UM0324 datasheet(64/105 Pages) STMICROELECTRONICS

64 / 105 page

Library functions

UM0324

64/105

There are two different field weakening operation regions (see Figure 39):

●

the constant power region, where rotor flux is decreased inversely with the speed

(considering the influence of the voltage drop across Lls) while slip frequency increases

until breakdown value;

●

the constant power·speed region, where rotor flux is decreased, but keeping the slip

frequency fixed at breakdown value.

Figure 39.

Torque vs. speed characteristic curve

In order to help you select the most suitable values of flux reference and torque saturation

(as needed by the CalcRotFlxSlipFreq function), a spreadsheet is available, to be filled out

with the following system parameters:

●

Mains AC voltage, rms, Volt (cell B1, Volt);

●

motor rated current, peak amplitude, (cell B2, Ampere); as said before, this data is to

be matched with inverter current rating;

●

motor rated magnetizing current, peak amplitude, (cell B3, Ampere);

●

magnetizing inductance Lm, (cell B4, Henry);

●

leakage inductance Lls ( Llr), (cell B5, Henry);

●

stator resistance rs, (cell B6, Ohm)

●

rotor resistance rr , (cell B7, Ohm);

●

maximum measurable current Imax, peak amplitude, (cell B8, Ampere).

UM0324 Datasheet(PDF) 64 Page - STMicroelectronics