ANALYSIS OF A PWM INVERTER CONTROLLED SINGLE PHASE INDUCTION GENERATOR

Abstract

The use of induction machine is widely accepted application as motor in industrial drive systems. And as generator, it is widely used in wind power generation, small hydro and micro hydro stations. The induction machine is simple, reliable, cheap, and lightweight and requires very little maintenance. Selection of single-phase induction generator is the better option for small power generation (below 20 kW) for remote and rural villages. If the machine used as motor or generator, it require reactive power to establish the magnetic flux in the machine. If the machine is connected in parallel with grid, machine will take the reactive power from the grid. In this present dissertation work, both the motor and generator have been simulated. The motor model has been simulated for three different modes of operation, which are as split-phase motor, capacitor start motor and capacitor start and run motor. In these three connections, the characteristics like starting torque, auxiliary and main winding fluxes, currents flowing in the two winding, electromagnetic torque developed by motor to counter the load torque have been observed. Advantages of starting and running capacitors are observed. The power factor is improved by adding the running capacitor. The single-phase induction generator has been simulated with load connected in series and parallel to load capacitor. The other capacitor is connected in auxiliary winding. Voltage build-up, steady state has been observed. Finally, PWM inverter controlled Single-phase induction generator has been simulated. Whenever single-phase induction generators are working as stand-alone case voltage and frequency are depends on the excitation of the system and on input power respectively. To keep the voltage constant, the reactive power required by machine be supplied. For this purpose PWM inverter is connected in the auxiliary winding to supply the reactive power required by load and induction generator. Simulation results of induction generator connected to resistive load and R_L load (high power factor and low power factor loads) have been presented.