An assessment of the noncharacteristic harmonics generated by adjustable speed drives

The generation of noncharacteristic harmonics in the AC supply feeding adjustable speed drives is experimentally investigated, taking into account the effect of the modulation index, the DC filter cutoff frequency and the output frequency. The test performed included a single ASD connected to the mains, two inverters connected to the DC link and two ASD's connected to the grid, all under balanced supply. The behavior with an unbalanced supply is also reported.