Matrix Drive Efficiency 1

[Marke]

Anyone got any information on the Matrix Drive efficiency?
I am told it is very good, but have not found any figures.

Best regards,
Mark

Mark Empson
Advanced Motor Control Ltd

 

[Skogsgurra]

I saw some early work on matrix inverters at ABB Västerås and the single conversion should make good efficiency possible. But there are a lot of switching artefacts going both to grid and to motor, so I think that the necessary filters will set efficiency back quite a bit. And, no. No numbers that I know about.

Gunnar Englund

http://www.gke.org

--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

 

[jraef]

Mark,
I evaluated them for an automatic storage and retrieval system back in 2011 to use on the lifts, because of their being line regenerative. I even recall asking this forum for opinions at the time because I had never used one. We ended up going a different direction because the vendor could not point to one single installation in all of California at the time, so my the client didn't want to be a guinea pig. But one issue I found, at least at that time, was that the efficiency was based on direct line to load but because of how it worked, you were limited to 87% voltage to the motor, meaning you could not have full torque and full speed, you had to pick one or the other. The solution they offered (because we needed that) was a boost transformer ahead of the drive. That then decreased the efficiency to being about the same as a conventional VFD. That actually was not a big deal for our application because the duty cycle was very low, but I thought it worth mentioning to you since you specifically asked about efficiency.

I also heard back from several sources that the matrix converter technology is less forgiving of line disturbances, I imagine because there is no DC bus and there are a lot more transistors to fail (18 as I recall). They (Yaskawa) tebutted that the boost transformer would help protect it by adding impedance. Sure, somewhat I guess, but again it would mean the efficiency loss to you.

That was of course 6 years ago, a lot may have changed since then, I don't know.


"You measure the size of the accomplishment by the obstacles you had to overcome to reach your goals" -- Booker T. Washington

 

[Marke]

Hi Gunnar and Jeff

Thank you for your comments.

There is evidently a new generation product available and it has a much improved level of control, but I am having some difficulty understanding some of the claims that have been made to me.
It has been suggested that in the "straight through mode", there are no losses, and power factor correction is not needed.
My understanding is that in the straight through mode, the input phases are connected straight through to the output phases by the use of diodes in series with IGBTs for each phase.
I believe that this is essentially a sold state contactor in between the supply and the motor, so the VARs are still supplied to the motor from the supply,and thee is voltage drop across the diodes and the IGBTs, so I would expect the same power factor as under full voltage control and about 2.5 volts drop per phase, so at least 1% losses for a 400V drive while in straight through mode. (rated speed)

Comments??

Best regards,
Mark.

Mark Empson
Advanced Motor Control Ltd

 

[waross]

Is this helpful? Found on page 484.

https://www.yaskawa.com/products/drives/industrial-ac-drives/general-purpose-drives/u1000-industrial-matrix-drive[/URL]]Drive Models 2o0028 to 2o0248
Table A.7 Watt Loss 200 V Class Three-Phase Models
Drive Model
Normal Duty Heavy Duty
Rated Amps
(A)
Heatsink
Loss (W)
Interior Unit
Loss (W)
Total Loss
(W)
Rated Amps
(A)
Heatsink
Loss (W)
Interior Unit
Loss (W)
Total Loss

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[Marke]

Thanks Bill, found the manual with the losses spelled out. Not too different from standard drive as expected. Physics usually wins out!!

Mark Empson
Advanced Motor Control Ltd

 

[jraef]

Have they solved the issue of the output voltage never being 100% of input though?


"You measure the size of the accomplishment by the obstacles you had to overcome to reach your goals" -- Booker T. Washington

 

[Marke]

Jeff, that is an interesting question.
They talk about straight through mode at full speed where one switch per phase is turned hard on (looks like a soft starter using a reverse parallel connected IGBT and series diode for each phase) so should be full voltage minus diode and IGBT drops. It has been suggested that in this mode, there are no losses which defies physics.
Will try to get access to one that I can test and let you know - eventually.

Mark Empson
Advanced Motor Control Ltd

 

[jraef]

OK, then yes, that sounds like their work-around to overcome the limitation they had when I last looked at them. Interesting. Sounds like a solid state bypass contactor of sorts.


"You measure the size of the accomplishment by the obstacles you had to overcome to reach your goals" -- Booker T. Washington