A six-phase multilevel inverter for MEMS electrostatic induction micromotors

The construction of miniaturized rotating electric machines through microfabrication techniques is becoming a reality. Applications of such micromotors include miniaturized pumps, compressors, fans, coolers and turbogenerators. However, the characteristics of these devices make the design of power electronics for them challenging. These characteristics include high-voltage and high frequency operation, tightly constrained operating waveforms and timing, and capacitive input impedances. This paper explores the design of power electronics for microfabricated electrostatic induction machines. The authors describe the structure and operation of these machines, and establish the operating requirements of power converters for them. They provide a comparison of inverter topologies for this application, and propose an appropriate architecture. The design and experimental evaluation of a prototype six-phase, five-level inverter for this application is presented. The inverter operates at frequencies up to 2 MHz and at voltages up to 300 V, and meets the stringent waveform and timing constraints posed by this application.