WOLFRAM SYSTEM MODELER

Motor

Second order thermal model of a motor

Diagram

Wolfram Language

In[1]:=
SystemModel["Modelica.Thermal.HeatTransfer.Examples.Motor"]
Out[1]:=

Information

This information is part of the Modelica Standard Library maintained by the Modelica Association.

This example contains a simple second order thermal model of a motor. The periodic power losses are described by table "lossTable":

timewinding lossescore losses
0 100 500
360 100 500
360 1000 500
600 1000 500

Since constant speed is assumed, the core losses keep constant whereas the winding losses are low for 6 minutes (no-load) and high for 4 minutes (over load).

The winding losses are corrected by (1 + alpha*(T - T_ref)) because the winding's resistance is temperature dependent whereas the core losses are kept constant (alpha = 0).

The power dissipation to the environment is approximated by heat flow through a thermal conductance between winding and core, partially storage of the heat in the winding's heat capacity as well as the core's heat capacity and finally by forced convection to the environment.
Since constant speed is assumed, the convective conductance keeps constant.
Using Modelica.Thermal.FluidHeatFlow it would be possible to model the coolant air flow, too (instead of simple dissipation to a constant ambient's temperature).

Simulate for 7200 s; plot Twinding.T and Tcore.T.

Parameters (1)

TAmb

Value: 293.15

Type: Temperature (K)

Description: Ambient temperature

Components (11)

lossTable

Type: CombiTimeTable

Description: Table look-up with respect to time and linear/periodic extrapolation methods (data from matrix/file)

windingLosses

Type: PrescribedHeatFlow

Description: Prescribed heat flow boundary condition

winding

Type: HeatCapacitor

Description: Lumped thermal element storing heat

Twinding

Type: TemperatureSensor

Description: Absolute temperature sensor in degCelsius

winding2core

Type: ThermalConductor

Description: Lumped thermal element transporting heat without storing it

coreLosses

Type: PrescribedHeatFlow

Description: Prescribed heat flow boundary condition

core

Type: HeatCapacitor

Description: Lumped thermal element storing heat

Tcore

Type: TemperatureSensor

Description: Absolute temperature sensor in degCelsius

convectionConstant

Type: Constant

Description: Generate constant signal of type Real

convection

Type: Convection

Description: Lumped thermal element for heat convection (Q_flow = Gc*dT)

environment

Type: FixedTemperature

Description: Fixed temperature boundary condition in Kelvin