Control Strategies & Performance Parameters of chopper

Control Strategies

a. The output dc voltage can be varied by the following methods.

b. Pulse width modulation control or constant frequency operation.

c. Variable frequency control.

Pulse Width Modulation

tON is varied keeping chopping frequency ‘f’ & chopping period ‘T’ constant. Output voltage is varied by varying the ON time t ON

Variable Frequency Control

1) Chopping frequency ‘f’ is varied keeping either tON or tOFF constant.

2) To obtain full output voltage range, frequency has to be varied over a wide range.

3) This method produces harmonics in the output and for large tOFF load current may become discontinuous

Performance Parameter

The performance Parameter of Step UP & Step down Converter is as follows

1) Ripple Current of Inductor

2) Maximum Switching Frequency FMAX

3) Condition for Continuous & Discontinuous Inductor Current

4) Minimum value of inductor to maintain continuous Inductor Current

5) Ripple content of output voltage & output current

6) ripple content of input current