A reliable, interface-friendly medium voltage drive based on the robust IGCT and DTC technologies

摘要

The use of voltage source converter topology for medium voltage drive products allows to realize the utility interface compatible with IEEE 519-1992 by means of a series 12-pulse (or optionally a 24-pulse) diode rectifier without any harmonicfilters or power factor correction equipment. On the motor side the three-level voltage source inverter, also known as the neutral-point clamped (NPC) inverter, is the preferred one. In combination with the newest snubberless IGCT (IntegratedGate-Commutated Thyristor) technology ft is possible to build MV inverters without series connection up to 4kV line-to-line voltage and higher. This results in a highly efficient and reliable MV converter system with a minimum parts count. By using a LC-filter between inverter and motor terminals, feeding of standard motors without derating becomes possible. With the use of the direct torque control (DTC) as developed for low voltage drives the MV drives applications benefit from the synergies with lowvoltage drives. Specific add-ons for the NPC inverter and the loss4ess resonance control of the LC-filter are needed. The DTC and the IGCT are in commercial operation for several years, showing their expected very high level of reliability and robustness. Both technologies reach the today's known limits of physics either in silicon or in torque control dynamics.