Voltage shrinkage at higher speed around 0.3 of rated of speed and i'm computing line to line voltage from PWM which i captured using logic analyzer.

Hey I'm controlling pmsm motor using FOC , i observed at that higher speed the duty cycle as well as line to line voltage is shriniking what can be the possible reason behind that ?

the pink region is sinousodul waveforms of line to line voltage as you can see that at higher speed it shrinked.

[Rosa]

The shrinking line-to-line voltage (pink area) at higher speeds is expected behavior in PMSM FOC systems.

It typically means the motor has entered the field-weakening region, where the controller intentionally reduces the effective flux to stay within the DC-bus voltage limit and maintain safe inverter operation.

[akshay]

Hii Rosa,

It can't be field weakening as I mentioned it is just 0.3 of rated speed which is below that base speed i believe ( i'm not exactly sure how to calculate that i'm assuming it is 50 percent of rated speed ) as we apply field weakening when it pass the base speed region by giving negative id current and i plotted my pi controller output for vq voltage which comes like this w.r.t speed and you can see vd is not going that negative in this region.

and as i'm operating at 24v , max vq which i can go before field weakning is Vdc/root(3) which is around 13V but here we hardly crossing 6V.