I think it will be hard to isolate the inductance of one coil due to the mutual coupling effects between coils. I think the best option would be to do a full 3D electromagnetic simulation using FastHenry or Ansys HFSS would be a good idea.

Thanks for your answer Mr. Desi.

But I want to measure inductance or flux with experiment, and analytical or numerical results aren't important as experimental result as on my research.

I am not familiar with this specific motor type, but If this is a system with 6 coils then maybe you could measure the 6x6 impedance matrix Z. In order to do this you apply a current to the first coil, while the other coils are open circuits and measure the voltages induced accross each coil. You do this 6 times, one for each coil and you get the complete matrix Z. You can find this procedure here:

https://www.researchgate.net/publication/3266136_A_one-step_finite_element_formulation_for_the_modeling_of_singleand_double-circuit_transmission_lines?ev=prf_pub

Article A one-step finite element formulation for the modeling of si...

Thanks for your answer Mr. D. Triantafyllidis.

But, in my purpose the motor must be on - line. Your method has been done with pulse injection in one coil and measure voltage on the other coils, however this is an off- line method that isn't my goal.

I'm sorry, but I do not understand what exactly your goal is. You wish to create a model of the motor, while the motor is running? This could be possible, but the model will be load-depentant. You could apply voltage to each pair of coils and measure the current response. In before you must measure the dc resistance of the coils with an ohm-meter. Now, you should be able to calculate a model for each coil. But, if you change the load of the motor the current response will change, so this will be a very limited model... Please, keep in mind that the effective impedance of motors depends on the axis load, so there is no "one" magic number for every motor.

I would recommend that you look at this paper. It may provide many useful pointers.

Debiprasad Panda; Ramanarayanan, V., "Mutual Coupling and Its Effect on Steady-State Performance and Position Estimation of Even and Odd Number Phase Switched Reluctance Motor Drive," Magnetics, IEEE Transactions on , vol.43, no.8, pp.3445,3456, Aug. 2007

Since you are going to measure the inductance while the motor is running, you can do 1 thing - Measure the total inductance of all coils and then divide it by the number of coils, to get inductance of one coil, as they are connected in series. You can use a simple LCR meter for the purpose.