1 中文 1963 字 Labview-based virtual function Signal Generator V Marozas, R Jurkonis 1 Introduction Since 1986, the U.S. NI (National Instrument) companies to the concept of virtual instrumentation, along with computer technology and measurement technology, virtual instrument technology has also been developed rapidly. Virtual instrument means: use of the existing PC, with a specially designed instrument hardware and proprietary software, the formation of the basic functions of both the ordinary instrument, there are usually no special equipment features of the new instrument. Compared with the traditional instruments of its features are: better measurement accuracy and repeatability; measurement speed; system set up time is short; instrument function defined by the user; scalability; technical updates and quick. Virtual instrument software as the core, the software company Youyi U.S. NI Labview virtual instrument software development platform most commonly used. Labview is a graphical programming language, mainly used to develop data acquisition, instrument control and data processing and analysis software, and powerful. Currently, the development of software in the international test, measurement and control industry, popular, measurement and control areas in the country has also been widely used. Function Generator is a scientific research and engineering design in a widely used general-purpose equipment. The following function signal generator with a virtual design and development of specific description is based on graphical programming language Labview virtual instrument programming and implementation of technology. 2 2 virtual function signal generator structure and composition 2.1 Virtual Function Generator front panel This virtual function signal generator mainly consists of a PCI bus, multi-function data acquisition card and appropriate software. Them installed on a PC running Windows95/98/2000/NT the machine, shall constitute a powerful function of signal generator. The design of the virtual function signal generator reference signal generator SG 1645 power functions, front panel shown in Figure 1. Figure 1 virtual function signal generator front panel The function generators front panel function of the following components: instrument control button, the output frequency control window (including the frequency of display units), frequency fold into control, waveform selection, frequency tuning button, dc bias, square wave accounts for Air ratio adjustment, the output waveform amplitude control buttons. Frequency tuning range: 0.1 1 Hz; DC bias: -10 10V; square wave duty cycle: 0 to 100%; output waveform range: 0 10V. Also increased the number of modification of voltage-controlled components such as panel input count input, synchronous output, voltage output. Modification of the use of these components is intended to increase the aesthetics of the instrument, and as far as possible with real instruments consistent user interface 2.2 Virtual Function Signal Generator hardware structure This virtual function signal generator hardware input and output data acquisition card and a certain 3 configuration requirements of the PC, the data input and output depend on input data acquisition card, the definition of output achieved. This design uses the PCI-1200 data acquisition card is a good cost-effective products, with the D / A conversion functions, can generate the digital signals into analog signals and digital-analog converter and high precision, but also has filtering capabilities, which Smooth the output waveform. It supports the unipolar and bipolar analog signal input, the signal input ranges of -5 +5 V and 0 10V. Provide 16 single-ended / 8 differential analog input channels, 2 independent of the DA output channels, 24-line TTL digital I / O, 3 16-bit timer counters and other features. Some of the hardware interface for data input or output channel settings. Some of the hardware interface block diagram shown in Figure 2: Figure 2 4 3 Virtual Function Signal Generator Design and Implementation Some use professional LabVIEW6i software virtual instrument graphical development tools. Virtual function signal generator output waveform mainly in software production and the output signal frequency display. Changes in the frequency of the output waveform is a concrete realization of data acquisition waveform data written to the buffer among the buffers by setting the update frequency (to change the internal clock frequency) to achieve the output data frequency. The process is mainly in the use of Labview data acquisition sub-module of the AO START function modules. Function from the implementation point of view, this design features a virtual function signal generator structure includes two modules: Module waveform generator (FG module) and frequency change control unit (DISPLAY) module. Waveform generator module and call FGEN module. FGEN module for the digital waveform generator module. Digital waveform generator module 3.1 Waveform generated virtual function signal generator module is the core of the software. The module can be realized using sine, square, sawtooth, triangle and other waveforms. Sine wave generation principle is by calling the sin (x) function to implement. In this design, the design of each component sine wave cycle from 1000, using similar language in the For loop C as x assignment, so that the implementation of a For loop, you can generate a cycle of sine wave generating the data needed, and then use While Circulation, make the program repeatedly executed, can be continuously output sine wave. Square wave, sawtooth, triangle and sine wave generation theory produce similar principles are achieved through the mathematical sequence of numbers representative of the waveform. Compared with the analog signal, generated using the software method of digital waveform sequence although there are some errors, but the election cycle as long as a sufficient number of points, you can make errors to a minimum, the least impact on the results. Waveform generated by the software one of the biggest advantage is greatly reduced the cost of the instrument and the instrument of small intelligent. Waveform generator modules front panel shown in Figure 3, waveform generation module block diagram shown in Figure 3 Change of 3.2 unit of frequency control module 5 When the output frequency dynamic range is large, with a single spin button control, due to a small rotation angle, you will have a greater change in the frequency, to the frequency of accurate Shezhi brought greater Kunnan, and frequency by using a knob Times by combining the output frequency can greatly improve the control accuracy. In order to improve control accuracy of the output frequency, which in this design, by using the unit of frequency change control module, the output control accuracy can be achieved 0.001Hz. The modules front panel shown in, the module block diagram shown in Figure 4 . Figure 4 6 4 Total Results: As a Labview graphical programming software development and testing system is a powerful, convenient and efficient programming tools. Similarity between the good, open, exclusive, making the test development cycle is short, low cost and high quality. Labview-based virtual machine interaction with the function signal generator is good, easy to operate and so on, to a wide range of applications and in scientific research, production and other fields. 1 Pan H Z, et al. LabVIEW-based virtual Function Signal GeneratorJ . Control Enginerring Practice, 2. Evans P D, Brown D. Simulation of brushless DC drivesc IEE Proceedings B, Electric Power Applications， 137(5) : 299-308 3. Ren Spe, Alan K. Wallace and Joel Davis. Modeling of brushless dc drive systems with pulse-width modulated excitationJ, Mathematical and Computer Modelling, Volume 11, 1988, Pages 1166-1171. 4. Jawad Faiz, M. R. Azizian and M. Aboulghasemian-Azami. Simulation and analysis of brushless DC motor drives using hysteresis, ramp comparison and predictive current control techniquesJ, Simulation Practice and Theory, Volume 3, Issue 6, 15 January 1996, Pages 347-363. 5. J. Figueroa, C. Brocart, J. Cros and P. Viarouge. Simplified simulation methods for polyphase brushless DC motorsJ. Mathematics and Computers in Simulation, Volume 63, Issues 3-5, 17 November 2003, Pages 209-224. 6. J. Shao, D. Nolan, and T. Hopkins. A Novel Direct Back EMF Detection for Sensodess Brushless DC (BLDC) Motor DrivesC. Applied Power Electronic Conference (APEC 2002), 2002: 33-38. 7. Doo-Hee Jung and In-Joong Ha. Low Cost Sensorless Control of Brushless DC Motors Using a Frequency Independent Phase Shifter J IEEE Transactions on power electronic, 2000, 15: 744-752. 8. Kuang-Yao Cheng and Ying -Yu Tzou. Design of a Sensorless Commutation IC for BLDC Motors J IEEE Transactions On power electronic, 2003, 18: 1365-1375. 7 基于 Labview 的虛擬函數信號發生器的設計 V Marozas, R Jurkonis 1前 言 自從 1986 年美國 NI(National Instrument)公司提出虛擬儀器的概念以來 ,隨著計算機技術和測量技術的發展 ,虛擬儀器技術也得到很快的發展。虛擬儀器是指 :利用現有的 PC 機，加上特殊設計的儀器硬件和專用軟件 ,形成既有普通儀器的基本功能 ,又有一般儀器所沒有的特殊功能的新型儀器。與傳統的儀器相比其特點主要有 :具有更好的測量精度和可重復性 ;測量速度快 ;系統組建時間短 ;由用戶定義儀器功能 ;可擴展性強 ;技術更新快等。虛擬儀器以軟件為核心 ,其軟件又以美國 NI 公司的 Labview 虛擬儀器軟件開發平臺最為常用。 Labview 是一種圖形化的編程語言 ,主要用來開發數據采集，儀器控制及數據處理分析等軟件 ,功能強大。目前 ,該開發軟件在國際測試、測控行業比較流行 ,在國內的測控領域也得到廣泛應用。函數信號發生器是在科學研究和工程設計中廣泛應用的一種通用儀器。下面結合一個虛擬函數信號發生器設計開發具體介紹基于圖形化編程語言 Labview 的虛擬儀器編程方法與實現技術。 8 2虛擬函數信號發生器的結構與組成 2.1 虛擬函數信號發生器的前面板 本虛擬函數信號發生器主要由一塊 PCI 總線的多功能數據采集卡和相應的軟件組成。將它們安裝在一臺運行 Windows95/98/2000/NT 的 PC 機上，即構成一臺功能強大的函數信號發生器。本虛擬函數信號發生器的設計參考了 SG 1645 功率函數信號發生器，前面板如圖 1 所示。 本函數信號發生器的前面板主要由以下幾個部分構成：儀器控制按鈕，輸出頻率控制窗口（包括頻率顯示單位），頻率倍成控制，波形選擇，頻率微調按鈕，直流偏置，方波占空比調節，輸出波形幅度控制按鈕。頻率微調范圍： 0.1 1 Hz；直流偏置： -10 10V；方波占空比： 0 100%；輸出波形幅度： 0 10V。此外還增加了許多修飾性的元件如面板上的壓控輸入、記數輸入、同步輸出、電壓輸出等。使用這些修飾性的元件的目的是為了增加儀器的美觀性，并盡量與真實儀器的使用界面相一致 2.2 虛擬函數信號發生器的硬件構成 本虛擬函數信號發生器的輸入輸出的硬件部分為一數據采集卡和具有一定配置要求的 PC 機，數據的輸入輸出靠對數據采集卡輸出輸入口的定義來實現。本設計采用的 PCI-1200 數據采集卡是一塊性價比較好的產品，具備數 /模轉換的功能，能將產生的數字信號轉換成模擬信號且數模 轉換精度高，而且還具備濾波功能，從而使輸出波形光滑。它支持單極和雙極性模擬信號輸入，信號輸入范圍分別為 -5 +5V 和 0 10V。提供 16 路單端 /8 路差動模擬輸入通道、 2 路獨立的 DA 輸出通道、 24 線的 TTL 型數字 I/O、 3 個 16