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  #1  
Old 11-22-2002, 12:59 PM
The-Maxx The-Maxx is offline
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What's an inverter microwave

I see a lot of ads right now for inverter microwaves, all of which say it's better, but don't explain what's better about it. What does inverter refer to here, and how does it work?
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  #2  
Old 11-22-2002, 01:43 PM
Liberal Liberal is offline
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According to Panasonic (PDF):

Quote:
The benefits offered by Inverter microwaves include more even cooking and better cooking control through `true' selectable power levels; up to 1200 watts of power for faster cooking; and increased internal capacity of up to 44 litres that allows a larger turntable size for bigger dishes as well as permitting two-level cooking
Here's their how it works page.
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Old 11-22-2002, 02:27 PM
mangeorge mangeorge is offline
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Regular microwaves don't really vary the power level, they cycle on and off. The inverter types actually vary the power level of the microwave energy.
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Old 11-22-2002, 02:57 PM
GaryM GaryM is online now
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My folks have one of these. It seems to be good in theory, and actually works quite well at the lower power levels, but the programming for time and power level is not as straight forward as other "conventional" microwave ovens I've owned.
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Old 11-24-2002, 12:41 PM
Balthisar Balthisar is online now
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Hmmm... Panasonic's website wasn't really that useful. And GaryM, there are crappy UI's on microwaves and computers -- probably some human-interface guy didn't do a good job -- not necessarily the inverter's fault.

So, here's a brief microwave course. Microwaves (and RADAR) have a tube called a magnetron. You pump in current, and a very specific frequency and power-level of microwave current comes out. You can paint an enemy plane or point it at food to get it hot. Too little input power, though, and the magnetron won't work. Too much input power, and you burn out the magnetron. So you adjust the "heat" of the magnetron by turning it on and off (incidently this is how a resistance welder using SCRs/thyristors works).

An inverter, though, is any device that takes DC power and turns it back into an alternating form. In the case of a microwave, you'll take 110VAC sine in, rectify it, and invert it into whatever frequency and waveform you want. Let's say the inverter is a set of four large transistors -- IGBT's for example (think I Got Big Transistors). Well, given a DC power source, you can control the voltage level, frequency, and wave shape of the ouput power. Feed this to a modern magnetron, and you get true power control. Incidently, this is how a modern resistance welder using inverter technology works.

There's a lot more to it, but my military work with RADAR and both these technologies contributed directly to my current work with resistance welding controls. The only difference is a welder has no receiver and isn't at 9GHz.
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Old 12-29-2013, 07:25 AM
Chronos Chronos is offline
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I once saw a "how things work"-type article about microwaves that explained that the physics of microwaves made it inherently absolutely impossible to vary the power of microwaves (which I recognized as balderdash immediately). I wonder if the author of that article has since retracted, given how common it is now?
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Old 12-29-2013, 10:32 AM
JWT Kottekoe JWT Kottekoe is offline
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This seems to be marketing buzz by Panasonic.

Since a magnetron only works efficiently at a fixed power output, microwave ovens adjust the power level by turning the magnetron on and off. The Panasonic microwave oven uses a power inverter (DC to AC converter) to accomplish this by modulating the width of the "on" pulses. There is nothing fundamentally different about their approach, but there may be advantages in energy efficiency or in speeding up the power cycling.

As long as the cycling time is much shorter than the total cooking time, it should make very little difference how fast you switch the power on and off.

Last edited by JWT Kottekoe; 12-29-2013 at 10:33 AM..
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Old 12-29-2013, 11:01 AM
Colibri Colibri is offline
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Note: This thread is from 2002, and was bumped by a spammer.

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