外文翻译--基于虚拟仪器技术的风机性能自动测试系统(编辑修改稿)

外文翻译--基于虚拟仪器技术的风机性能自动测试系统(编辑修改稿)内容摘要：

process has increased, the reading error was avoided and the measurement accuracy and experiment efficiency were improved. The system has been widely applied to many fan production factories and research institutes. 2 Hardware design of the system Hardware of this system, which is the basis of signal acquisition, conversion, enhance and processing, consists of fan, motors, wind pipe, sensors, puter, data acquisition board, frequency conversion governor, etc. The block diagram of system structure is shown in . Among those ponents, puter and plugin DAQ board play an important role in the system. With the high performance DAQ board, not only data acquisition, A/D conversion but also frequency control, step motor control etc are realized. Considered of the technical indexes such as samplingfrequency, accuracy, A/D amp。 D/A conversion rate, resolution, the DAQ board PCI6024E from National Instruments (), with which 200 ks/s, 12bit performance on 16 singleended analog inputs can be got up to, is selected. The 6024E features digital triggering capacity, as well as two 24bit, 20 MHz counter/times。 and 8 digital I/O lines. Two 12bit analog outputs are also featured by the 6024E[6]. The fan parameters: flux, static pressure, torque and rotation speed are measured by corresponding sensors including differential pressure transmitter ( BC69 type, accuracy is FS ), static pressure transmitter (JYB type, accuracy is 1%FS), and torque amp。 rotate speed sensor ( AKC205 type, accuracy is 0. 3%FS). The sensor outputs are all standard current signal with 4~20 mA. To meet the DAQ board input signal type and range, 0 ~ 5 V voltage signals are achieved from 4~20 mA current signals by an interface board which is used for signal transformation. Through the analog output channel on 6024E, 0~5 V voltage signal which is corresponding on 0~50 Hz of AC frequency, are sent out to control frequency converter ( type, MITSUDISHI, Japan). Then, the fan speed changes with variable voltage. The regulating unit of working status, which is designed by the authors, is the rotating baffle structure posed of round baffle, shaft coupling, creeper gear and step motor etc. (See the ). This kind of structure can not only realize the auto control but also is small and flexible. Three digital I/O port on the 6024E are used to send out three phase pulse to control the rotation angle of step motor. The step motor drives the round baffle through the creeper gear to revolve inside the wind pipe, resulting in the change of aperture gap between the round baffle and windpipe, thereby altering the flux of airflow inside the windpipe, namely the alteration of working status is realized. The creeper gear can prevent the position of round baffle changing when the airflow is too strong. To insure the measurement accuracy, several antiinterference means are adopted such as differential inputs of signals to eliminate the mon mode interference, good earth of signal line and instruments, digital filtering technology in software[7]. 3 Software design of the system Data processing Data processing in this system includes three aspects: processing acquired signals to weed out various disturbing signals。 using hydrodynamics formulas to calculate performance parameters of fans。 fitting performance parameters based on least square method to draw performance curves of fans. Calculation of performance para。