Analysis of the response of L and LCL filters in controlled rectifiers used in wind generator systems with permanent magnet synchronous generators

This paper presents the comparative study of the response of a Controlled Rectifier in a wind power system with a synchronous permanent magnet generator when a L filter and a LCL filter are used between the generator and the rectifier. The Rectifier is modeled considering an L filter and an LCL filter. In addition, the PWM switch model is used to linearize the controlled rectifier and obtain the equivalent circuit at the operating point and the equivalent circuit at small signal. From the equivalent small signal circuit, the transfer functions of the rectifier are obtained. These transfer functions are used to implement rectifier control loops. One of the main advantages of using the switch model in the rectifier is that it allows the rectifier to be simulated without the control loops. This allows a comparison of the variables of the rectifier with different filter types, in this case, a L filter and a LCL filter. The Duty cycles are calculated from the operating point circuit. In addition, the rectifier is simulated in open loop with a sinusoidal modulation. This in order to analyze which filter is better in terms of Total Harmonic Distortion and efficiency. From the results obtained from the simulation, the rectifier with the L filter has a better performance in the total harmonic distortion in current and efficiency (THDi=4.85%, FP=99.8729% y Eff=99.99%) compared to the rectifier with the LCL filter (THDi=7.91%, FP=97.914% y Eff=93.06%).