Three-phase voltage-type AC to DC power supply with improved performance

With the growing need for efficient energy conversion and stricter enforcement of ac side harmonic standards, Pulse Width Modulated Voltage Source Rectifier (PWM-VSR) based power supplies are expected to find increased use in industrial applications. However due to feedback control systems and power circuit topology, the dynamic performance of these power supplies is dependent on the operating conditions resulting in changes in the operating levels of the voltages and currents following load and line disturbances.;The main objective of this thesis is to improve the ruggedness and reliability of PWM-VSR based power supplies in an industrial environment by proposing a self tuning digital control system capable of automatically adjusting to the changes in the load and network conditions. This results in an optimal steady state and dynamic performance over a wide range of operating conditions. Moreover detection and estimation of system voltages and currents in software lead to diagnostic and protection algorithms which improve the ride through capability.;An insight into the steady state behavior of the power supply system is given by Fourier analysis of non-sinusoidal switching functions while the dynamic performance is predicted by small signal analysis of the power supply and the proposed control strategy. A systematic design procedure based on the steady state and dynamic analysis is highlighted with a design example.;A 5.6 kVA, 215V AC to DC power supply is experimentally built to verify the various results predicted by steady state and dynamic analysis. A digital controller based on a 32 bit floating point Digital Signal Processor chip is used to implement the control system.