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Current control and decoupling circuit of induction motor

04 Apr

  1. Induction motor model

 

(1)

(2)

(3)

(4)

(5)

where:

 

 

  1. Decoupling circuit (non-linear compensation)

In the rotor flux oriented vector control, when the vector is well oriented, the rotor flux is aligned with the d-axis frame. Therefore, the q-axis rotor flux becomes zero (). Substituting
into Eqs. (3) and (4), these equations become Eqs. (6) and (7) as follows:

(6)

 

(7)

or


(7a)

 

D-axis voltage equation:

Substituting and Eq. (6) into Eq. (1), we have the following equation:


(8)

or


(8a)

Eq. (8a) has the non-linear terms those are defined in the following equation:


(9)

 

Q-axis voltage equation:

Substituting
and Eq. (7a) into Eq. (2), we have the following equation:


(10)

or


(10a)

Eq. (10a) has the non-linear terms those are defined in the following equation:


(11)

Then if we use the PI controller for the current controller, these nonlinear terms should be removed from Eqs. (8a) and (10a). Then the dq-axis current controllers output should be as follows:


(12)


(13)

 

If we design to make the current response to be a one-order delay response as follows:

(14)


(15)

then the transfer function of the current controllers should be as follows:


(16)


(17)

Finally, by substituting Eq. (15) into Eq. (9), then Eqs. (6) and (14) into Eq. (11), we have:


Here is assumed (18)


(19)

 

 

Vector current control with decoupling circuit:

Sumber : Materi Kuliah Electrical Drive Control System (Pak Feri Yusivar)

 
 

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