The Development Of Multifunctional Instrument For The Measurement Of AC/DC Electric Parameters

With the development of science and technology, the measurement of fine, intelligent requirements continue to increase, the measurement accuracy of electrical measuring instrument such as a voltmeter, ammeter, frequency meter, power meter, also has been greatly improved. These electrical measuring instruments is the important basis for the production and business decision, analyzing the operating state of electric equipment. However, electrical measuring instrument to detect the electric parameters, a variety of special instrument. This is to measure the work to bring great convenience, and low efficiency, high cost. This paper developed a multifunctional measuring instrument of AC and DC a low cost, high precision.In this paper, the design of the multifunction measuring instrument by a DSP and a plurality of single chip micro controller for AC/DC. The instrument system is divided into two parts, the upper and lower machine. The host computer for industrial control computer, is mainly responsible for human-computer interaction, and the lower machine is responsible for data collection, analysis, calculation, processing and data through serial port PC host computer, the operating instructions. DSP microprocessor TMS320VC33 as the core control algorithm of AC signal, the MCU C8051F350 as the control core of the DC signal operation. Uses high performance 16 bit ADS8364 and 24 bit high precision, low power ADS1240 converter were collected on the AC signal and the DC signal, to ensure the accuracy of measurement. The instrument can realize the measurement the AC voltage, current, frequency, phase, power, harmonic and DC voltage, current, ripple and many other parameters.This paper gives the functional requirements of multifunction meter and the main technical indicators, and the overall structure of the multifunction meter hardware, software design. According to the requirements of the design of instrument system, this paper designs the hardware and software based on the idea of modular design, and elaborates the design method of each module of hardware circuit and software program.The harmonic detection algorithms are analyzed and compared, the advantages and disadvantages of each algorithm are given. because of the traditional FFT algorithm has frequency spectrum leakage and picket fence effect, study on the windowed interpolation FFT algorithm. The simulation results show that, the measuring precision is improved, and at the same time, the application of this algorithm in the instrument, achieved good practical resultsFinally, according to the electric power parameters related to verification regulation, the function and performance parameters test of AC and DC multifunctional measuring instrument were made, and the test results are presented. The test results show that, the system can achieve the desired goals, and has practical value.