Fundamentals of Power Electronics with MATLAB
Designed as a hands-on reference, this text teaches students and engineers how to use MATLAB as a simulation and computational tool for power electronics.
TABLE OF CONTENTS Fundamentals of Power Electronics with MATLAB
Chapter 8: Thermal Management
INTRODUCTION
Power electronic devices typically operate at high temperatures. It is not uncommon, for example, for power devices to get hot enough to vaporize water at the surface of the device package. The heat generated by a power device must be transported to the surrounding environment at a sufficient rate so that the internal temperature of the device from does not exceed the maximum temperature specified by the manufacturer. If the maximum temperature is exceeded, the device will be destroyed. The temperature of electronic devices also affects their reliability; higher temperatures result in shorter component lifetimes. Device specifications and reliability issues thus dictate how much thermal energy must be managed to maintain the temperature of an electronic device at a safe level.
THERMAL MODEL OF ELECTRONIC DEVICES
Thermal modeling can be a very detailed and complex procedure that requires the solution of multidimensional partial differential equations. In very critical applications, the thermal computations are performed by computer programs that generate a temperature distribution profile throughout the system being modeled. Fortunately, the great majority of heat problems that arise in power electronics are solvable with very simple thermal models. The simplest model results when thermal energy is considered to flow only in one dimension under steady-state conditions.
One-Dimensional Heat Flow
The heat generated in a power electronic device occurs in the semiconductor material inside the device package. Since the semiconductor material comprises PN junctions, the internal temperature of the device is referred to as the junction temperature. The heat...
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