开关电源EMI设计(英文版)

Integrated EMI/Thermal Design for

Switching Power Supplies

Wei Zhang

Thesis submitted to the Faculty of the

Virginia Polytechnic InsTItute and State University

in parTIal fulfillment of the requirements for the degree of

Integrated EMI/Thermal Design for

Switching Power Supplies

Wei Zhang

(ABSTRACT)

This work presents the modeling and analysis of EMI and thermal performance

for switch power supply by using the CAD tools. The methodology and design guidelines

are developed.

By using a boost PFC circuit as an example, an equivalent circuit model is built

for EMI noise predicTIon and analysis. The parasiTIc elements of circuit layout and

components are extracted analytically or by using CAD tools. Based on the model, circuit

layout and magnetic component design are modified to minimize circuit EMI. EMI filter

can be designed at an early stage without prototype implementation.

In the second part, thermal analyses are conducted for the circuit by using the

software Flotherm, which includes the mechanism of conduction, convection and

radiation. Thermal models are built for the components. Thermal performance of the

circuit and the temperature profile of components are predicted. Improved thermal

management and winding arrangement are investigated to reduce temperature.

In the third part, several circuit layouts and inductor design examples are checked

from both the EMI and thermal point of view. Insightful information is obtained.