Record efficiency?

[Rhesusminus]

How high efficiency is possible with class D. I saw a sales brochure claiming 97% efficiency in a range of 100W - 500W Public Address amplifiers. I have designed both class D amps and switching power supplies, and my first reaction was that this was a load of hogwash.

Is it at all possible to achieve this kind of efficiency in an amplifier?
I mean, I would have to struggle hard to achieve this kind of efficiency in any kind of power supply!

[IVX]

i've at moment 97% H-bridge 400VDC 100KHz 300W, but after replacing the poor IRF mosfets to new ST, i'll wait >98% and at 600-700w. So even 99% for low frequence switching and for half bridge isn't impossible.

[fredos]

I reach it, but you should use APT or IXYS fast and low RDSon mosfet, with low lose rectifier, etc....Impossible to reach with ''commercial'' mosfet, you have to move to industrial parts.

Fredos

www.d-amp.com

[Pafi]

Is it at all possible to achieve this kind of efficiency in an amplifier?

Fredos can reach at least 100%.

In a complete amplifier (power connector->filter->rectifier->PFC->DC/AC->trafo->rectifier->choke,capacitor->bridge->filter, plus fan, modulator, signal processor circuitry, etc...) I can't believe such efficiency. In the power modul, it's OK.

i've at moment 97% H-bridge 400VDC 100KHz 300W, but after replacing the poor IRF mosfets to new ST, i'll wait >98% and at 600-700w. So even 99%

What kind of amplifier is this? (400V 0,8A?)

Be careful! 3% loss or 1% loss is a huge difference! Don't underestimate the power of switching loss! :-) (Unless you use ZVS)

[soongsc]

Originally posted by Pafi


Fredos can reach at least 100%.

In a complete amplifier (power connector->filter->rectifier->PFC->DC/AC->trafo->rectifier->choke,capacitor->bridge->filter, plus fan, modulator, signal processor circuitry, etc...) I can't believe such efficiency. In the power modul, it's OK.



What kind of amplifier is this? (400V 0,8A?)

Be careful! 3% loss or 1% loss is a huge difference! Don't underestimate the power of switching loss! :-) (Unless you use ZVS)

There's a thread "Free Energy Devices" that shows a device said to generate more energy given it.

[IVX]

fredos, why only APT or IXYZ? Infineon presented month ago 500v 130mOhm 48nC, not so bad thing. BTW, how to obtain samples from Infineon?

[BWRX]

Originally posted by IVX
BTW, how to obtain samples from Infineon?

You have to know somebody on the inside

[fredos]

290nC...Total gate charge...Nothing impressive, specialy the 120ns turn-off...Far from APT or IXYS!

Fredos

[FastEddy]

IVX / BWRX: " ... BTW, how to obtain samples from Infineon? ..."

Infineon buys stuff, they never sell stuff. Check out their web site = filled with "carreer opportunities" and new supplier information ... meaning they are in expansion mode. Their customers appear to be big companies with long term projects ... or race tracks and car shows. (As Forbes.com would say: "short the stock.")

[FastEddy]

Class-D is a new breed of cat. Just as flouresent bulbs are more efficient than incandecent bulbs, "switching" pulse width modulation amps are more efficient than "brute force" or current dump amps (type A or AB). The over all thermal efficiencies tells the true nature of Class-D, being as they deliver most of the power to the load instead of consuming a significant amount of power as heat. The number being bandied about for "efficiency" of Class-D are generally erronious. The numbers to look for for comparison should be thermal efficiencies. Modern motor speed control using pulse width modulation is significantly more thermally efficient than simple variable resistance control (same, same w/ Class-D) ... that's why the EPA & the EU want to see more of 'em = less heat generated = more environmentally correct = less power consumed for the job.

Put your hand on Class-A or Class-A/B amp heat sinks after several hours of continuous operation ... then try the same with a Class-D amp of the same power, relatively same heat sinks ==

A well designed pulse width modulation amp (Class-D) should have thermal efficiencies greater than 85% or more ... over all thermal efficiency ... from power plug to speaker terminals.

(Also that 6.3 volt filiment in a vacuum tube is called a heater .. for good reason ... )

The true tests should be the specs like THD ... and the listening experience, not the efficiencies. Unless you want sodium vapor lighting in your living room, there is still no substitute for an incandecent bulb to read by IMOP.