Control of three phase power converters. I: Voltage generation II: Current regulation

Part I: Control of three-phase voltage generation for UPS applications. The core of any three-phase voltage generating system is a three-phase inverter capable of providing three-phase balanced, undistorted voltages regardless of any loading conditions and irrespective of any variations in the source. The inverter's performance is mainly determined by the employed controllers; therefore, the control issues of three-phase Voltage Source Inverter (VSI) have drawn much attention over the last two decades.;This part of dissertation focuses on the control of voltage generation for both three-phase three-wire system and three-phase four-wire system. Two controllers were proposed, one controls three-legged VSI while another serves four-legged VSI. For both, circuit-level decoupling and mapping were employed to decouple the two VSIs into a set of buck converters in every 60° region. The controllers can thus be realized through a combination of rotational logic and conventional buck controllers. The implementations of the two proposed controllers are simple and flexible, with no DSPs, no microprocessors needed and a variety of implementation combinations exist. The controlled VSIs demonstrate experimentally high performance, i.e. ability to handle 0-100% resistive loads, highly non-linear load and highly unbalanced load as well as total rejection of source voltage perturbation.;Part II: Control of current regulation for regenerative rectifiers. A power rectifier is required for converting the AC current from the grid into a DC current for feeding an adjustable speed drive. The low efficiency, high harmonic generation and inability to send braking power back prohibit the conventional diode rectifier to bridge the AC power grid and adjustable speed drive. What needed is a regenerative rectifier with unity power factor and regenerative power processing ability.;The second part of this dissertation presents a controller for three-phase boost rectifier to act as such a regenerative rectifier based on prior researches on One Cycle Controlled Power Factor Correction (PFC) rectifier and Grid-Connected Inverter (GC1). The new controller employs a circuit-level decoupling method to decouple three-phase boost rectifier into parallel-connected boost converters in every Or region. Then, instead of designing a current compensation loop, the new controller injects reference signals, whose amplitude is adjusted according to the rectifier's power level and incorporates the sensed output currents into the parallel-connected boost converters' DC gain equation to force the output currents to stay in expected waveforms through the physics of the employed three-phase boost rectifier.;The implementation of the proposed controller is very simple, while the rectifier under control is proven experimentally to operate either as a PFC rectifier or as a GCI according to motor operation status, in both cases, the currents are sinusoidal and the transition between the two modes is fast and smooth.