AC_Model

The AC_model element is used to decrease the number of electric periods required to reach steady state when feeding windings of inductive loads with voltage sources in the external circuit editor. It assumes that the average current over one electric period in all windings defined in the AC_model is zero.

After each electric period, the initial current value of the windings is automatically manipulated to compensate for the offset current of the previous electric period. This allows you to modify currents for AC windings at the beginning of each period without interrupting the transient process. If the offset current of the last period is below a defined tolerance, no manipulation of the phase currents is triggered.

To change the name of the model placed on the sheet, click the symbol on the sheet, and change the name of the component in the property window (Value field in the DeviceName line, with the Param Values tab selected).

The AC_Model contains the following parameters:

DeviceName, which identifies the name of device model.
Windings, which is the AC winding list separated by commas. For example, PhA, PhB, PhC. Setting this parameter to “All” will include all windings.
Frequency, which shows the frequency of the AC currents in Hz.
Tolerance, which is the ratio of the DC component to the AC amplitude that defines the threshold value triggering a manipulation of the initial current for the subsequent electric period.

Note: For Maxwell 2D/3D designs of AC machines, RMxprt automatically enables an alternating flux (AF) model in the voltage definition for each winding to reduce transient solution time to reach steady state when the Maxwell 2D or 3D model is created. Also refer to Using the AF (alternating flux) model for information on using the AF model to fast reach steady state for transient simulations whose excitation is the Sinusoidal Voltage Source component.