Yesterday evening I read the ST documentation of their V2.0 library for ACIM motor. FOC principle is the same as PMAC, the only diffrence comes from the software block which manage the rotor flux position : for PMAC the rotor flux position can be established with hall, encoder or estimated with a sensorless algorithm. In ACIM, the rotor flux position is
estimated with a software block which use the measured rotor speed, the measured Iqs and Ids (from measured phase current and Clarke+Park tranformation), and
motor characteristics.
Thus it seems that for ACIM it's very important to have a perfect knowledge of motor characteristics. For example, the IFOC ST library for ACIM needs :
Quote:
#define ROTOR_TIME_CONSTANT
Define here (in μs), the rotor open circuit time constant of the motor τ r:
τ r = Lr/rr = (Lm + Llr) / rr
#define POLE_PAIR_NUM
Define here the stator winding pole pair number;
#define RATED_FREQ
Define here (in 0.1Hz) the right-hand boundary of the constant torque region (see
Figure 6): in that region we have rated current, rated flux, rated torque, rated power
#define NOMINAL_FLUX
Define here the required magnetizing current im (positive, peak value), expressed in q1.15 format
#define NOMINAL_TORQUE
Defines the maximum value for the motor’s rated torque expressed in q1.15 format.
#define FLUX_REFERENCE_TABLE: this look-up table (256 signed 16-bit values)
provides reference values of current ids (expressed in q1.15 format), according to
increasing stator frequencies (see Section 4.5.4 on page 70);
TORQUE_REFERENCE_TABLE: this look-up table (256 signed 16-bit values) provides saturation values of current iqs (expressed in q1.15 format), according to increasing stator frequencies (see Section 4.5.4 on page 70).
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