UPS design / chip - Page 1
Forum section: electronics / projects

author: cncjerry
author_rank: Unknown
timestamp: January 10, 2023, 06:05:21 pm
content: I want to backup some equipment using paralleled 20V 2A/H, 4/AH batteries. I need 15V, 12V, 5V outputs and already have a distribution board of LT3045 regulators. Is there a "single-chip" solution? I've looked at commercial UPS, have a 12V APC that needs a battery, I guess I could use a DC-DC converter for the 15V but I've had really good results using Dewalt 20V tool batteries. They have great capacity, durable and can be used in tools obviously. I used them on my phase noise test system and that runs for two days. I'm going to take a look at Arduino solutions.Thanksjerry

author: james_s
author_rank: Super Contributor
timestamp: January 10, 2023, 06:26:14 pm
content: I'm not sure I understand what the chip you're looking for needs to do. Is it a battery charge management IC you need? Or something to handle the changeover from line to battery, or something else?

author: cncjerry
author_rank: Unknown
timestamp: January 10, 2023, 06:55:19 pm
content: All the above. I was wondering if there was a single chip solution that handled charging, changeover, etc. I'm looking at arduino related projects but if you search on Arduino UPS, 99% are supplying the arduino. I guess manufacturers generally use a micro of some type.I guess I don't understand UPS that well. I don't know if the battery is online at all time in parallel with the supply or if it is switched-in. If switch-in, there can't be any delay or minimal enough to allow the caps to keep the voltage up.

author: james_s
author_rank: Super Contributor
timestamp: January 10, 2023, 08:51:30 pm
content: There are two main types of UPS. Standby is the most common in consumer applications, it consists of a battery, a charge controller and an inverter. During normal operation line power is passed through to the load and also powers a charger that maintains the battery. When power is lost, the UPS turns on the inverter and a relay switches the output from the line to the inverter. The other main type is online double conversion, this runs the inverter all the time to power the load and when line power is available it is used to keep keep the battery topped up and supply the load indirectly through the inverter. There various subtypes of both but that is the main difference.Changeover can be as simple as a relay that has its coil powered by the incoming supply, when that is lost it drops out and the relay contacts switch the load over to the backup battery. For charging the battery there are lots of different solutions out there.

author: rmozel
author_rank: Newbie
timestamp: January 10, 2023, 09:29:31 pm
content: I guess you need a redundant power supply that outputs 20V either from a AC/DC converter or from a bunch of parallelized DeWalt batteries. You can solve this with power path prioritizer/controller and ideal OR-ing diode circuitry. Linear Tech and TI has several components and solutions although I am not sure if you can find monolithic or single IC solution. It mainly depends on your current and tolerable handover voltage droop requirements. For charging, it may be beneficial to use DeWalt's solution.Consider checking:Linear/Analog Devices: powerpath, ideal diodes, load switches.TI: Power Muxes, ideal diodes, OR-ing controllers.

author: bidrohini
author_rank: Regular Contributor
timestamp: January 11, 2023, 02:00:35 am
content: Have you seen this SMPS design?

author: BradC
author_rank: Super Contributor
timestamp: January 11, 2023, 03:26:54 am
content: Quote from: james_s on January 10, 2023, 08:51:30 pmMy favourite are the APC SmartUPS. The Inverter/Charger is permanently connected to the load side, and the device switches between inverter and charger within ~8ms of a mains anomaly. It simply opens a relay on the input to disconnect as it switches to inverter. One transformer "assembly" (there may be multiple transformers with windings in series or parallel depending on voltage). Elegant and simple.

author: james_s
author_rank: Super Contributor
timestamp: January 11, 2023, 04:25:51 am
content: Quote from: BradC on January 11, 2023, 03:26:54 amWhat's the quiescent consumption? I had an older SmartUPS I got rid of because I found it drew almost 20 watts, that adds up to a huge amount of wasted power. The UPS's I'm currently using all draw under 3 watts, most under 2.

author: BradC
author_rank: Super Contributor
timestamp: January 11, 2023, 09:44:26 am
content: Quote from: james_s on January 11, 2023, 04:25:51 amYeah, about there. Works out about 2% of the VA rating. “Huge” is relative. If you can come up with a unit that can provide > 10 hours on battery at an average draw of 250W with > 2KW peaks, a changeover of less than 1/4 of a mains cycle and a smaller overhead I’m all ears.

author: james_s
author_rank: Super Contributor
timestamp: January 11, 2023, 05:53:38 pm
content: Those are some pretty unusual constraints. I've never measured how quickly mine change over but it's quickly enough that I've never seen it cause any problems. 250 watts for 10 hours is a lot of power, 2.5kWh, that must be a really large battery bank you've got on there. Mine will go an hour or two, more than enough time to get out the generator and set that up at a leisurely pace.

author: cncjerry
author_rank: Unknown
timestamp: January 11, 2023, 08:10:54 pm
content: I have an APC 12v, just needs a battery. That is 5A/h, 28w or 2.2A. From cold start, I need about 15w (summation of all voltages). I don't want SMPS as this is a low noise system. I need two. One is for a phase noise test set and the other for a GPSDO. When the GPSDO is operating, the power drops to about 10w once the oscillator is warmed up.I use the Dewalt batteries on the phase noise test system. This takes all the grid noise out. The 20V is broken down to 15V, 12, 5V and probably should be doing my own 3V too.I can put together a custom UPS using an STM32 or arduino but was trying to avoid it. I've built high function software charging systems for NiMH and LiPos but was hoping to find a single chip solution.The point about power path is good. It would be nice to be able to switch the batteries automatically by dropping them in parallel. For instance, as the voltage(s) drop, turn on a light that says to swap them out one at a time. I have quite a few of them. I'd then use the Dewalt charger (when the power comes back on).Jerry