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Topic: measuring the current of the Dc motor  (Read 746 times) previous topic - next topic

koronus

hi
is there any way to measure the current of the dc motor, actually I want to give the periodic voltage to the dc motor and I need the periodic values of the current which flow in the motor

groundFungus

Some DC motor drivers have a current output.  To help find one we need to know the rated voltage and stall current of your motor.

Place a shunt (low value resistor) in series with the motor.  The voltage dropped by the resistor is proportional to motor current (see Ohm's law).  Depending on the setup, amplification of the output may be necessary.

Use a current sensor .

koronus

Some DC motor drivers have a current output.  To help find one we need to know the rated voltage and stall current of your motor.

Place a shunt (low value resistor) in series with the motor.  The voltage dropped by the resistor is proportional to motor current (see Ohm's law).  Depending on the setup, amplification of the output may be necessary.

Use a current sensor .
thank you so much

koronus

please help to wire the dc motor with ACS712 current sense module, I know how to connect the ACS712 with power supply but I don't know how to connect the dc motor to the circuit, actually, I want to give the voltage to the dc motor and read the current with ACS712

groundFungus

#4
Dec 10, 2018, 09:41 pm Last Edit: Dec 10, 2018, 09:42 pm by groundFungus
What are you using to drive the motor?  A transistor?  Relay?  H-bridge?   Part number or link to the driver?

What is the stall current of your motor?

outsider

Quote
I want to give the periodic voltage to the dc motor
If you are talking about PWM, you may not be able to measure the pulsating current without heavy filtering.

koronus

#6
Dec 11, 2018, 06:21 am Last Edit: Dec 11, 2018, 06:22 am by koronus
What are you using to drive the motor?  A transistor?  Relay?  H-bridge?   Part number or link to the driver?

What is the stall current of your motor?
I'm using L293D shield and the stall current is 11.96 A

koronus

If you are talking about PWM, you may not be able to measure the pulsating current without heavy filtering.
yes I want to use PWM, "FILTERING" what did you mean?

Wawa

I'm using L293D shield and the stall current is 11.96 A
That's ten times the absolute maximum peak current that the L293D can handle.
Leo..

koronus

That's ten times the absolute maximum peak current that the L293D can handle.
Leo..
so what should I do?

groundFungus

#10
Dec 11, 2018, 10:33 am Last Edit: Dec 11, 2018, 10:34 am by groundFungus
Quote
so what should I do?
Get a proper motor driver.

Pololu carries many DC brushed motor drivers.  Some have current sense outputs.

MarkT

hi
is there any way to measure the current of the dc motor, actually I want to give the periodic voltage to the dc motor and I need the periodic values of the current which flow in the motor
If you mean you are using PWM to drive the motor, you may find the current is varying much less
than you think, motors are inductive, smoothing out the current waveform.
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

koronus

If you mean you are using PWM to drive the motor, you may find the current is varying much less
than you think, motors are inductive, smoothing out the current waveform.
you mean that I could give the smaller values of the voltage and not the maximum range?

MarkT

#13
Dec 11, 2018, 10:53 pm Last Edit: Dec 11, 2018, 10:53 pm by MarkT
No, I don't mean that at all.

I mean the current is varying less than you might think if you thought it followed the voltage waveform.
You might not need to work about timing the reads to match the PWM.
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

koronus

No, I don't mean that at all.

I mean the current is varying less than you might think if you thought it followed the voltage waveform.
You might not need to work about timing the reads to match the PWM.
so is it possible to use this method for reading current values with the L293D shield and ACS712 30A and the 12V DC motor and the difference between the stall current and the maximum current of the motor driver isn't important? If yes, please help about the circuit (actually wiring)

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