Pulsonix-Spice is supplied with a number of models for inductors and transformers that correctly model saturation and, for most models, hysteresis. As these components are nearly always custom designed there is no catalog of manufacturers parts as there is with semiconductor devices. Consequently a little more information is needed to specify one of these devices. This topic describes the facilities available and a description of the models available.
Core Materials
The available models cover a range of ferrite amd MPP core materials for inductors and transformers with any number of windings. The complete simulation model based on a library core model is generated by the program according to the winding specification entered.
Model Details
The models for saturable components can be found in the simulator’s model file cores.lb. Most of the models are based on the Jiles-Atherton magnetic model which includes hysteresis effects. The MPP models use a simpler model which does not include hysteresis. These models only define a single inductor. To derive a transformer model, a subcircuit model that constructs a non-magnetic transformer using controlled sources is generated automatically. The inductive element is added to the core which then gives the model its inductive characteristics.
The model does not currently handle other core characteristics such as eddy current losses nor does it handle winding artefacts such as resistive losses, skin effect, interwinding capacitance or proximity effect.
Using Saturable Devices
Many different parts have been provided that, through the Inductor dialog map to the simulator’s saturable model sub-circuits mentioned above.
These parts are in the supplied SPICE parts library. Each part has its Spice Type Built-in Function set to Saturable Transformer / Inductor, and each has different number of Primary or Secondary counts.
There is a generic part called “Saturable Transformer” in the Spice library. When this is added to the design the Inductor dialog is displayed for you to choose the required Primary or Secondary counts. Changing these will force the component to be replaced with a Part from the Library that matches the new specification. If no suitable Part exists, an error message will be given giving details of the Part that will need to be created.