Power converters....well , solar inverters are all the rage now........spewing out AC into the mains from the solar farms.
Also, bidirectional car battery chargers are good with all this grid balancing stuff.
Or what about good old electric motor drives.
If you are in China, what about good old switch mode powerr supplies......China makes just about all of them on the planet now.
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If you really want to boil your brain..then what about the single stage PFC'd Cuk converter.
Then theres the 99% efficient power factor correctors using "solid state rectifier bridges"...(thats not there real name but ive forgotten it)
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Or what about hybrid converters, which give resonant operation , but without the drawbacks of more simple resonant converters
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If you like music, then what about a Class D audio amplifier.
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Which university are you at.....what do they specialise in
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I worked with a guy who did a phd in current regulated BLDC motor drives...but couldnt find a job in it...because most BLDC drives are voltage mode, so to speak.