Friction
Model of angular velocity dependent friction losses
Library
Modelica/Electrical/Machines/Losses
Description
The friction losses are considered by the equations
tau / tauRef = (+w / wRef) ^ power_w for w > +wLinear - tau / tauRef = (-w / wRef) ^ power_w for w < -wLinear
with
tauRef * wRef = PRef
being the friction torque at the reference angular velocity
wRef. The exponent power_w is
approximately 1.5 for axial ventilation and approximately 2.0 for radial ventilation.
For stability reasons the friction torque tau is approximated by a linear curve
tau / tauLinear = w / wLinear
with
tauLinear = tauRef*(wLinear/wRef) ^ power_w
in the range -wLinear ≤ w ≤ wLinear with wLinear = 0.001 * wRef. The relationship of torque
and angular velocity is depicted in Fig. 1
 |
Fig. 1: Friction loss torque versus angular velocity for power_w = 2 |
See also
If it is desired to neglect friction losses, set frictionParameters.PRef = 0 (this is the default).
Parameters
| Name | Label | Description | Data Type | Valid Values |
|---|---|---|---|---|
mo_frictionParameters | frictionParameters | Friction loss parameters | FromModelica('Modelica.Electrical.Machines.Losses.FrictionParameters') | |
mo_useHeatPort | useHeatPort | =true, if heatPort is enabled | Number | 0 |
| Name | Label | Description | Data Type | Valid Values |
|---|---|---|---|---|
mo_phi | phi | phi | Structure | |
mo_phi/fixed | fixed | Cell of scalars | true | |
mo_phi/start | start | Cell of scalars | ||
mo_tau | tau | tau | Structure | |
mo_tau/fixed | fixed | Cell of scalars | true | |
mo_tau/start | start | Cell of scalars | ||
mo_w | w | w | Structure | |
mo_w/fixed | fixed | Cell of scalars | true | |
mo_w/start | start | Cell of scalars | ||
mo_lossPower | lossPower | lossPower | Structure | |
mo_lossPower/fixed | fixed | Cell of scalars | true | |
mo_lossPower/start | start | Cell of scalars |
Ports
| Name | Type | Description | IO Type | Number |
|---|---|---|---|---|
flange | implicit | Shaft end | input | 1 |
support | implicit | Housing and support | input | 2 |
Port 3 | implicit | Optional port to which dissipated losses are transported in form of heat | input | mo_useHeatPort |