Input current and its fundamental component of a fully controlled bridge rectifier
Input current and its fundamental components:
- By observing the voltage waveforms we can conclude that the current waveform is also periodic over an interval π, so finding out an expressions for i0 over an interval of length π will be sufficient.
- Therefore, in the interval α ≤ ωt ≤ π α,
- Now at steady statei0|ωt = α = i0|ωt = π α since i0 is periodic over the interval α ≤ ωt ≤ π α. Using this boundary condition we get:
- The input current displacement factor defined as the cosine of the angle between input voltage (vi) and the fundamental component of input current (ii1) waveforms is cosα (lagging).
We can get,
- The i/p current distortion factor is
- The i/p power factor is
- The rectifier appears as a lagging power factor load to the input ac system. Larger the ‘α’ poorer is the power factor.
- The input current ii also contain significant amount of harmonic current (3rd, 5th, etc) and therefore appears as a harmonic source to the utility.
Questions of this topic
A single phase fully controlled bridge converter operates in the continuous conduction mode from a 230V, 50HZ single phase supply with a firing angle is 30 degrees. The load resistance and inductances are 10Ω and 50mH respectively. Find out the 6th harmonic load current as a percentage of the average load current.