Battery / Phase Current Ratio Tuning Infineon

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Does using Johnn in CR's method draw more current from the battery for less acceleration by having a smaller ratio of battery to phase? Or is actual battery current draw related not only to the controller battery current limit but as well as the ratio set? I need a DC current meter...

John in CR's method:

Step 1:
-Set battery current limit to something modest (low power)
-Set phase current to the same value (1:1 ratio)

Step 2:
-Apply 100% throttle and see how the motor spins up in free air
-Ride to feel what take off and top speed feel / sound like
-Increase only phase current a small step

Repeat testing and increasing phase current until the motor sounds and feels to be powered properly.
Do not expect powerful acceleration yet.

Step 3:
Note the ratio you have reached and increase BOTH battery and phase currents while maintaining that ratio found in Step 2.

I have an 18 FET 4110 and it came from factory with a 65A battery limit, and a 2.8 Battery to Phase ratio. My motor is a "1500W" 10" Scooter motor with a kV of 16.5ish.

I was unable to notice any starved properties at 1:1 (60A, 60A) other than it barely produced any torque. Free air spin up seemed the same.

I reached a ratio of 1:1.5 battery to phase where I could actually move around. I decided at this point to use this ratio to up my battery and phase amps.

I am now at 88A battery with a battery to phase ratio 1:1.55 and performance is acceptable now.

However if this 88A battery limit is accurate that would be a greater discharge rate that I would like for my battery. Also the controller SEEMS to get warmer for less acceleration.

Over time I will be able to measure and gather better data. Edit: My method turns out to be : Set battery and phase (1:1) current limit to my battery discharge limit then increment phase current limit till take off torque is acceptable.

John in CR said:
The way I do it is to first determine the proper ratio for that motor controller combination. Set the battery limit at modest power and set the phase limit the same, 1:1 ratio. No field weakening or overspeed settings. Spin it up no load, and also give it a road try up to max speed, so you can hear and feel what the motor is like when starved of phase current on takeoff and at the top end. Often it won't even spin up to full no-load speed. In small increments increase phase current until it doesn't sound or feel starved of current, but you're not looking for hard launch yet. Once it seems to be functioning and sounding correct at that modest power level note the phase:battery limit ratio. Now start turning both up at the same time and maintaining that ratio until you get to the desired power and thrust on takeoff that you want. The end result will be higher power than you had the other way, but the motor and controller will be less stressed, ie less heat, especially under load at lower rpm. FWIW, Zombiess used a similar approach to come up with a 1.8:1 optimum ratio for his 4t Cromotor.
 
It sounds like your battery is the limitation, because the controller can go higher. The relatively soft acceleration is the lower Kt, torque per amp, of a high Kv motor, which needs proportionately higher current. The already warm controller is in large part due to that controller brand struggling with the lower inductance of high Kv motors.

The penalty of using high phase/battery current limit ratios is excess motor heat. More torque means more heat. When you tune so high that launch torque can easily flip the bike or throttle response is too jerky, then what seems cool and powerful comes back around and bites you in the ass in the form of heat, especially at partial throttle under higher loads like off road up hills.

Instead of extra waste heat at low speeds your new settings gives you more real power and acceleration through the mid-range where making some extra heat isn't such a danger to your motor.
 
John in CR said:
It sounds like your battery is the limitation, because the controller can go higher. ...

... When you tune so high that launch torque can easily flip the bike or throttle response is too jerky, then what seems cool and powerful comes back around and bites you in the ass in the form of heat, especially at partial throttle under higher loads like off road up hills.

Instead of extra waste heat at low speeds your new settings gives you more real power and acceleration through the mid-range where making some extra heat isn't such a danger to your motor.

I dono why but even after reading a lot of material on the forums about controller settings it didn't all make sense, even after my first tune attempt I wasn't totally sure. Now I believe it makes much more sense.

My battery is current limited, I opted for capacity rather than power (cost being the limiting factor). Once I get a DC current meter on the batt I will be able to tune closer to the limits.

More real power indeed, pulls harder at higher speeds. Funny thing is, being a moped I have limited the speed to 66% aka 45kmph. The system will do over 55kmph at 50V (my battery voltage).

Added to OP: "My method turns out to be : Set battery and phase (1:1) current limit to my battery discharge limit then increment phase current limit till take off torque is acceptable."
 
the way I have done it in the past is.. along the same lines as John has described.

set battery current to something safe i.e 40-50A , set over current detection to 0.0s ( this is very important ) set phase to approx x1.5 battery current
you need a watt meter, amp meter or calibrated ca on the bike. on a slightly uphill ( maybe a 2-4% grade) piece of road accelerate hard ( from stop ) upto top speed or until it stop accelerating but throttle is at WOT( this may take a while so you need a longish stretch of road ) then check watt meters max current pull, if the max current pulled is less than your set battery current then you need to increase the phase current, maybe by 10A or if the set battery current is reached then reduce phase current by 10A. You keep increasing or decreasing the phase current until the max current pulled from the battery is what you have set it to. Once you have found a battery/phase ratio where the max battery current is always reached then this will be the ratio you would use when increasing the battery and phase current together.

If the phase current is to low then you will never reach full speed or max battery current.

My controllers use a ratio of around x1.7 for the motors, gearing , my riding style and total weight of my bikes

edit:
Another method I have used is set at a much lower battery limit maybe 20A and a phase limit of 30A with the wheel off the ground go WOT and then start applying the brake to slow the driven wheel down ( loading the motor ) when the wheel is appox halve the max speed watch the battery current on the watt meter this should go to your set max battery current and should stay there as the driven wheel gets slower and slower until the controller cuts out ( locked rotor fault protect ) and the same applies increase or decrease phase current until you see the set max battery current limit hit always just before the controller cuts out. each test on needs to take around 5secs so its a much quicker method of finding the optimum phase setting for the motor.

Once you have found your optimum phase ratio you can always turn the battery current down and keep the phase limit at the optimum.
 
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