DC machine (excited)

Separately excited DC machine; wire the field in parallel for shunt operation.

  • electrical
  • rotational
  • Modelica Standard Library
  • 5 ports
  • 7 parameters
BlockDC machine (excited)KinddcShuntMachineLibraryMachines

Description

A DC machine with a wound field on its own pair of terminals. Supply the field separately for a separately excited machine, or connect it in parallel with the armature for shunt operation.

The flux is linear in the field current. The machine constant at nominal field current is derived from the nominal operating point, as for the permanent-magnet machine, and scales with ie / IeNominal.

Example

DC machines Permanent-magnet, shunt, and series DC machines on 100 V, with their shaft speeds.

100 V (PM)Ground (100 V (PM))100 V (shunt)Ground (100 V (shunt))100 V (series)Ground (100 V (series))PM machineSpeed (PM)Shunt machineSpeed (shunt)Series machineSpeed (series)Load 0.42 N·m·sFrame
In Gradara, select a DC machine (excited) block and press F1, then choose Open example. It opens as a new model in My models, ready to run.

Also in this example:DC voltageGroundFixed (rotational)Torsion damperSpeed sensor (ideal)DC machine (PM)DC machine (series)

Ports

Conserving terminals 5

  • a+pin_apelectrical

    Positive armature terminal. Current into pin_ap is the armature current ia.

  • a−pin_anelectrical

    Negative armature terminal.

  • e+pin_epelectrical

    Positive field terminal. Current into pin_ep is the field current ie.

  • e−pin_enelectrical

    Negative field terminal.

  • shaftflangerotational

    Shaft, rotational, carrying the rotor inertia Jr. The stator is fixed to ground internally.

Parameters

  • Nominal voltageVaNominal100 V

    ≥ 0

    Armature voltage at the nominal operating point, in volts. Must exceed Ra · IaNominal.

  • Nominal currentIaNominal100 A

    ≥ 0

    Armature current at the nominal operating point, in amperes.

  • Nominal speedwNominal149.2 rad/s

    ≥ 0

    Speed at the nominal operating point, in rad/s (default 1425 rpm).

  • Nominal field currentIeNominal1 A

    ≥ 0

    Field current at the nominal operating point, in amperes.

  • Armature resistanceRa0.05 Ω

    ≥ 0

    Armature resistance, in ohms.

  • Armature inductanceLa0.0015 H

    ≥ 0

    Armature inductance, in henries.

  • Rotor inertiaJr0.15 kg·m²

    ≥ 0

    Rotor moment of inertia, in kg·m².

Equations

Modelica
kΦN = (VaNominal − Ra · IaNominal) / wNominal
pin_ep.v − pin_en.v = Re · ie + Le · die/dt, with Re = 100 Ω and Le = 1 H
pin_ap.v − pin_an.v = Ra · ia + La · dia/dt + kΦN · (ie / IeNominal) · ω
τe = kΦN · (ie / IeNominal) · ia
Jr · dω/dt = τe + flange.τ

Implementation

Modelica Standard Library 4.1.0Modelica.Electrical.Machines.BasicMachines.DCMachines.DC_ElectricalExcited
MSL documentation

Assumptions and limitations

  • The field resistance (100 Ω) and inductance (1 H) are fixed and not exposed, so IeNominal is reached at 100 V · IeNominal across the field.
  • Linear magnetics: no saturation or armature reaction.
  • No friction, core, stray-load, or brush losses. Temperatures are fixed at 20 °C.

Tips

  • With no field current the machine produces no torque and no back EMF. Energize the field before, or together with, the armature.
  • For shunt operation with the defaults, a 100 V supply gives the nominal 1 A field current.

See also

Select a block in Gradara and press F1 to open its page offline.