Hey, Currently I am pursuing masters in Electrical Engineering. In my curriculum

Question

Hey, Currently I am pursuing masters in Electrical Engineering. In my curriculum I am having one project. I request you to help me for that project. I look forward your positive response as soon as possible.

Given ;-Switching frequency : f s = 140 kHz; Carrie peak voltage: Vs = 15 V

Input Voltage: Vin = 45 V

Output Voltage: Vo = 18 V

Load: R L = 4 W

Inductance : L = 110 mH

Inductance Resistance: R=0.01 W

Sensing Resistance: Rt = 0.1 W

Capacity : C = 6 mF; Rc = 0.04 W

This is a DC-DC converter system similar to that in Project 1, but with different parameters.

Modeling:

1-Derive the transfer function from the duty cycle d(t) to the inductor current.

2-Derive the transfer function from the inductor current to the load voltage.

3-Design by using the root locus method:

3.1-Design an inner loop control for the current, using a P controller, such that the inner loop has a damping ratio larger than 0.7. Discuss the tradeoff among the rising time, peak time, and steady-state error.

3.2-Design an outer loop control for the load voltage, using a PI controller, such that the outer loop has an overshoot smaller than 20%. Discuss the tradeoff among the rising time, peak time, and steady-state error.

4-Design by using the frequency domain method:

4.1- Inner Loop Design: Design an inner loop control as in Part 3.1.

4.2-Design an outer loop control for the load voltage, using a PI controller, such that the outer loop has a phase margin at least 90 degree. Discuss the tradeoff between bandwidth of the (outer) closed-loop system and phase margin.

5-Simulate the overall closed-loop system, in its transfer function form, with your designed controllers (using Matlab or Simulink).

6-Simulate the overall closed-loop system, in its circuit form, with your designed controllers (using PSIM or the Matlab/Simulink toolbox). In your simulation, you may use a transfer function for your controller, rather than an operational amplifier.

Explanation / Answer

PART 1 ANSWER: W.K.T., diL/dt=((1-D)T)V0/L

For a DC-DC CONVERETR.

Hence transfer function if we apply Laplace transform is:

[1-D(S)]/ IL(S)=S2L/V0

PART 2: LdIL/dt=TV0-DV0T

IL(S)/V0(S)=L[1-D]/S2

PART 3: LT[OUTPUT]/LT[INPUT]>0.7

LT=LAPLACE TRANSFORM

0.7<L2/[1-D]

DESIGN A P CONTROLLER WITH DUTY CYCLE

D>0.983

PART 3.2

ANY FURTHER QUERIES PLEASE POST ON THE BLOG

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