Variable Speed Drives and Digital Power Factor Correction

[k1133]

Am writing a market research paper. Business major. Bare with me

 

I am trying to understand whether power factor correction controller can be used with Variable Speed Drives? I have read that passive PFC cannot/should not be used with VSD. But I have not found any information on the digital pfc and the drives.

 

If these digital PFC controllers are already being used, does anyone know what companies sell these controllers?

 

Thank you so much

 

Juliane

[marke]

Hello k1133

 

Welcome to the forum

 

First, can you define what you mean by a digital PFC controllers.

This could and would normally refer to the controllers used to switch the banks of correction capacitors in and out on a bulk correction system, but, this could also be used to ferfer to active correction using a form of inverter technology to reduce the distortion power factor as well as displacment power factor.

 

If you are referring to the firs option, then they can be used to control capacitors on the same supply as VSDs, but they will not improve the pf of VSDs.

 

In the case of active correctors that actually modify the waveform rather than supply negative VARs, then yes, they can be used to improve th pf of VSDs.

 

Best regards,

[jraef]

Just because I am a spelling nazi and you are a student...

 

Were you propositioning us to get naked with you, or did you mean "bear with me" ?

[Guest]

Thank you, marke. That's really helpful.

 

I meant the active controller. Which I understand can be analog and digital. Right?

 

I seem to have found some really good information on who produces the active PFC controllers*, but cannot find information on which type of product can be used to improve VSDs. Could you help me on that?

 

*http://www.ednasia.com/article.asp?articleid=4468

 

p.s. re jraef: how is my spelling in this message? And yes, I meant "bear with me". Sorry.

 

 

*http://www.ednasia.com/article.asp?articleid=4468

[marke]

Hi again

 

That article covers components that would be incorporated into the design rather than as an add on afterwards.

 

I believe that all VSDs should be designed using active rectification that eliminates harmonic currents and that is what these components are for. This technology is not applied because of the additional cost and size and because there is no definite requirement for it. If there were enforcable regulations covering the maximum harmonic currents or minimum distortion power factor, then manufacturers would have no choice but to use this type of technology as is commonly used in communications type switchmode power supplies.

 

Best regards,

[k1133]

Hi - thanks for the anwers....

 

could you clarify for me what type of controller is called digital and what type is called analog?

 

I am reading about the OCC controllers* - are they considered digital PFCs or analog PFCs?

 

Will such OCC controller become obsolete when/if AC/DC converters will converge to digital?

 

Thank you for your patience

 

Juliane

*http://www.irf.com/product-info/smps/fs8383.html

[marke]

Hello k1133

 

It is dependent on the type of circuitry employed. If the system employes analog circutiry internally only, then it is analog. If it includes some digital processing (ideal for non linear relationships) then it is digital.

 

Best regards,