Gate units of todaypsilas converters are in most cases voltage sources charging the input capacitance with a fixed gate resistor. In some publications, fixed current sources are implemented to support the charging process with a supplementary gate current. These solutions are implemented in an analog way and are designed and respectively optimized for fixed parameters and devices. During operation, there is no adaption process to adjust the switching transients to their actual optimum. The possibilities to implement new features or to adapt the units for a different device are related with time and effort.
Manufacturers of power semiconductors and modules intend to rate the maximum junction temperature up to 200°C. This results in higher temperatures at other components of the inverter system as well. In this paper, it is presented a method to identify thermal constraints in an inverter design by combining analytical and numerical analysis of the thermal spreading. Furthermore, an overview of the thermal limits of the inverter's components is given. The resulting thermal constraints of an air-cooled system are discussed, and it is introduced an inverter design to avoid over-temperatures. Finally, the test results achieved from the constructed inverter at 200°C junction temperature are presented.
Natural convection cooling offers advantages such as low cost, high reliability, noiseless operation and positioning independent from other cooling circuits. Since the main disadvantage is a relatively low heat transfer, an analytic model is required to efficiently design natural convection heat sinks according to the applied design constraints. This paper describes a natural convection thermal model which can be applied to parallel plate heat sinks in order to find an optimum heat sink design. First, the theoretical model was applied to different commercially available heat sink profiles, from which the most suitable profile was chosen for an inverter prototype. As a reference, FEM simulations were performed. Thermal measurements were carried out to validate the model. Then, the achieved thermal performance was compared to the theoretical optimum design. It was found out that described model predicts the resulting heat sink temperatures with a practical accuracy compared to measurements. Therefore, the approach described in this paper is a mathematically simple and validated model for the design of natural convection heat sinks. Furthermore, with an optimum design the heat sink volume can be reduced by 45% compared to a commercially available heat sink profile.
Gate units of todaypsilas converters are in most cases voltage sources charging the input capacitance with a fixed gate resistor. Consequently, there is hardly no possibility to adapt quickly the gate unit to different semiconductor devices. During operation, there is no adaption process to adjust the switching transients to their actual optimum. The possibilities to implement new features or to adapt the units for a different device are related to time and effort. Therefore, in this paper the idea of a digital gate unit is explained and presented.
