Robust Digital Control for Interleaved PFC Boost Converters Using an Approximate 2DOF Current Controller
In recent years, improving power factor and reducing harmonics distortion of power supply used in electrical instruments are needed. In general, a current conduction mode boost converter is used for an active PFC (Power Factor Correction). Especially, an interleaved PFC boost converter is used to make a size compact, make an efficiency high and make a noise low. In this paper, the design method using an Approximate 2-degree-of-freedom (A2DOF) controller for a current control system and using a digital PI controller for a voltage control system is proposed. The digital PI controller is designed to enlarge the control bandwidth of the voltage control system. By this design method, the power factor can be improved more, the input current distortion can be made smaller and the output voltage regulation can also be suppressed smaller. These controllers are actually implemented on a micro- processor and are connected to the PFC converter. Experimental studies demonstrate that the combination of the digital A2DOF current controller and the digital PI voltage controller are effective. And it is shown that this combination is better than the one of usual phase lead-lag compensation controllers in the power factor, the input current distortion and the output voltage regulation.
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