Analysis of current source induction motor drive fed from photovoltaic energy source

The transient and steady-state analysis of an induction motor fed from a photovoltaic energy source through a current-source inverter is presented. It is shown that the steady-state and dynamic behaviors of the motor differ considerably from the case in which it is fed from a perfect current source. In particular, the steady-state capability of the motor is limited by the chopping ratio of the DC-DC converter and the switching frequency of the current-source inverter. Analysis of the small signal perturbation equations of the system shows that the system is lightly damped for operating voltages of the array that are less than that of the array voltage corresponding to array maximum output power. For some values of array voltage, it has a nonminimum phase characteristic due to the nonlinear relationship between the array voltage and current. This nonminimum phase characteristic adds an inherent difficulty to the design of a robust closed-loop feedback controller for the motor drive system