An Improved and Digital Current Control Strategy for One Cycle Control Based Three-phase Boost Rectifier under Unbalanced System

Abstract

A new tendency in development of power supplies is Power Factor Corrected (PFC) rectifiers which can work without harmonic pollution to source. Literature[1] proposes a new one-cycle controlled three-phase boost PFC rectifier which has many advantages[2]. But the rectifier is analog based and difficult to control input currents flexibly under unbalanced source. This paper improves the control strategy and introduces a new general current control equation which can control the input currents flexibly under unbalanced source. By selecting different current control parameters (CCP), we can achieve four control goals: (1) the same method as that in literature [1]; (2) input currents fully in-phase with its own input voltages; (3) constant input power; (4)balanced input currents. Under unbalanced input voltages, in the case of constant input power of controller, a new control strategy is presented to achieve minimum input line loss by adjusting the input currents. Experimental results are presented to verify the theoretical analyses. The system is implemented in full digital, and one Texas Instrument's DSP TMS320LF2811 is used as the digital controller.