Umit45
Junior Member level 1
Hi everyone!
I am trying to find the parameters of a surface mounted PM synchronous motor using the application note AN4680 (PMSM Electrical Parameters Measurement) and had some queries regarding it.
The Ld and Lq inductance measurement process is mentioned as follows
I wanted to know how does step 1 in both the cases ensure the alignment of the rotor with d and q axis respectively. I tried to work it out mathematically, for d axis inductance measurement, if we connect phase A to +5V and ground phase B and C,
Vd=(2/3)*Va*cos(theta),
(from Park's transformation)
now if we assume theta to be zero, only then will Vq will be zero.
Similarly, if we connect phase B to +5V, ground C and open phase A, how is it concluded that we have aligned the rotor in the q -axis.
Secondly,during Lq (q axis inductance measurement) measurement it is mentioned that the current response creates a torque in the q-axis and the motor may rotate but I did not find any rotation in the rotor during both Ld and Lq measurement.
Could you please point out if I missing any point in the document.
I appreciate your help,
Thanks,View attachment Freescale AN4680.pdf
I am trying to find the parameters of a surface mounted PM synchronous motor using the application note AN4680 (PMSM Electrical Parameters Measurement) and had some queries regarding it.
The Ld and Lq inductance measurement process is mentioned as follows
I wanted to know how does step 1 in both the cases ensure the alignment of the rotor with d and q axis respectively. I tried to work it out mathematically, for d axis inductance measurement, if we connect phase A to +5V and ground phase B and C,
Vd=(2/3)*Va*cos(theta),
(from Park's transformation)
now if we assume theta to be zero, only then will Vq will be zero.
Similarly, if we connect phase B to +5V, ground C and open phase A, how is it concluded that we have aligned the rotor in the q -axis.
Secondly,during Lq (q axis inductance measurement) measurement it is mentioned that the current response creates a torque in the q-axis and the motor may rotate but I did not find any rotation in the rotor during both Ld and Lq measurement.
Could you please point out if I missing any point in the document.
I appreciate your help,
Thanks,View attachment Freescale AN4680.pdf
