SPRUHJ1I January 2013 – October 2021 TMS320F2802-Q1 , TMS320F28026-Q1 , TMS320F28026F , TMS320F28027-Q1 , TMS320F28027F , TMS320F28027F-Q1 , TMS320F28052-Q1 , TMS320F28052F , TMS320F28052F-Q1 , TMS320F28052M , TMS320F28052M-Q1 , TMS320F28054-Q1 , TMS320F28054F , TMS320F28054F-Q1 , TMS320F28054M , TMS320F28054M-Q1 , TMS320F2806-Q1 , TMS320F28062-Q1 , TMS320F28062F , TMS320F28062F-Q1 , TMS320F28068F , TMS320F28068M , TMS320F28069-Q1 , TMS320F28069F , TMS320F28069F-Q1 , TMS320F28069M , TMS320F28069M-Q1
Once the rated flux is measured the stator inductance identification process starts (Figure 7-22).
In order to identify the stator inductance of the PMSM motor, the algorithm injects a current into the D-axis, also known as ID. The current must be negative, and it is set in user.h. As a general rule, this current should be between 10% and 20% of the rated current of the motor, negative in sign. The following value is set for a 4 A motor, hence the current used to identify the stator inductance was set to -0.5 A as shown:
#define USER_MOTOR_IND_EST_CURRENT (-0.5)
And the time spent for stator inductance identification is configured in user.c as follows:
pUserParams->LsWaitTime[EST_Ls_State_Init] = (uint_least32_t)( 3.0*USER_EST_FREQ_Hz);
pUserParams->LsWaitTime[EST_Ls_State_Fine] = (uint_least32_t)(30.0*USER_EST_FREQ_Hz);
Figure 7-23 shows the time it takes to run the inductance identification state. It also shows the current amplitude injected. Although we set the current to be -0.5 A this current is injected into the D-axis, so it will be noticed in the phase current waveform as an amplitude of 0.5 A plus the current needed to keep the load moving. Since it is required to move all the mechanical load from the shaft, the current amplitude will be close to 0.5 A as shown.