Objective:

For this project, a buck converter is to be designed that will convert 42 V input to an

output voltage based on your group number:

Output voltage: (N+5) volts dc where N is the last digit of your ZID.

The following steps should be accomplished in the design:

A) For this project the controller shown in fig. 3 can be approximated by the equivalent

circuit of fig. 4. Calculate the gain Kp required so that the steady state error of

the system for a step input is less than 1%. Although the system is a nonlinear system

its average behavior for a given operating point can be approximated with a linear

transfer function. See Appendix A for the development of this transfer function.

Assume the triangle wave peak, Vp, has a value of 5 V for your calculations.

V

ref.

V

Vp

Ov

out

Kp

M

Page 3 of 6

To Voltage-

Controlled

Voltage-Source/nB) Calculate values for Lf and Cf in fig. 1 to keep the capacitor voltage ripple less than

0.01v. Calculations should be based on a 50 kHz switching frequency. The rated

output current is to be 2 A. The linearization theory used for the control is based on

assuming the bandwidth of the closed loop system is considerably smaller than the

switching frequency, that is

@ << 2πfs.

The choice of Lf and Cf should therefore ensure the system bandwidth is small

enough. See Appendix A for information on the system bandwidth.

C) Simulate the buck converter using a SPICE based software at rated load current.

Show your design meets the design requirements.

For the report, follow the outline given in Appendix B. The report should just contain a

summary of the method and not a formal report.

References

[1] D. W. Hart, Power Electronics, McGraw Hill, 2010, pp. 302 - 325.

[2] N. Mohan, Power Electronics: A First Course, Wiley, 2023, pp. 99 - 105; Appendix

4B.