Endelig: En offentlig elektronik konkurre nce med et højt mål

(Svar til dk.teknik.elektronik )

  1. jul 2014, Google vil give en million dollar til opfinderen af en lille vekselretter.

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Det bliver interessant:

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Nogle af kravene: Citat: "...

  • Must be able to handle up to 2 kVA loads ...
  • Must be in a rectangular metal enclosure of no more than 40 in^3 ...
  • Will be taking in 450 V DC power in series with a 10 ? resistor
  • Must output 240 V, 60 Hz AC single phase power
  • Must have a total harmonic distortion + noise on both voltage and current of < 5% ...
  • Must have a DC-AC efficiency of greater than 95% ..."

Mon Google vil anvende dem til at drive deres PCere via solceller?

Glenn

Reply to
Glenn
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"Glenn" skrev i en meddelelse news:53d3b782$0$302$ snipped-for-privacy@news.sunsite.dk...

snakkede om at springe ensretter og ladelyt og power factor dims over, og

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Ulrik Smed 
Aarhus
Reply to
Ulrik Smed

On 26/07/14 20.46, Ulrik Smed wrote: ...

...

Der allerede lavet innovation i denne retning - det er blot ikke bredt kendt:

adskillige Synergetics Partnere har lavet en inverter modulationsteori, som er eksceptionel. F.eks. kan alle harmoniske op til ca. 22. harmoniske af 50 eller 60 Hz udfases via et specielt timing-design af

anvendes til elbiler og AC elektromotorstyring incl. BLDC:

Magic Sinewaves: An Executive Summary:

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Citat: "... Proper system design will require low pass filtering of these higher order harmonics. Compared to other digital sinewave generation methods, these unwanted harmonics are quite high in frequency and thus should be fairly easy to deal with. As before, real world quantization will increase the zero intermediate odd harmonics to finite but acceptably low real values. ... Until some recent considerable serendipity requiring exceptionally tedious brute force methods ( involving over a decade of research ), there was not the slightest hint that any solutions at all existed for the above equations. Let alone ones highly useful for power quality and energy efficiency. Hence the believed uniqueness and originality of the Magic Sinewave approach. I presently believe that no closed form method of solving the above equations is currently known. Nor is any likely to even exist. Instead, an iterative standard tool related to Newton?s Method can be used. One that otherwise is crudely known as "shake the box". ... A group of highly sophisticated JavaScript Magic Sinewave calculators are now available and have been posted to
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[ nu:
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] With solutions presently offered as high as 384 zeroed low harmonics.

A solution set for the above equations would be... ..."

"Magic sinewaves" are repeating long sequences of ones and zeros. [i retning af PWM] They can get created from ordinary but extremely carefully chosen digitally switched pulses. Se f.eks.:

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Introduction to Magic Sinewaves (pdf):

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Three Phase Magic Sinewaves (pdf):

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Magic Sinewave Demo Hardware! (pdf):

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Steplocked Magic Sinewave Synthesis (pdf):

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Don Lancaster', Synergetics og adskillige Synergetics Partnere har lavet

harmoniske af 50 eller 60 Hz.

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Jul 1, 2008 Inverter Design Shines in Photovoltaic Systems | Renewable Energy Applications:

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Citat: "... A proposed photovoltaic current-source grid- connected inverter has small volume, low total harmonic distortion, high power factor and simple control, and also simplifies photovoltaic system design. ..."

Jun. 19, 2013, SiC MOSFETs Enable Next-Generation Solar Inverters:

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Glenn

Reply to
Glenn

sinus, og ikke 'modified sinus'.

Det minder jo om en 1 bit 'bit stream' DAC. Mon man kunne lave det som 'multibit' med forskellige DC forsyninger som man switcher imellem? Ligesom

kravene til lavpasfilteret, men giver et ret komplekst net af switche.

--
Ulrik Smed 
Aarhus
Reply to
Ulrik Smed

On 27/07/14 11.06, Ulrik Smed wrote: ...

Flerniveau (flerserieforbundne) vekselrettere (eng. Multilevel Inverters) og overtone udfasning/eliminering:

F. Filho, L. M. Tolbert, B. Ozpineci, Y. Cao, "Real Time Selective Harmonic Minimization for Multilevel Inverters Connected to Solar Panels Using Artificial Neural Network Angle Generation," IEEE Transactions on Industry Applications, vol. 47, no. 5, Sept.-Oct. 2011, pp. 2117-2124:

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Citat: "... This work approximates the selective harmonic elimination problem using artificial neural networks (ANNs) to generate the switching angles in an

11-level full-bridge cascade inverter powered by five varying dc input sources. Each of the five full bridges of the cascade inverter was connected to a separate 195-W solar panel. The angles were chosen such that the fundamental was kept constant and the low-order harmonics were minimized or eliminated. ..."

John N. Chiasson, Leon M. Tolbert, Keith J. McKenzie, Zhong Du, "A Unified Approach to Solving the Harmonic Elimination Equations in Multilevel Converters," IEEE Transactions on Power Electronics, March

2004, vol. 19, no. 2, pp. 478-490.
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Citat: "... Here it is shown that, by considering all possible switching schemes, one can extend the lower range of modulation indices for which such switching angles exist. A unified approach is presented to solve the harmonic elimination equations for all of the various switching schemes. ..."
Reply to
Glenn

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