What are the best practices for thermal management of power electronics in biomedical applications?

1 Choosing the right converter topology

The converter topology is the arrangement of switches, diodes, capacitors, and inductors that convert the input voltage and current to the desired output. The choice of the converter topology affects the efficiency, size, weight, and cost of the system, as well as the heat generation and dissipation. Some of the factors that influence the converter topology selection are the input and output voltage levels, the power rating, the switching frequency, the isolation requirements, and the control strategy. Generally, higher efficiency and lower switching frequency lead to lower heat generation, but they may also increase the size and weight of the components. Therefore, a trade-off analysis is needed to find the optimal converter topology for each application.

2 Selecting the appropriate components

The components of the power electronic converter, such as switches, diodes, capacitors, and inductors, have different characteristics and ratings that affect their thermal behavior. For example, switches and diodes have conduction losses and switching losses that depend on their voltage and current ratings, their on-state resistance, their forward voltage drop, and their switching speed. Capacitors and inductors have parasitic resistances that cause power dissipation and heating. Therefore, selecting the appropriate components for the converter topology and the operating conditions is essential for minimizing the heat generation and maximizing the efficiency and reliability of the system.

3 Implementing effective cooling methods

Cooling methods are the techniques that transfer the heat from the power electronic components to the ambient environment. Cooling methods can be classified into passive and active methods. Passive cooling methods rely on natural convection, radiation, or conduction to dissipate the heat without using any external power source or moving parts. Examples of passive cooling methods are heat sinks, heat pipes, thermal pads, and thermal vias. Active cooling methods use external power sources or moving parts to enhance the heat transfer by forced convection or phase change. Examples of active cooling methods are fans, pumps, liquid cooling, and thermoelectric cooling. The choice of the cooling method depends on several factors, such as the heat generation rate, the temperature limit, the available space, the weight constraint, the cost, and the noise level.

4 Modeling and simulating the thermal behavior

Modeling and simulating the thermal behavior of the power electronic system is a useful tool for predicting and optimizing the temperature distribution, the heat flux, and the thermal resistance of the components and the system. Modeling and simulating the thermal behavior can help to evaluate the performance and reliability of the system under different operating conditions and scenarios, to identify potential hot spots and thermal stresses, to compare different converter topologies and components, and to design and test different cooling methods. Several software tools are available for modeling and simulating the thermal behavior of power electronic systems, such as SPICE, MATLAB, ANSYS, COMSOL, and FEM.

5 Monitoring and controlling the temperature

Monitoring and controlling the temperature of the power electronic system is a valuable practice for ensuring the safety and functionality of the system and preventing thermal runaway or failure. Monitoring and controlling the temperature can be achieved by using sensors, such as thermocouples, thermistors, or infrared cameras, to measure the temperature of the components or the system, and by using feedback loops, such as PID controllers, to adjust the input or output parameters of the system, such as the voltage, current, frequency, or duty cycle, to regulate the temperature within a desired range. Monitoring and controlling the temperature can also provide useful information for diagnosing and troubleshooting the system in case of faults or anomalies.

6 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?