How do we use vector control for single phase motor & drive?

That really depends what you mean by vector control!! To my knowledge you certainly can not benefit from the very fast torque response that is possible with correctly tuned field oriented control on 3 phase systems. I guess the type of "singe phase" motor will also have an impact.

Vector motor controllers provide the ability to independently control both the torque producing and flux producing current within the rotating machine. It has been awhile since I was knee deep in this product type of control product development but I am not sure why the algorithms would not be the same for single phase.

There are several manufacturers who provide single phase in to 3 phase out for single phase applications. (AC Tech, Vacon etc.) The customer would then need to change the motor. If it's an industry standard IEC or NEMA fram size this should be a fairly simple process.

There are a couple of single phase in to single phase out manufacturers but they require the use of PSC motors which would probably make the system more expensive.

Whenever we had customers ask us about single phase motor speed control we would suggest the 1st solution above.

Gents - I think you are missing the point of the post, Bojian is talking about controlling single phase motors with "Vector control". Single phase motors are extremely complex to analyse and in many ways control than 3 phase motors.My gut feel is that if the motor is small (presmuably it is as othewise you would use 3 phase) then rather than try and use a single phase motor go for a 3 phase PM and save youself a lot of grief!!

Hi all, I have a question. I think single phase motor operates under pulsating mmf instead of rotating mmf like that in three-phase motors. Single phase drive is not able to deliver a rotating voltage vector, either. Is vector control for single phase supposed to mimic three phase drive just in control software?

If you can access the ieeexplore, I would recommend a paper below:
F. Blaabjerg et al, "Two-phase induction motor drives"

I think the point is moot. Only two kinds of single phase motors are suitable for VFD control anyway; PSC and Shaded Pole. Neither motor is a reasonable candidate for high torque applications and are not suitable for use below 50% speed, the two main reasons to want vector control above scalar control. So what's the point? Not surpassingly, nobody makes a vector control VFD for 1phase motors.

Jeff – well put that man!!

Jeff. Exactly! Your reply is perfect.

Wow. There is not much to go on here. Is this an application or an academic exercise? I would request that some more specific information be given.

It has been my experience that less than 10% of all motor control applications needed vector control and about 1% needed an encoder or other sensor. Jeff is right - I have never heard of a single phase vector control drive. There are just too many ways to solve this with 3 phase motors.

A little rule I use for Vector Control: 1) Do you need 100:1 speed control? Yes-Open loop vector, No- CT is fine 2) Do you need 100% torque at zero speed? (this is 1000:1 speed control or better) Yes-Closed loop vector, No- Open loop vector is fine.

Many of today's VFDs provide very good torque control at low speeds even in CT mode. To save costs, a single phase in / 3 phase out VFD will usually not have Closed Loop Vector support. I have seen some that just use a very good Voltage Boost and call it Vector!