A lot more than 50% of the compression and pumping systems above 3 MW require a variable-speed drive. Frequently medium-voltage motors fed by frequency converters and parallel shaft gears are chosen. Others are using epicyclic gears with a hydrodynamic superimposition drive.

Taking benefit of the state of the art in electrical motors and frequency converters, the driving program for the superimposition of the earth carrier is based on a Permanent Magnet Synchronous Superimposition (SI) electric motor and a dynamic Front-End Cycle Converter. So – E stands for Electric.
That is a high-speed gear drive system incorporating components that allow the use of a low-cost constant-speed (electric) driver for a variable-speed application.

A lot more than 50% of the compression and pumping systems over 3 MW need a variable-speed drive. Often medium-voltage motors fed by frequency converters and parallel shaft gears are chosen. Others are employing epicyclic gears with a hydrodynamic superimposition drive.
It started with hydraulic Variator Gearbox liquid couplings making slippage with results very little much better than the throttle.
The look of hydraulic clutches then improved and included a torque converter and a superimposed epicyclic drive.
Variable Frequency Drives (VFD) were developed and, simultaneously, the expense of the shaft trains increased, and so did efficiency. The issue of THD (Total Harmonic grid Distortion) rose and kept VFD out of many applications.

Taking advantage of the state of the art in electric powered motors and frequency converters, the driving system for the superimposition of the earth carrier is based on a Long term Magnet Synchronous Superimposition (SI) electric motor and a dynamic Front-End Cycle Converter. So – E stands for Electric.
This is a high-speed gear drive system incorporating parts that allow the utilization of a low-cost constant-speed (electric) driver for a variable-speed application.

All of the over plots were taken by analyzing the current to the motor. In a normal situation, the vibration will be monitored and stored on a periodic basis. If the 360 Hz signal is present in the vibration spectrum, it is not normally of any concern. If, however, additional unexplained frequencies come in the vibration spectra, then it would be advisable to check out both the current waveform and the current spectrum. In the pages that follow, a few examples of problems discovered in DC drives and motors are provided.”
It started with hydraulic liquid couplings generating slippage with results not much much better than the throttle.
The design of hydraulic clutches then improved and included a torque converter and a superimposed epicyclic drive.
Variable Frequency Drives (VFD) were developed and, simultaneously, the expense of the shaft trains increased, and so did efficiency. The problem of THD (Total Harmonic grid Distortion) rose and kept VFD out of several applications.