Multimodular current-source SPWM converters for a superconducting magnetic energy storage system

The advantages of using multiple modules of the current-source, sinusoidal pulse-width-modulated (SPWM), three-phase, six-valve converters as the power conditioner for the superconducting magnetic energy system are highlighted. A high degree of controllability is obtained by using dynamic SPWM trilogic as the operating strategy. Very low switching losses are assured by using two carrier triangles per modulated cycle. By partial connection of converter modules, and by phase-shifting the triangle carriers, the following are obtained: increasing the current capacity to the level required by the superconducting magnet; reducing conduction losses; meeting harmonic standards, without the need of an expensive filter, by harmonic cancellation; and achieving a high frequency bandwidth