clean 9.6 volt DC at 5.0 amps from varying 18 to 90 VAC source

[vorflag]

Need to design a circuit to provide avionic clean 9.6 volts DC at 5.0 Amps. regulated, from a varying AC source of 18 to 90 VAC (alternator) Need short circuit and shutdown protection for output over-voltage or current with a reasonably quick risetime response and recovery rate. 10Ms?
The device will be used to power GPS and low-power aircraft VHF comm radios on light aircraft that do not have a battery.
In trouble here-Haven't designed any circuits since 1965!
Need all suggestions and current/application/component source info and suggested circuit ideas I can breadboard and analyze. Thanks!

 

[csr]

You may need to shape up your input from a varying source voltage to a fix voltage source. Say 15 Volts AC to be exact. From then on, introduce an ac-dc voltage rectifiers rating with a forward current of 10A and a computer grade filter capacitors. Now you can have a pure DC voltage somehow with bleeder resistor component in it. You can now apply an adjustable voltage regulator ICs with a few biasing component with a short circuit protection in it. C.A.A.

 

[vorflag]

C.A.A. Yeah, Thanks! I figured I would load the alternator with a fixed dissapative resistance to stabilize to around 15 to 20 volts. Sort of a constant "load." Will use full wave rectifier circuit, with C electrolytics for filters and tap a bleeder to an IC regulator, and a zener diode setup. Truth is the engine RPm does not vary the output voltage raw AC quite as much as I thought. Appreciate your comments. I can start this approach. The challenge is not to waste any more watts to IR losses than I have to.
VORFLAG

 

[melone]

Engine RPM will not vary the alternator output, LOADS will!!!! Did you ever try monitoring the alternator output will turning on and off your headlights or A/C? Try it and see what happens. Your power supply better be very robust!

Automotive applications are VERY demanding and require significant work to make them effective for all possible conditions. Why don't you simply use a standard OTS regulator with a protection zener clamp (around 20 V)on the front end? I have found that a simple LM323 with a good 12W heatsink work well in all of my designs.

Just an idea. Keep us posted!

 

[koolkid]

Use a buck converter or even a forward converter. However a good design is not for beginners, as the SMPS will more likely oscilate.
It's a tough design given the input voltage range.

For a good design house see

http://www.1stquadrant.com/services.htm

It normally takes several years to become proficient at switch-mode power supply.