Analysis Of Dc-Link Voltage Ripple In Voltage Source Inverters Without Electrolytic Capacitor

In this paper, the DC-link voltage ripple is analyzed for an inverter without electrolytic capacitor. As the capacitance density of non-electrolytic capacitors are significantly lower than electrolytic capacitors, for a non-electrolytic capacitor based three-phase inverter, the DC-link voltage ripple is much higher than traditional inverter, which will cause more THD on load current and originates voltage stability problems when cascaded with the front-end converter. To avoid these disadvantages, the DC-link voltage ripple must be fully analyzed for a non-electrolytic DC-link capacitor three-phase inverter. This paper presents the voltage ripple analysis of the voltage source inverter under the modulation methods of SPWM and SVPWM. The results show that the DC-link voltage ripple has special patterns which relate to switching frequency, modulation ratio, output current amplitude, load power factor, and reference voltage angle. According to these analysis, the minimized DC-link capacitance can be selected to satisfy voltage ripple requirement.