Phase current

[gensem]

Lets pretend im running 200 amps from the battery with 2.5x phase, wich would allow phase amps to be 500.
How is all thoses amps transfered to the hub motor... are they equally split by the 3 phase wires or sometimes a single phase would be able to see, lets say 250-300 amps?


Thanks

 

[itchynackers]

I believe the current only flows in 2 phases at a time. One "flows" inward, second "flows" out. Maybe someone else can elaborate.

 

[boostjuice]

^^ Basically correct. Each of the 3 phase wires leading to the termination nodes inside the motor needs to handle the full current.

 

[itchynackers]

So the energized phase needs to handle the full phase current for 2/3 of the time while accelerating (I think).

1. Energized (flowing in)
2. Off
3. Energized (flowing out)

As you approach top speed, I think the phase current approaches battery current.

 

[gensem]

So the energized phase needs to handle the full phase current for 2/3 of the time while accelerating (I think).

1. Energized (flowing in)
2. Off
3. Energized (flowing out)

As you approach top speed, I think the phase current approaches battery current.

Yah, voltage rises again and the current do get drop to battery levels at speed.

So when someone say "I melted my phase wires using 40amps" he was probably dumping over a 100 amps on the poor thin phase wire?

 

[Lebowski]

how may phases carry current depends on your motor and on the controller.

The simple controllers connect 2 out of 3 motor wires to the battery (with some PWM inserted). If your
motor is wired in WYE the current will flow through the 2 connected coils. If your motor is wired
in delta current will flow through all 3 coil, even when only 2 motor connections are powered.

A good sinewave / vector based controller will always power all 3 motor terminals.

 

[itchynackers]

When can we get one of those? lol Seems like it would be way more efficient too.

 

[Lebowski]

When can we get one of those? lol Seems like it would be way more efficient too.

I was running with sinewaves this weekend on my 30F build but I blew one of the NMOS transistors, probably
due to an error in my hastely botched output stage (was eager to try sinewave stuff). Or maybe I killed
a driver somewhere when I tried the 1 MHz PWM signal....

 

[gensem]

Ok, so for the el cheapo infineon controllers that we use. I would probably see 250 amps in a single phase, is it?

 

[itchynackers]

I believe so. The phases can probably take many more amps for brief periods. Thermal sensor should be on your to do list.

 

[botz244]

and when someone says sensorless its just sending juice down the wires on off , i have a 3540 and a lyen controller sensorless why would you want extra wires sensors

 

[Kiwi]

Would someone be keen to explain to me HOW a controller multiplies the current.

later.....ah found this post http://endless-sphere.com/forums/viewtopic.php?f=2&t=19590&start=90
all I need to know there.

 

[gensem]

I was reading some of my old posts... I hardly regret about doing something or not doing something. But If I was to choose again I would get a degree in electronics.

 

[Alan B]

Ok, so for the el cheapo infineon controllers that we use. I would probably see 250 amps in a single phase, is it?

500 amps instantaneous current * 2/3 of the time = 333 amps average

 

[John in CR]

Would someone be keen to explain to me HOW a controller multiplies the current.

later.....ah found this post http://endless-sphere.com/forums/viewtopic.php?f=2&t=19590&start=90
all I need to know there.

The battery supplies current at pack voltage. The controller sends a variable voltage at or less than pack voltage to the motor for our speed control by changing the width of those pulses. Current limiting is also accomplished by narrowing the width of those ON pulses to the motor. Other than the small losses in the controller, the power coming out of the battery is sent to the motor. Volts X Amps = Power , so if the voltage going to the motor is lower than pack voltage, then the current going to the motor must be higher than what is supplied by the battery. At low duty cycles (low throttle or during heavy current limiting), the phase currents can be multiplied many times higher than battery current.

At least that's how I understand it.

John

 

[John in CR]

Lets pretend im running 200 amps from the battery with 2.5x phase, wich would allow phase amps to be 500.
How is all thoses amps transfered to the hub motor... are they equally split by the 3 phase wires or sometimes a single phase would be able to see, lets say 250-300 amps?

Thanks

FWIW my motors seem to run better with 2.6:1 than 2.5:1 on the phase vs battery side current limit ratio. At 2:5 or less, the motor makes more sound during acceleration and sounds "starved and strained". I'm sure it varies by motor, so it's the kind of thing you want to experiment with, since with a high power motor you want to keep that ratio as low as possible to protect the controller.

What controller do you have that you believe can handle 200A/500A ? I want some while I patiently wait for sine wave controllers and the even more quiet running that should accompany them.

John

 

[gensem]

FWIW my motors seem to run better with 2.6:1 than 2.5:1 on the phase vs battery side current limit ratio. At 2:5 or less, the motor makes more sound during acceleration and sounds "starved and strained". I'm sure it varies by motor, so it's the kind of thing you want to experiment with, since with a high power motor you want to keep that ratio as low as possible to protect the controller.

What controller do you have that you believe can handle 200A/500A ? I want some while I patiently wait for sine wave controllers and the even more quiet running that should accompany them.

John

I was just pretending and I tought that 200amp would drag more attention to my question than 20amp.
I dont really wanna push the envelope im waiting for a 24 fet 4110 controller and ll probably use it with 80-100 main amps.
Maybe a 36fet 4110 could handle 200amps but I dont really feel like going much over 10kw.