Analysis, modeling and design of a wide range constant power source

Physical vapor deposition (PVD) processes, often called plasma processes, are used in diverse industries (semiconductor circuits, flat panel displays, data storage media) for materials deposition. The power supply in a PVD process normally operates in a constant output power mode since the deposition thickness depends on the power level. An exception is when fast micro arcs occur in plasma in which case the power supply should behave as a constant current source. Ideally, the power supply should be able to provide constant power over a wide output voltage range in order to meet different process requirements.; This thesis addresses possible technical approaches and trade-offs in the realization of the power supplies for PVD processes. An analysis of losses and component stresses shows that conventional solutions based on a single stage topology or a dual stage topology consisting of a power factor correction (PFC) rectifier and an isolated DC/DC converter are not the best solutions for the power supply technical requirements. A dual stage architecture is proposed and compared with the existing solutions in terms of efficiency, power density and cost. The dual stage design consists of a phase-shifted isolated bridge DC-DC converter, which includes a simplified three-phase PFC rectification, followed by a novel zero-current-switching nonisolated interleaved buck DC-DC converter.; Analysis and modeling of losses and component stresses, as well as a design procedure are described for the proposed dual stage design. An equivalent averaged-switch circuit model for the output stage is derived and experimentally verified. This model is used to examine control loop challenges for the outer power control loop and the inner current control loop. A digital average current mode controller with adaptive gain is introduced to enable wide-bandwidth current control over wide ranges of power and voltage in the harsh plasma environment. Analysis, modeling and design results are verified on a 25 kW experimental power supply prototype.