Reaserch On Stability Issues Of Matrix Converter Fed Permanent Magnet Synchronous Motor Drive

Matrix Converter has received a lot of attention from researchers due to some advantages over traditional rectifer-inverter type power converters, such as small reactive components, reduced harmonic injection to the power grid, reversible energy transforming, compact structure and high power density. As a result, the promising prospect on development of matrix converter has been widely noticed. An unstable oscillation emerges when output power of matrix converter exceeds some upper limit. The oscillation increases harmonics and results a breaking hazard to the power devices of matrix converter, which makes research on the stability issues of matrix converter very important to its practical application.The stability issues on matrix converter are studied by considering its nonlinear dynamic characteristics. The essential cause of the unstable oscillation is analyzed for an electrical drive fed by three phase to three phase matrix converter in a view of nonlinear dynamic theory, and behavior of the system close to the upper limit of output power is investigated. A fundamental-harmonic model is derived in rotating dq coordinate system. The model is linearized at the equilibrium point, and the characteristic root loci are acquired by solving the Jacobian matrix numerically. The Hopf bifurcation nature of unstable oscillation of matrix converter is concluded by checking Poincaré-Andronov-Hopf theorem, with output power as its bifurcation parameter. Behavior of the system near the critical power is examined by simulation and experiment. Simulation results coincide with experimental results very well in the low frequency region, which proves the validity of the fundamental-harmonic model.Chaotic dynamic characteristics of the fundamental-harmonic model of matrix converter are studied. Dimensionless equations of the system are derived and analyzed by simulation. The trajectories from simulation show some typical chaotic characteristics such as the extreme sensitivity to initial values and self-similarity. Fast Fourier transform (FFT) of the simulation results is done to analyze its characteristic in frequency domain, and the Lyapunov Exponents of the system are calculated. The analysis and calculation results verify chaotic behavior of the studied matrix converter drive system qualitatively and quantitatively respectively. Experimental research is also developed. The trajectories drawn by using experimental data express similar behavior with simulation results. It expresses a possible, but not definite, chaos in the electrical drive system fed by matrix converter.An extended stability research on permanent magnet synchronous motor(PMSM) drive system fed by matrix converter(MC-PMSM) is launched, and the stable operation region variation against system parameters are analyzed. The input-output relationship of matrix converter is expressed simply using the"duty-cycle space-vector". The differential equations of the system, including both power stage and control stage, are derived with the variables in rotating coordinates, and a small-signal equation is obtained. Then stable region and its boundary can be determined according to a Lyapunov-type stability analysis. Power characteristics of the stable boundary is presented and analyzed, and the influence of the parameters of input and digital filters on stable region is discussed. Numerical calculation results show that the output power limit of matrix converter varies with operating points of the PMSM, and is not constant. In addition, the influence of the parameters on stability appears to follow some rules. The modeling and analyzing is verified by computer simulations. Experimental research is carried out to give qualitative verification. The research of this paper can be used as a guide for stability design and parameters selection for MC-PMSM systems.