AC Drives Without DC Link Capacitors

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technology Associate Join Date: Nov 2008 Posts: 31	AC Drives Without DC Link Capacitors 01/28/2010 12:08 AM
	Dear All Is the AC drive with no DC bus capacitors possible ? or present already in market ?
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	Pathfinder Tags: DC Bus

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JRaef Guru Join Date: Sep 2006 Location: California, USA, where the Godless live next door to God. Posts: 4665 Good Answers: 804	#1 Re: AC drives without DC link capacitors? 01/28/2010 12:44 PM
	"AC Drive" is an ambiguous term. There are types of AC drives that do not have DC conversion at all, so therefore no DC link capacitors. But if you are referring to what we are commonly using now, i.e. PWM Inverter Drives, then the answer is no. The capacitors are necessary to smooth out the DC bus ripple that is a result of rectifying AC 3 phase power. I personally don't know of another cost effective way of doing that. Certainly many designs use DC link chokes to reduce the ripple and reduce the amount of capacitance necessary, but at some point you run up against the laws of diminishing returns; it just gets too expensive to try to avoid the caps. Why do you ask? __________________ All I every really wanted to be, was... A LUMBERJACK!.
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technology Associate Join Date: Nov 2008 Posts: 31	#3 In reply to #1 Re: AC drives without DC link capacitors? 02/03/2010 6:27 AM
	Dear Sir I asked this question because during a Major electrical exhibition last month here in India one gentlemen said to me that his AC drive / VFD/ VVFD / Inverter doesn't have DC bus capaciotrs........?????? Of course Make of that he kept secret.
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MalcolmK Power-User Join Date: Jul 2008 Location: UK Posts: 205 Good Answers: 50	#2 Re: AC Drives Without DC Link Capacitors 01/29/2010 4:23 AM
	The matrix converter is a transistor based design using no DC caps. The complex nature of the design and use of 18 transistors and low volume production means it is much more expensive than a conventional voltage source design Fuji Electric have two versions, I think, rated at 45 and 55kW which would find applications in suitable projects where this technology offers significant advantages over the standard design. Maybe cranes or high performance lifts. Yaskawa also headlined this at a lift exhibition using core Fuji technology, I think. Matrix may be seen as the 'holy grail' in the past 20 years or so but costs will mean there will probably still be some considerable time before this becomes mainstream. __________________ Something new every day!
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You might be interested in: AC-DC Adapters, DC to AC Converter Chips, DC-AC Inverters

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