# Current Harmonic Suppression Algorithm for Asymmetric Dual Three-Phase PMSM
## 6 Experimental Verification
\begin{table}
\begin{tabular}{c c} \hline \hline
**Parameter, Unit** & **Value** \\ \hline Inductance value \(\mathrm{d}\), \(\mathrm{H}\) & \(8\times 10^{-5}\) \\ Inductance value \(\mathrm{q}\), \(\mathrm{H}\) & \(8\times 10^{-5}\) \\ Leakage inductance value, \(\mathrm{H}\) & \(7.2\times 10^{-5}\) \\ Flux, Wb & \(5\times 10^{-3}\) \\ Pole pairs & 4 \\ Resistance, \(\Omega\) & \(1.13\times 10^{-2}\) \\ Rated torque, N*m & \(3\pm 2.5\%\) \\ Rated speed, rpm & 1860 \\ Rated phase current, A & 50 \\ Rated power, W & 500 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Machine parameters. \begin{table}
\begin{tabular}{c c} \hline \hline
**Parameter, Unit** & **Value** \\ \hline DC-link voltage, V & 12 \\ Turn-on delay, ns & 10 \\ Turn-off delay, ns & 22 \\ Saturation vol. V & 0.95 \\ Diode forward vol. V & 0.9 \\ Dead time, \(\mathrm{\mu s}\) & 1 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Specifications of voltage source inverters (VSI). Figure 17 shows the experimental results after adopting the proposed resonant controller, which is equivalent to Case 3. The reference voltages are synthesized based on the proposed SVPWM method, as illustrated in Section 5. The waveforms of phase currents have been improved. The fifth and seventh current harmonics are significantly reduced. The THDs of the phase A current value are reduced to 3.52% and 3.25% respectively with the proposed resonant controller, as shown in Figure 18.  
Figure 19 depicts the experimental results after adopting both the proposed feedforward voltage compensation and resonant controller, which is equivalent to Case 4. The reference voltages are synthesized based on the proposed SVPWM method illustrated in Section 5. The waveforms of phase currents have been improved a lot, while the fifth and seventh current harmonics are significantly reduced. The THDs of the phase A current are reduced to 2.97% and 2.65% respectively with the proposed combination method, as shown in Figure 20. The THDs are the smallest among the four above-mentioned cases. Figure 14: Total harmonic distortions (THDs) of the phase A current without adopting voltage compensation and resonant controller in \(x\)-\(y\) subspace, (**a**) speed is maintained at 500 rpm and (**b**) speed is maintained at 1000 rpm. Figure 13: Phase A and D currents without adopting voltage compensation and resonant controller in the \(x\)-\(y\) subspace, (**a**) speed is maintained at 500 rpm and (**b**) speed is maintained at 1000 rpm. Figure 16: THDs of the phase A current after adopting the proposed feedforward voltage compensation method only, (**a**) speed is maintained at 500 rpm, and (**b**) speed is maintained at 1000 rpm. Figure 17: Phase A and D currents after adopting the proposed resonant controller only, (**a**) speed is maintained at 500 rpm, and (**b**) speed is maintained at 1000 rpm. Figure 15: Phase A and D currents after adopting the proposed feedforward voltage compensation method only, (**a**) speed is maintained at 500 rpm, and (**b**) speed is maintained at 1000 rpm. Figure 19: Phase A and D currents after adopting both feedforward voltage compensation and a resonant controller, (**a**) speed is maintained at 500 rpm, and (**b**) speed is maintained at 1000 rpm. Figure 20: THDs of the phase A current after adopting both feedforward voltage compensation and a resonant controller, (**a**) speed is maintained at 500 rpm and (**b**) speed is maintained at 1000 rpm. In order to facilitate the analysis, Table 3 shows the comparison of the THDs for four different cases under 500 rpm where the phase currents are 20 A and 35 A, respectively. The switching frequency is 10 kHz with 1 \(\mu\)s of dead time. It can be seen that the THD when the phase current is 35 A is smaller than the THD when the phase current is 20 A, because the fundamental component is smaller when the phase current is 20 A.