ACI Motor Simulation32 Block Parameters and aci33sim example

Altair Forum User

Submitted by murthyakella on Mon, 07/30/2012 - 20:44 

Hi,

Could anyone please answer the following questions about the ACI Motor Simulation block and its use in the example diagram 'aci33sim'(Embedded->Examples-> Digital Motor Control-> AC Induction Motors)?

1. The 'ACI Motor Simulation32' in the above mentioned example simulates a real time motor. It uses following parameters (stator resistance= 1.723 ;rotor resistance= 2.011 ; Base phase voltage = 184.752; Base current = 5 ; Base Torque =7.35105194; etc). I would like to cross relate these simulation parameters with the real motor data. My question here is: Where can I find the motor and its data(such as resistance, inductances, voltages, currents and torques etc)?

2. What is the formula for base torque used in the 'ACI Motor Simulation32' block?

3. I think there is a mistake in the UI of the 'ACI Motor Simulation32' block relating to stator and rotor induuctances. These were shown as stator and rotor leakage inductances instead on the UI. Is that true?

Thanks!

Altair Forum User

Submitted by murthyakella on Mon, 07/30/2012 - 20:55.

Hi,

I found the answers for the above questions at the below site: http://read.pudn.com/downloads122/sourcecode/others/518651/work/ACI3_3SIM_281x/matlab/aci3_3_m_origin.m__.htm 

Thanks!

Altair Forum User

Submitted by Anders89 on Tue, 07/31/2012 - 03:04.

We really like customers who solve their own problems. Nice work Murthyakella!

Altair Forum User

Submitted by murthyakella on Thu, 08/02/2012 - 05:26.

Hi,

I still have a few unresolved questions pertaining to the PI controller in this example.

1. Defining Kp and Ki values of PI controller:

Usually, for field oriented control of an induction motor, amplitude optimum technique is used to calculate the kp and ki parameters of the PI current controller.

That is: Kp= (sigmaLs)/(2T_sam) and Ki = Kp/T_1 where T_1 = (sigmaLs)/ (R_s + R_r(Lm/Ls)2) where T_1 = (sigmaLs)/ (R_s + R_r(Lm/Ls)^2)(I_base/U_base) and T_sam = T_current_measurement_interval + T_delay_converter If we have to include the base values: Kp= (sigmaLs)/(2T_sam)(I_base/U_base) and Ki = (Kp/T_1)*(I_base/U_base) where the base values refer to the peak phase current and peak phase voltage respectively.

However, in this example, Kp and Ki are defined as 2*(I_base/U_base) and 0.001. Clearly, these values are not as per the above formula of amplitude optimum.

a. So, is there a mistake in the amplitude optimum formula theory that I have described above? Could anyone please throw some light on how these PI values are calculated in this vissim example?

b. Also, if there is a case wherein Ki/Kp value as per the formula turns out to be more than 128, then what should be done?

1. Defining Kc value of PI controller:

Also is there any also tip for defining the Kc value so that PI controller saturation is tuned better?

Thanks!

Altair Forum User

Submitted by davewilson on Thu, 08/02/2012 - 21:44.

I don’t believe that there is ANY standard way to set the P and I gains. Different people put different emphasis on different aspects of the controller performance. Some want NO overshoot. Others don’t care as much about overshoot, but want the fastest rise time. To compound the complexity, there are different control topologies with different integrator clamping strategies, which also affect the selection of P and I. Finally, the guidelines for setting P and I in the velocity loop are totally different from how you set them in a current loop. So it really is all over the map.