Custom BLDC Controller Closed Loop

[Ykick]

Wise electrician once said: “AC hurts, DC kills!”

Short wire runs its best to avoid excessively high DC voltages. Look up the differences between 250V and 600V fuse. You can see it’s about 2”. Simply put, high voltage can jump greater distances through plain air.

50V-100Vdc is very little real difference other than helping to reduce wire gauge.

But insulate well because if VDC grabs you, it’s very hard to get free since it never crosses 0V like VAC.

 

[glenn0010]

Helllo,

TBH I am more scared to increase my voltage than the current. Do you think the motor I linked in the top can handle 72V?

Don't be scared of DC voltage. Amperage is what kills. Voltage just F@#$@# hurts!

Any voltage and any amperage is dangerous. A watch battery has enough of both to drop you stone cold dead if you hold it in your hand, and are very unlucky. It's probably never actually happened or ever will, but it is technically possible. A Taser stun gun pumps out 120,000 volts. while it's moderately uncomfortable ( ) it's rarely deadly.
I work for a phone company, and we're around voltage all the time. Ringing voltage on a phone line is 88 volts, while normal talk voltage is 48. If you grab a line when it's ringing, you feel it, although we take no extra precautions against contact with it. It's considered safe, though uncomfortable to get hit with it. It's also a lot of fun to hit someone else with, and so Hijinx ensue. Add some amperage behind it, and you may get burned. Many of us have, but it's rarely something more serious than a dab of ointment and a bandaid will cure.

To sum up, you can't be afraid of voltage and hope to work on anything electrical. Fear is probably as dangerous as apathy when working on anything that can kill you.


edit (I'm Shocked! I made it through a whole post about electricity without making one single pun!)
(Oh, wait...)

OHHH HAHAH you misunderstood me Im not afraid for myself I am afraid for the motor . Since the motor is rated at 48V do you thing it can handle 72V? A guy on this forum said that he got this 1kW rated motor to 3.5k+ but he didn't say if he overvoltaged or overcurrented it. I tried sending him a Pm but he didn't respond so far.

 

[Drunkskunk]

Ah! LOL

OK, If it's one of the 9C/MXUS/901/Clone motors that most of those 1000 watt kits are, then it's safe to someplace over 120 volts, and really doesn't start to wake up and perform until you get up around 60 volts. The controller usually needs to be replaced for something in a higher voltage flavor.

Those 28mm stator motors are really only good for 2000 watts reliable power without modifying them. But adding cooling and swapping out the phase wires for something thicker can get them up to 3000 watts pretty easy for short periods. 3500 watts is possible but the motor is limited by it's ability to shed heat.

 

[glenn0010]

Ah! LOL

OK, If it's one of the 9C/MXUS/901/Clone motors that most of those 1000 watt kits are, then it's safe to someplace over 120 volts, and really doesn't start to wake up and perform until you get up around 60 volts. The controller usually needs to be replaced for something in a higher voltage flavor.

Those 28mm stator motors are really only good for 2000 watts reliable power without modifying them. But adding cooling and swapping out the phase wires for something thicker can get them up to 3000 watts pretty easy for short periods. 3500 watts is possible but the motor is limited by it's ability to shed heat.

The motor that I am going to buy is this one : http://e-bike-diffusion.com/index.php?module=produit&prd_id=509&url_retour=http%253A%252F%252Fe-bike-diffusion.com%253A80%252Findex.php%253Fmodule%253Dcategorie%2526code_cat%253D26%2526page_start_num%253D3

What battery pack would you recommend for running it at say 2000W? There are so many variable regarding the batteries (mainly price) that I am getting to the point of just buying the 48V 15ah pack and running at 1kw-2kw and be done with it. Obviously if the battery pack can handle the 50A constant rating quoted to me

 

[macribs]

*Subscribed*

 

[glenn0010]

What they are telling you and what they have published are two different things. I would call that highly dubious and avoid it completely.

They claim the 30000mha (30 amp hours) battery is capable of 1C, 45 amps. That math doesn't add up as 30 x 1 = 30, not 45.

If you aren't already aware, the "C" rating is the output of a battery expressed as the number of times it's capacity. 1C means 1 times it's capacity, so a 10Amp hour battery at 1C would have a maximum 10 amp continuous output. A 10 amp hour battery with a 2C rating would have a 20 amp output. So a 30Ah battery at 1C can't have an output of 45 amps. And it would be unlikely that a battery made from the same cells but lower capacity would have a higher output.

Buying Ebay batteries is a high stakes gamble. Some people win. Many people lose their money and receive unserviceable junk.

One of those “experience” things - whenever “sales engineers” say max 50A, I automatically assume 25-30A best case.

Be very careful with battery packs direct from China. Basically, no reasonable return mechanism = Caveat Emptor!

Your design is begging for high C rate battery pack. Hard to do properly and cheaply. That’s why many of us make a deal with Devil and learn about RC Lipo.

So yes you guys are basically right. After some more communication, it turns out that now the 15ah pack is 30A continuas. I kind of knew it was too good to be true. Now TBH I am still tempted to buy it at 500$. This is because it easy to use just plug and play, and it s 'safe', although it would limit me to 1kW.

Could you guys recommend an 44-48V HK pack build ? Although I am very wary about this. I have been scouring the ES battery tech threads and it seems to be very tedious and very risky to build your own LiPo pack. And currently I can't afford my F-ups.

 

[glenn0010]

Ok guys,

So here is my attempt to build my own HK Pack. Please tell me if it is viable and if I need any thing else.

The battery I will use is this: http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=35828

I will buy 6 of these, pairing up 2 in series and the connecting them together in parallel. So I would have 3 'banks in parallel'
This would cost me 312 Euros with shipping. However I have to make 6 separate orders which sucks. Also quick question, I am getting then shipped from the EU HK warehouse, do I have to pay any customs tax when they get to malta which is in europe, surely not right?

Battery Voltage monitor:
I am planning to buy these: http://www.hobbyking.com/hobbyking/store/__29652__HobbyKing_8482_Lipoly_Low_Voltage_Alarm_2s_6s_.html
The alarm starts at 3.3V is this too low?
Also 2 of these should be enough right since the packs are in paralell. I was planning to connect them to the first pair one on each.

Charger:
Will this do the job?
http://www.hobbyking.com/hobbyking/store/__58285__IMAX_B6AC_V2_Professional_Balance_Charger_Discharger.html
Also how would I charge my pack?
I have read that you can buy a parallel JST-XH harness. Does this mean that I can charge them all at once without disconnecting the pack? Also will it take forever to charge the pack?

Sorry for all the questions but I am a battery noob.
Thanks

 

[mateusleo]

Ok guys,

So here is my attempt to build my own HK Pack. Please tell me if it is viable and if I need any thing else.

The battery I will use is this: http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=35828

I will buy 6 of these, pairing up 2 in series and the connecting them together in parallel. So I would have 3 'banks in parallel'
This would cost me 312 Euros with shipping. However I have to make 6 separate orders which sucks. Also quick question, I am getting then shipped from the EU HK warehouse, do I have to pay any customs tax when they get to malta which is in europe, surely not right?

Battery Voltage monitor:
I am planning to buy these: http://www.hobbyking.com/hobbyking/store/__29652__HobbyKing_8482_Lipoly_Low_Voltage_Alarm_2s_6s_.html
The alarm starts at 3.3V is this too low?
Also 2 of these should be enough right since the packs are in paralell. I was planning to connect them to the first pair one on each.

Charger:
Will this do the job?
http://www.hobbyking.com/hobbyking/store/__58285__IMAX_B6AC_V2_Professional_Balance_Charger_Discharger.html
Also how would I charge my pack?
I have read that you can buy a parallel JST-XH harness. Does this mean that I can charge them all at once without disconnecting the pack? Also will it take forever to charge the pack?

Sorry for all the questions but I am a battery noob.
Thanks

Some lipo buzzers have a button to adjust the alarm voltage, not sure about that one. I have one and the button stays between the buzzer as you can see in the image:

About the charge, ir will work, but it will also take forever to charge your pack. If you paid attention, you noticed it can charge at max 50W. At 6s (22,2v) it will only be able to output 2A of charging current. I suppose you will charge the 6 packs in parallel, as the charger limitation is 6s. So 6*5000=30000 mAh = 30Ah of capacity. Considering the charger able to charge at 2A, it will take 5 hours to charge the whole pack. I'd look for a ~200W 8A capable charger, since it will be able to charge the pack in about 4 hours. This is a good example (http://www.hobbyking.com/hobbyking/...y_A_6_10_200W_Balance_charger_discharger.html) it can output 200W and up to 10A, so at 22.2v it will be able to output arround 8A, which is kinda good. You can always pick up stronger chargers, but 200w seems good price. Don't forget to get a 200W capable power supply, the cheaper ones arround are the computer types, such as ATX, they are cheap as frock and can output 250w~ pretty easy.

 

[glenn0010]

About the charge, ir will work, but it will also take forever to charge your pack. If you paid attention, you noticed it can charge at max 50W. At 6s (22,2v) it will only be able to output 2A of charging current. I suppose you will charge the 6 packs in parallel, as the charger limitation is 6s. So 6*5000=30000 mAh = 30Ah of capacity. Considering the charger able to charge at 2A, it will take 5 hours to charge the whole pack. I'd look for a ~200W 8A capable charger, since it will be able to charge the pack in about 4 hours. This is a good example (http://www.hobbyking.com/hobbyking/...y_A_6_10_200W_Balance_charger_discharger.html) it can output 200W and up to 10A, so at 22.2v it will be able to output arround 8A, which is kinda good. You can always pick up stronger chargers, but 200w seems good price. Don't forget to get a 200W capable power supply, the cheaper ones arround are the computer types, such as ATX, they are cheap as frock and can output 250w~ pretty easy.

Firstly I think you mean 15 hours to charge the whole pack with the first charger. But I am running the pack at 44.4V 15ah 3 paralell banks of 2 6s batteries in series. So the charging time would be halved, however in that configuration would I be able to charge them all at once?

 

[glenn0010]

Ok guys so I have been scouring ES to see how I can charge 'my' pack without dismantle every time. I try to be as practical as possible (LAZY) so is there a way of charging my whole pack easily?

It would be in this configuration. I would have 3 banks of 2 6s batteries in series, then I would wire the 3 banks in parallel for a 44.4 V 15ah pack. Now the question is how do I charge the pack all at once without blowing them up and without disconnecting the pack evrey time and charging them in series?

Best regards Glenn

 

[Drunkskunk]

So you have 6 packs of 6S batteries?

The safest easy way is with two 6S chargers. One charger per 6s parallel group, being powered by two different power supplies. Make sure they are large chargers that can handle charging 333 watt packs each. I use BC 168 chargers to balance my packs, an some 30 amp power supplies from HK.
Also, be sure you have the packs wired together through the balance leads while using the battery. Bad things could happen if you don't when it comes time to charge them.

Bulk charging through a BMS is the easiest way, but it's far from a safe way, and I really don't recommend it for your first large format battery. It's not a question of if you'll have an explosion, but when.

 

[mateusleo]

Firstly I think you mean 15 hours to charge the whole pack with the first charger. But I am running the pack at 44.4V 15ah 3 paralell banks of 2 6s batteries in series. So the charging time would be halved, however in that configuration would I be able to charge them all at once?

You have to pay attention at the charger ratings: the one you first listed only handles 50A or 5A, whatever is reached first. For example, it WILL NOT charge a 1V battery at 50A, because the maximum output voltage is 5A, as it WILL NOT charge a 22V battery at 5V, because thats 110W and its limit is 50W. You said you are going to run the packs in 12s for 44.4V, the first listed charger will not be able to charge at 44.4V, maximum 22.2V for that one. 12S chargers are kinda hard to find. I highly recommend you to find a LiPo BMS that fits your needs, because it will not only protect you from over dischage and overcharge as it will also charge the pack by itself, plug and charge, nothing to worry about. They are kinda cheap on aliexpress (pay attention on power and amp ratings) (http://www.aliexpress.com/premium/l...ative_id=SB_20150714173118&isViewCP=y&catId=0). But u'll also need a charger for that, you can find chargers by looking for "XX Volts charger"

 

[glenn0010]

But how do I do it since I am using 6s batteries. How will I connect the balance leads?

 

[glenn0010]

So you have 6 packs of 6S batteries?

The safest easy way is with two 6S chargers. One charger per 6s parallel group, being powered by two different power supplies. Make sure they are large chargers that can handle charging 333 watt packs each. I use BC 168 chargers to balance my packs, an some 30 amp power supplies from HK.
Also, be sure you have the packs wired together through the balance leads while using the battery. Bad things could happen if you don't when it comes time to charge them.

Bulk charging through a BMS is the easiest way, but it's far from a safe way, and I really don't recommend it for your first large format battery. It's not a question of if you'll have an explosion, but when.

Really is using a BMS very risky?

 

[mateusleo]

So you have 6 packs of 6S batteries?

The safest easy way is with two 6S chargers. One charger per 6s parallel group, being powered by two different power supplies. Make sure they are large chargers that can handle charging 333 watt packs each. I use BC 168 chargers to balance my packs, an some 30 amp power supplies from HK.
Also, be sure you have the packs wired together through the balance leads while using the battery. Bad things could happen if you don't when it comes time to charge them.

Bulk charging through a BMS is the easiest way, but it's far from a safe way, and I really don't recommend it for your first large format battery. It's not a question of if you'll have an explosion, but when.

Really is using a BMS very risky?

I can't say much about LiPo, so i listen to more lipo experienced people, but in LiFePO4 BMS is the safest way to go, also with 18650.

 

[glenn0010]

Ok guys,

So I have made a diagram on how the pack will be connected and wired both as a supply and for charging. The info is all in the picture below. First off for future reference is the pack in this conflagration 2s3p?

The pack should be 44.4V 15ah correct? When using the pack should the balance leads be connected in parallel to each other like in the first diagram?

So to charge I will disconnect the purple wire and will charge bank 1 and bank 2 as shown in the diagram. Can I charge them this way? Also for charging that would mean that I have a 6s 30ah pack correct? So say with a 2A charge it would take 15hrs to charge right?



Do you guys think this will work?

Best Regards Glenn

 

[mateusleo]

Ok guys,

So I have made a diagram on how the pack will be connected and wired both as a supply and for charging. The info is all in the picture below. First off for future reference is the pack in this conflagration 2s3p?

The pack should be 44.4V 15ah correct? When using the pack should the balance leads be connected in parallel to each other like in the first diagram?

So to charge I will disconnect the purple wire and will charge bank 1 and bank 2 as shown in the diagram. Can I charge them this way? Also for charging that would mean that I have a 6s 30ah pack correct? So say with a 2A charge it would take 15hrs to charge right?



Do you guys think this will work?

Best Regards Glenn

Yeah, thats gonna work. You can charge the banks all at once, but only parallel each back balances leads to iself, don't put all the 6 balance leads together or they will more likely short something when you setup on 44.4v. Since you charge Bank 1 and Bank 2 individually, its ok, you don't have to charge pack by pack.

 

[Drunkskunk]

Yeah, you'll want to connect all the balance leads of the banks together like your first diagram. That will give you essentially 2 big battery packs of 3 smaller packs each, wired up as 22 volt, 15AH. 6s3p each. With the balance leads connected, the 3 packs will stay balanced to each other all the time. You would then charge it exactly the same as you would a 6S1p pack, it will just take longer.

Using a charger like the BC 168 that charges through the balance leads is faster than trying to charge through the main leads and then have the charger try to balance by burning off the excess in each cell. About 3 hours charge time per 6s3p pack when charged st 5A.
It's what I'm using to charge a pack twice the size of yours. 24s3p, though I do it with 4 chargers.

Bulk charging is pretty much suicide. There is nothing safe about it. Using a BMS makes it marginally safer, but until you have enough experience with large format Lipo, it's just a very bad idea. It's not a question of if you're going to have a problem, it's just a matter of when.

 

[glenn0010]

Ok guys,

So I took your advice and worked with my brain not my heart.

I ordered the 48V 15ah LiFePo4 30A conitunas pack for several reasons:
1. Plug and Play
2. Simple to charge
3. Less Dangerous than LiPos
4. Longer lifetime around 1000 cycles as opposed to 200.

I really had my heart set on overwatting the motor but 1-1.3 kW will do for my first bike

Soon I will be on holiday for a while so I will not post updates for a while after the 28th.

After I get back I will order my motor and start work on making my ESC using the STM32 microcontroller.

Thanks for all your help! Really appreciate it

Best Regards Glenn

 

[glenn0010]

Hey Guys I'm back

Sorry for the delay but I was really busy with work this summer (+laziness) and all I did was ordered the parts, now the actual work will begin.

The 48V 1kW Motor:





The 48V 15aH battery:





View attachment 2




The Microcontroller:



Now I will program the microcontroller and build a circuit to conver the 48V DC to the 3 Phase needed to control the motor

What do you guys think?

Best Regards Glenn

 

[mateusleo]

Hey Guys I'm back

Sorry for the delay but I was really busy with work this summer (+laziness) and all I did was ordered the parts, now the actual work will begin.

The 48V 1kW Motor:

View attachment 6

View attachment 5

The 48V 15aH battery:

View attachment 4

View attachment 3

View attachment 2

View attachment 1


The Microcontroller:



Now I will program the microcontroller and build a circuit to conver the 48V DC to the 3 Phase needed to control the motor

What do you guys think?

Best Regards Glenn

The microcontroller can do much more than convert the dc into 3 phases. In fact, you could use to to calculate speed, energy spent, theres plenty of things you could do since you are programming it yourself. Are you still going to use a CVT? If so, could also use the controller to control a strong as frock servo to control cvt's relation. Keep us updated, good luck!

 

[glenn0010]

The microcontroller can do much more than convert the dc into 3 phases. In fact, you could use to to calculate speed, energy spent, theres plenty of things you could do since you are programming it yourself. Are you still going to use a CVT? If so, could also use the controller to control a strong as frock servo to control cvt's relation. Keep us updated, good luck!

Hey Yes that Microcontroller is can do a lot of things due to it being 32 bit and its high clock speed. And yes I am planning to add extra features like RPM of motor total wattage used and also ect. However the main priority will obviously be to run the motor first.

Do any of you guys by any chance know what the connector for the hall sensors of the motor is called. Since I would like to get the other half so it would look better instead of just wires going out of that connector.

Thanks !

 

[mateusleo]

The microcontroller can do much more than convert the dc into 3 phases. In fact, you could use to to calculate speed, energy spent, theres plenty of things you could do since you are programming it yourself. Are you still going to use a CVT? If so, could also use the controller to control a strong as frock servo to control cvt's relation. Keep us updated, good luck!

Hey Yes that Microcontroller is can do a lot of things due to it being 32 bit and its high clock speed. And yes I am planning to add extra features like RPM of motor total wattage used and also ect. However the main priority will obviously be to run the motor first.

Do any of you guys by any chance know what the connector for the hall sensors of the motor is called. Since I would like to get the other half so it would look better instead of just wires going out of that connector.

Thanks !

I think those connectors are common in motorcycles and maybe in cars too

 

[glenn0010]

I'll ask around for the connector shouldn't be that difficult. Work is commencing now on building the 3 phase controller.

 

[John in CR]

The earlier discussions about voltage may or may not be correct. It depends on the rpm it has with the designed 48V pack, and the no-load current at that rpm. Back in the summer Drunkskunk was referring to hubmotors, which are typically used far below their rpm potential, so increasing voltage isn't an issue. With a motor designed for out of wheel use it could very well be optimized for 48V operation, and going significantly higher could result in undo iron losses resulting in excess motor heat.