| Abstract |
Technological improvements in power semiconductors have made possible an important increase both in the switching frequency and in the rated power of the adjustable speed drives (ASD) used in electrical drives. As a drawback, ASD generate pulsed-output voltages with a high rate of voltage rise (dv/dt) that can be greater than 5000V/µs. These dv/dt can cause problems in other elements of the system: premature aging of the machine insulation, bearings deterioration, and EMI. Besides, dv/dt and the output voltage amplitude at motor terminals can increase as a consequence of the stray elements of the cable. In order to deal with these adverse effects, new models are needed that incorporate the high-frequency behaviour of cable elements. In this paper, a generic model for the power cable is proposed to study the low- and high-frequency behaviour of currents and voltages in three-phase drives. With this model, the cables that are used at present can be analysed. In addition, an experimental technique is proposed to calculate model parameters that is based on the operation mode of the electrical drive. The model has been validated for the three most common types of cables: unshielded, with external shield or armour, and shielded conductors. |
