I am tasked with the job to design a regulator circuit for a brushless 5KW
3PH AC burshless generator that gets it's output rectified to produce a 340VDC power source.This is my first expereince with a generator.
Coming from a background in linear and switchmode power supplies, the first thing I notice is how slow a generator responds to changes in excitation coil current; and how awfully large the output ripple with a rich splash of harmonics relating to the number of poles in the output and exciter windings.
The big issue I am facing is load dump transient response. The generator takes several hundreds of milliseconds to reduce it's output voltage after a
15 amp load is removed from the 340VDC rectified output.Odd I find because the excitation coil is shut off by the regulator circuit alomst instantly and I can see it decays to nothing in just under 100ms.
I notice the generator output can handle going from no load to full 15 amp load in less than 100ms.
I am told the rotating excitation coil inside has some diodes on it, and that this is a typical construction of a brushless generator.
Why is the load dump response time so slow, and what can be done to speed it up? What type of output over-voltage protection schemes are typically used in a generator based DC power supply? I can't have downstream electronics modules connecting to my output getting blown-up! Yet to clamp or limit or otherwise regulate or filter 5KW of power for almost 1/2 second long transients where the outptu voltage can double, seems like an expensive prospect?
If anyone knows a better news group or this type of question please do suggest. I appreciate this is borderline power electrical and not entirely electronics. However, I'm looking for answers that are more creative than just to to use a large series filter inductor, shunt capacitor bank, and over-voltage cut-out relay. My application is cost and size and weight sensitive.
Suggestions anyone?
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