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Switching supply units used today are of light weight and compact design, but also susceptible to errors due to the incorporated electrolyte capacitors. Film capacitors would have much longer service lives. However, they need up to ten times more space. Scientists of KIT's[*] Light Technology Institute (LTI) have now developed a digital control method for use of film capacitors that need slightly more space only.
The control method runs on a microprocessor integrated in the supply unit and detects disturbing environmental impacts, such that e.g. higher voltage fluctuations can be balanced. Hence, storage capacitors of reduced capacity are sufficient. Michael Heidinger, LTI, summarizes the advantages: "Use of these film capacitors eliminates the main cause of failure of power supplies, i.e. electrolyte capacitors. Depending on the design, service life may be increased by a factor of up to three." The result is a much reduced maintenance expenditure.
This one is digital.
[*] Karlsruhe Institute of Technology.
(Score: 5, Informative) by bzipitidoo on Friday May 17 2019, @12:05AM (1 child)
Okay, talk of "capacitor errors" was weird, but it's true that electrolytic capacitors are often the weakest link in a power supply, and electronics in general. A power supply going bad is one of the top hardware failures that afflict computers and the capacitor is the most likely component of a power supply to fail and thereby cause the failure of the power supply. And it's not just the explicitly separately boxed components that make up a power supply, it's also a lot of capacitors and electronics on the motherboard. The other top hardware failures are fans and hard drives, essentially anything else that is not solid state, and has mechanics. Optical media drives are another high failure rate piece of hardware-- and as weak a link as they are, I am baffled by this custom of having an additional completely unnecessary motor in there to eject and retract the tray.
As for silicon based solutions to analog energy problems, don't sneer. They work. They work great. Such electronics are why we now have inverters the size of a 3.5 hard drive for a $100 or so, instead of the size of a cube refrigerator for over $1000. An inverter is a crucial device for such things as electric cars, essential for varying the frequency of the AC electricity that is supplied to AC motors, in order to make them run at different speeds. It's also essential for home solar panel installations, with its ability to convert DC into AC, which is quite a bit harder than converting the other direction.
There's really not been much alternative to the electrolytic capacitor. There are dry capacitors, but as mentioned in the summary, they take a whole lot more room, so much they really are impractical. No one wants to quadruple or worse the size of a desktop computer to make room for dry capacitors.
One other thing worth a mention is the capacitor plague of the early 2000s. Thanks to a bad formulation, a lot of capacitors manufactured in those years had much shorter lives than even their already short expected lifespans. They began to fail in as little as 3 years. If you looked at these capacitors, they would show telltale bulges at the ends, and even some electrolyte would leak out and leave a brown stain on the board underneath it. Electronics manufacturers were saved from having to do massive recalls and replacements by technological advancement. By the time a computer manufactured in the first half of the 2000s was beginning to spontaneously reboot every hour or so because its power supply was failing thanks to those defective capacitors, the computer was obsolete anyway. Most people simply upgraded to a new computer a little earlier.
(Score: 2) by RS3 on Friday May 17 2019, @12:25AM
Great post! Way back in the day (80s) I had gotten a little involved with 4-phase step (stepper) motors. Very simple drive circuits, torque dropped off quickly as RPM rose, etc. Then mid-90s was asked to evaluate and implement a Parker-Hanfin (sp?) "CompuMotor" step motor controller. They used very high voltage (200+) but pulse-width modulated, to drive the motor to insane speeds, rock-solid torque, no missed steps, and "micro-stepping" - holding armature between magnets by varying coil currents. All done by microprocessor control, sensing and analyzing winding amps, back-EMF, etc. Geeky, but I was quite impressed. (To get the really insane speeds you had to run an "autotune" routine, and they warned you it might tear up an attached mechanism.)
Much more recently I installed some industrial motor controllers (slang term: "freq drive" or just "drive"). They take 120 VAC, voltage-double rectify, filter, and 3-phase "H-bridge" drive 3-phase AC motors, all using a microprocessor, sensing winding current, back-EMF, etc. These were for 3 HP pumps. By default they'll only drive the motor up to 60 Hz (USA), but you can easily reprogram them to go much higher and run the motor much faster than stock, if the load can take it. I was stunned at the size of the thing- maybe 2" x 3" x 6", and no discernible heat. So it's not a stretch to control a switching supply transformer this way too.
And they're using this for residential water well pump motors- doing away with the storage tanks (big wet storage capacitor!) and maintaining pressure. (I'm not sure I like it- gotta see the power used in standby / maintain pressure...)