Analysis of isolated self-excited induction generator feeding a rectifier load

Both transient and steady-state performances of an isolated self-excited induction generator (SEIG) supplying a rectifier load are presented. A hybrid model based on abc and q-d induction machine models is employed to describe the dynamic equations of the studied system to improve simulation results. The stator voltage equations of the SEIG studied are described by a three-phase abc model which can be directly interfaced to the rectifier circuit. The rotor variables are properly transformed into q-d co-ordinates and the elements in the rotor inductance matrix are time-invariant. The controlled rectifiers, including both semi and full converters, are modelled by using three switching functions, which are designated to be tristate switches for each converter leg. Combining the SEIG model proposed with the rectifier model, the transient characteristics of the SEIG under various loading conditions are simulated and evaluated. The FFT algorithm is used to analyse the voltage and current harmonic content under steady-state conditions. Experimental results obtained from a laboratory 1.1 kW induction machine driven by a DC motor are also performed to confirm the effectiveness of the proposed approach.