DRV8316: current sampling issue

Hi team,

The SOA, SOB, SOC voltages are simultaneously extracted and converted into current. With a fixed electrical angle set, the cross-axis current is increased, and the corresponding duty cycle is changed accordingly, with three-phase current changing. But there is a phase where the voltage on one phase (rising trend) saturates.

SOX = Vref/2 ± gain*Iout, sum of three phase currents is theoretically 0, and SOA+SOB+SOC should theoretically be 3/2x Vref. However, the reality is that as the cross-axis current increases, the three voltages and the three currents become smaller.

The customer would like to know what might be the possible cause? Thanks.

Best Regards,

Cherry