1. Harmonics
Ben Kemink

2. The Analysis
A higher harmonic is a sine wave, with a frequency that is an integer multiple of the fundamental frequency.
Harmonic analysis resolves a distorted wave form into a DC-component, the fundamental sine wave and its higher harmonics.
Distorted wave
resolve
fundamental wave
7th harmonic wave
Amplitude
frequency
fundamental
component
3rd harmonic
5th harmonic
7th harmonic
5th harmonic wave
3rd harmonic wave

3. Influence of the OBSERVATION WINDOW
When a RECTANGULAR WINDOW is applied, the sampling period must be synchronized with the input signal period.

4. How many harmonics are needed to obtain a certain accuracy?
The error is measured against RMS values!
Note:
The fundamental (= first harmonic) and the higher harmonics are pure sine-waves!
This table shows the relationship between the number of harmonics included and the remaining error as a percentage of the ideal waveform.
(k=harmonics order number)

5. How many Harmonics are enough?