DC‐link low‐frequency current and voltage ripple analysis in multiphase voltage source inverters with unbalanced load

Inverter's performance and operating mode may be negatively affected by inverter input (dc-link) current voltage ripple. It is a common experience that even theoretically balanced loads with perfectly supply voltages, such as multiphase ac motors supplied pulse-width modulation (PWM) inverters, in practice show certain degree of unbalance, the range few percent, which introduces low-frequency instantaneous power oscillation. This reflects ripple on dc-link side (i.e. at double-fundamental frequency). A possible method to analyse this matter through symmetric sequence components. In particular, based first negative component considering equivalent impedance calculated dominant frequency, amplitude corresponding work for general load. Finally, design capacitor inverters proposed requirements referred dc The feasibility developments has been verified three-, five- seven-phase both numerical simulations comprehensive experimental tests, always showing good matching.