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Figure: 3.3 Frequency modulation waveforms
Current Limit Control:
As
is obvious from its name,
in this control strategy, a specific limit is applied on the current variation.
In this method, current is allowed to fluctuate or change only between 2 values i.e. maximum current (I
max) and minimum current (I min). When the current is at minimum value, the chopper is switched ON.
After this
instance,
the current starts increasing, and when it reaches up to maximum value, the chopper is
switched off allowing the current to fall back to minimum value. This cycle continues again and again.
Figure: 3.4 current limit control waveforms
Classification of Choppers
Depending on
the voltage output, choppers are classified as −
1.
Step Up chopper (boost converter)
2.
Step Down Chopper(Buck converter)