PLECS 3.2 Online Help

DC Machine

Purpose

Simple model of DC machine

Library

Electrical / Machines

Description

pict

The machine operates as a motor or generator; if the mechanical torque has the same sign as the rotational speed the machine is operating in motor mode, otherwise in generator mode. In the component icon, the positive poles of armature and field winding are marked with dots.

Electrical System

pict

Electromagnetic torque:

Te = Laf ⋅if ⋅ia

Induced voltage of the armature winding:

Ea = Laf ⋅if ⋅ωm

Mechanical System

       1
ωm  =  -(Te - F ωm - Tm)
       J

Parameters

Armature resistance
Armature winding resistance Ra   in ohms (_O_  ).
Armature inductance
Armature winding inductance La   in henries (H).
Field resistance
Field winding resistance Rf   in ohms (_O_  ).
Armature inductance
Field winding inductance Lf   in henries (H).
Field-armature mutual inductance
Field-armature mutual inductance Laf    in henries (H).
Inertia
Combined rotor and load inertia J   in Nms2  .
Friction coefficient
Viscous friction F   in Nms.
Number of pole pairs
Number of pole pairs p  .
Initial rotor speed
Initial mechanical speed ωm,0   in radians per second (s- 1  ).
Initial armature current
Initial current ia,0   in the armature winding in amperes (A).
Initial field current
Initial current if,0   in the field winding in amperes (A).

Inputs and Outputs

Mechanical torque
The input signal Tm   represents the mechanical torque at the rotor shaft, in Nm.

The output vector “m” contains the following 2 signals:

(1) Rotor speed
The rotational speed ωm    of the rotor in radians per second (s-1  ).
(2) Electrical torque
The electrical torque Te   of the machine in Nm.