Controllable Stationary Voltage and Frequency Power Conversion Based on Electromagnetic Induction

Stationary voltage and frequency power-conversion techniques are widely applied in modern industry. Power transformers and power electronic converters are most commonly used for sinusoidal AC-AC power conversion. Power transformers have a high voltage rating and high power capacity, but they cannot change the output frequency. Power electronic converters are flexible and can achieve both voltage and frequency conversion, but they are fragile to overvoltages, have limited voltage and current ratings and power capacities, and are primarily used in low- and medium-power/voltage applications. The goal of the research for this dissertation is to explore and develop new stationary voltage and frequency power-conversion technologies based on electromagnetic induction. This work resulted in four important innovations. First, a magnetic device, called a magnetic flux valve (MFV), was invented. This new device takes advantage of the converse magnetoelectric effect and its reluctance can be regulated continuously, precisely, and quickly by changing an external control voltage applied on the device. Second, a novel power transformer, called an adjustable-voltage-ratio (AVR) power transformer was invented. Given a fixed-amplitude AC input, the output amplitude of the transformer can be fast and continuously regulated by controlling the MFVs inside the AVR transformer. Third, a novel stationary voltage and frequency conversion device, called an electromagnetic power converter, was invented. By appropriately connecting the windings of and controlling the MFVs in the electromagnetic power converter, the magnetic flux inside the converter generated by a sinusoidal source connected to the input can be controlled, modulated, and then synthesized to generate a pure sinusoidal magnetic flux that induces a sinusoidal voltage with the frequency and voltage controllable in wide ranges at the output of the converter. Fourth, a new concept and theory, called magnetic flux modulation and synthesization, was proposed. Based on this concept and theory, an electromagnetic power converter can be built to realize multiphase-to-multiphase stationary AC-AC voltage and frequency conversion. Prototypes of the MFV, AVR transformer, and electromagnetic power converter were designed, constructed, and tested to prove the concepts of the proposed innovations