Calculation of Torque Constant For DC-Brush Motors
Calculation of Torque Constant For DC-Brush Motors
(OP)
I am currently trying to design an armature for an electric motor. In trying to work out what my expected torque characteristics would be, I ran across an equation which calculates this value using flux, # of conductors, current, armature paths, and # of poles. I know the equation is correct because I used it to verify the parameters of a known motor. However, nowhere in the equation does it mention the diameter of the armature. Since packaging is an issue, I would like that parameter as part of my analysis. Does anyone know where to find some literature that shows how the armature diameter influences motor torque?





RE: Calculation of Torque Constant For DC-Brush Motors
As the armature gets smaller, (less surface area) the total flux drops for the same flux density. This will also reduce torque. If you try a couple of simple designs of different diameter rotors your software should show the difference.
respectfully
RE: Calculation of Torque Constant For DC-Brush Motors
Basic sizing guidelines are provided in “Design of Brushless Permanent-Magnet Motors” by J.R. Hendershot and T.J.E. Miller. This discusses a “classical output equation which applies to all electrical machines”;
T=KDr2Lstk, where K is the output coefficient, Dr is the rotor diameter and Lstk is the rotor stack length.
RE: Calculation of Torque Constant For DC-Brush Motors
T = 0.1175*Z*phi*Ia*P/m*R/100,000,000
T = Torque (Lb.-Ft)
Z = Total number of armature conductors
Phi = Total flux per pole (Lines)
Ia = Armature current (Amperes)
P = Poles
‘m = parallel paths
R = Conductors average radius (Ft)
RE: Calculation of Torque Constant For DC-Brush Motors
RE: Calculation of Torque Constant For DC-Brush Motors
Va = emf + Ia*Ra
emf = Z*phi*rpm/60*P/m/10,000,000
Va = Applied Armature voltage.