PLECS 2.0 Online Help |
The text entries Manufacturer, Part number, and Comment are for documentation purposes only. The Type selector serves as a filter for the Thermal description menu entry. It must be set according to the semiconductor type it is intended to be used with.
In order to access the data sheet in a PLECS model it must be saved in a subdirectory on the thermal search path. See section Thermal Library for details of the structure of the thermal library.
Switching losses are defined as a 3D lookup-table in the Turn-on loss and Turn-off loss tabs. The energy for each switching event depends on the blocking voltage, the device current and the device temperature. PLECS uses a linear interpolation technique to calculate the actual losses from the given values.
New interpolation points for temperature, voltage and current are added and removed with the Edit menu or the context menu in the table. Multiple values can be added separated by semicolons or spaces.
To rotate and tilt the 3D view move the mouse within the view while keeping the left mouse button pressed.
Conduction losses are defined by means of the on-state voltage drop as a 2D lookup-table in the Conduction loss tab. The voltage drop depends on the device current and the device temperature. PLECS uses linear interpolation to calculate the actual voltage drop from the given values.
New interpolation points for temperature and current are added and removed with the Edit menu or the context menu in the table. Multiple values can be added separated by semicolons or spaces.
The thermal equivalent circuit of a component describes its physical structure in terms of thermal transitions from the junction to the case. Each transition consists of a thermal resistor and a thermal capacitor. They can be edited in the Therm. impedance tab of the thermal editor. The thermal equivalent circuit is specified either in Cauer or Foster form.
The structure of a Cauer network is shown in the figure below. In the thermal
editor the number of chain elements and the values for
and
for each
chain element need to be entered.
Cauer network
The figure below illustrates the structure of a Foster network. In the thermal
editor the number of chain elements and the values for
and
for each
chain element need to be entered. Foster networks can be converted to Cauer
networks by pressing the button Convert to Cauer.
Foster network