Sinusoidal modulation with higher harmonics limitation

Abstract

Sinusoidal modulation techniques are highly applied in the power electronics converters technology and generate harmonic distortion in the load side. The harmonic components generate many problems such as interference with control signals. This paper presents the study results of the carrier based, sinusoidal, modulation method performed for the three-phase, three-wire voltage source inverter. As a result of the carrier based modulation strategy, the output voltage higher harmonics components in the spectrum are observed. They are connected with a carrier signal and with other harmonics sources, e.g. non-linearity load. Using the fluctuation of the switching frequency in the digital modulation system the higher harmonic components of the inverter output voltage can be actively limited. Presented results of the carrier base modulation strategy with the switching frequency fluctuation are selected issues of the control system with the use of a FPGA device. The amplitudes of the output voltage frequency components are reduced in the system with the linear fluctuation of the switching frequency and in the system with the sinusoidal fluctuation of the switching frequency. The results of the sinusoidal modulation method with two kinds of the switching frequency fluctuation used in the voltage source inverter were analyzed and compared.