Multi Output Power Supply - Page 1
Forum section: electronics / projects

author: godfather
author_rank: Contributor
timestamp: February 24, 2016, 05:13:11 pm
content: I am Designing a Power Supply For My Motor Control Drive that would be used in EV.High Voltage and High Current Variable Output 0-150V DCFixed Power Output +/-5 v @ 3AmpFixed Power Output +/-12 v @ 3AmpVariable Power Output +1.2v~3.6V @ 1Amp3 Displays-16x2 LCD for Each Current and Voltage

author: Monkeh
author_rank: Super Contributor
timestamp: February 24, 2016, 05:15:18 pm
content: I'm sure you'll manage to fit a motor drive for a bus in that.

author: godfather
author_rank: Contributor
timestamp: February 24, 2016, 05:23:05 pm
content: Quote from: Monkeh on February 24, 2016, 05:15:18 pmSure,Its a large Cabinet for a drive that can accommodate a Bus Drive.But I will use it for my Testing purpose as a Multi Power source.

author: Siwastaja
author_rank: Super Contributor
timestamp: February 24, 2016, 05:25:17 pm
content: Quote from: godfather on February 24, 2016, 05:13:11 pmHaving seen many forum discussions like this (and having designed EV motor drives), my BS detector sounds a huge alarm right here. Maybe it's wrong this time, but just to avoid major headaches, maybe post a bit more about what you are designing?

author: godfather
author_rank: Contributor
timestamp: February 24, 2016, 05:32:57 pm
content: Quote from: Siwastaja on February 24, 2016, 05:25:17 pmYou are Correct,It is a bit more about what I am designing.But I need help to select the method to design a PWM based 0~150v Dc Variable Supply Topology.I know that I can Simply put a Variac with an 1:1 Transformer with rectifier and Filters,But that solution is rather bulky.So I had an Idea of Using PWM+Mosfets to miniaturize my design.What I am thinking is that ,I would used a normal 220v to 100v Transformer and use a DC to Dc Buck Converter to get my Variable output .Any Suggestions?

author: Siwastaja
author_rank: Super Contributor
timestamp: February 24, 2016, 05:57:03 pm
content: For what do you need 0-150V DC variable supply in an EV?

author: station240
author_rank: Unknown
timestamp: February 24, 2016, 06:32:34 pm
content: The usual idea is to put the PWM switching in motor drive circuit, and have a fixed bus voltage.There are some places where a 0-150V type supply would be useful, eg super capacitor bank. But for electric motors there is a voltage below which the motor won't turn anyway.Basic idea is to have the following modules:1) Motor drive (3 phase, BLDC or something else)2) Boost converter to supply a fixed high voltage Bus. Takes input voltage from battery.3) Battery pack (96V, 144V, 288V or some commonly used voltage)4) Battery charger, takes AC or HV DC input.Now #2 can also generate the lower voltage supplies.#4 can be an off the shelf EV battery charger, if you use a common voltage for the battery.So much of the design depends on what components you use for the battery, motor and motor drive.Perhaps you could come up with a design that bypasses the Boost Converter at lower speeds for better efficiency.ps: Just beware there some some useless designs for DC-DC and motor drivers online. Beware of anything that doesn't show an actual physical PCB etc. No easy way to say this, but many of the junk designs I found involved people from India.

author: godfather
author_rank: Contributor
timestamp: February 24, 2016, 06:37:04 pm
content: Quote from: Siwastaja on February 24, 2016, 05:57:03 pmTo test the Performance of Motor drive at various voltages.And I would build some DC to DC Controllers in future also.

author: godfather
author_rank: Contributor
timestamp: February 24, 2016, 06:54:21 pm
content: Quote from: station240 on February 24, 2016, 06:32:34 pmBeautifully written guidelines.I am considering your Guidelines for my design and would get back soon.

author: Siwastaja
author_rank: Super Contributor
timestamp: February 24, 2016, 07:39:51 pm
content: Forget the boost converter (bidirectional buck/boost really), even though it's used in some, mostly ancienct, hybrid vehicles, it's not worth it in a modern EV. It's a huge increase in complexity, wastes valuable energy (driving range) as heat, costs a fortune and brings you absolutely no benefits whatsoever. That's exactly why they are not used today.The only practically sane and manageable architecture is that the DC link is the battery. Motor is controlled with a simple bridge, which is a half-bridge (two switches) for brushed DC motors, or a three-phase bridge (six switches) for AC motors such as "brushless DC" or induction motor. These structures are simple and intrinsically bidirectional, enabling regenerative braking. Avoid any extra complexity. You want to maximize efficiency and at the same time minimize the cost. If your full drive power is going through any custom magnetics, you are doing it horribly wrong; they are expensive and difficult to design. Ancient hybrid Toyotas could get away with that because the power levels were so poor due to limited electric top speed; also, those cars were prototype-like and designed to be quite expensive, some kind of technological miracles.Practically every electric vehicle today uses this simple structure, for good reasons.If you, for some reason, want to study the effect of different DC link voltages, just do it by removing series battery modules from the pack! You want to end up with as high a battery voltage as realistically possible, depending on your component ratings. I can't see a point in designing a huge power converter just for testing. If it's a learning experience, then fine, but it will get your attention away from the EV motor drive part, which is different.96V, 144V and 288V are just random numbers and not "commonly used voltages". They may be common "nameplate" voltages in some hobbyist EV conversions due to lead acid heritage (8, 12 and 24 pcs of 12V blocks respectively), but that doesn't mean anything to begin with, and especially nothing today.Motor drive is always a DC/DC converter in itself (motor being the inductor), and it doesn't care about the voltages as long as component ratings allow for it. Inreality, around 400V is a commonly used voltage (used in most production EVs), because it's the practical design limit using common semiconductors (especially IGBTs) specified at 600V. Voltages commonly used by hobbyists are: anything below 100V(max) due to regulations; and something between about 140-160V to get good performance from some popular series wound DC motors while minimizing series cell modules to ease the BMS issue. So reading between the lines from the OP, he's probably using a brushed series wound DC motor and the typical brands would work great with the suggested maximum voltage of 150V.The DC link voltage varies depending on the battery voltage, so you design your system so that you get good enough performance with minimum voltage, and your components can handle the maximum voltage. A 100s li-ion pack may range, for example, from 300V to 420V. If the motor is specified at 300V, then you can expect full specified power in all situations, but because the motor controller + motor is essentially a buck converter, you can use 400V DC link even with a motor with smaller voltage rating, as long as you configure your controller properly.So I'd say, start from learning about the motor control! It's a complete must! It also depends on the motor type. You can't think it from the viewpoint of supplying pure DC to the motor. A motor controller is not a current/voltage supply. It workswiththe motor, not as a separate "thing". You'll understand it quite easily when you look it up and actually try it, because it's rather easy, especially with brushed DC.

author: station240
author_rank: Unknown
timestamp: February 24, 2016, 10:45:55 pm
content: Having to use 400V or so worth of batteries isn't that practical, but as lower voltages = more heating of motor coils, then you still need a higher voltage.By not practical, I mean cost, weight, even more lethal voltages.Like it or lump it, even high voltage battery packs still use modules, and these modules are values like 12V, 24V. Eg Tesla's 400VDC pack (actually 375V), is 16 modules @ ~24V each, Tesla Powerwall also uses 2 such modules (different cell chemistry though) for 48V. You can also get packaged LiFePo packs with inbuilt BMS that are a nominal 12V.Also batteries output lower voltages as they discharge, so you need to take that into account if running the motor controller direct from the battery.

author: Skimask
author_rank: Super Contributor
timestamp: February 25, 2016, 02:08:08 am
content: I fully expected this thread to start something like:"Does anybody have a spare multiple output power supply they'd like to donate to my company?"

author: Siwastaja
author_rank: Super Contributor
timestamp: February 25, 2016, 08:17:06 am
content: Quote from: station240 on February 24, 2016, 10:45:55 pmCommon myth originating from hobby EV forums, but not true at all. A motor can be designed for any voltage, and as long as it's within sane limits, efficiency is not affected. Sweet spot for design is very wide. A motor can be designed to deliver 100 kW at anything between 100 and 1000 volts very easily. Existing motors can also be rewound for different voltages; been there, done that too.QuoteVoltage choice doesn't affect cost or weight much. Higher voltage saves copper in the cabling between the battery pack and motor controller, but increases BMS cost somewhat.Or is this going to be another EV forum myth thing, "higher voltage means more batteries and they weigh and cost more!", which is the stupidest thing I've ever heard and I'm surprised how people (who also measure the energy content with the unit "amp") still don't understand the most basic equations such as P = U*I.Hobbyist may want to use lower voltages for increased safety against electric shocks, but then again, in an EV, there is a lot more to safety than the direct shock hazard.QuoteLimiting yourself to module voltages at 12V or 24V is the dumbest thing I can imagine - the only reason seems psychological, the numbers sound familiar (from lead acid systems). Then again, the "nameplate" voltage numbers are meaningless. Designing an EV battery system (I have designed and constructed one a bit similar to TESLA) is mechanically a difficult task, especially in a conversion car where the space is limited and often weirdly shaped. Sure, try to make the modules identical if at all possible, but design for any number of series cells in a module, not some stupid predetermined number. For example, I designed modules that were 7s, divided into 12 identical module, for a 42 kWh pack made from 4000 18650 cells. Luckily, 7s happens to be closest to what could be called "24V", so they satisfy your condition, but in a slightly different design, 6s or 8s might have been the only physically possible. The space in a standard gasoline car converted into EV is limited when you aim for ranges over 200km. Don't limit yourself with completely arbitrary limits when there are enough real limits to begin with.QuoteExactly. Especially the most energy dense chemistries have their curve shapes so that some "nominal" voltage is absolutely meaningless. It's a large range (e.g., between 250 and 420 volts over all conditions) and all calculation must be performed at two extreme points; the middle point doesn't matter.

author: CM800
author_rank: Frequent Contributor
timestamp: February 25, 2016, 06:15:11 pm
content: Quote from: Siwastaja on February 25, 2016, 08:17:06 amI would like to dispute this, Over in the motion control industry, we have many customers moving to higher voltage motors and drives for efficiency reasons... for example I^2RAlso take into account high current low voltage motors are harder to wind and DO have more restive losses associated.... Just ask any of the motor manufactures like the ones I am dealing with right now for a customer project.

author: BravoV
author_rank: Super Contributor
timestamp: February 25, 2016, 06:28:24 pm
content: Quote from: Siwastaja on February 24, 2016, 05:25:17 pmSiwastaja, I'm pretty confident your BS detector is quite accurate, calibration is not needed.Just for your references :->1st failed attempt->2nd ongoing attempt

author: Siwastaja
author_rank: Super Contributor
timestamp: February 25, 2016, 08:25:14 pm
content: Quote from: TCWilliamson on February 25, 2016, 06:15:11 pmThis Bullshit Again. Your customers are just clueless, which is completely normal in any field. Sure, going to higher voltage may have benefits, but these benefits are not inside the motor. Also, there are no major differences in the total system efficiency.Let's assume a motor #1 with winding resistance R1 = R, nominal voltage V1= V, nominal current I1= I.Let's double the voltage for motor #2 with same specs otherwise. This will halve the current to get the same power: V2 = 2V, I2 = 0.5I. When doubling voltage, you double the number of turns in a winding. The length of the wire doubles, and to make room for that, the cross section of said wire halves. Two times the length of wire with half the cross section -> R2 = 4RI^2R losses for motor 1 are I1^2 * R1= I^2R,and for motor 2 they are: I2^2 * R2= (0.5I)^2 * 4R = 0.25I^2 * 4R = I^2R- exactly the same, as expected,as it wouldn't make any sense that it would be otherwise, as you can see if you really give it a thought (or if you have seen motors in your life!). Motors at all voltages exist and they all can have very good efficiencies. If you disagree, please post the derivation of the formula how the design voltage affects I^2R losses. I'm especially interested in the exponent you think there is.Of course, extremes will be difficult because connecting thick input wires to 100 parallel strands (as used in motor winding instead of one thick wire due to skin effects and ease of winding) to make just one or two turns is just not practical. On the other side, insulating for many kilovolts is difficult, too.For example, I was rewinding a motor that had 3 parallel strands before, 15 after (IIRC), originally 35 turns was reduced to 7 turns (again, IIRC); this changed the motor voltage from original 400V to 80V.You can think it another way, too: motors always have a bunch of wire strands going through the laminations. Every single wire carries a current, and creates a magnetic force depending on that current, contributing to the total magnetic field. If you have a fixed number of wires, and a fixed current going through every one of them, you can configure those wires in different combinations of series or parallel. Nothing changes inside the motor windings, every wire contributes just at it did before, but the ratio of voltage and current in thepower input wireschanges.This is everyday stuff in motor design. Just like a relay coil can operate at 5VDC or 24VDC just as easily with the same power. You just design the windings for the voltage you want, avoiding problematic extremes.

author: station240
author_rank: Unknown
timestamp: February 26, 2016, 03:38:24 am
content: Quote from: BravoV on February 25, 2016, 06:28:24 pmLOL, can't even afford test equipment.Guess he has three choices:1. Start with something simple, perhaps an electric auto rickshaw with some old car batteries is more in his price range.2. Cobble an electric car out of junk, which will no doubt be a huge joke, or just a small electrical fire.3. Go back to trying to pry money/favours out of investors and EEVblog members.

author: godfather
author_rank: Contributor
timestamp: February 26, 2016, 10:16:57 am
content: Quote from: Skimask on February 25, 2016, 02:08:08 am@Skimask-You Expect too much from people.I feel sorry for you,That I could not Full fill your expectation.To make every think clear for you as you are unable to understand. "I AM DESIGNING A MULTI OUTPUT POWER SUPPLY"I hope that this might help you.

author: godfather
author_rank: Contributor
timestamp: February 26, 2016, 10:58:57 am
content: Quote from: Siwastaja on February 24, 2016, 05:57:03 pmI want to create the power supply that would act as a input source for my invertor to test and to know what limits the drive would reach.Quote from: Siwastaja on February 24, 2016, 07:39:51 pmYou are right about you explanation.I will not go for a DC-DC convertor to test the Motor controller drive on different voltages.I would build a basic power supply (Linear type) With 110v DC Voltage output with proper Emergency OFF Switch and M.C.B.You said right about the Bi-directional convertor that have been used previously in Hybrid cars,It seems impractical to use this type of topology in my design,Because the level of complexity involved is high and Performance is not worthwhile.Quote from: station240 on February 24, 2016, 10:45:55 pmApart from that I would use a 3 Amp Ac Variac in the Multi Power supply It would be a great unit to work with because I can keep my Work Beach tidy while working with high voltage and low voltages.Quote from: BravoV on February 25, 2016, 06:28:24 pmWhat you want to convey?I am unable to figure out what you are contributing here!Quote from: station240 on February 26, 2016, 03:38:24 amLOL

author: BravoV
author_rank: Super Contributor
timestamp: February 26, 2016, 11:04:56 am
content: Quote from: godfather on February 26, 2016, 10:16:57 amPretty confident all readers here understand what this thread for, even though you emphasizing the word "designing" but read again the 1st post your self, you are just showing the box, nothing about electronic circuit at all.Share your "design" here, then hopefully people will start to understand what you want with this thread, cause currently people are confused such as :- Are you asking for comments regarding the box if its suitable ? Nothing about the electronic circuitry ?- Are you asking for help on how to build such power supply ? Which is unlikely right ? As you're so bold and proud that you have the design "CIRCUIT" in hand.Please enlight us.

author: godfather
author_rank: Contributor
timestamp: February 26, 2016, 11:29:22 am
content: Quote from: BravoV on February 26, 2016, 11:04:56 amI am working on the circuit it-self, So please be patient,I'll update soon.Here is the detail of the front panel that I am using right now to display voltage and Current-7" LCD With a SSD1963 Controller Coupled with STM32F401 Neucleo.

author: BravoV
author_rank: Super Contributor
timestamp: February 26, 2016, 01:26:39 pm
content: Quote from: godfather on February 26, 2016, 11:29:22 amGreat to hear thatExpecting to see the real circuit soon as you claimed, also I believe you're an expert in electronic, as you're currently looking for investor at your other project design, the one that needs a donation of a free scope.Btw, when it comes to power supply design, most people here are interested at the "real" analog section 1st, while the display and mcu although are still important, they will not generate too much interest at early stage.You do have the circuit now, right ? Or at least at early stage ?Please show us the draft design, no need to be in representative form, heck, even a picture of your scratch work using pencil on a paper will be fine.

author: Skimask
author_rank: Super Contributor
timestamp: February 26, 2016, 02:28:43 pm
content: Quote from: godfather on February 26, 2016, 10:16:57 amIexpect too much from people?Really?Are you numb from the neck up?

author: Skimask
author_rank: Super Contributor
timestamp: February 26, 2016, 02:33:48 pm
content: Next thread is going to be:How to use STM32F401 Neucleo coupled with 7" LCD by way of SSD1963.