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3/13/2012 7:24 AM | |
Posts: 165 Rating: (25) |
Hi experts Recently I read the vector control of an induction motor from "G120/G120D FUNCTIONAL MANUAL". My fundamental doubt is: "Inverter canprovide only Variable Voltage and Variable Frequency to the motor according to the PWM pattern. if we change the input voltage frequency,we can control the motor speed. Same way If we change the PWM duty cycle, we cancontrol themotor inputvoltage magnitude. So we have onlytwo options (PWM frequency or PWM duty cycle)to control the motor speed or torque. Then how do you control or vary the flux producing component and torque producing component induvidually? What is the responsible controlinput (frequency or voltage) for Id and Iq? By clark - park transforamtion , we can resolve or calculate id and iq values from Iu,Iv and Iw. But to change these id and iq value, what is the physical contol parameter need to be changed? Is it motor input voltage frequency or input voltage magnitude or any other third parameter? " If you have any idea please share with me.... Thanks Regards Mothilal AttachmentG120D Function Manual_VC.pdf (306 Downloads) |
Last edited by: Mothilal at: 3/13/2012 7:25 AM |
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4/21/2012 6:58 PM | |
Joined: 7/8/2009 Last visit: 8/5/2024 Posts: 1976 Rating: (477)
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Hi Mothilal, Here is explanation from one of techincal report I have The field orientation concept implies that the stator current components supplied to the machine should be oriented in phase (the direct flux component) and in quadrature (torque component) in relation to the rotor flux vector. The rotor flux is obtained from the d-axis component of the current space vector. The slip frequency at which the rotor current space vector lags behind the rotor field is obtained from the q-axis component of the current space vector. It is necessary to control independently the stator d and q current components. In reality, it is possible to control the physical phase currents i1, i2 and i3, as function of time. Therefore, using a matrix operations, the quantities between the rotating d-q axis reference frame are transformed in the stationary i1, i2, i3 reference frame, and vice-versa. In short, to control the rotor flux in the machine the d current component reference is used, and to control the produced torque the q current component reference is used. The d-q components enable the calculation of rotor flux and the slip speed, and therefore the i1, i2, i3 reference currents can be generated. In the Figure 1.17, the currents i1, i2, i3, are measured, and are used to calculate the d-q currents. The d-q current references are generated by the speed and the position control loops. For More detail Please have a look at following https://www.automation.siemens.com/tf/WW/en/Posts/72806#top Regards, Devesh Vithani |
I dont Like people driving Fast, thats the reason I overtake them ;) |
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