3 Phase Inverters.

Aug 23, 2003 1 Replies

Hi All,



After reading John Stevensons reply re Inverters, I looked up the R.S. catalogue and was surprised at how low the price actually is, especially as these things seem to command a price of at least double this on ebay. Can anyone tell me the principal of operation of the output stages in these devices. The 3 phase generator is no problem, but I wondered if the output stage uses power transistors as switches, and leaves the coil inductance to give an approximate sine wave, or whether these transistors are actually used as linear amplifiers ?.



Best regards,



Tom.



Nunce excretia in extractum est.



They use power FETs in switching mode to synthesize the output waveforms. In the process they generate large amounts of radio frequency interference which is reduced by filters. The price reduction has been effected not only by volume sales but specialist semiconductors which need the bare minimum of passive components around them. There is no way they could use linear amplifiers as the low efficiency would lead to so much power to be dissipated as heat!

Bob

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