Combination of Flywheel Energy Storage System and Boosting Modular Multilevel Cascade Converter

Abstract

This paper deals with a pulsed power supply system combining flywheel energy storage system (FESS) and a modular multilevel cascade converter (MMCC) for power compensation in performing rapid excitation of highly inductive and pulsed heavy loads. The FESS system consists of an induction motor with a flywheel to store kinetic energy. Parallelly connected capacitors cause self-excitation phenomena in an induction motor, and it works as an induction generator. Furthermore, the induction generator generates more than twice of electric power of its rated value for a short time. We can apply the proposed FESS to particle accelerators for physics experiments or medical use, and plasma shape and position control in pulsed nuclear fusion devices that require pulsed highpower. In addition, the coils in these applications that generate magnetic fields have large inductances. In plasma control and repetitive operation applications, it is necessary to change current rapidly. We can realize high-speed current control by using the proposed MMCC that can output a voltage higher than the input voltage. By combining the FESS and MMCC, a power supply may be realized with the ability to implement rapid current control while compensating for large power consumption and without significant load disturbance on the power grid.