Question on Motor Parameter Measurement Using X-NUCLEO-IHM16M1 (1.5A RMS Limit)

[pelino]

I am currently evaluating the X-NUCLEO-IHM16M1 motor control expansion board and would like to ask whether it is suitable for measuring the electrical parameters of the motor described below.

The motor specifications (translated from the datasheet image) are as follows:

• Rated Voltage: DC 24 V

• Rated Torque: 0.063 N·m

• Rated Speed: 4,000 RPM ±10%

• Rated Current: < 1.7 A

• Rated Output Power: 26 W

• No-load Speed: 5,000 RPM ±10%

• No-load Current: < 0.3 A

• Number of Poles / Phases: 8 poles / 3 phases

• Insulation Class: Class B

• Operating Temperature: –10 °C to 40 °C

According to the X-NUCLEO-IHM16M1 documentation, the maximum output current is specified as 1.5 A RMS.

My question is:

• Is it possible to use the Motor Profiler tool in STM32 Motor Control Workbench to measure Rs, Ld/Lq, and Ke for this motor when using the X-NUCLEO-IHM16M1, considering its 1.5 A RMS current limitation?

Any guidance or recommended measurement limitations would be greatly appreciated.

Thank you very much for your support.

Best regards,

Pelino

[GMA]

Hello @pelino,

Refer to the "4.2 Current sensing" chapter of the X-NUCLEO-IHM16M1 user manual document.
You can profile your motor with an Imax value and modify it in the resulting JSON file to set the actual maximum current of the motor.

[pelino]

According to the documentation, changing the shunt resistor from 330 mΩ to 100 mΩ increases the measurable current range from 1 A to 1.5 A.

However, the datasheet specifies the output current as 1.5 A RMS.
Does this mean that the device can actually reach 1.5 A RMS only when the shunt resistor is changed, and that with the default 330 mΩ shunt resistor the usable current range is limited to around 1 A?

I have also been informed that when changing the shunt resistor from 330 mΩ to 100 mΩ, the current-sense gain must be adjusted accordingly.

How should the gain be modified in this case?
Is there a recommended calculation method or guideline for setting the gain when the shunt resistance is reduced?

Additionally, if the shunt resistor is changed from 330 mΩ to 50 mΩ, would it be possible to drive a motor operating at approximately 2 A, and still perform motor parameter identification
(Rs, Ld/Lq, Ke, etc.) using Motor Profiler?

Finally, I would like to understand why the current range is limited to 1 A when using a 330 mΩ shunt resistor.
Is this limitation due to the maximum allowable shunt voltage, ADC input range, or current-sense amplifier saturation, rather than the output stage capability itself?

[GMA]

Hello @pelino,

As mentioned in the documentation: The mounted resistor of 330 mΩ allows an up to 1 A reading without distortion. It is not mentioned that is an absolute maximum value.

Same this with RMS value compared to absolute maximum value.

[pelino]

In MCSDK, the current can be detected in the Current Sense block as shown below, and the maximum value is indicated as 3.09 A.

However, I do not clearly understand why the datasheet specifies the current as 1 A.