附录 外文原文
Single-chip fuzzy logic controller design and an application on a permanent magnet dc motor
Abstract
This paper describes a low-cost single-chip PI-type fuzzy logic controller design and an application on a permanent magnet dc motor drive. The presented controller application calculates the duty cycle of the PWM chopper drive and can be used to dc–dc converters as well. The self-tuning capability makes the controller robust and all the tasks are carried out by a single chip reducing the cost of the system and so program code optimization is achieved. A simple, but effective algorithm is developed to calculate numerical values instead of linguistic rules. In this way, external memory usage is eliminated. The contribution of this paper is to present the feasibility of a high-performance non-linear fuzzy logic controller which can be implemented by using a general purpose microcontroller without modified fuzzy methods. The developed fuzzy logic controller was simulated in MATLAB/SIMULINK. The theoretical and experimental results indicate that the implemented fuzzy logic controller has a high performance for real-time control over a wide range of operating conditions.
Keywords Dc motor drive;Fuzzy logic controller;Microcontroller;Application; Simulation
1. Introduction
In switch-mode power supplies, the transformation of dc voltage from one level to another level is dc–dc conversion and accomplished by using dc–dc converter circuits, which offers higher efficiency than linear regulators. They have great importance in many practical electronic systems, including home appliances, computers and communication equipment. They are also widely used in industry, especially in switch-mode dc power supplies and in dc motor drive applications. The dc–dc converter accepts an unregulated dc input voltage and produces a controlled dc output at desired voltage level. They can step-up, step-down and invert the input dc voltage and transfer energy from input to output in discrete packets. The one disadvantage of dc–dc converters is noise. At every period to charge in discrete packets, it creates noise or ripple. The noise can be minimized using specific control techniques and with convenient component selection. There are well-known control techniques including pulse-width modulation (PWM) where the switch frequency is constant and the duty cycle varies with the load.
PWM technique affords high efficiency over a wide load range. In addition, because the switching frequency is fixed, the noise spectrum is relatively narrow, allowing simple low-pass filter techniques to reduce the peak-to-peak voltage ripple. For this same reason, PWM is popular with telecom power supply applications where noise interference is of concern.
The most important requirement of a control system for the dc–dc converter is to maintain the output voltage constant irrespective of variations in the dc input voltage and the load current. However, load changes affect the output transiently and cause significant deviations from the steady-state level of dc output voltage, which must be controlled to equal a desired level by the control systems. The inherent switching of a dc–dc converter results in the circuit components being connected periodically changing configurations, each configuration being described by a set of separate equations. Transient analysis and control system design for a converter is therefore difficult since a number of equations must be solved in sequence. Although the state-space averaging is the most commonly used model to obtain linear transfer functions to solve this problem, it neglects significant parts of non-linear behavior of dc–dc converters. Development of non-linear controllers for dc–dc converters have gained considerable attention in recent years. A fuzzy logic model based controller is chosen as the non-linear controller for this study. Fuzzy logic control (FLC) has been an important research topic. Despite the lack of concrete theoretical basis many successful applications on FLC were reported and various applications for dc–dc converters and electrical drives have been published and can be found in the literature (So et al., 1996, 1995; Mattavelli et al., 1997; Brandsetter and Sedlak, 1996; Hyo et al., 2001; Gupta et al., 1997; Zakharov, 1996; Vas, 1998, 1999). FLC has a wide-spread application on the non-linear and complex systems as well as linear systems due to its capability to control the systems that might not have a transfer function between input and output variables. Experi-ences show that fuzzy control can yield superior results to those obtained by conventional control algorithms.
In the meantime, new fuzzy microcontroller chips are available on the market and are able to execute fuzzy rules very fast with their mask programmed algorithms that have some drawbacks such as restriction in implementing any desired algorithm. Digital signal processing (DSP) integrated circuits (IC) are capable of computing and processing the system variables very quickly with high precision. But most of the DSP circuits are expensive and do not contain peripherals such as analog to digital (A/D) and digital to analog (D/ A) circuits for conversion and PWM generator on chip, and need to be added externally. A fuzzy controller application among the others on dc–dc converters used a TMS320-DSP and fuzzy controller with an evaluation module plus some external chips. They were an A/D converter for feedback signal evaluation, a D/A converter for converting the calculated quantity into a control output and a PWM chip to generate the appropriate duty cycle for the semiconductor switching elements ( 剩余内容已隐藏，支付完成后下载完整资料
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