Studies On AC Voltage Measure By Digital Sampling

A Technology scheme about measuring AC voltage signal by digital sampling and proving it available and feasible from the definition of AC voltage and the principle of digital sampling and the circumstantially evident experiment as well. Normally the method of AC-DC transform which is based on analog-circuit is used to measure AC voltage, and the measure accuracy is restricted by the inherent defect of AC-DC transform. After analyzing the current principle of measuring AC voltage and the advantage and disadvantage of the circuit, the method of measure AC voltage by digital sampling is advanced. All information can be achieved when measuring AC voltage signal by digital sampling, not only the RMS and the frequency of AC voltage signal.Measuring AC voltage by digital sampling is achieved by researching and developing sampling circuit and arithmetic, especially the low frequency signal. The range of AC voltage measured is below 2V (RMS) , below 2k Hz (especially below 200 Hz) .Sample circuit is constituted of two parts: analog-circuit and digital-circuit. In the analog-circuit, AC voltage being measured is transmitted to the input of the sampling ADC through voltage follower, where the noise from the digital-circuit should be blocked off. Digital-circuit is the key part of the sampling circuit, in which the process controlling of MCU is the stress and the difficulty. ATMEGA64 AVR MCU is chosen in the sampling circuit and RISC (reduced instruction set computer) makes the controlling flexible and fast speed.Comparing the large amount experiment data with FLUKE 5790A, the consistency is so good that the deviation of sampling data and FLUKE 5790A is better than AC measure specification of high precision multi-meter currently.