Noise in current sensing as low ampere

[JPate.7]

Hello sir,

we designed our own board based on EVSPIN32F0602S1. We changed shunt value to 0.125 ohm for 40A. But when we start motor, we get noise in startup parameter. Motor work fine on load. But in no load motor spin and stop working. We get problem for reading motor current in open loop and low ampere. So we have to change any other component near op-amp or comparator ?

[Cristiana SCARAMEL]

Hello @Community member​,

the EVSPIN32F0602S1 board have an overcurrent protection set to 8.5 Apeak.

If you want to manage higher current surely you need to increase the overcurrent threshold.

Refer to the dedicated section 6.3 Overcurrent detection and current sensing measurement in the user manual UM2629 for the proper components sizing.

The board mount two 0.1 ohm shunt resistors in parallel (2 W rating), so the resulting single shunt resistor is 0.05 ohm.

If you mount 2x 0.125 ohm you must consider that the power dissipation on the shunt is:

--> Rshunt x I^2 = 0.0625 x 40^2 = 100W!

The first step is to check these components.

Then shares more details about your applications, for example:

• Main supply ratings
• driving method: FOC or 6-step sensored, or 6-step sensorless
• FW used
• any others useful information.