STARTING TRANSIENTS IN SLIP ENERGY RECOVERY INDUCTION-MOTOR DRIVES .1. FORMULATION AND MODELING

A detailed study of the rotor phenomena including the rectifier commutation angle and inverter harmonics is facilitated by the use of the actual rotor conduction sequence variables instead of transformed variables that are used in most other IM drive systems. The starting transients of slip energy recovery IM drives comprising three stages are presented here; (a) the starting from zero speed with a starting resistor connected to the output of the rotor rectifier; (b) a transition period in which the inverter is connected through a dc link; (c) the final period when the starting resistor is disconnected from the rectifier output. This paper uses a hybrid model which retains the actual rotor phase variables but transforms those of the stator only, to examine the starting transients of a slip energy recovery drive system. The model has the advantage of not having a variable inductance matrix. Hence the computation time is substantially reduced.