Virtual instrumentation for power supply harmonic measurement

The work reported here presents a virtual instrument (VI) for total harmonic distortion (THD) measurement index with a high accuracy, this is due to the use of high characteristics windows and DFT (discrete Fourier transform) interpolation algorithms are specially interesting in power switching supplies measurements. In the PWM switching regulators frequency characterization the stimulus signal amplitude has to be small enough to keep the converter in its linear region of operation, but it has to be also large enough to be distinguishable from the random noise. This VI allows the amplitude and frequency range obtention. The THD generated by a nonlinear load in the power distribution system can be measured by this VI. The THD generated in the power distribution system by a flyback DC-DC switching converters has been measured.