## 3 Results and Discussion
### Equivalent Circuit Parameters of Field Test  
This paper built a practical set of equipment based on personal computers by using personal computers with peripheral equipment, data acquisition systems and data output modules and appropriate software programs to complete a real-time online monitoring system. The complete  
\begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Polynomial Fractional Coefficients**} & \multicolumn{3}{c}{**Induction Machine Parameters (\(\Omega\))**} \\ \cline{2-4}  & \(\mathbf{\eta=0.95}\) & \(\mathbf{\eta=1.00}\) & \(\mathbf{\eta=1.05}\) \\ \hline \(\alpha_{2}=64.6\) & \(X_{m}=280.7\) & \(X_{m}=280.0\) & \(X_{m}=295.1\) \\ \(\beta_{0}=38.0\) & \(X_{s}=24.3\) & \(X_{s}=17.0\) & \(X_{s}=9.88\) \\ \(\beta_{1}=6912.0\) & \(X_{r}=9.0\) & \(X_{r}=17.0\) & \(X_{r}=25.1\) \\ \(\beta_{2}=24,548.2\) & \(R_{s}=38.0\) & \(R_{s}=38.0\) & \(R_{s}=38.0\) \\ \(\beta_{3}=305.0\) & \(R_{r}=11.4\) & \(R_{r}=12.0\) & \(R_{r}=12.6\) \\ \(\beta_{4}=21,352.1\) & & & \\ \hline \hline \end{tabular}
\end{table}
Table 1: Comparison of the analysis results.  
Figure 4: Polynomial fractional analysis results. (**a**) Input resistance comparison; (**b**) Input reactance comparison.  
hardware architecture consisted of an induction machine, sensors, analog-to-digital converters, control circuitry, a computer, and setup as shown in Figure 5. The induction machine was three-phase, four-pole, 1/2 HP, 60 Hz. The voltage and current signals were obtained from the voltage probe and the current transformer, respectively, and the rotor speed was obtained through the frequency-to-voltage converter, then converted into the deuterium signal by the analog-to-digital converter and stored in the computer. The analog-to-digital converter was a National Instruments 6036E data acquisition device. The sample rate was set at 1024 samples/s, with the number of samples set at 922 and a sample period of 0.9 s. The power control circuit was switched by an electromagnetic switch, while independent on/off control of the device could be performed on command. The host computer was used as a monitoring device using National Instruments LabVIEW as a human machine interface.  
The simulated slip-impedance characteristic curve is shown in Figure 6. It was found that these coefficients were very high-fitting to the experimental one and had quite satisfactory results. The simulated slip-impedance characteristic curve with induction machine parameters from IEEE 112 test is also shown in Figure 6. Some obvious errors were found, which arose from unpredictable nonlinear components and other disturbances; however, this method still obtained the largest approximation.  
Figure 5: Schematic diagram of the field test.  
Figure 6: Parameter estimation results in the field test. (**a**) Input resistance comparison; (**b**) Input reactance comparison.  
Due to the saturation phenomenon in the induction machine, some of the parameters appeared nonlinear as the operating point changed. For the saturation phenomenon, generally speaking, the nonlinear inductance represents the magnetic saturation effect, and the inductance value at saturation is smaller than that at unsaturation, and under different currents, different inductance values are used. This will also complicate the equivalent circuit; however, since the estimated curve was very close to the actual curve in this example, magnetic saturation was not considered.