The three-phase PWM rectifier is widely used in a wide diversity of applications in recent years. These rectifiers have many advantages such as bi-directional power flow, low harmonic distortion of line current, unity power factor, control of DC-link voltage. When considering all these features, the three-phase PWM rectifier is the most important part in PETs. In this study, three-phase voltage source PWM rectifier has used for PET system. The dc bus voltage in the three-phase PWM rectifier is generally controlled by a PI controller (Blasko and Kaura, 1997). But, it is difficult to find the parameters of the PI controller. So, many researchers are focused on this problem and they have been proposed many methods (Djerioui et al., 2012; Monfared et al., 2010; Acikgoz and Sekkeli, 2014). The three- phase PWM rectifier structure is as shown in Fig.2.