The resulting dataflow diagram, shown on Fig. 8, can be used to build a speed control loop (Fig- ure 4-8.), in which the difference between the desired speed and the measured speed feeds a PI controller that determines the stator voltage frequency. To decrease the complexity of the con- troller, the input of the V/f law and of the space vector PWM algorithm is the absolute value of the stator voltage frequency. If the output of the PI controller is a negative number, two of the switching variables driving the power transistors of the inverter are interchanged.
Space Vector PWM data flow diagram