Friction

Model of angular velocity dependent friction losses

    Friction

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

frictiontorque.png
Fig. 1: Friction loss torque versus angular velocity for power_w = 2

See also

FrictionParameters

If it is desired to neglect friction losses, set frictionParameters.PRef = 0 (this is the default).

Parameters

Friction_0

NameLabelDescriptionData TypeValid Values

mo_frictionParameters

frictionParameters

Friction loss parameters

FromModelica('Modelica.Electrical.Machines.Losses.FrictionParameters')

mo_useHeatPort

useHeatPort

=true, if heatPort is enabled

Number

0
1

Friction_1

NameLabelDescriptionData TypeValid Values

mo_phi

phi

phi

Structure

mo_phi/fixed

fixed

Cell of scalars

true
false

mo_phi/start

start

Cell of scalars

mo_tau

tau

tau

Structure

mo_tau/fixed

fixed

Cell of scalars

true
false

mo_tau/start

start

Cell of scalars

mo_w

w

w

Structure

mo_w/fixed

fixed

Cell of scalars

true
false

mo_w/start

start

Cell of scalars

mo_lossPower

lossPower

lossPower

Structure

mo_lossPower/fixed

fixed

Cell of scalars

true
false

mo_lossPower/start

start

Cell of scalars

Ports

NameTypeDescriptionIO TypeNumber

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