Voltage Balancing Control for Four-Switch Three-Phase Active Front-End Rectifier

This paper proposes the novel capacitor voltage balancing control for the current-sensorless controlled four-switch three-phase active front-end rectifier (FSTPAFER). In comparison with conventional capacitor voltage balancing control, the proposed virtual current injection voltage balancing control (VCIVBC) is able to balance the capacitor voltage without using a low-pass filter to obtain the dc difference between two capacitor voltages. The proposed control requires only two sensed capacitor voltages to process some simple algebraic calculations that can reduce the low corner frequency pole to restrict system response. Moreover, the transfer functions of the FSTPAFER are derived by the state average model in the synchronous rotating frame (SRF), and the stability of the system is verified by the bode plot in the frequency domain. The performance of the proposed control is validated by its experimental result in DSP TMS320F28335, and the result shows the proposed scheme has adequate performance during the change of the load.