Altivar 1260 Medium Voltage Drives Page 45 Waveform

Waveform 45 Altivar 1260 MV variable speed drive Three level NPC topology generates output voltage waveform with three voltage levels in phase to DC link neutral point voltage (+Vdc/2, 0, -Vdc/2), and five levels in phase-to-phase voltage (+Vdc, +Vdc/2, 0, -Vdc/2, -Vdc). In addition, modulation only allows Vdc/2 voltage jumps. Nevertheless, all Altivar 1260 converters include a sine wave filter as standard. This filter is designed in order to reach the following goals: O Long cable lengths (>250 meters) O Accommodate standard non-converter duty motors O THDi <2% O Shaft torque ripple <1% O Peak voltage <= 6KV O Dv/dt (max) <= 50V per microsecond O Reduced common mode currents O Less overall stress on motor insulation and bearings Maximum peak voltage at motor terminals is calculated with the following equation: Phase-to-phase voltage waveform @ 100% output voltage, 4.16KV Example testing The following table shows values for maximum peak voltage and maximum dv/dt: Vmotor (V) Vdc (V) Umax (V) dV/dt ( s) 4160V 7200 6000 50 V PhPh_PK = x 1.5 + V DC V DC 2 Motor voltage Inverter voltage 2.8kv over voltage = .62 kV/us Rise time = 3.7 us

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