The real time estimation of input and output quantities of three-phase induction motors by sensing the instantaneous stator voltages and currents has been presented. The estimated input quantities of the induction motor are the rms voltage, rms current, active power, reactive power, apparent power and power factor. The estimated output quantities include the rotor speed, electromagnetic torque, output power and efficiency.

The proposed algorithms used for the estimation of input and output quantities have been modeled and simulated in the MATLAB environment using the SIMULINK toolbox. The use of SIMULINK software along with the Power System Block Set toolbox has reduced the length and complexity of programming. The graphical user interface of the SIMULINK software makes it very user friendly.

The real time implementation of the algorithms for estimating the input and output quantities of the induction motor has been carried out in the LabVIEW RT enviornment using the National Instruments RT series DAQ device (PXI-7030/6040E). LabVIEW is based on the graphical programming language G, which is fully integrated for communication with the National Instruments plug-in data acquisition (DAQ) boards. LabVIEW RT can be used to build applications involving data acquisition, data processing, storage, analysis and program development. Hall-effect voltage and current sensors have been used to sense the stator voltages and currents of the induction motor respectively. Data acquisition has been carried out by the RT series plug-in DAQ device present inside the host computer. The analog input signals from the sensors are interfaced to the DAQ device through the I/O interfacing board SCB-68. The estimation algorithms have been configured as virtual instruments (VIs) using the labVIEW software. The algorithms for the estimation of input and output quantities have been validated by measurement of the actual input and output quantities of the induction motor. Thus, the real time estimation of input and output quantities of induction motor has been achieved.