| Abstract |
A rotating system tie frequency converter for supplying 16 2/3 Hz power to the variable
frequency railway network comprises a double-fed slip ring induction machine at the 3-
phase 50 Hz side. As the operating speed will not differ from the synchronous spe.ed by more
than a few percent, only the same small part of transferred power - the slip power - appears at
the rotor side. The appropriate rotor voltage for the setpoint value of shaft torque is generated
by a PWM inverter with a DC link; usually low voltage and high current will be found in power
transfer operation at the rotor side. In the state of the art solution, a line commutated thyristor
rectifier I inverter, connected to a line transformer, accomplishes the further transfer of active
power to the line. This proposed circuit consists of a second PWM inverter instead of the thyristor
unit. The novel circuitry is compared to the standard. By proper line PWM inverter control,
induction machine losses can be reduced and the transient behavior at line faults can be
improved essentially (reduced peak currents and reduced time for regaining undisturbed operation).
Additionally, it is possible to reduce the rated power of the converter transformer. |
