Thread: Power MOSFETs
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Old 15th May 2019, 11:55 pm   #55
Julesomega
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Location: Stockport, Greater Manchester, UK.
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Default Re: Power MOSFETs

Quote:
Originally Posted by Argus25 View Post
I don't really understand your objection. Every well designed power supply unit, analog or switching type, samples its own output and feeds it back to the drive circuitry to make sure its voltage is regulated and stays stable under varying loads and many have overvoltage and some undervoltage and many current overload protection too. These are features expected in every well designed supply. Really, these features should be added if you feed a sine wave source into an amplifier module to derive the power.

Perhaps this might not apply if you are a power grid generator (I assume that is what CEGB is) sending power down a street to a remote location where is not possible or even useful to sense the voltage easily, at least at the source you can still sense the current.
Hi guys, I'm afraid you've missed my point about regulating the voltage supplied to the load, whether the load be your kitchen lights or some power conversion system. If you expect the CEGB to control the brightness of your lights by varying their supplied voltage, everyone's going to be in trouble when you go to bed and turn off... etc. etc. but this is what was being suggested in earlier posts.

For the power conversion case, let's assume you have a 5V DC regulated supply on the bench for some TTL logic. Trying to maintain the output voltage by controlling the input voltage with a Variac would be daft (over-voltage events?). What you should be trying to do is maintain a constant supply voltage against load changes: this needs a constant voltage, or low output impedance supply. The feedback should be internal to the supply system, and a class-B amplifier (or class-D) has its own NFB loop to achieve this. You set the 1600Hz source amplitude and the amplifier gain to give the required output voltage and rely on the amplifier's (internal) feedback maintain the output voltage. Any competent audio amplifier will do this.

The original aircraft supply would try to do the same, though it would be unlikely to regulate it so fast or accurately as the amplifier.
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