Capstone Design Project in Power Electronics

Overview

Learners will design a DC-DC converter that powers USB-C devices (20 V at 3 A) from a dc input voltage source such as a lithium-ion battery pack or a desktop computer power bus. Aspects of the project will include:

● Design of converter power stage and magnetics. Requires mastery of courses 1, 2, and 5.
● Simulation to verify correct steady-state operation. Requires mastery of courses 1, 2 and 4.
● Design of converter control system. Requires mastery of courses 3 and 4.
● Simulation to verify correct control system operation. Requires mastery of courses 3 and 4.
● Preparation of milestone reports documenting the design and its performance

The reports will be peer graded.

Syllabus

Introduction and Power Stage Design
-Select a converter circuit approach for the bidirectional dc-dc converter to interface a lithium-ion battery pack to a USB load. Begin the design of the power stage components and LTspice simulation.

Power Stage Design and Documentation
-Finish the design of the power stage components and the converter power stage LTspice simulation. Document your steady-state converter design for submission of Milestone 1.

Preliminary Controller Design
-Develop an averaged model of your power converter. Select a control approach (voltage mode, peak current mode, or average current mode control), and begin the design of the control loop(s) to meet requirements on crossover frequency and maximum closed-loop output impedance. Begin development of LTspice averaged simulation of your controller design.

Preliminary Controller Design and Documentation
-Complete development of an averaged model of your power converter, its control loop(s), and an LTspice averaged simulation. Document your control circuit design for submission to Milestone 2.

Complete Design
-Begin development of an LTspice switching model of your closed-loop converter system, to verify that your system meets load current transient requirements. Improve your design as necessary. Begin addition of current limiting to your circuit.

Complete Design and Documentation
-Complete development of an LTspice switching model of your closed-loop converter system, and verify that your system meets load current transient requirements. Complete the addition of current limiting to your circuit, to prevent inductor saturation during transients. Demonstrate your final design, including: operation at the specified operating points, closed-loop response to a step change in load current, current limiting, inductor and capacitor size, and efficiency. Document the final design for submission to Milestone 3.