Analysis and design of modular three-phase power factor correction schemes for utility interface

The extensive use of non-linear and electronically switched loads in power system has lead to higher incidences of harmonic distortion of the voltage and current waveforms. Harmonic currents degrade power quality and are considered the main source of many system malfunctions. Technical guidelines and standards regarding suppressions of system harmonic contents have been enacted. This dissertation proposes several new three-phase power factor correction (PFC) schemes using single-phase PFC modules.; An integrated single-switch approach is first proposed. This is essentially an add-on solution to standard ASD's. This approach is based on circulating third harmonic current between neutral and DC mid-point by utilizing a lossless resistor. Single-phase PFC emulates this resistor to control the amplitude of the current, which is implemented by the dynamic breaking chopper available in standard adjustable speed drives (ASD's). This approach is also capable of reducing harmonic distortion in multiple drives. Analysis, design and simulations are conducted to determine the performance of the proposed scheme with different line impedances and with and without dc-link inductance in the ASD. Experimental results are presented using commercial ASD retrofitted with the proposed approach.; Second scheme proposes a three-phase PFC using two standard single-phase PFC modules. In this approach, three-phase input is transformed into two-phase by means of 0.14 pu autotransformer. Two standard single-phase PFC modules are employed to process two-phase power to do output. Split inductors and diodes are employed to limit the interaction between the two phases. A method to eliminate the interaction between phases is also described. Due to cascade operation of two PFC stages, low frequency (120Hz) ripple in dc-link is cancelled.; An active interphase transformer (IPT) scheme is proposed to draw sinusoidal input line currents, in the third study. This scheme utilizes a unique combination of a low kVA 12-puse rectifier system with single-phase boost PFC. In response to load conditions, the amplitude of the triangular current from the secondary winding of the IPT is controlled by the boost PFC. The 0.05 pu PFC is not exposed to line transients under varying load conditions. The proposed system is rugged, and in the event of active control were to fail the system reverts to 12-pulse system with 5th and 7th harmonic cancellation.; In the fourth study, a wide input range active multi-pulse rectifier for utility interface is proposed. The scheme combines multipulse method using Y-Δ transformer and boost rectifier modules. Diode switching vector is utilized to shape the input line currents. A current control scheme is proposed to achieve sinusoidal line current under wide range of input voltage changes and output load conditions.; Analysis, design examples and Experimental results are detailed for each scheme.