4. Simulation Model
A MATLAB/Simulink simulation analysis for battery charging is presented here to demonstrate the system
performance in different operating conditions. The operating conditions are based on the change in wind velocity,
wind velocity of 25m/s is taken here for analysis. A 5HP slip ring induction machine is taken as DFIG, connected to
variable speed wind turbine. The rated capacity of the battery is taken as 10Ah. The initial battery voltage is taken
as 45.8V.
In open loop model shown in Fig. 3 the output of DFIG is connected to a diode bridge rectifier through RL filter.
The output of diode rectifier is connected to the input terminal of the battery through DC link. In open loop model
there is no control algorithm applied to control the DC link voltage. In this case battery may over charge, depending
on the wind speed. In closed loop model, a control algorithm using PI controllers is used to maintain the DC link
voltage constant. A buck converter is used in order to control the DC link voltage. The voltage available for