Testing Electronic Speed Controller without motor

Thread Starter

jcatkeson

Joined Feb 10, 2023
14
Hi I recently bought one of these:
https://www.aliexpress.us/item/2255801148821043.html

I am trying to establish if it works or not, but without a motor. Is that possible?

I have looked at the output with a meter and with a simple oscilloscope. There are a few ripples when it is turned on and then it goes to 0V flat.

How I connected it:
Power inputs connected to ground and 12v.
Each of the 3 output lines connected to ground by a 10kohm resistor because the directions say it must run with a load.
Meter and oscilloscope connected to ground and to one of the output lines.
Slowly swept the speed knob from 'off' to max.
Tried all 3 outputs, zip.

If this testing is good enough, then I will return it to the seller as broken. But am I testing it right?

Thanks,
John
 

Alec_t

Joined Sep 17, 2013
14,280
Shouldn't the load resistors go between phases A,B,C rather than from phase to ground?
1mA load current may not be enough to operate any current-sensing arrangement inside the controller?
 

Thread Starter

jcatkeson

Joined Feb 10, 2023
14
Shouldn't the load resistors go between phases A,B,C rather than from phase to ground?
I hadn't thought of that. I just tried it with the resistors between the phases. The output is a little different but it still goes flat after a few seconds.

1mA load current may not be enough to operate any current-sensing arrangement inside the controller?
I also tried it with 100ohm resistors, if that makes any difference. The output was the same.

Do all controllers current sense? I can't find any information on how they're supposed to react to no motor feedback. Freeze? Keep cycling blindly? Catch fire?

Thanks...
 

MaxHeadRoom

Joined Jul 18, 2013
28,619
Do all controllers current sense? I can't find any information on how they're supposed to react to no motor feedback. Freeze? Keep cycling blindly? Catch fire?

Thanks...
Not all, depends on the controller/intelligence!
That unit shown could be for sensorless control, i.e. the motor is exercised at power up via two windings and the third detects the rotor pole location. From then on it is synced without any
sensors required.
 
Last edited:

MisterBill2

Joined Jan 23, 2018
18,179
If the motor does not need separate sensors then it detects the voltage feedback and current from the three windings. So it will quickly shut down. So you need a 3-phase motor of some kind.
There is no other application, besides driving a motor, that I can imagine, for a BLDC motor controller. So why getone if there is no motor to control???
 

Thread Starter

jcatkeson

Joined Feb 10, 2023
14
There is no other application, besides driving a motor, that I can imagine, for a BLDC motor controller. So why get one if there is no motor to control???
Mad science experiment. ;) I want to send 3 phase square waves through 3 high voltage generators to run an *electrostatic* motor.

I found a workaround by feeding low power 3 phase square waves through 3 IRLZ44N transistors, which then deliver enough power to switch the HV gens on and off at 2 kilohertz.

So far so good, but the PWM ESC is sitting on a shelf. Thanks for letting me know why that didn't work!
 

MaxHeadRoom

Joined Jul 18, 2013
28,619
Do the IC's present on the board show any microprocessor numbers?
There does not appear to be any sensor inputs, so possibly like most ECM 3ph motors. the controller exercises the motor first in order to find the pole locations and from there on, knows the rotor position.
It generally requires a on-board micro to do this.
 

Thread Starter

jcatkeson

Joined Feb 10, 2023
14
Do the IC's present on the board show any microprocessor numbers?
There does not appear to be any sensor inputs, so possibly like most ECM 3ph motors. the controller exercises the motor first in order to find the pole locations and from there on, knows the rotor position.
It generally requires a on-board micro to do this.
It's all surface mount tiny components, but the 3 largest chip types have these numbers:

Texas Instruments GM2145A LM339 Comparator?

JY01C 1485000083 Google says 'Motor driver IC'. Probably what you are looking for.

JY21L2 1CWA - 3 of these. Not sure, but resemble 555 timers.
 
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