Modelica.Electrical.Machines.Losses.InductionMachines

Information

Extends from Modelica.Icons.VariantsPackage (Icon for package containing variants).

Package Content

Name	Description
Brush	Model considering voltage drop of carbon brushes
StrayLoad	Model of stray load losses dependent on current and speed
Core	Model of core losses

Modelica.Electrical.Machines.Losses.InductionMachines.Brush

Information

Model of voltage drop and losses of carbon brushes. This threephase model uses three DC Brush loss models.

Extends from Modelica.Electrical.MultiPhase.Interfaces.TwoPlug (Component with one m-phase electric port).

Parameters

Type	Name	Default	Description
Integer	m	3	Number of phases
BrushParameters	brushParameters		Brush loss parameters

Connectors

Type	Name	Description
PositivePlug	plug_p
NegativePlug	plug_n
HeatPort_a	heatPort	Heat port of the resistor

Modelica definition

model Brush "Model considering voltage drop of carbon brushes"
  extends Modelica.Electrical.MultiPhase.Interfaces.TwoPlug(final m=3);
  parameter Machines.Losses.BrushParameters brushParameters 
    "Brush loss parameters";
  Modelica.Thermal.HeatTransfer.Interfaces.HeatPort_a heatPort 
    "Heat port of the resistor";
  DCMachines.Brush brush[3](each final brushParameters=brushParameters);
equation 
  connect(plug_p.pin, brush.p);
  connect(brush.n, plug_n.pin);
  for j in 1:m loop
    connect(brush[j].heatPort, heatPort);
  end for;
end Brush;

Modelica.Electrical.Machines.Losses.InductionMachines.StrayLoad

Information

Stray load losses are modeled similar to standards EN 60034-2 and IEEE 512, i.e., they are dependent on square of current, but without scaling them to zero at no-load current.

For an estimation of dependency on varying angular velocity see:
W. Lang, Über die Bemessung verlustarmer Asynchronmotoren mit Käfigläufer für Pulsumrichterspeisung, Doctoral Thesis, Technical University of Vienna, 1984.

The stray load losses are modeled such way that they do not cause a voltage drop in the electric circuit. Instead, the dissipated losses are considered through an equivalent braking torque at the shaft.

The stray load loss torque is

  tau = PRef/wRef * (i/IRef)^2 * (w/wRef)^power_w

where i is the current of the machine and w is the actual angular velocity. The dependency of the stray load torque on the angular velocity is modeled by the exponent power_w.

See also

StrayLoad parameters

If it is desired to neglect stray load losses, set strayLoadParameters.PRef = 0 (this is the default).

Extends from Modelica.Electrical.MultiPhase.Interfaces.OnePort (Component with two electrical plugs and currents from plug_p to plug_n), Machines.Interfaces.FlangeSupport (Shaft and support).

Parameters

Type	Name	Default	Description
Integer	m	3	Number of phases
StrayLoadParameters	strayLoadParameters		Stray load loss parameters

Connectors

Type	Name	Description
PositivePlug	plug_p
NegativePlug	plug_n
Flange_a	flange	Shaft end
Flange_a	support	Housing and support
HeatPort_a	heatPort	Heat port for modeling the heat flow

Modelica definition

model StrayLoad 
  "Model of stray load losses dependent on current and speed"
  extends Modelica.Electrical.MultiPhase.Interfaces.OnePort(final m=3);
  extends Machines.Interfaces.FlangeSupport;
  parameter Machines.Losses.StrayLoadParameters strayLoadParameters 
    "Stray load loss parameters";
  Modelica.SIunits.Current iRMS=Machines.SpacePhasors.Functions.quasiRMS(i);
  Modelica.Thermal.HeatTransfer.Interfaces.HeatPort_a heatPort 
    "Heat port for modeling the heat flow";
equation 
  v = zeros(m);
  if (strayLoadParameters.PRef<=0) then
    tau = 0;
  else
    tau = -strayLoadParameters.tauRef*(iRMS/strayLoadParameters.IRef)^2*
           smooth(1,if w >= 0 then +(+w/strayLoadParameters.wRef)^strayLoadParameters.power_w else 
                                   -(-w/strayLoadParameters.wRef)^strayLoadParameters.power_w);
  end if;
  heatPort.Q_flow = tau*w;
end StrayLoad;

Modelica.Electrical.Machines.Losses.InductionMachines.Core

Information

Core losses can be separated into eddy current and hysteresis losses. The total core losses can thus be expressed as

  P = PRef * (ratioHysteresis * (wRef / w) + 1 - ratioHysteresis) * (V / VRef)^2

where w is the actual angular remagnetization velocity and V is the actual voltage. The term ratioHysteresis is the ratio of the hysteresis losses with respect to the total core losses for the reference voltage and frequency.

In the current implemenation hysteresis losses are not considered since complex numbers are not provided in Modelica. Therefore, implicitly ratioHysteresis = 0 is set. For the voltage and frequency range with respect to Fig. 1, the dependency of total core losses on the parameter ratioHysteresis is depicted in Fig. 2. The current implementation has thus the drawback over a model that considers ratioHysteresis > 0:

• underestimation of the losses in the constant field region (w < wRef)
• overestimation of the losses in the field weakening region (w > wRef)

Fig. 1: Voltage versus angular velocity

Fig. 2: Core losses versus angular velocity with parameter ratioHysteresis

Note

In the current implementation it is assumed that ratioHysteresis = 0. This parameter cannot be changed due to compatibility reasons.

See also

Core loss parameters

Parameters

Type	Name	Default	Description
CoreParameters	coreParameters
Losses
AngularVelocity	w		Remagnetization angular velocity [rad/s]

Connectors

Type	Name	Description
SpacePhasor	spacePhasor
HeatPort_a	heatPort	Heat port for modeling the heat flow

Modelica definition

model Core "Model of core losses"
  parameter Machines.Losses.CoreParameters coreParameters(final m=3);
  Machines.Interfaces.SpacePhasor spacePhasor;
  Modelica.Thermal.HeatTransfer.Interfaces.HeatPort_a heatPort 
    "Heat port for modeling the heat flow";
  input Modelica.SIunits.AngularVelocity w "Remagnetization angular velocity";
  Modelica.SIunits.Conductance Gc "Variable core loss conductance";
protected 
  Modelica.SIunits.AngularVelocity wLimit = noEvent(max(noEvent(abs(w)),coreParameters.wMin)) 
    "Limited angular velocity";
equation 
  if (coreParameters.PRef<=0) then
    Gc = 0;
    spacePhasor.i_ = zeros(2);
  else
    Gc = coreParameters.GcRef;
    //  * (coreParameters.wRef/wsLimit*coreParameters.ratioHysteresis + 1 - coreParameters.ratioHysteresis);
    spacePhasor.i_ = Gc*spacePhasor.v_;
  end if;
  heatPort.Q_flow = -3/2*(+spacePhasor.v_[1]*spacePhasor.i_[1]+spacePhasor.v_[2]*spacePhasor.i_[2]);
end Core;