Modeling Using MPLAB® Mindi™

The classical way of modeling a DC motor is as two differential equations, one for the mechanical and one for the electrical dynamics as shown in below:

Jθ¨+bθ˙=Ki

Li˙+Ri=VKθ˙

MPLAB Mindi is only capable of simulating circuit elements, therefore the mechanical equation is transformed into an equivalent circuit representation. This is achieved by saying that Rlos=b/K2 , LI=J/K2 and iemf=θ˙K . This gives the differential equation:

LIiemf˙+Rlosiemf=i

Li˙+Ri=Viemf

The model of the DC motor consists of three parts; Motor_Electrical, Motor_Mechanical and Motor_Load.