Numerical optimization techniques applied to PPM signal design

A computer-oriented algorithm is developed for designing optimum waveforms for a pulse-position-modulation communication system. Nonlinear modulation threshold effects are incorporated directly into the design by introducing constraints on the sidelobe peaks of the autocorrelation function. The search is performed over the class of signals satisfying constraints on average power, peak power, and bandwidth. The optimum signal in this class is the one whose autocorrelation function has the sharpest central peak while the sidelobe peaks are below the specified constraint level. Numerical results for a realistic problem are presented, and the effect of introducing the correlation and peak power constraints is studied. It is shown that a large reduction in the sidelobe peaks is possible with relatively little loss in the sharpness of the central peak.     

无刷直流伺服驱动系统设计

本文通过对全数字直流伺服驱动系统的理论研究,进行控制策略的分析与应用,实现系统的高响应和高精度。首先从永磁直流电机的数学模型出发,建立动态数学模型,考虑各种干扰及参数变化,把相应的控制策略运用到电机控制,了解伺服驱动的内在结构,研究最佳控制策略,使系统的性能达到预期目标。研究模糊自适应控制系统,编写了PID改进算法,优化了对转速的稳定、精确控制。用MATLAB软件建立伺服系统模型,并仿真PID改进算法对电机转速的控制。     

Fuzzy logic applied to speed control of a stepping motor drive

Nowadays, thanks to the development of microprocessors, stepping motors are widely used in robotics and in the numerical control of machine tools where they have to perform high-precision positioning operations. Nevertheless, the variations of the mechanical configuration of the drive, which are common to these two applications, can lead to a loss of synchronism for high stepping rates. Moreover, the classical open-loop speed control is weak and a closed-loop control becomes necessary. In this paper, the fuzzy logic principle is applied to control the speed of a stepping motor drive with feedback. An advanced test bed is used in order to evaluate the tracking properties and the robustness capacities of the fuzzy logic controller when variations of the mechanical configuration occur. The experiment has been performed using a low-cost 16 bit microcontroller in order to verify the design performance     

永磁同步电机伺服系统自抗扰控制器设计

对永磁同步电机(PMSM)调速系统中的时变输入提出具有更高跟踪精确度的改进型自抗扰控制策略.传统的自抗扰控制主要针对阶跃信号进行快速和无静差追踪,对时变信号存在较大的跟踪误差,使自抗扰控制的应用受限.文中对稳态误差的存在原因进行了理论分析,进而设计带有微分前馈和并联线性扩张状态观测器(P-LESO)的改进型转速自抗扰控...     

Transmitter drive using digital techniques to give frequency modulation

This letter describes an f.m. drive for transmitters operating at medium frequencies. The drive uses digital techniques, giving a centre frequency that is highly stable but still allows frequency modulation, is linear and has a high modulation index. It was developed initially for the BBC's motoring service proposal (CARFAX).     

伺服环路控制器的数字化设计

为解决模拟电路在伺服控制系统中存在的器件漂移、抗干扰能力差、变量不易监视等诸多不足,对某船载卫通站伺服环路模拟控制器进行了分析,提出计算机控制代替模拟控制的方法。首先通过电路分析得出模拟控制器的传递函数,再采用零阶保持器法对模拟控制器传递函数进行数字化,并给出了便于编程的控制算法,得到了相应的数字控制器传递函数。经过M...     

Extended-window interpolation applied to digital filter design

This paper develops a procedure for the design of frequency-selective interpolation operators that can be computed and saved once and for all. These operators are used to design real-time digital operators: interpolators, FIR differentiators, IIR filters, and composed interpolation and filtering operators. Each real-time operator is a matrix relating sets of data points to sets of interpolated values. Since these matrices are characterized by low norms, they permit reduced-word implementations, and are suitable for real-time processing with array processors and massively parallel machines. The design of the interpolation operators uses windows that, unlike traditional approaches, extend beyond the data interval up to the length permitted by the dimensionality theorem. A new form of the dimensionality theorem is used to minimize the minimax interpolation error within a predetermined frequency range, which may be either the passband of the antialiasing filter or the passband of an analog prototype filter. The main application presented in the paper is the design of combined digital filters and interpolators, which will be referred to as interpolating filters. The frequency responses of such filters, as well as the interpolated time responses, almost coincide with those of the corresponding analog prototypes     

Simulation-based design optimization methodologies applied to CFD

Finding the optimal physical design for an electronic system is extremely time-consuming. In this paper, we describe a sequential global optimization methodology that can lead to better designs in less time, and illustrate its use by optimizing the design of a heat sink for a simple system. The results show the need for a global approach, the insights that can be gained through automated design optimization, and illustrate the efficiency of the reported methodology in finding the optimum design.     

Experimental fault-tolerant control of a PMSM drive

The paper describes a study and an experimental verification of remedial strategies against failures occurring in the inverter power devices of a permanent-magnet synchronous motor drive. The basic idea of this design consists of incorporating a fourth inverter pole, with the same topology and capabilities of the other conventional three poles. This minimal redundant hardware, appropriately connected and controlled, allows the drive to face a variety of power device fault conditions while maintaining a smooth torque production. The achieved results also show the industrial feasibility of the proposed fault-tolerant control, that could fit many practical applications     

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.     

Efficient matrix techniques applied to transmission tower design

Self-supporting transmission towers are highly indeterminate structures. Until recently, analysis of such structures was accomplished by determinate methods due to the number of calculations involved in indeterminate methods. Results from the former were often questionable because elastic properties of members were not considered. Today, large numerical problems are being solved with high-speed digital computers as a matter of routine. This paper presents a technique for efficiently solving large systems of symmetrical linear equations obtained from an indeterminate method of analysis without resorting to matrix inversion. A procedure for incorporating the analysis into a tower design program is then given.     

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.     

Discrete-time LQG/LTR design and modeling of a disk drive actuatortracking servo system

This paper presents the discrete-time LQG/LTR design of a disk drive track following servo system. The servo compensator designed through linear-quadratic Gaussian control combined with loop transfer recovery (LQG/LTR) consists of a Kalman filter for state estimation and state feedback for control. The desired tracking servo performance is first formulated through a frequency shaped return ratio of the Kalman filter and subsequently recovered at the output of the plant/compensator loop through the automatic design of a discrete-time linear quadratic (LQ) regulator. Particular attention has been given to modeling the calculation time delay and bias force estimation. The excellent robustness and performance characteristics of a continuous time LQG/LTR design are theoretically unachievable due to the extremely low sampling rate and nonminimum phase plant characteristics. However, both time and frequency domain simulations show that reasonable stability margins and performance can still be recovered. This technique nearly eliminates all the trial and error typical of a conventional pole placement design of a similar system. The direct discrete-time design can handle extremely low sampling rates associated with embedded servo systems. The technique can also be used for designing multi-rate and multi-input servo systems     

Discrete-time mode switching control with application to a PMSM position servo system

This paper presents a mode switching control (MSC) scheme in discrete-time domain for fast and precise set-point tracking in servo systems subject to control saturation and unknown disturbance. The basic idea is to combine the proximate time-optimal servomechanism (PTOS) and the composite nonlinear feedback (CNF) control, using the output position as the only measurable information for feedback. The PTOS is responsible for fast targeting in servo systems when the tracking error is large, and once the system trajectory enters into some specified region, the CNF will take over the control to ensure a smooth settling without compromising the fast transient performance. A reduced-order extended state observer is adopted to estimate the speed signal for feedback and the disturbance for compensation. The asymptotical stability of the proposed MSC scheme is analyzed and the switching conditions are provided. Simulation and experimental results on a permanent magnet synchronous motor (PMSM) servo system verify that the proposed control scheme is effective in improving the tracking performance for a wide range of target set-points.     

Estimated acceleration feedback applied to a telescope servo system

Methods of increasing the bandwidth of a telescope servo system have been investigated. The results of this research, both via simulation and practical evaluation, have shown that the application of acceleration feedback can increase the position servo loop bandwidth by a factor of 4. Acceleration feedback has been applied successfully to the servo system of a real machine. This has been achieved both by the use of accelerometers and by software-based acceleration calculation and state estimation techniques. The performance of the software-based techniques matches that of the accelerometer if the sampling rate of the servo system is high enough.     

基于MOSFET设计优化的功率驱动电路

在分析了功率MOSFET结构特性的基础上,讨论驱动电路的设计,从而优化MOSFET的驱动性能,提高设计的可靠性。     

基于MOSFET设计优化的功率驱动电路

在分析了功率MOSFET其结构特性的基础上,讨论驱动电路的设计,从而优化MOSFET的驱动性能,提高设计的可靠性。     

Intersample ripple-free multirate control with application to a hard disk drive servo

This paper discusses the intersample ripple problem in multirate control design. Supplementations and corrections have been made to the multirate control scheme proposed in . Moreover, the proposed method is applied to a 5.25-in hard disk drive servo system. The experimental results show that the proposed method can handle the intersample ripples existing in the conventional design very well and that the new multirate control design demands a much smaller control input profile than the conventional design.     

CMOS low-noise amplifier design optimization techniques

This paper reviews and analyzes four reported low-noise amplifier (LNA) design techniques applied to the cascode topology based on CMOS technology: classical noise matching, simultaneous noise and input matching (SNIM), power-constrained noise optimization, and power-constrained simultaneous noise and input matching (PCSNIM) techniques. Very simple and insightful sets of noise parameter expressions are newly introduced for the SNIM and PCSNIM techniques. Based on the noise parameter equations, this paper provides clear understanding of the design principles, fundamental limitations, and advantages of the four reported LNA design techniques so that the designers can get the overall LNA design perspective. As a demonstration for the proposed design principle of the PCSNIM technique, a very low-power folded-cascode LNA is implemented based on 0.25-/spl mu/m CMOS technology for 900-MHz Zigbee applications. Measurement results show the noise figure of 1.35 dB, power gain of 12 dB, and input third-order intermodulation product of -4dBm while dissipating 1.6 mA from a 1.25-V supply (0.7 mA for the input NMOS transistor only). The overall behavior of the implemented LNA shows good agreement with theoretical predictions.