There might be a small misconception here. A PC's power supply is indeed a switcher. However, it is very common to ensure uninterrupted voltage to the input of the switcher, by means of a UPS (uninterruptible power supply) that provides AC line power, and sustained by a battery in the UPS. Generally UPSs filter out any incoming line voltage glitches long before their internal DC to AC generators see it. A good quality UPS puts out a sine wave, lesser quality ones output stepped AC voltages. Some PC power supplies do not handle stepped AC in super well.
Really, only UPS that have value are online ones. They take AC and convert it to DC at around 48-96V. Batteries (usually 12V ones connected in chain to get that 48-96V) give out same voltage. Batteries and output of AC-DC converter connected together through diodes. Regardless of what source is giving power, that 48-96V DC then converted to 155 or 315V DC depending on grid voltage, 110V AC or 220V AC. This 155/315V DC then converted to 110/220V AC sine. There are no direct connection between input and output and switching to battery and back occur absolutely seamless. When mains disappear, current continue to flow from batteries like nothing happened. When power is back, you get current from AC-DC converter again. Last stage in that scheme, DC-AC converter, is really not necessary for most tech usually connected via UPS.
You could find parts of online UPS as separate modules, also today you could find modules for building solar power systems based on online UPS principle, when in addition to mains AC-DC converter and battery, to the same 48-96V DC rails also connected solar panels that will be used when they give enough voltage in absense of grid power. Or they will charge batteries if grid is OK. So you could build DIY cheap online UPS using this modules, car batteries and whatever additional source of electricity you have and get a power source that will seamlessly move from one source to another and back by design. If you need it only for modern devices with switching power supply, you don't need to buy final DC-AC converter, which is usually not something cheap, due to expensive high-voltage high-power transistors, you could power your tech from 155/315V DC without any issues.
The thing is, ALL switchers are built to only handle a few milliseconds of stored energy and they MUST be fed sustained power or they simply stop output once the temporarily stored energy is drained from their inductors or capacitors. No switcher will continue to put out power a few milliseconds after input power stops. Thus any switcher needs to have either a UPS input or a very stable AC line, and this means all PCs have to have a UPS or be able to tolerate interrupted power, which is not easy as that glitches CPUs.
So called "smart" UPS produce glitches too. When grid power is OK, they connect it to the output directly. On the power loss they switch to battery powered DC-AC converter or switch additional windings on power transformer. For price saving reasons they do it with relays. All that processes create noticeable glitches in output. Moreover, to avoid need for syncronisation of grid frequency with DC-AC converter ones, "smart" UPSes usually skip at least half of AC period while switching from mains to battery and back.
I don't even mention all that "line conditioners" They perfectly pass half wave gaps that gives noticeable glitch on the output of loaded power supply. They are fine only for cutting high frequency noise from power grid.
So, only online UPS are useful for real protection against glitches, since they always create output from scratch (48-96V DC) using their DC-DC and DC-AC converters, so nothing from input could crawl to the outpur and switching from mains to battery and back is seamless.
I dispute some of that. Line conditioners rely heavily on power stored in the magnetic fields of their inductors. A half wave gap in input power results in an exponential decay in output during that period as the magnetic field collapses. Where did you get the 'perfectly pass half wave gaps' from? That's untrue.
Not all UPSs use relays, some designs use power switching semiconductors with a far faster switching time and they can respond a lot faster than either a mechanical contact or 1/60 of a second half cycle time which is 8 milliseconds. Any input power dropout obviously detectably occurs within that time framework and requires a response time in the range about 1 to 4 ms, perhaps a 1/4 cycle period.
There might be a small misconception here. A PC's power supply is indeed a switcher. However, it is very common to ensure uninterrupted voltage to the input of the switcher, by means of a UPS (uninterruptible power supply) that provides AC line power, and sustained by a battery in the UPS. Generally UPSs filter out any incoming line voltage glitches long before their internal DC to AC generators see it. A good quality UPS puts out a sine wave, lesser quality ones output stepped AC voltages. Some PC power supplies do not handle stepped AC in super well.
Really, only UPS that have value are online ones. They take AC and convert it to DC at around 48-96V. Batteries (usually 12V ones connected in chain to get that 48-96V) give out same voltage. Batteries and output of AC-DC converter connected together through diodes. Regardless of what source is giving power, that 48-96V DC then converted to 155 or 315V DC depending on grid voltage, 110V AC or 220V AC. This 155/315V DC then converted to 110/220V AC sine. There are no direct connection between input and output and switching to battery and back occur absolutely seamless. When mains disappear, current continue to flow from batteries like nothing happened. When power is back, you get current from AC-DC converter again. Last stage in that scheme, DC-AC converter, is really not necessary for most tech usually connected via UPS.
You could find parts of online UPS as separate modules, also today you could find modules for building solar power systems based on online UPS principle, when in addition to mains AC-DC converter and battery, to the same 48-96V DC rails also connected solar panels that will be used when they give enough voltage in absense of grid power. Or they will charge batteries if grid is OK. So you could build DIY cheap online UPS using this modules, car batteries and whatever additional source of electricity you have and get a power source that will seamlessly move from one source to another and back by design. If you need it only for modern devices with switching power supply, you don't need to buy final DC-AC converter, which is usually not something cheap, due to expensive high-voltage high-power transistors, you could power your tech from 155/315V DC without any issues.
The thing is, ALL switchers are built to only handle a few milliseconds of stored energy and they MUST be fed sustained power or they simply stop output once the temporarily stored energy is drained from their inductors or capacitors. No switcher will continue to put out power a few milliseconds after input power stops. Thus any switcher needs to have either a UPS input or a very stable AC line, and this means all PCs have to have a UPS or be able to tolerate interrupted power, which is not easy as that glitches CPUs.
So called "smart" UPS produce glitches too. When grid power is OK, they connect it to the output directly. On the power loss they switch to battery powered DC-AC converter or switch additional windings on power transformer. For price saving reasons they do it with relays. All that processes create noticeable glitches in output. Moreover, to avoid need for syncronisation of grid frequency with DC-AC converter ones, "smart" UPSes usually skip at least half of AC period while switching from mains to battery and back.
I don't even mention all that "line conditioners" They perfectly pass half wave gaps that gives noticeable glitch on the output of loaded power supply. They are fine only for cutting high frequency noise from power grid.
So, only online UPS are useful for real protection against glitches, since they always create output from scratch (48-96V DC) using their DC-DC and DC-AC converters, so nothing from input could crawl to the outpur and switching from mains to battery and back is seamless.
I dispute some of that. Line conditioners rely heavily on power stored in the magnetic fields of their inductors. A half wave gap in input power results in an exponential decay in output during that period as the magnetic field collapses. Where did you get the 'perfectly pass half wave gaps' from? That's untrue.
Not all UPSs use relays, some designs use power switching semiconductors with a far faster switching time and they can respond a lot faster than either a mechanical contact or 1/60 of a second half cycle time which is 8 milliseconds. Any input power dropout obviously detectably occurs within that time framework and requires a response time in the range about 1 to 4 ms, perhaps a 1/4 cycle period.