Building a two quadrant voltage supply - questions - Page 1
Forum section: electronics / projects

author: hbozyq
author_rank: Contributor
timestamp: September 08, 2022, 11:31:49 am
content: Hi all. I am building a two quadrant voltage supply. Two quadrant means its capable to sink/source current to the load. This is for some application like regenerating motor or sync swtich converters, sometimes they may produce energine rather than consumpt power. Another application is charge/discharge battery to the store voltage.The PSU should be capable around 20v 3a source and 5-8a(discontinually)/3a(continually) sink .Now the first idea is using someting like class AB amplifiers as power stage. it may need a big heatsink.My second idea is using a sync buck converter. while the load current is somehow reverse, its able to pump the energy to the input side and bleed with a resistor controled by a mosfet.Which one is better and why? Or any better solution?Any suggestion is fine. Thank in advance. And sorry for my broken English, I am not a native speaker.

author: Warpspeed
author_rank: Contributor
timestamp: September 08, 2022, 10:47:03 pm
content: Linear power stage would be simpler and should respond faster, but be very sure to check the safe operating area of your semiconductors.Simultaneous continuous applied voltage and high current can lead to hot spots and result in thermal runaway.A switching power supply avoids this problem, but creates other problems. It becomes much more difficult to get it to respond very quickly to step load changes. That is not going to happen charging or discharging a battery, but for other applications speed of response may be critical.

author: NiHaoMike
author_rank: Super Contributor
timestamp: September 09, 2022, 03:42:45 am
content: If you use a mains frequency transformer instead of a switching supply, you can use synchronous rectification to regen the power back to the grid.

author: jonpaul
author_rank: Super Contributor
timestamp: September 09, 2022, 03:56:17 am
content: bonjour 2 and 4 quadrants SMPS are old and well knownat these power levels regeneration of absorbed power is not practical requirement.Suggest some deeper researchj

author: hbozyq
author_rank: Contributor
timestamp: September 09, 2022, 04:52:39 am
content: In my case "regen" is in terms of load. How PSU itself handle the reverse power is not a problem.

author: mag_therm
author_rank: Frequent Contributor
timestamp: September 09, 2022, 05:07:54 am
content: Quote from: hbozyq on September 09, 2022, 04:52:39 amAlong with your post #1, this might mean that theloadis operating in Quadrant Q1 & Q4Q4 "regen" can mean:a) Regen into a braking resistor.b) Regen into the source of Q1 (that is saving saving energy)A block diagram of your idea would be useful. Reference to class AB amplifier seems not relevant for a DC load( motor) or a battery,and your mention of three applications includingbattery loaddepends on whether source is AC or DC.

author: hbozyq
author_rank: Contributor
timestamp: September 09, 2022, 06:12:47 am
content: The main purpose is keep the output voltage stays invariable(positive) regardless of the current direction. Hence need to dissipate the renergy from load while the current is reverse.

author: magic
author_rank: Super Contributor
timestamp: September 09, 2022, 07:06:29 am
content: Quote from: NiHaoMike on September 09, 2022, 03:42:45 amIntriguing idea, do you know any published example of this actually working?

author: mag_therm
author_rank: Frequent Contributor
timestamp: September 09, 2022, 11:43:06 am
content: Quote from: magic on September 09, 2022, 07:06:29 am2 & 4 Quadrant regenerative converters are used on 3 Phase in MW range DC drives on high inertia reversing loads such as rolling in steel mill, cranes, paper winders etc.Another application is the HVDC transmission links which use reversing converters for bidirectional energy flow between grids.I never heard of single phase, but it is possible.

author: Marco
author_rank: Super Contributor
timestamp: September 10, 2022, 01:04:50 pm
content: Quote from: NiHaoMike on September 09, 2022, 03:42:45 amFor a synchronous AC load, it works in its niche but it's kinda useless for the general case. 3 phase to DC still involves switching.

author: Terry Bites
author_rank: Super Contributor
timestamp: September 13, 2022, 10:54:01 am
content: I'd be looking at "bidirectional DC-DC converters".Here's a deep dive, but you get the idea.https://www.mdpi.com/1996-1073/9/7/501

author: NiHaoMike
author_rank: Super Contributor
timestamp: September 13, 2022, 12:37:17 pm
content: Quote from: magic on September 09, 2022, 07:06:29 amLT4320 circuit could be adapted to allow it to sink current, would have to try it since it could possibly be the world's simplest grid tie inverter that works. It would also be beginner/education friendly if the mains side is suitably enclosed.It can also be done with switching supplies although then it would require a much higher increase in complexity.https://www.meanwell.com/webapp/product/search.aspx?prod=BIC-2200