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How to determine the induction motor parameters (Lls, Llr, Lm, Rr, Rs..) from datasheet information?

Duc Le on 19 Apr 2022
Latest activity Reply by Duc Le on 9 May 2022

I have a datasheet of an induction motor (as figure below). I want to simulate it on matlab/simulink, but I don't know it's parameters (Lls, Llr, Lm, Rr, Rs).

I tried to search about open circuit test and blocked rotor test to determine these parameters, but some of information doesn't appear on datasheet and I don't have the real motor to test on it (datasheet is only think I have).

Could someone help me with this?

2 Comments

Samuel Lakew
Samuel Lakew on 19 Apr 2022 (Edited on 19 Apr 2022)

Hi, Duc Le, I believe you have everything you need from your data sheet. From a simplified equivalent circuit, you can start by solving the slip S, rotor current, magnetizing current, rated phase voltage and current, rotor resistance etc.

Remember, you have rated rotor speed, Wr of 690 rpm, which means using the formula n = 120f/p, substituting n=690, your number of pole is p=8.7, which is close to an even number of 8, so p=8 or pole pair =4. Then you can easily estimate the machine synchronous speed as We = 120*50/8 = 750rpm.

Slip speed, Ws = (We-Wr) Slip, S = (We-Wr)/We

Vs = 380v ...since delta connection but Is = 3.75/sqrt(3)

Torque, T = P_mech/Wr = 1e(03)/(690*pi/30) = 13.84Nm (almost the same as the nameplate) do the rest in a similar way ...

. . . .

Duc Le
Duc Le on 9 May 2022
- On DC test
Rs = 1,5 * V_dc/I_dc = 1,5 * (380/2,16) = 263,27 Ω
- On locked-rotor test
cos⁡φ = P_ph/(V_ph * I_ph )=(1000/3)/(380*2,16)=0,40
Rr = (V_ph/I_ph)*cos⁡φ - Rs=175,92*0,4 - 263,27 = -192,9 Ω
This is a negative value, could you help me with this?

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