1. Flexible Transformer Winding Configurations
Transformers are available in a wide variety of winding configurations, covering the vast majority of applications. In Multisim 12.0, you can find these components in the Basic Group, TRANSFORMER Family, as shown in Figure 1.
Figure 1. Sample of configurations
The configurations follow the NPMS naming convention. N represents the number of windings on the primary side and M represents the number of windings on the secondary side. The number of turns in each of the windings is parameterized in the component's properties window (Value tab) as shown in Figure 2.
Figure 2. Simple user interface
2. The Transformer Model
The model of these transformers is based on the common T-model topology, shown in Figure 3, for a 2P2S (2 primary, 2 secondary) winding configuration:
Figure 3. T-model topology of a transformer
By default, only the elements in the dashed “Ideal Transformer” section of the above circuit are included – all other elements are turned off. In this case, since core magnetization is not considered, there is no build-up of current in the magnetizing inductance. And, since the leakage inductances and coil resistances are ignored, the result is a truly “ideal” transformer model because it is able to transform DC and AC quantities with 100% efficiency and with ideal coupling.
However, the user can easily add complexity to the model by selectively adding non-ideal behavior such as core inductance, saturation, and leakage inductance.
3. Migration to the New Components
If you know what characteristics you need to model and the values of the respective parameters, then the migration path should be as simple as selecting the correct configuration (1P1S or 1P2S in most cases) and entering the parameters into the fields.
For example, if you need an ideal two-winding transformer with a 30-to-1 turns ratio, then select the 1P1S component, open its Properties, go to the Value tab and enter the value as follows:
Figure 4. Turns parameters
If you want to add complexity to the model by modeling the core using a linear magnetizing inductance of 13.4mH, then switch to the Core tab and enter the value as follows:
Figure 5. Core parameters
Transformers very often have tap windings. If you want to model a tapped transformer, simply connect the appropriate windings together as follows:
Figure 6. Tapped transformer
The transformers_mapping.xls file includes a mapping table that will help you select the new transformer models in Multisim.