A NOVEL RANDOM SWITCHING TECHNIQUE FOR HIGH PERFORMANCE INVERTER CONTROL

Abstract

ABSTRACT A novel random switching technique for high performance inverter control is presented in this paper. Since the switches of power devices are randomized, the acoustic noise generated by the voltage and current harmonics of inverter control can be significantly reduced. It will also be shown that the technique has been developed without changing the sampling and modulation schemes, Asymmetric Regular-Sampling and double edge modulation schemes respectively, which have been widely used in practical inverter control systems. Therefore, the modifications necessary to upgrade the performance of inverters using the proposed random switching technique can be easily incorporated into existing digitalized inverter control systems, e.g. vector control systems. Furthermore, in comparison with the conventional randomized pulse position technique [10] which may result in single edge modulation and thereby causes greater mean value of flux error for drive control, the proposed random switching technique provides less mean value of flux error due to double edge modulation. In comparison with conventional inverter control techniques based purely upon the Asymmetric Regular-Sampling technique, e.g. space vector modulation [17], which results in fixed voltage and current harmonic spectra and therefore generates annoyed acoustic noise, the proposed random switching technique can reduce this kind of noise by randomizing the switches. Once the switches are randomized, the first dominant harmonic which dominates the generation of acoustic noise can be dramatically reduced. A novel Random Space Vector Modulation (RSVM) technique will be presented based upon the novel random switching technique. The RSVM technique is realized using a Digital Signal Processor (DSP) and the experimental results will be shown to confirm the theoretical analysis.