Measured output current lower than asked value

[BL1]

Hi,

Using SPINFamily Evaluation Tool 3.2, STnucleo-f401re and IHM03A1, I'm trying to drive a 48V-9A motor.

On IHM03A1, I add 15mOhm/3W resistances in parallel of R1 and R2, so R1 and R2 value is now 13mOhm.

According to @Cristiana SCARAMEL​ recommandations, in SPINFamily interface, I choosed current mode, set run current to 9A (117.19mV) and overcurrent threshold to 13.22A (343,75mV).

But measured output current is below 8A, do you have recommandations to increase output current up to 9A ?

Thanks,

Laetitia

[Cristiana SCARAMEL]

Hi @BL​,

the set run current (117,19 mV / 13 mOhm = 9 A) does not take into account the accuracy of the value of the sense resistors and the variation of their value with the temperature.

If you increase the TVAL_RUN value to the next value (125 mV), can you appreciate the increasing of output motor current?

Did you solve the thermal protection issue?

[BL1]

Hi @Cristiana SCARAMEL​ ,

With TVAL_RUN at 125mV (=9.6A), we mesured 8.5A.

Next step is at 10,2A, but as chip limitation is 10A, will it support this value?

And yes thanks, I just answered the topic

[Cristiana SCARAMEL]

Hi @BL​,

if that's the case setting 132,81 mV (= 10.2 A) the actual motor current will be lower than the set one (from your values it seems you have an equivalent sense resistor of about 14.7 mOhm).

[BL1]

Hi @Cristiana SCARAMEL​ ,

Ok so maximum supported current is 10A measured on motor phases

[Cristiana SCARAMEL · Accepted solution]

@BL​ the maximum supported current is the actual current managed by the device (current flowing between the OUTx pins of each full-bridge)

[BL1]

@Cristiana SCARAMEL​ thank you very much !