Steval-esc002v1 bulk capacitors.

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Hi what is the rationale to dimension the capacity of the to two bulk capacitors C22,C21?

There are a lot of ESC COTS that havent these big caps.

Thanks

Motor control hardware

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Dario CUCCHIBest answer

ST Employee

Hi @FRagg.1 ,

The capacitors C21 and C22 are used to provide current during variations of the current in the motor.

Without capacitors C21 and C22 you can have drops on the bus voltage but also overvoltage when the energy stored in the motor comes back to the bus supply.

Drops of the supply down to the UVLO protection of the device can turn-off the power stage.

Overvoltage can damage the battery pack or the device.

In general, performance of the ESC are better if the bus voltage is more stable.

C21 and C22 are chosen in order to cover a wide range of motors and target currents.

If you want to decrease these capacitor to save space, I can suggest to do some tests with you specific motor at the target current and see which is the acceptable oscillation on the voltage supply, according to your application requirements.

I hope this can help. Have a good day !