## Appendix A \begin{table}
\begin{tabular}{c c} \hline \hline
**Symbols** & **Definition** \\ \hline \(u_{\text{a}}\) & Phase A bridge leg terminal voltage \\ \(u_{\text{b}}\) & Phase B bridge leg terminal voltage \\ \(u_{\text{c}}\) & Phase C bridge leg terminal voltage \\ \(u_{\text{n}}\) & Phase N bridge leg terminal voltage \\ \(i_{\text{a}}\) & Phase A filter inductor current \\ \(i_{\text{b}}\) & Phase B filter inductor current \\ \(i_{\text{c}}\) & Phase C filter inductor current \\ \(i_{\text{n}}\) & Phase N filter inductor current \\ \(u_{\text{AO}}\) & Phase A output voltage of the matrix converter \\ \(u_{\text{BO}}\) & Phase B output voltage of the matrix converter \\ \(u_{\text{CO}}\) & Phase C output voltage of the matrix converter \\ \(U_{\text{dc}}\) & Input DC voltage of high-frequency link \\  & three-phase four-leg matrix converter \\ \(U_{\text{d}}\) & Input voltage of ordinary three-phase four-leg inverter \\ \(M(t)\) & Function of time \\ \(\theta\) & Phase angle \\ \(\omega\) & Angular velocity \\ \(L\) & Three-phase filter inductor \\ \(L_{\text{n}}\) & Neutral line inductor \\ \(C\) & Filter capacitor \\ \(k\) & Dynamic response adjustment factor \\ T & high frequency transformer \\ \(u_{\text{ca}}\) & sawtooth wave \\ \(u_{\text{sa}}\) & sinusoidal modulation wave \\ \(u_{\text{SPWM}}\) & Positive SPWM pulse \\ \(\overline{i}_{\text{SPWM}}\) & Negative SPWM pulse \\ \(u_{1}\) & Positive high frequency square wave \\ \(u_{2}\) & Negative high frequency square wave \\ \(u_{\text{Stia}}\) & Four driving signals of phase A bridge leg \\ VD & Diode in nonlinear circuits \\ \(C_{\text{a}}\) & Capacitor in nonlinear circuits \\ \hline \hline \end{tabular}
\end{table} 
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