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issue on ADC sampling point

Lzhiy.1
Associate II

in fuction:

uint16_t R3_2_SetADCSampPointSectX( PWMC_Handle_t * pHdl )
/* sector number needed by GetPhaseCurrent, phase A and B are sampled which corresponds
     * to sector 4 */
    pHandle->_Super.Sector = SECTOR_4;

Phase A and B is corresponding to sector 4 or 5.

in sector 4 or 5 as the picture below,to avoid sample the phase C whose duty cycle is close to 100%,I think it should sample phase B and C instead of phase A and B.why.

0693W00000GY7lVQAT.jpg

1 REPLY 1
THA.1
Associate II

Current should be sampled when the corresponding phase is OFF, the low-side power switch is ON and current flows through the shunt resistor. In sector 4 or 5, phase C could be almost ON, duty cycle close to 100% as you mentioned, that is, the minimum required sampling time may not be allowed for phase C (but guaranteed at phase A and B).