Talk:Vector control (motor)

This is indeed a different topic. However the relation is very strong to standard vector control, and that information would be useful added to the current information regarding vector control.

coordinate transformation
why double transformation first from stationary reference frame to rotor reference frame and then from rotor to field reference frame?

I think rotor speed is needed for comparison with reference value and then making the torque reference with a PI controller and for flux estimation. —Preceding unsigned comment added by Paymani (talk • contribs) 14:25, 23 July 2010 (UTC)


 * For the forward transforms, alpha-beta currents are used to estimate the angle. In both forward and inverse transforms, splitting the Park and Clarke transforms reduces the number of sine and cosine computations required.
 * Colin0325 (talk) 01:47, 28 September 2022 (UTC)

Induction vs PM Motors
This article seems to be addressing only vector control of induction motors. It should note that this technique is also used for controlling permanent magnet motors. There, the step of determining the induced rotor current and flux is not needed. JDHeinzmann (talk) 20:38, 8 April 2011 (UTC)

Question
Surely the best way to control the speed of an induction motor is by frequency control. Why use anything else? Speed control by slip would reduce the torque and increase the risk of the motor stalling. Biscuittin (talk) 22:39, 26 March 2011 (UTC)
 * Quote: "Vector control (also called Field-Oriented Control, FOC) is one method used in variable frequency drives to control the torque (and thus finally the speed) of three-phase AC electric motors by controlling the current fed to the machine". This doesn't make sense to me.  Surely speed control would be either by frequency, or by slip, but not both. Biscuittin (talk) 22:47, 26 March 2011 (UTC)


 * Speed control by just frequency does not give precise control of the spacial relationship between stator flux and rotor flux. In flux vector control, the controller ensures that the stator flux is always at right angles to the rotor flux, thus utilizing the stator current solely for producing torque.  If this angular relationship is not maintained, there is a component of the stator current that is wasted in that it is present but not producing torque and thus is only contributing to heating of the motor.  (Of course, some non-torque producing current can be introduced deliberately at high speeds to change the back emf constant of the motor and achieve higher motor speeds than the available bus voltage would otherwise permit.)  The frequency needed to commutate the motor falls out automatically as a result of the flux vector control method.  The reverse is not true.  Using only frequency control does not generally result in the best phase relationship between stator and rotor flux for efficient use of power. JDHeinzmann (talk) 20:38, 8 April 2011 (UTC)

Is there a simpler way to explain vector-control drives?
Assuming that one understands slip in an induction motor, it seems to me that vector control establishes the stator flux vector so that at any given time, allowing for slip, the rate at which the stator flux vector advances develops the required rotor torque at the desired speed. Afaik, given sufficient cooling, the motor speed can go down to zero. In such a case, the stator vector is rotating at a speed (and therefore frequency) that creates the amount of slip needed to develop required rotor torque. If less torque is needed, the vector rotates more slowly. A slight increase in vector speed, given the same torque requirement, makes the rotor start to rotate. If this be true, then it should be a lot easier to understand.

It's very possible that I misunderstand vector control, however!

Regards, Nikevich (talk) 08:30, 1 September 2011 (UTC)

Motor model equations incorrect
There are several errors in the motor equations in the graphic that are easily discovered by comparing with equations 10a and 10b in the original Holtz paper reference. Can CBLambert regenerate this graphic, or is there an easy way to put LateX in line in the article instead of using a graphic? — Preceding unsigned comment added by 50.201.248.206 (talk) 00:55, 20 January 2015 (UTC)
 * Current LateX-version of motor equations, now numbered (1) & (2), are missing three minus signs, i.e., 2 minus signs in (1), 1 minus sign in (2), there being a minus immediately to the right of the equal sign in equation (1). And my efforts to get these minus signs to display have been unsuccessful. Does someone else have a solution?Cblambert (talk) 17:35, 19 January 2021 (UTC)

FOC Block Diagram Incorrect
The FOC system block diagram entitled "Sensorless FOC Block Diagram" is incorrect. The block entitled "Position and speed estimator" has an error with respect to its inputs.

The estimator block shows alpha and beta currents (Iα and Iβ) being inputted from the corresponding Clarke transformation block at the top... that part is correct as these currents are then re-coordinated via Park transformation to produce direct and quadrature currents. However, to the right of the estimator block, two more current inputs for alpha and beta currents (Iα and Iβ) are shown. The estimator block should instead show alpha and beta voltages (Vα and Vβ) derived from the phase voltage feedback (i.e., back-EMF signals).

I recommend that the figure be updated to correct the Vα and Vβ error.
 * I agree with recommendation that the figure be updated to correct the Vα and Vβ error. I don't have the MS Visio program with which the block diagram was created but I do have the original Visio file.Cblambert (talk) 20:22, 19 January 2021 (UTC)