Fundamental topologies of three-phase LC resonators and their applications for oscillators

There exists an increasing need in power electronics for efficient three-phase inverters. They can find application in power control of AC motors or as an intermediate stage in DC-DC converters. It seems that employing three-phase oscillators for such inverters can be an appropriate solution. However, for the sake of efficiency and also simplicity, it should be beneficial that the three-phase oscillators will consist of high-Q three-phase resonators. The present paper describes several circuits that can be entitled three-phase resonators. The discussion is mainly related to the topological structures of the systems. A numerical simulation of their dynamics is also given., The three-phase resonators consist of six reactors (three inductors and three capacitors), and not merely of three as might have been expected. This is probably due to the duality existing in electromagnetics. Active elements are added mainly for sustaining the oscillations. However, a further task for them is to assist in balancing the three-phase system. Some of the models are advantageous since they have in inherent property to constrain the DC bias in the three-phase variables, both in the currents and in the voltages, to zero.