、可靠,在众多领域有着极其广泛的应用,研制一种性能稳定的直流电机驱动器具有重要的意义.介绍了RS232及SPI串行总线的通讯原理,在此基础上开发了上位机监视平台和下位机直流电机控制电路.为了便于使用,还增设人机界面.实验证明,该监控系统具有较高的数据传输速率、良好的实时性、较高的稳定性和友好的人机对话功能.     

Perfect tracking control based on multirate feedforward controlwith generalized sampling periods

In this paper, a novel perfect tracking control method based on multirate feedforward control is proposed. The advantages of the proposed method are that: (1) the proposed multirate feedforward controller eliminates the notorious unstable zero problem in designing the discrete-time inverse system; (2) the states of the plant match the desired trajectories at every sampling point of reference input; and (3) the proposed controller is completely independent of the feedback characteristics. Thus, highly robust performance is assured by the robust feedback controller. Moreover, by generalizing the relationship between the sampling period of plant output and the control period of plant input, the proposed method can be applied to various systems with hardware restrictions of these periods, which leads to higher performance. Next, it is shown that the structure of the proposed perfect tracking controller is very simple and clear. Illustrative examples of position control using a DC servomotor are presented, and simulations and experiments demonstrate the advantages of this approach     

基于FPGA及DDS技术的USM测试电源的设计

超声波电机的运转需要一个两相相差90°（或可调）的高频交流信号源。本方案采用DDS技术的设计思路,用VHDL硬件描述语言对FPGA器件编程产生了两相四路高频信号。该信号经过驱动隔离电路施加于H桥逆变器中,在电感的平滑作用下,生成了满足USM测试要求的可调频、调相、调幅的两相高频交流信号源,成功地对USM45电机进行了驱动测试。该电路可用于研究超声波电机的运行状态的研究及获取其最佳工作点参数。     

Nonlinear control of a series DC motor: theory and experiment

The control problem for a series DC motor is considered. Based on a nonlinear mathematical model of a series-connected DC motor, it is shown that the combination of a nonlinear transformation and state feedback (feedback linearization) reduces the nonlinear control design to a linear control design. To demonstrate its effectiveness, an experimental study of this controller is presented. These experimental results are also compared with a simulation of the closed-loop system. Finally, it is shown that a nonlinear observer (with linear error dynamics) for speed and load torque can be constructed based only on measurements of the motor current. Experimental results of this speed and load-torque estimator are also presented     

Robust current controller for three-phase inverter usingfinite-state automaton

A novel feedback current controller for a three-phase load driven by a power inverter is proposed. The main design specifications are robustness to load electrical parameters, fast dynamical response, reduced switching frequency, and simple hardware implementation. To meet previous specifications a multi-variable hysteresis type controller is proposed, designed as a finite-state automaton and implemented with a programmable logic device. After a general introduction, system analysis is performed, control targets are specified, and the proposed control strategy is presented and discussed. Further, actual controller architecture, based on simple analog-logic hardware, is shown and experimental results are presented using an induction motor as the inverter load. However, this does not limit the wider applicability of the proposed controller that is suitable for different types of three-phase AC loads     

Recent progress in the development in solid-state AC motor drives

The author summarizes important developments in AC drive design that have occurred in the past several years. He discusses: converter technology, covering the matrix converter, PWM voltage and current link converters; and resonant link converters; AC motor technology, covering stepping motor drives, DC brushless motor drives, and synchronous reluctance motors; and control technology for AC drives, covering online and offline parameter identification and efficiency-maximizing control     

An MRAC-based nonlinear speed control of an interior PM synchronous motor with improved maximum torque operation

A model reference adaptive control (MRAC)-based nonlinear speed control strategy of an interior permanent magnet (IPM) synchronous motor with an improved maximum torque operation is presented. In most servo systems, the controller is designed under the assumption that the electrical dynamics are neglected by the field-oriented control. This requires a high-performance inner-loop current control strategy. However, the separate designs for a high-performance current regulator and a robust speed controller need considerable effort. To overcome this limitation, an MRAC-based nonlinear speed control strategy for the IPM synchronous motor is presented, considering the whole nonlinear dynamics. Nonlinear speed control is achieved by an input–output linearization scheme. This scheme, however, gives an unsatisfactory performance under the mismatch of the system parameters and load conditions. For the robust output response, the controller parameters are estimated by an MRAC technique in which the disturbance torque and flux linkage are estimated. The adaptation laws are derived from Lyapunov stability theory. In view of the drive efficiency, the motor has to provide the maximum torque for a given input. To drive the IPM synchronous motor under improved maximum torque operation, the estimated flux linkage is employed for the generation of the d-axis current command. The robustness and output performance of the proposed control scheme are verified through simulation results.     

Robust nonlinear control of brushless DC motors for direct-driverobotic applications

The control problem associated with brushless DC motors (BLDCMs) for direct-drive robotic applications is considered. In order to guarantee the high-performance operation of BLDCMs in such applications, the effects of reluctance variations and magnetic saturation are accounted for in the model. Such a BLDCM model constitutes a highly coupled and nonlinear dynamic system. Using the transformation theory of nonlinear systems, a feedback control law, which is shown to compensate for the system nonlinearities, is derived. Conditions under which such a control law is possible are presented. The need for the derivation of explicit commutation strategies is eliminated, resulting in reduction of the computations involved. To guarantee the high-performance operation of the system under substantial uncertainties, a robust control law is derived and appended to the overall control structure. The inclusion of the robust controller results in good tracking performance when there are modeling and measurement errors and payload uncertainties. The efficacy of the overall control law is investigated by considering a single-link direct-drive arm actuated by a BLDCM     

Sensorless PM brushless DC motor drives

To control PM brushless DC motors, position and speed sensors are indispensable because the current should be controlled depending on the rotor position. However, these sensors are undesirable from standpoints of size, cost, maintenance, and reliability. There are different ways of approaching this problem, depending on the flux distribution. The paper presents the speed and position sensorless control of PM brushless DC motors with a sinusoidal flux distribution. Two approaches are presented and compared with each other; one is based on the voltage model of the motor and another is based on the current model. The starting procedure is also a very difficult problem under sensorless drives, because the sensorless drive algorithm uses voltage and current for estimation of rotor position, but no information is available before starting. A novel starting method is presented by using a salient-pole machine. Experimental results based on DSP-TMS320C25 controller are shown for comparisons, which demonstrate desired characteristics both in steady-state and starting conditions     

Motor control and torque coordination of an electric vehicle actuated by two in-wheel motors

In this research, an electric vehicle actuated by two in-wheel DC motors is developed. By properly coordinating the motor torques, both drive-by-wire and electrical steering can be achieved. Two critical issues respectively related to the design of motor controllers and the coordination of the two motor torques under control saturation are investigated in this study. Firstly, as for the in-wheel motors that are used for driving and steering simultaneously, their operation covers a wider dynamic range that forward acceleration (deceleration), and reverse acceleration (deceleration) may occur alternately. To perform driving and steering smoothly and efficiently, each motor should be switched to an appropriate mode to generate the torque demanded. Secondly, during the high-speed maneuvering, the high back-emf voltage in the motor coil substantially reduces the motor’s torque generating capability. Since the electrical steering depends on the differential torque of two wheels, when electrical steering is demanded in this case, torque/current saturation may occur in either one of the motors and the electrical steering performance could be seriously degraded. To address these issues, controllers of two levels are proposed. For the low-level controller (the motor controller), it operates the motor automatically in an appropriate mode for performance and efficiency consideration. An input transformation is introduced to cancel the nonlinearity in current dynamics so as to control the motor torque easily and precisely regardless of mode switching. For the high-level controller (the torque coordination controller), besides generating reference commands to the low-level controllers, during control saturation it can also properly re-distributes control signals to maintain consistent steering performance and provides compensation for integrator windup. The control system is implemented and the performance is experimentally and numerically validated.     

Modeling and control strategies for a variable reluctancedirect-drive motor

A high-performance ripple-free dynamic torque controller for a variable-reluctance (VR) motor intended for trajectory tracking in robotic applications is designed. A modeling approach that simplifies the design of the controller is investigated. Model structure and parameter estimation techniques are presented. Different approaches to the overall torque controller design problem are discussed, and the solution adopted is illustrated. A cascade controller structure consisting of a feedforward nonlinear torque compensator, cascaded to a nonlinear flux or current closed-loop controller is considered, and optimization techniques are used for its design. Although developed for a specific commercial motor, the proposed modeling and optimization strategies can be used for other VR motors with magnetically decoupled phases, both rotating and linear. Laboratory experiments for model validation and preliminary simulation results of the overall torque control system are presented     

基于TMS320LF2407A的电机控制实验平台的设计

采用TI公司最新的面向电机控制的DSP芯片TMS320LF2407A，设计了一个通用的电机控制实验平台，用户可以在这个平台上进行异步电机、同步电机、直流电机等多种电机的各种控制策略的实验，使用非常方便灵活。     

Application of Artificial Neural Network to Robust Speed Control of Servodrive

This paper deals with the problem of robust speed control of electrical servodrives. A robust speed controller is developed using an artificial neural network (ANN), which creates a nonlinear characteristic of controller. An original method of neural controller synthesis is presented. The synthesis procedure is performed in two stages. The first stage consists in training the ANN and at the second stage controller settings are adjusted. The use of the proposed controller synthesis procedure ensures robust speed control against the variations of moment of inertia and stator magnetic flux. Simulations and laboratory results validate the robustness of the servodrive with permanent magnet synchronous motor     

DAC7714在嵌入式激光跟踪仪中的应用

在某型激光跟踪仪的设计中,通过实时控制俯仰、方位两路电机,实现目标的快速、平稳跟踪。使用AT91RM9200处理器,扩展12位DA转换器DAC7714,完成2路直流电机的控制。阐述了在嵌入式Linux环境下该芯片驱动程序开发过程,说明了该驱动程序与测试程序及内核的之间关系。通过驱动程序、测试程序代码的讲解,归纳出嵌入式驱动程序开发的共性及具体开发流程,为嵌入式开发打下基础。     

A nonlinear speed control for a PM synchronous motor using a simpledisturbance estimation technique

A nonlinear speed control for a permanent-magnet (PM) synchronous motor using a simple disturbance estimation technique is presented. By using a feedback linearization scheme, the nonlinear motor model can be linearized in the Brunovski canonical form, and the speed controller can be easily designed based on the linearized model. This technique, however, gives an undesirable output performance under the mismatch of the system parameters and load conditions. An adaptive linearization technique and a sliding-mode control technique have been reported. Although good performance can be obtained, the controller designs are quite complex. To overcome this drawback, the controller parameters are estimated by using a disturbance observer theory where the disturbance torque and flux linkage are estimated. Since only the two reduced-order observers are used for the parameter estimation, the observer designs are considerably simple and the computational load of the controller for parameter estimation is negligibly small. The nonlinear disturbances caused by the incomplete linearization can be effectively compensated by using this control scheme. Thus, a desired dynamic performance and a zero steady-state error can be obtained. The proposed control scheme is implemented on a PM synchronous motor using a digital signal processor (TMS320C31) and the effectiveness is verified through the comparative simulations and experiments