tailieunhanh - High Performance Driver P6b

Summarising the procedure: speed loop is held open, d-axis current command is set to rated and q-axis current command of the alternating square waveform is imposed. If the rotor time constant value in the controller is correctly set, speed response has to be triangular function. Figure is valid for the correct (rated) value of the rotor time constant and speed response is a triangular function in this case. | HIGH PERFORMANCE DRIVES 63 Summarising the procedure speed loop is held open d-axis current command is set to rated and q-axis current command of the alternating square waveform is imposed. If the rotor time constant value in the controller is correctly set speed response has to be triangular function. Figure is valid for the correct rated value of the rotor time constant and speed response is a triangular function in this case. However if the rotor time constant significantly deviates from the correct value times rated value in Fig. the speed response is unsatisfactory and far from required triangular waveform. . DESIGN OF THE CONTROL SYSTEM FOR AN INDIRECT FEED-FORWARD CURRENT-FED ROTOR FLUX ORIENTED INDUCTION MACHINE Calculation of all the necessary values required for indirect rotor flux oriented control will be illustrated using an example. Consider a three-phase four-pole star connected squirrel-cage induction machine whose parameters at 50 Hz are Rs 10 Q Rr Q XYS Q Xyr Q Xm 132 Q. Rated current and voltage equal A and 380 V. The machine is to be operated as an indirect rotor flux oriented current-fed induction machine. Current control is performed with phase current controllers so that actual and reference phase currents can be assumed to be the same for the purpose of calculation. The speed is to be controlled from zero up to its rated value using a constant rated value of rotor flux. The rated torque and inertia of the machine are Nm and kgm2 respectively. It is required to determine all the values needed for realisation of indirect rotor flux oriented control. These are the rated rotor flux the rated stator d-axis and q-axis currents all in terms of rms and peak values and the value of the slip speed for rated torque operation. Next since the scheme under consideration contains only the speed controller it is necessary to determine the parameters of the speed PI controller. This is done using the so-called .