DC machine (series)

Series-excited DC machine (traction motor).

  • electrical
  • rotational
  • Modelica Standard Library
  • 5 ports
  • 6 parameters
BlockDC machine (series)KinddcSeriesMachineLibraryMachines

Description

A series-excited DC machine, as used for traction. The field winding has its own terminals; connect it in series with the armature so the same current flows through both. The torque then grows with the square of the current.

The machine constant is derived from the nominal operating point, with the field carrying IaNominal at that point.

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 (series) 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 (excited)

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

    Terminal voltage at the nominal operating point, in volts. Must exceed (Ra + 0.01 Ω) · IaNominal.

  • Nominal currentIaNominal100 A

    ≥ 0

    Current at the nominal operating point, in amperes; also the nominal field current.

  • Nominal speedwNominal149.2 rad/s

    ≥ 0

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

  • 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 + Re) · IaNominal) / wNominal, with Re = 0.01 Ω
pin_ep.v − pin_en.v = Re · ie + Le · die/dt, with Le = 0.5 mH
pin_ap.v − pin_an.v = Ra · ia + La · dia/dt + kΦN · (ie / IaNominal) · ω
τe = kΦN · (ie / IaNominal) · ia, so τe = kΦN · ia² / IaNominal when ie = ia
Jr · dω/dt = τe + flange.τ

Implementation

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

Assumptions and limitations

  • The field resistance (0.01 Ω) and inductance (0.5 mH) are fixed and not exposed.
  • Linear magnetics: the flux keeps rising with current, with no saturation.
  • No friction, core, stray-load, or brush losses. Temperatures are fixed at 20 °C.

Tips

  • The field is not connected internally. For series operation, wire pin_an to pin_ep and supply the machine between pin_ap and pin_en.
  • Unloaded, a series machine speeds up without bound. Always attach a load.

See also

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