METHOD FOR BOOSTING THE OUTPUT VOLTAGE OF A VARIABLE FREQUENCY DRIVE

摘要

A sine wave filter including an inductor for each phase (three inductors) an d three delta- or Y-connected capacitors is employed within a borehole power system, coupled within a three phase power system at the surface between the output of a variable frequency drive and a three phase power cable transmitting power to a borehole location, and boosts the output voltage of the drive. The sine wave filter is designed to have a resonant frequency higher than the maximum operational frequency of the drive, and a Q such tha t, at the maximum operational frequency of the drive, the filter provides a voltage gain equal to the ratio of the desired voltage to the drive's maximu m output power at the maximum operational frequency. The sine wave filter also smooths the voltage waveform of a pulse width modulated variable frequency drive.