数字式工频有效值多用表的研制

Development of a digital multimeter of power frequency root mean square

数字式工频有效值多用表可以简化用于测量电压有效值、电流有效值、有功功率、无功功率、功率因数、电压基波分量及总谐波有效值等一系列工频参数的设备。文中设计采用MSP430F149为主控制单元,用12位高精度AD采样,前端通过由TLC7528构成的可编程放大器实现小信号放大,提高采样精度。中间加入两路采样保持,实现小误差高速采样。采样点送入MSP430后,采用FFT算法分析工频信号频谱,经过数据处理,获取各参数值。试验证明,文中设计成本低廉,可靠性高,测量结果精度较高,具有广阔的应用和推广前景。

Digital multimeter of power frequency RMS （Root Mean Square ） greatly simplifies the common equipments that used for measuring power frequency parameters, such as the voltage RMS, current RMS, active power, reactive power, power factor, voltage base wave component, total harmonic RMS, and so on. In this design, MSP430F149 is used as the main control unit, with 12 bits AD chip for high precision sampling. In the front, a programmable amplifier composed of TLC7528 is used for amplifying small signals and enhancing sampling accuracy. High-speed sampling with small error is realized by holding two sampling. After the sampling data are input into MSP430, the power frequency signal spectrum is analyzed by Fast Fourier Transform （FFT） algorithm. The parameters＇ values are obtained after certain data processing. The tests demonstrate that this multimeter has low cost, high precision and liability, and it has a bright prospect of application and popularization.