Help understand Phase Current and Rated Current

[zooz]

Recently I installed a new 12 FET 4110 Mark II Extreme Modder Sensorless LYEN Edition Controller. I've got HS3540 rear motor.

Lyen controller is great, but what I do not understand are those below:

* Phase Current - was set to 100 by default
* Rated Current - was set to 30 by default

Previously I had a Crystalyte 48V 40A controller which I could not change any values, so it was straight forward. What about this Lyen controller? Say I want to run it on 50A, is that possible? What values should I set for phase and rated currents? I believe there is some sort of ratio or something, how does it relate to each other?

Excuse me my ignorance, but I still learning a lot of things, so any help is appreciated.

-- zooz

 

[Jeremy Harris]

The Xiechang controllers, like the one you have, have some programmable settings, as you've worked out. The current limits are determined primarily by the number and type of FETs that the controller is fitted with. In your case Ed Lyen has fitted IRFB4110 FETs to the Xiechang controller he's assembled for you, and these are probably OK for 45 to 50 A on that motor you have. I'd add a small warning here that if the motor had a low resistance/inductance then it might not be OK to increase the current limit to 50 A.

There is only one true current limit in the controller, the one that shows as "rated current" in the description. The phase current isn't measured and all that the phase current setting does is change the value of a multiplier in the controller. The controller alters the current limit depending on rpm and throttle setting, to make sure that the peak phase current to the motor doesn't get too high.

The "rated current" is the maximum current drawn by the controller from the battery pack. It isn't a very accurate setting and you may find that the true maximum current will be a few amps different from the setting.

The phase current is the estimated maximum current that can flow from the controller to the motor. Because the controller is able to convert voltage to current, in effect, it is possible to have a much higher current flowing to the motor, at a lower voltage, than flows from the battery to the controller. The phase current is the current that the FETs carry, so it's not a great idea to set this too high.

I'd start off by changing the rated current to 45 A, leaving the phase current as it is and seeing how you like it. In general terms increasing the rated current limit will increase power across the whole rpm range, increasing phase current will only increase power at the very bottom of the rpm range (this isn't too accurate, but close enough to how it works). If you find that the throttle response is a bit aggressive at the very low end, when pulling off, for example, then reducing the phase current can tame that a bit.

There are other setting that have a significant effect, too. In particular the "block time" setting determines the time that the controller is allowed to exceed the rated current limit. This allows the controller to effectively run at a much higher current for a few seconds, but there is potential to blow FETs if this is set too high. Most people seem to find a block time of one or two seconds OK, I believe (I run with mine set to 1).

Others will have views on these settings and may disagree with what I've said above, as much of this comes down to experience, the particular motor and battery being used and the way you want the bike to perform.

 

[Lebowski]

and the effect on the feel of the bike are:

the rated current (together with the battery voltage) determines the amount of (horse)power the motor will generate

the max phase current determines the max torque the motor will generate. Keep in mind that when rpm goes up the max torque
will be reduced to stay within the (horse)power limit.

 

[Jeremy Harris]

and the effect on the feel of the bike are:

the rated current (together with the battery voltage) determines the amount of (horse)power the motor will generate

the max phase current determines the max torque the motor will generate. Keep in mind that when rpm goes up the max torque
will be reduced to stay within the (horse)power limit.

Worth bearing in mind that these controllers have no way of knowing what the phase current is, though, so that setting isn't a true phase current limit at all. What they do is assume a constant motor LR (using the sort of time constant for a typical hub motor) and then estimate peak phase current at high duty cycle and low rpm using a multiplier set by that parameter in the programming software. This means that the phase current tapers off rapidly as the rpm reaches the demanded rpm from the throttle. In effect the phase current setting on these controllers only has an appreciable effect at low rpm, high throttle demand.

 

[zooz]

Absolutely great information. Thank you very much! Now I can safely program my controller.

 

[Kingfish]

+1 on the high Phase current values equating to more Bottom-End. :wink:

Setting it high: The bike will climb hills like a banshee at the expense of distance. Great for my local area with steep hills and all, but I had to back it down to get distance out of my pack. Learned this the hard way on an 80 mile/129 km journey; the pack died and I still had one more hill to climb and 10 miles/16 km to go.

It definitely pays to experiment to find what’s right for your style of riding. As a rule, start out at Phase = √3 * Rated, and work upwards. For my cross-country jaunts, I dabbled with values as high as 2.5X of Rated, but eventually backed down for thrift.

Best of fun, KF

 

[John in CR]

Zooz,

Check out this post along with MWKeefer's subsequent posts in the same thread. http://endless-sphere.com/forums/viewtopic.php?f=2&t=18675&hilit=mwkeefer+block+time#p272438 . It's great info on controller tuning for performance to suit you. The same approach helped me get to 30kw peak with my controller without popping it, and obtaining that peak power input to coincide with the meat of my bike's power curve. I settled on a setting of 1.3:1 phase:rated relationship for my SuperV.

With a speedier wind motor, a relationship of over 3:1 Phase:Rated in the current limits can be very stressful on your controller. The reason is because it would allow too high phase currents when you don't want them, and when they can be harmful to your motor as well. Use block time to help make take-offs better, and then use the phase current limit to fine tune take-off as well as top speed. I don't understand why the phase current limit can affect top speed but it does. Doing it that way keeps phase current more controlled during climbs, where partial throttle and a high ratio can cause phase current spikes that aren't necessary and is especially difficult for the controller a lead to a quick death because the spiking goes on for much longer periods of time instead of a few seconds like during take-off.

John

 

[The Mighty Volt]

Recently I installed a new 12 FET 4110 Mark II Extreme Modder Sensorless LYEN Edition Controller. I've got HS3540 rear motor.

Lyen controller is great, but what I do not understand are those below:

* Phase Current - was set to 100 by default
* Rated Current - was set to 30 by default

Previously I had a Crystalyte 48V 40A controller which I could not change any values, so it was straight forward. What about this Lyen controller? Say I want to run it on 50A, is that possible? What values should I set for phase and rated currents? I believe there is some sort of ratio or something, how does it relate to each other?

Excuse me my ignorance, but I still learning a lot of things, so any help is appreciated.

-- zooz

Hi Zooz, what part of London are you in? I recently relocated from Ireland to Greenford.

The Lyen 12 Fet with the 4110 Fet's will run 50 Battery amps no problem. One question: what size wheel are you running the HS in?

This is important. I used to run 65amps {Battery} in an X5305 in a 20" wheel with the 18 Mosfet version of the same controller.

If your HS3540 is in a 28" or 26" wheel, then i would lower the battery amps down to around 35-45 tops.

If you run it in a 20" or 24" wheel, then you can let it go to 50.

 

[zooz]

Recently I installed a new 12 FET 4110 Mark II Extreme Modder Sensorless LYEN Edition Controller. I've got HS3540 rear motor.

Lyen controller is great, but what I do not understand are those below:

* Phase Current - was set to 100 by default
* Rated Current - was set to 30 by default

Previously I had a Crystalyte 48V 40A controller which I could not change any values, so it was straight forward. What about this Lyen controller? Say I want to run it on 50A, is that possible? What values should I set for phase and rated currents? I believe there is some sort of ratio or something, how does it relate to each other?

Excuse me my ignorance, but I still learning a lot of things, so any help is appreciated.

-- zooz

Hi Zooz, what part of London are you in? I recently relocated from Ireland to Greenford.

The Lyen 12 Fet with the 4110 Fet's will run 50 Battery amps no problem. One question: what size wheel are you running the HS in?

This is important. I used to run 65amps {Battery} in an X5305 in a 20" wheel with the 18 Mosfet version of the same controller.

If your HS3540 is in a 28" or 26" wheel, then i would lower the battery amps down to around 35-45 tops.

If you run it in a 20" or 24" wheel, then you can let it go to 50.

Hi mate,

Welcome to London!

I am in north west side of the city. About 8 miles from Greenford, but I usually do ebike trips all over the place, also I commute to work to Victoria. Have you moved your bike to London too? - Would be great to meet up for a beer and talk ebike stuff

Mine is 26" wheel. I have it setup now to 50A, but have it limited to 35-40 on my CA.

So here is another question, is it better to set the required amp limit and desired block time on the controller itself and have no limits on a cycle analyst or is it better to have a controller pull more amps and put a limit on a CA?

If anyone could list advantages and disadvantages - that'd be great.

Thanks!

 

[The Mighty Volt]

I've moved all my ebike gear to Greenford with me, and I want to get my X5 back on the road ASAP. Would love to meet up as soon as I am settled and e-mobile. Buses are expensive and cycling is for the very brave. Thats why I like my e-bmx, it lets me compete and stay alive lol

In my experience, using the cycle analyst to limit amps is something you should really only do if you can't already programme the controller. If you can programme the controller, which you can do with your infineon, then its better to let the controller do its job and leave the CA alone to do its job, namely provide heads-up information and the like.

 

[gensem]

Be aware that I smoked a lyen 12fet using 50a on a cromotor during a long hill. The fets are under greater stress while in low speeds (using higher phase current).

 

[Jeremy Harris]

Be aware that I smoked a lyen 12fet using 50a on a cromotor during a long hill. Be aware that the fets are under greater stress while in low speeds (using higher phase current).

Doesn't surprise me at all. It's why I added this warning earlier in this thread:

I'd add a small warning here that if the motor had a low resistance/inductance then it might not be OK to increase the current limit to 50 A.

The cromotor has a low winding resistance and a fairly low inductance, when compared to most other hub motors, so it's going to allow controllers like this to overshoot on phase current to a much greater degree (because these controllers can't actually sense phase current, they sort of guess it from an assumed motor LR).