Unbalance supply and its effect on rectifier input filter kVA ratings

A properly designed input filter traps one or more undesirable input current harmonic components. The effects of these various current harmonics on the filter kVA are evaluated for various operating conditions such as balanced and unbalanced supply voltage, constant DC load current, and with varying delay angles. An electrical circuit simulator software package is used to simulate the rectifier, as well as the filter and voltage sources. The authors establish a quantitative relationship between the degree of unbalances and the consequent change of input filter kVA rating. This is done for a naturally commutated phase controlled and also for a forced commutated programmed pulse-width-modulated (PWM) power converter.<<ETX>>