Implementation of AC servo controllers employing frequency-domainoptimization techniques

The design and implementation of a permanent magnet synchronous motor drive based on H₂ and H_∞ optimal control theory are presented. A mathematical model of the drive is introduced. Based on appropriate assumptions, the model is reduced to a second-order, linear time-invariant system so that the H₂ and H_∞ optimization techniques are applicable. H₂ and H_∞ controllers are derived on the basis of the simplified model. A stability analysis is conducted, and stability regions based on controller tuning parameters and sampling periods are constructed. The relationship between closed-loop bandwidth and sampling period due to discretization effect is investigated. Implementation of the controllers and experimental results are described. A multiprocessor-based, fully digital control system is used to realize and experimentally verify the H₂ and H_∞ control algorithms. Controller performance is evaluated in terms of speed and position responses, and closed-loop and sensitivity frequency responses     

Identification, digital control and fuzzy logic techniques applied to a synchronous generator

The experimental results obtained in the design and implementation of an decoupled digital speed and voltage controller for a micro-energy system are reported in this work. The studied system is formed by a 9 Kw DC motor driving a 10 KVA synchronous machine. There are two control loops in the proposed controller: the speed control (speed governor) and the control of the stator's voltage (automatic voltage regulator). Each control loop was designed using linear control techniques and fuzzy control techniques. Tests on the system show the performance of the proposed controllers.     

Analysis and implementation of a real-time predictive currentcontroller for permanent-magnet synchronous servo drives

A real-time current controller for PWM inverter-fed permanent-magnet synchronous motor drives is presented and analyzed. The proposed current control scheme is based on predictive control with a parallel integral loop added to compensate for the inaccuracy of the motor model and for the variations of motor parameters and DC voltage source. The proposed current control scheme is analyzed and its performance is evaluated by computer simulation. An EPROM-based implementation is presented in which calculations and pulsewidth modulation are executed by lookup tables resulting in high-speed operation. The controller performance is evaluated using a prototype l kW PM synchronous servo drive. Experimental results are given and discussed     

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.     

基于改进型重复控制的三轴转台解耦与控制

针对三轴转台伺服系统位置精度要求不断提高,提出了改进型重复控制与微分前馈控制相结合的复合控制作用于伺服系统的位置回路。根据某型三轴转台伺服系统的组成,分析并建立了电流环、速度环与位置环的模型,并于位置环设计了改进型重复控制器。设计时,考虑了三轴转台的三个框架转动时互相产生的耦合影响,并分析三个框架同时转动时三轴转台的内框快速性与稳定性。仿真结果表明,采用复合控制策略时三轴转台的位置控制响应快、精度高、抗干扰性强,满足系统性能指标。     

A new fuzzy logic-based controller design method for DC and ACimpressed-voltage drives

This paper deals with the design of fuzzy logic-based controllers (FLBC) for DC and AC electric drives. Industrial drives employ the cascaded PI control with a subordinated current control loop to make sure that the current does not exceed the admissible value and improve dynamic performances. The nonlinear FLBC characteristics permit one to achieve the performances of the cascaded control using only one control loop. This is feasible by a suitable choice of the scaling factors together with the rules of the fuzzy controller. The authors propose a minimum number of rules and the criteria, based on physical considerations, to determine the input and output gains instead of using the trial and error procedure. The designed FLBC is able to control the speed of a DC drive as well as the rotor speed and flux of a vector-controlled induction motor drive. Computer simulations show the effectiveness of the new fuzzy-controller design method. The reduced number of rules and membership functions and the application flexibility together with the possible implementation on low cost μPs lead the authors to think that the proposed tuning criteria will be widely adopted     

Design and implementation of vector-controlled induction motordrives using random switching technique with constant sampling frequency

Recent results have shown that random switching techniques reduce electromagnetic interference, annoying acoustic noise, and other undesirable effects. However, to incorporate random switching techniques into digital-controlled induction motor drives, it requires dynamic adjustment of the gains of controllers. This paper presents details of the design and implementation of induction motor drives using a new random switching technique. It is shown, and confirmed by experimental results in this paper, that the sampling frequency of inverter control is constant, and therefore it is not required to adjust the gains of controllers dynamically. The details of controller design of the random switching inverter-controlled vector drives are fully explored, including the controller design in the discrete-time domain and the effect of the random technique on the speed response. Moreover, the advantages and disadvantages of inverter-controlled vector drives using random switching techniques are highlighted by experimental results     

Direct torque control induction motor drives withself-commissioning based on Taguchi methodology

This paper presents the analysis and design of direct torque control (DTC) induction motor drives with self-commissioning. Neither motor parameters nor controller parameters are known a priori. The self-commissioning process consists of the calculation of motor parameters, including stator resistor, inertia and friction coefficient, as well as the design of the controller. The effects of several factors, including test conditions for deriving motor mechanical parameters and natural frequency for controller design, on the performance of speed response are investigated using Taguchi's method which is widely used in quality engineering to significantly reduce the number of experiments. Therefore, the presented drive system cannot only provide self-commissioning but also dramatically improve the performance of speed response, which is evaluated using the performance index of root-mean-squared error (RMSE) of speed. Experimental results derived from a PC-based experimental system are presented to fully support the theoretical development and analysis     

A microcontroller-based induction motor drive system using variablestructure strategy with decoupling

The sliding-mode control concept is applied in the outer loop of a speed drive system utilizing a series-connected wound rotor induction machine (SCWRIM). A design procedure is outlined for the sliding-mode speed controller. The methods of decoupling and torque linearization for the SCWRIM are derived using the field-orientation as well as the torque angle control concepts. Sliding-mode control with cascaded integral operation is used to reduce torque chattering and steady-state error. Accelerator sliding lines are introduced to enable better utilization of the torque capability of the drive system. The parameter-insensitive response provided by this method of control is demonstrated. The effects on the dynamic and static performance with varying drive inertia and load disturbance are studied and compared with the conventional approach using PI control. The influences of sampling effects on sliding-mode control performance are also illustrated and discussed. Microcontroller-based implementation of the speed drive system is employed. Both simulation and experimental results are presented     

Design and implementation of a high-performance field-orientedinduction motor drive

The design and implementation of a high-performance controller for a field-oriented induction motor drive is presented. Dynamic modeling based on the stochastic technique is performed. Based on the estimated drive model, a two-degree-of-freedom controller is proposed so good dynamic responses in both the speed tracking and regulation characteristics can be achieved. The parameters of the controller are found using a proposed systematic design procedure according to the prescribed specifications. Having designed and tested the performance of the controller by simulation, the hardware implementation is successfully made, and some experimental results are given to demonstrate the effectiveness of the proposed controller     

Robust motion controller design for high-accuracy positioningsystems

This paper presents a controller structure for robust high speed and accuracy motion control systems. The overall control system consists of four elements: a friction compensator; a disturbance observer for the velocity loop; a position loop feedback controller; and a feedforward controller acting on the desired output. A parameter estimation technique coupled with friction compensation is used as the first step in the design process. The friction compensator is based on the experimental friction model and it compensates for unmodeled nonlinear friction. Stability of the closed-loop is provided by the feedback controller. The robust feedback controller based on the disturbance observer compensates for external disturbances and plant uncertainties. Precise tracking is achieved by the zero phase error tracking controller. Experimental results are presented to demonstrate performance improvement obtained by each element in the proposed robust control structure     

Cascade Control of PM DC Drives Via Second-Order Sliding-Mode Technique

This paper presents a novel scheme for the speed/position control of permanent-magnet (PM) dc motor drives. A cascade-control scheme, based on multiple instances of a second-order sliding-mode-control (2-SMC) algorithm, is suggested, which provides accurate tracking performance under large uncertainty about the motor and load parameters. The overall control scheme is composed of three main blocks: 1) a 2-SMC-based velocity observer which uses only position measurements; 2) a 2-SMC-based velocity control loop that provides a reference command current; and 3) a 2-SMC-based current control loop generating the reference voltage. The proposed scheme has been implemented and tested experimentally on a commercial PM dc motor drive. The experimental results confirm the precise and robust performance and the ease of tuning and implementation, featured by the proposed scheme.      

基于DSP与FPGA的运动控制器研究

设计了一种基于DSP与FPGA的运动控制器。该控制器以DSP为控制核心,用FPGA构建运动控制器与传感器以及电机驱动器的接口电路。充分发挥了DSP强大的运算能力和FPGA的并行处理能力。具有信息处理能力强、模块化程度高、编程容易、运动控制精度高等优点,可以实现高精度的速度环和位置环的双闭环控制,能够满足运动控制器的实时性和精确性要求。     

A robust speed controller for induction motor drives

A speed controller considering the effects of parameter variations and external disturbance for indirect field-oriented induction motor drives is proposed in this paper. First a microprocessor-based indirect field-oriented induction motor drive is implemented and its dynamic model at nominal case is estimated. Based on the estimated model, an integral plus proportional (IP) controller is quantitatively designed to match the prescribed speed tracking specifications. Then a dead-time compensator and a simple robust controller are designed and augmented to reduce the effects of parameter variations and external disturbances. The desired speed tracking control performance of the drive can be preserved under wide operating range, and good speed load regulating performance can also be obtained. Theoretic basis and implementation of the proposed controller are detailedly described. Some simulated and experimental results are provided to demonstrate the effectiveness of the proposed controller     

Mechatronics of electrostatic microactuators for computer diskdrive dual-stage servo systems

A decoupled control design structure and discrete time pole placement design method are proposed for MEMS-based dual-stage servo control design in magnetic disk drives. Dual-stage track following controllers are designed using a decoupled three-step design process: the voice coil motor (VCM) loop design, the microactuator (MA) inner loop design, and the MA outer loop design. Both MIMO (when the MA relative position sensing is available) and SIMO (when the MA relative position sensing is not available) designs are considered. The effect of MA resonance mode variations on the stability and performance of the controllers are analyzed. Self-tuning control and online identification of the MA model are developed to compensate for the variations in the MA's resonance mode     

FleXilicon Architecture and Its VLSI Implementation

In this paper, we present a new coarse-grained reconfigurable architecture called FleXilicon for multimedia and wireless communications, which improves resource utilization and achieves a high degree of loop level parallelism (LLP). The proposed architecture mitigates major shortcomings with existing architectures through wider memory bandwidth, reconfigurable controller, and flexible word-length support. VLSI implementation of FleXilicon indicates that the proposed pipeline architecture can achieve a high speed operation up to 1 GHz using 65-nm SOI CMOS process with moderate silicon area. To estimate the performance of FleXilicon, we modeled the processor in SystemC and implemented five different types of applications commonly used in wireless communications and multimedia applications and compared its performance with an ARM processor and a TI digital signal processor. The simulation results indicate that FleXilicon reduces the number of clock cycles and increases the speed for all five applications. The reduction and speedup ratios are as large as two orders of magnitude for some applications.      

LQG/LTR control of an AC induction servo drive

A new design method based on the linear-quadratic-Gaussian with loop-transfer-recovery (LQG/LTR) theory has been developed for the design of high performance AC induction servomotor drives using microcomputer-based digital control. The principle of field orientation is employed to achieve the current decoupling control of an induction motor. An equivalent model representing the dynamics of the decoupled induction motor has been developed. Based on the developed model with specified parameter uncertainties and given performance specifications, a frequency domain loop-gain-shaping method based on the LQG/LTR theory is proposed for the design of the servo loop controller. A microcomputer-based induction servomotor drive has been constructed to verify the proposed control scheme. Simulation and experimental results are given to illustrate the effectiveness of the proposed design method     

光电跟踪转台伺服控制策略研究

针对高性能光电跟踪转台负载重、摩擦大、跟踪精度要求高等特点,提出了基于复合控制的伺服控制策略,速度环路设计了带有扰动观测器的线性二次最优反馈控制器,并在前向通道增加了零相位误差跟踪控制器(ZPETC),提高速度环的跟踪性能,位置环采用非线性PID反馈控制方式降低超调,提高稳态精度;将低速率的位置给定信息分别进行插值细分和滤波,通过高增益微分器和卡尔曼预测滤波,对转台速度和加速度进行预测和估计,进行前馈实现复合控制,实践证明,这种策略可以有效提高大加速度下的跟踪精度。     

Advanced control of induction motor based on load angle estimation

An advanced control system with load angle adjustment is introduced. The method is based on the action of a phase-locked loop, in which a position synchronization of two vectors to obtain a constant command angle between them is realized. In the system presented, the vectors are stator current and rotor flux. The load angle is kept constant by changing the position of stator current vector as a result of tuning its pulsation. Proportional-integral and fuzzy logic controllers are used to control the load angle. Because of using the load angle controller and simple relations for state variables, the proposed idea does not require exact speed measurement. The discussed control system is not sensitive to motor resistance variations. This idea is realized on a fixed-point digital signal processor and field-programmable gate arrays. Experimental results for the control system fed by a voltage-source inverter and controlled using a predictive current controller are presented.     

Implementation of Hybrid Control for Motor Drives

This paper presents the implementation of a hybrid-control strategy applied to a permanent-magnet synchronous-motor (PMSM) drive. Hybrid control is a general approach for control of a switching-based hybrid system (HS). This class of HS includes a continuous process controlled by a discrete controller with a finite number of states. In the case of ac motor drives, in contrast to conventional vector control like proportional-integral control or predictive control, where the inverter is not taken into account by the controller, hybrid control integrates the inverter model and considers the state of the inverter as a control variable. It allows to obtain faster torque dynamics than vector-control algorithms. The hybrid control algorithm requires both computing velocity for real-time implementation and code flexibility for management of low-performance functions and analog-digital interfaces. Codesign appears as a promising methodology for partitioning hybrid-control algorithm between software (flexible) and hardware (velocity) while taking care of overall time constrains. In this paper, the implementation of hybrid-control algorithm for a PMSM drive is performed through a codesign approach on an Excalibur board, embedding a CPU-core (Nios-2 by Altera) inside an APEX20KE200EFC484-2X field-programmable gate array. The partitioning of software and hardware parts is explained. Experimental results show the effectiveness of the implementation. Performances, advantages, and limitations are discussed.