v0' fed to the input channel 0 of the ADC, while v1' fed to the second channel of the ADC input. Another channel ADC inputs are connected to the Ground to reduce the effects of cross-talk between the two entries. Voltage signal v0’ which represent the grid voltage and signal voltage v1’ which represent the load current, sampled by the ADC of microcontroller.
The higher the ADC clock, so sampling process will be faster, but tend to diminish the accuracy of the ADC. In order to obtain fast conversion time but the accuracy of eight bits, then the ADC is run with prescaler = 16. This means that the ADC is run using a clock frequency of 691 kHz. Time to do a conversion or the conversion period (tc) is 14 times the clock period or about 20 microseconds. At 50 Hz input signal, sampling the voltage signal at intervals of 20 microseconds will provide a maximum error 0.1%
The Need for Phase Difference Measuring Instrument
Measure the Frequency of Grid Voltage rather than Measure the Frequency of Current
Voltage and Current Converter
The Signal Conditioning
Frequency Measurement
Phase Difference Measurement
Output Display Format
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