Matrix Technology in VFD

[bob]

Hi,

 

The introduction of the matrix convereter technology in AC variable frequency drive will have a major impact in a very future. The matrix converter drives use an array of semiconductor switches to connect the three phases of the supply directly to the motor in a precisely timed sequence.

This method of operation reduces harmonic generation to approximately 8% of the level associated with conventional drives, while also offering almost unity power factor.

The elimination of the DC-bridge section of the drive makes it easy to arrange for energy to be returned to the supply during braking, and also removes the need for energy-wasting, heat-generating braking resistors.

A further benefit is that the new drives need no large electrolytic capacitors.Since the unavoidable deterioration of these capacitors is the principle life-limiting factor , their elimination boosts both drive reliability and lifespan.

This technology is limited to small drive size for the time being but large application will surely not last long.

What do forum members think about the matix technology ?

 

Bob

[jraef]

This was disussed briefly in this forum 3 years ago, haven't heard any more about it.

 

http://www.lmpforum.com/viewthread.php?tid=51#pid250

 

Doyou know of anyone who has made it work yet?

[marke]

Hi Bob

 

The matrix converter has been around for quite some time, although is only now beginning to become commercially available. I believe that Yaskawa now have a matrix converter available.

 

The concept of the matrix converter is essentially an enhancement of the old cycloconverter that has been around for many years.

There are a series of AC switches arranged such that any output phase can be connected to any input phase.

With the cycloconverter, these AC switches were SCRs and the limitation is that once an SCR is turned on, it stays on until the current through it passes through zero.

 

The Matrix converter uses IGBTs, either inside a rectifier bridge, or reverse parrallel connected with steering diodes, as the AC switches. This enable PWM techniques to be applied to gain full modulation of the output waveform.

 

The matrix comprises nine AC switchs, each switch being either one IGBT and four high speed rectifiers, or two IGBTs and Two high speed rectifiers. i.e. 9 IGBTs and 36 Rectifers, or 18 IGBTs and 18 rectifiers. This is a considerable increase on the silicon required in a standard drive, however should become more competitive when looking at an active front end drive.

The matrix inverter does not use a DC bus and so the large DC capacitors are eliminated.

 

I would expect that the overall efficiency of the matrix converter would be about the same as a standard inverter as the current must pass through at least one rectifier and one IGBT on the way to the motor and the same on the way back.

 

Best regards,

[bob]

Hi Marke and jraef,

 

Yaskawa is launching in great pomp this month the first Matrix drive. I saw one 22 k W Yaskawa matrix drive during a recent expo fair at Hanovre some couple of months ago.

 

Bob

[marke]

Hi Bob

 

That is very interesting. Thye have been making noises about it for some time, but I am interested to see the pricing.

 

Best regards,

[msdaif]

Rockwell as well says it will produce Matrix Converters shortly. And

Yaskawa says they will be available in the middle of year 2006.

 

Howver, I believe Matrix converters will be quite expensive.

 

To get research papers on this topic, the university of Birmingham, UK,

 

has a lot of papers on the subject and anyone can refer to some:

 

1. Matrix Converters by Dr. Pat Wheeler et al

 

http://www.eee.nottingham.ac.uk/pemc/matrix/dandc.pdf

 

2. A True 4Q Matrix Converter

 

http://www.eee.nottingham.ac.uk/pemc/matrix/PESC96.pdf

[jraef]

I read a couple of articles on it in trade journals (both of which appeared to be written by Yaskawa's marketing dept.) They state that it is meant only to be price competitive to full regenerative VFDs currently on the market, because that is the chief benefit of this new technology. Considering that regen VFDs are roughly 2x the price of standard 6 pulse VFDs, that is not too difficult to do, but it may prove to be a worthy alternative.

[bob]

Hi All ,

 

You may also refer to the link below for very interesting papers on this subject

http://www.eee.nottingham.ac.uk/pemc/matri...rix/papers.html

 

Bob

[Subhashish]

Hi bob

 

Is Yaskawa the only manufacturer who is showing interest in putting ahead this martix converter in business . In fact most of the recent papaers and reports I see are written by some one from Yaskawa .

But then with so much of benifits as the technology states ..like no DC link capacitors ,lower harmonic levels ( less than 8% of conventional machines) and no necessity for braking resistance & thus energy efficient ( with a by default Active front end technology provided using bidirectional switching matrix to feed back regenerated power to mains ) and better dynamic response to step inputs) I really wonder why other manufacturers are not coming up .

Do you know of any other manufacturer working in this field .

 

Regards

 

Subhashish

[Guest]

Rockwell

[bob]

Hi Subhashish,

 

The yaskawa drive , 22 k W , was officially launched in the Hanovre fair in April 2005 and they have todate supplied drives up to 75 k W . I also understand that Rockwell will launch a new drive in November this year and I trust it would be a matrix technology one.

 

Kind regards.

 

Bob