Question

Students are required to simulate the diode half bridge and full bridge rectifier using MATLAB. Together with the simulation, students are required to show the waveform associated with the respective circuits. Suggest ways to improve the output DC voltage by connecting the following filters:

1. Capacitor filters.

2. Inductor filters,

3. π filter

4. L filters.

                                    

Answer 1

A rectifier is used to convert AC voltage into a DC output, but there exists a ripple in the output wave form which can be removed by filters. The halfbridge rectifier passes either the positive half cycle pulses or negative half cycle pulses. A full bridge rectifier passes both the postive and negative cycles. The halfbridge and full bridge circuits are implemented in Matlab Simulink and are given below. Their outputs waveforms are given beside the corresponding circuits. An sine wave of 15 V peak amplitude and frequency of 60 Hz is given as input.

Half bridge rectifier:

Full bridge rectifier:

For removing these ripples the filters could be used.

1) using a capacitor filter of 470 microfarad gives the following output:

2)using an inductor filter of 370 milli henry gives the following result:

4)using an inductor, L=370 milli henry in series and a capacitor, C=10 micro farad in parallel with the load makes an L filter, which gave the following result:

3)A pi-filter is noting but two shunt capacitors, C1= 770 microfarad and C2=10 microfarad, with a series inductor, L1=370 milli henry which gave the following result:

As we can see the ripple is removed to a greater extent using a pi filter.