mounting hall sensors to R/C brushless motors

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Re: mounting hall sensors to R/C brushless motors

Post by liveforphysics » Sun Apr 12, 2009 7:25 am

Thank you Jeremy, I will mount them just like that when I get a little time off work again.


Here are some pictures of how the mounts adjust. Much like a car distributer, slotted holes and screws to clamp them in place. The hall bracket is made of ABS. Crude, but it should work ok for testing and seeing how I like it before I step-up to something more permanent.

Image

Image

Image

Image

Best Wishes,
-Luke
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Re: mounting hall sensors to R/C brushless motors

Post by Jeremy Harris » Sun Apr 12, 2009 9:03 am

Looks fine to me, Luke, I can't see any obvious reason why it wouldn't work.

I've spent the morning fitting IRFB3077 FETs into my baby Infineon, complete with mica insulators and a lapped-flat spreader bar. One thing worth looking out for on these controllers is the burrs inside the case where the spreader bar bolts on. On my case these were pretty big and stopped the spreader bar from fitting tight to the case. Easily sorted, but something equally easy to miss when putting the thing together.

The rest of my time has been spent making a programming interface for the Infineon, following the excellent post by philf here: http://endless-sphere.com/forums/viewtopic.php?f=2&t=8317&hilit=regen&start=30#p126939. It works a treat and I've already played around with some of the settings.

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Re: mounting hall sensors to R/C brushless motors

Post by fechter » Sun Apr 12, 2009 11:12 am

Nice work Jeremy,

Another approach might be to sneak the hall sensors in on the end of the stator, something like this:
Hall sensor in RC motor 2.jpg
Hall sensor in RC motor 2.jpg (66.12 KiB) Viewed 5241 times


On the end, it may work fine to have the sensors mounted with the face aimed toward the front of the motor, rather than toward the side. This would avoid the need for machining the slots and it looks like there may be adequate space inside the housing. There might be enough room to slide one into the end of the slot on top of the windings, but below the stator teeth.

The axis of flux measurment is perpendicular to the flat face on the sensor, so if you rotated them so the leads were coming out in the direction of the gap between the stator and the end plate, it should work the same. This might make fitting them easier in some motors.

The external approach seems like it should work fine too, as long as there is adquate flux outside the ring. If you can strongly attract a paperclip or piece of steel to the outside of the ring, it should be good. I like the adjustable timing feature, but I think you'll find that neutrally timed works the best.
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Re: mounting hall sensors to R/C brushless motors

Post by liveforphysics » Sun Apr 12, 2009 1:38 pm

I will start with neutrally timed, then measure acceleration and current draw. Then advance 5deg, measure acceleration and current draw, then retard 5deg and repeat.

I've never had any experience with a motor with this many poles, but I remember with low pole count RC motors, timing advance can sometimes make a big power improvement. Neutral may be the best for these motors, but the tinkerer in me won't let me be content until I give various advance and retard positions a whirl :)
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Re: mounting hall sensors to R/C brushless motors

Post by JEB » Sun Apr 12, 2009 6:46 pm

Fantasic brake through! Jeremy, will a non latching hall device work also? (I have some on hand). I think there is excess plastic on the sides of the device, file to fit?

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Re: mounting hall sensors to R/C brushless motors

Post by georgeycc » Mon Apr 13, 2009 1:02 am

hi all,
could anyone please tell me the ebay place to buy the infeneon controllers? i need more controllers to trash now :oops:


thanks!,
-george

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Re: mounting hall sensors to R/C brushless motors

Post by georgeycc » Mon Apr 13, 2009 1:09 am

George said he was able to mount them all on one side by flipping the one in the middle over. Now, I'm confused. If these just latch high or low when in a strong field, how does flipping them over help? I'm also still a little puzzled at the exact degrees spacing I need between the sensors. My mounts can adjust the full width of a stator pole, so I should be able to dial things in if I can get them mounted with the right spacing, but I'm still unclear on this.


flipping the sensors is equivalent (almost) to adding an inverter to the output of the sensor, so it is like making 1 to 0 and 0 to 1. your turnigy motor looks identical to mine, so i guess you could simply use my setting of mounting the sensors at the middle of two slots.

for example:
slot1 xxxxxxxx(sensor1, facing out)xxxxxxx slot2 xxx slot3 xxx(sensor2, facing in) xxxxx slot4 xxxxxx slot5 xxxx (sensor3, facing out) xxxxxx slot6
---------------------------->|<--------------2 slots------------------------------>|<------------------2 slots------------------------------->|

hope this helps to clarify.

-george

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Re: mounting hall sensors to R/C brushless motors

Post by liveforphysics » Mon Apr 13, 2009 1:21 am

Thank you George. That does help.

You have not even been here a month, and your work has all ready inspired and helped to bring new ideas to solving the RC controller problems. Jeremy seems to be very happy with the control this gives his motor, and I'm excited to be happy too! I can't wait to see what else you will bring the forum in the future.

Best Wishes,
-Luke
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Re: mounting hall sensors to R/C brushless motors

Post by Jeremy Harris » Mon Apr 13, 2009 3:26 am

Fechter, I'm pretty sure that putting the sensors at the end can be made to work, the only problem I found when playing about with a sensor as a probe (with the motor driven by the RC ESC) was that there was a fair bit of jitter on the sensor signal near the edges. This may have been induced by vibration though, as I was just holding the sensor against the stator through one of the end slots. Certainly fitting them in the centre has made the signal rock-solid, but I would be surprised if this is totally associated with that position. I chose to do it that way just to support the sensor leads a bit better, but some epoxy dribbled around them when fitted at the end would probably do as good a job.

JEB, I'd go for latching sensors, as they are cheap and reliable. Having the sensor latch tends to make it less vulnerable to noise, too. Honeywell SS411A sensors are readily available from Digikey for around £2 or so, other places sell them for less if you shop around. I guess you could try filing the edges of the sensor down, but the leads are pretty close to the edge of the package, so the chances are than the lead header is only "just" covered. Filling it down might expose the lead header and risk an inadvertent short to the stator.

George, The Infineon controllers can be purchased directly from Keywin Ge (e-crazyman(AT)gmail.com). The price for two 18 FET boards, with cases, all components except the FETs and all the mounting hardware, was $130 including shipping to the UK (I think shipping to the US is about the same). Keywin also sells on eBay, just look for his user name, e-crazyman. He currently has the 6 FET 48V, 15A controller on eBay for $22 plus $23 shipping. He also has the much bigger 12 FET, 72V, 45A controller on eBay for $75 plus $35 shipping. All told, if you want really high power, then buying bare 18 FET boards and fitting your own FETs is probably the best bet.

Jeremy
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Re: mounting hall sensors to R/C brushless motors

Post by recumpence » Mon Apr 13, 2009 7:25 am

Jeremy,

I am also very excited about this! I have been having good success with my modded (caps added) HV110s. However, I am still not 100% confident they are the best option considering your success here. At this point, assuming adding halls is easy enough for most motors, the only real benefit to using HV110s is the programability and very small size.

Also, I am not an electronics guy. I know just enough to be dangerous. I can do anything mechanical, though. So, mounting the halls is the easy part for me. Getting them wired up properly is another story, though.

Now I just want to see how easy it would be to mount halls to my Astro inrunner motors! :wink:

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Re: mounting hall sensors to R/C brushless motors

Post by Jeremy Harris » Mon Apr 13, 2009 9:38 am

Matt, the Infineon controllers are programmable, too. I've been playing with the programming on mine today and it's really easy to adjust things like the current limit, low voltage cut-off etc via the PC interface. The software for changing the settings is a bit "Chinese", but works OK once you've decoded what the various settings really do. The only tricky bit is making up the programming lead, but philf sorted that for us in the thread I linked to yesterday.

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Re: mounting hall sensors to R/C brushless motors

Post by liveforphysics » Mon Apr 13, 2009 9:46 am

Jeremy- Can you find out what to do to disable the turn-on delay? I've started playing with mine, and I find that makes it totally un-usable. 100% not ok to have delay, and a complete deal breaker.

Also, I'm running my 0-5v pot throttle rather than a hall effect throttle. I have a hall effect throttle, but it feels very cheesy compared to my magura throttle. It seem to not turn-on for the first half of the throttle twist with the pot. And ideas on that? When you find the solution to remove the delay, please post it up ASAP. It's a paper weight to me otherwise.

Thank you!
-Luke
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Re: mounting hall sensors to R/C brushless motors

Post by Jeremy Harris » Mon Apr 13, 2009 10:11 am

Luke,

There doesn't seem to be an obvious setting in the software to control turn on time, so I guess we'll need to look at the circuit to see how it's controlled externally. There are some timing settings in the software, but it's not clear quite what they do. One is marked "block time (s)" but the lowest setting is 1, which may be the default. There is also a setting marked "auto cruising time (s)" which seems to default to 15. It'd be nice to have a translation for all of the controller programmable settings, as the only ones that are obvious are the LVC and current limit ones.

The reason that your Magura throttle isn't working at the low end is down to the way the controller is set up on the throttle input. It seems to ignore the first volt of the control signal, presumably because the Hall throttles sit at around 1V when they are "off". The Magura goes right down to 0V, so the first 20% of the throttle movement won't do anything. I believe that the Magura can be adjusted to compensate for this, by adjusting the pot position inside the twist grip. You want to aim for a throttle off voltage of around 1V, although you may be able to experiment with this by twisting your throttle until the motor just starts and measuring the voltage at the throttle input. If you then adjust the throttle pot so that zero throttle is just a naffigravit less volts you should get a better response. You may find that this takes out some of the apparent throttle response delay, too.

Jeremy
Last edited by Jeremy Harris on Mon Apr 13, 2009 10:53 am, edited 1 time in total.
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Re: mounting hall sensors to R/C brushless motors

Post by liveforphysics » Mon Apr 13, 2009 10:32 am

That's good to know it can be rotated inside. I was thinking of maybe adding a second pot that I could adjust like a pull-up resistor between the tap and the high side to tweak it so it climbs to 5v much faster, but it would still sit around 0v at the bottom. I haven't actually mounted anything, or made finalized wiring, or even put my chain back on yet. It's ghetto rigged with alligator clips and hall wires twisted together everywhere, but it makes the motor spin. Seems kinda herky-jerky though, so I don't think I've got the sensor leads vs the phase leads in the perfect combo yet. I wish I had more time to play with it, but I have a ton of real work to do at the moment. I will post up some pics when I get it better sorted and looking more presentable.

Please find a solution to solving that turn-on delay. I will instantly paypal anyone $50 to gets the fix to that figured out, because I can't use something that doesn't respond when I need it to, and I will have to dump the Infinions for something else if it can't be fixed. That would suck, cause I beefed up all the high current traces with a double pass of solder wick, added a ton of cap, and swapped all the FETs to IRF4110's all ready.
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Re: mounting hall sensors to R/C brushless motors

Post by kfong » Mon Apr 13, 2009 11:03 am

Wow, great thread. I had thought it would be possible to do a sensored motor out of the RC stuff. Glad to see it being done. I will definitely be doing the same with my next build. We now have all the componenents to build a most excellent RC ebike. Seems like the only thing to fix now it the infineon delay. Is this typical of most ebike controllers or just with the infineon? Any other choices for a controller that people have been happy with.

Kin

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Re: mounting hall sensors to R/C brushless motors

Post by Jeremy Harris » Mon Apr 13, 2009 12:13 pm

Luke,

I've just been running my motor/controller on the bench again to look at the throttle problem. I don't seem to have any appreciable delay on mine, it seems to respond pretty quickly when I turn the 5k pot I've got hooked up to the throttle connections. I can confirm that for my controller zero speed is actually 1.28V at the throttle input. The safe setting is probably around 1V.

I may try some different software settings tonight, but for reference these are the settings I have at the moment (remember this is just a baby 6 FET Infineon I'm using as a test set-up):

Phase current = 70A
Rated Current = 15A (kept low for test purposes)
Limit Voltage = 20.1V
Tolerance = 1V
Block Time = 1S (the fastest setting)
Auto Cruising Time = 15S
Slip Current Charge Mode = 1
EBS Level = 2
Speed Mode = 0
Limit Speed = 99%
Speed 1 = 33%
Speed 2 = 66%
Speed 3 = 100%
Converse Speed = 35%

Maybe your controller is set up for a longer "block time"? I'll see what effect this has later tonight by re-programming my controller.

Jeremy
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Re: mounting hall sensors to R/C brushless motors

Post by liveforphysics » Mon Apr 13, 2009 12:37 pm

Mine lags for at least a full second from the time I open the throttle until it starts to make the motors turn. You can actually go WOT, and come back quickly, and it won't move the motor. The RC controllers always responded instantly. Anything with a lag/delay is useless for technical riding.

Can you make that block be zero?

Also, Methods told me there was something with the speed setting, that you could set to over 100%, and it boosted torque everywhere, epically on top end. He thinks it may be an electronic timing advance. Might be something worth taking a look at while you have it on the scope.

Thanks for the tip on where the throttle threshold voltage is. I wonder if that is something that could easily be changed in the hardware of the board, like removing a resistor or a jumper somewhere.
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Re: mounting hall sensors to R/C brushless motors

Post by Jeremy Harris » Mon Apr 13, 2009 1:44 pm

Well, I've just re-programmed my controller with a longer "block time" and it doesn't seem to make any difference. You can't set the "block time" to zero, 1S is as low as it will go.

Mine definitely doesn't lag to any noticeable degree, the motor spins up just as fast as I can turn the speed pot. I cannot get anywhere near winding the pot to full and back without the motor following it near-instantaneously.

Maybe there's a difference between the 6 FET controllers and the bigger ones? I've not yet built one of my 18 FET boards up, so haven't had a chance to play with it.

I've read that setting the "Limit Speed" to over 100% changes the motor timing, but I've not had any confirmation of that.

What's your test set-up? I'm wondering if there is some other effect causing the throttle lag you're seeing, like a low current limit? Have you tried changing the internal controller settings using the serial link?

Jeremy
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Re: mounting hall sensors to R/C brushless motors

Post by liveforphysics » Mon Apr 13, 2009 2:20 pm

That's fantastic news that your 6-fet doesn't lag. These 12fets have an awful delay. I'm about to post up some photos, and you can let me know if your uController is the same chip. If it's something in the chips firmware that can't be changed, I will just buy 6-fet controllers with no delay, heatgun off the chip, and swap them onto the 18fet boards that are comming. I can't imagine why they put a damn delay in these things. 1/2 the whole performance advantage to electric power should be instant torque response and delivery.

I don't have programmers yet :( Methy has a couple 18fet boards and some programmers that he is building into them so they juts have a USB jack on the side of the case, and then sending them up to me. Then I'm going to throw IRF4110s, as much cap as the case can hold, and 8awg all the current traces. I've got something clever up my sleeve for cooling :) Hopefully they will be able to burn my motors up, because I'm dying to have an excuse to do a custom re-wind on them :) I have so much motor cooling though, the controllers are going to have their work cut-out for them :)

I'm working on finalizing some connections and things right now, and I will post up some pictures as soon as things look somewhat presentable.

-Luke
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Re: mounting hall sensors to R/C brushless motors

Post by liveforphysics » Mon Apr 13, 2009 2:31 pm

I want to share my idea on why I think having timing control could be important. If you take a look at the spec sheet for the ss41, you can see it has a gauss threshold to make it latch.

http://parts.digikey.com/1/parts/948156 ... -ss41.html
Click the view datasheet link near the bottom



So, if you stick them physically in a neutral position, you actually have no idea how retarded the sensor is latching. In fact, odds are, if it can latch from 1/4" away from your magnet, then it likely latches as the magnet is just creeping up on the sensor. This could have the effect of advancing timing, but the extent the timing is advanced would depend on the square root of the distance that the sensor happens to be from the magnet.

What I'm thinking, is that your timing with your sensors very close to the magnets on the inside could act more advanced than my sensors on the outside, placed in identical locations. Or maybe the stator laminations re-direct the field so effectively that it shields your sensor, and my outside sensors reach the latch threshold first. I have no idea, but I'm looking forward to getting some data up on the effects of timing VS power/efficiency.
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Re: mounting hall sensors to R/C brushless motors

Post by Jeremy Harris » Mon Apr 13, 2009 2:43 pm

If the delay is built in as firmware and isn't adjustable with the programming software, then it might be possible to get hold of the full code for this controller (not just the dealer set-up software) and change the settings that way. Reading some of the documentation for this controller, it looks as if it has been deliberately designed to have a soft start. It may be that I'm just not seeing this on the bench because my motor is so lightly loaded.

The best thing would be to load the chip with a known good set of parameters using the programmer, adjust the throttle to get rid of the dead movement at the start and then see how it goes.

If the lag is a still a big problem, then maybe a call to Keywin Ge might just help, as he might know a way to re-programme the soft start.

Jeremy
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Re: mounting hall sensors to R/C brushless motors

Post by Jeremy Harris » Mon Apr 13, 2009 3:25 pm

Another thought came to me a while ago, whilst reading the delta/wye thread. Reading up on this, it looked like these RC model outrunners are wired in delta, for ease of manufacture. Delta gives a higher rpm/voltage constant (Kv) and also has a slightly lower efficiency, due to circulating currents in the unenergised windings.

A low Kv value is a pretty good thing for us, as it means less gearing down and slightly less transmission power loss. Add in the slightly better efficiency of a star (or wye) configured motor and it just seemed sensible to look at hacking a motor to this configuration. One of my poor Towerpro hack motors has been subjected to a a bit of disection. I found it only took me ten minutes or so to tease out all the wires and get access to both ends of each winding. Here's a picture of progress so far:

Image

The next stage is to wire the thing up in star configuration, fit some Hall sensors to this motor just like I did with the other one and see what happens.

Jeremy
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Re: mounting hall sensors to R/C brushless motors

Post by GGoodrum » Mon Apr 13, 2009 3:57 pm

I'd be very surprised if most RC outrunners were wired up in a delta configuration. The whole reason outrunners came into being was because they had high torque at low rpms, so they could drive a prop directly, without a gearbox.

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Re: mounting hall sensors to R/C brushless motors

Post by johnrobholmes » Mon Apr 13, 2009 4:03 pm

I can correlate, most outrunners are terminated Delta. It is faster to manufacture, you have one less solder joint and 1.78 less winds to wrap for a given KV.
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Re: mounting hall sensors to R/C brushless motors

Post by Jeremy Harris » Mon Apr 13, 2009 4:05 pm

I'm a bit surprised, as well, for the same reason. However, that photo shows that this particular big outrunner motor is definitely wired delta. It's easy enough to check any outrunner, as you just need to look for the centre tap join for the three windings. If there isn't one, then it has to be wired delta, AFAIK.

Jeremy
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