Some aspects of inverter-fed induction motors

A set of equations is obtained in terms of 4 machine parameters, stator voltages and currents and transformed rotor currents. The transformation is extended to include non-quadrature stator windings. A solution procedure in terms of a transition matrix is obtained for any operating condition where the supply voltage waveform is piece-wise constant. Steady state current and torque waveforms can be evaluated as well as constant speed transients. General expressions are obtained for the system matrix eigenvalues. A transition matrix determination using the eigenvalues and system matrix is developed and this shows how the eigenvalues influence the "electrical" modes. The solution procedure derived is in principle an exact one. An illustrative computer program to implement the required calculations for any given motor parameters is included and computed waveforms are compared with experimental results. The matrix approach based on the transition matrix is extended to the case where applied voltage waveforms are parts of sine waves. A homogeneous equation form simplifying the solution structure is obtained by defining pseudo s tate variables.