A lot more than 50% of the compression and pumping Variator Gearbox systems over 3 MW require a variable-speed drive. Frequently medium-voltage motors fed by frequency converters and parallel shaft gears are selected. Others are using epicyclic gears with a hydrodynamic superimposition drive.
Taking advantage of the condition of the artwork in electric powered motors and frequency converters, the driving system for the superimposition of the planet carrier is based on a Permanent Magnet Synchronous Superimposition (SI) 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 usage 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 selected. Others are employing epicyclic gears with a hydrodynamic superimposition drive.
It started with hydraulic fluid couplings generating slippage with results very little 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, at the same time, the expense of the shaft trains improved, therefore did efficiency. The problem of THD (Total Harmonic grid Distortion) rose and held VFD out of several applications.
Taking advantage of the condition of the art in electrical motors and frequency converters, the driving program for the superimposition of the planet carrier is founded on a Permanent Magnet Synchronous Superimposition (SI) motor and an Active Front-End Cycle Converter. So – E means Electric.
That is a high-speed gear drive system incorporating elements that allow the utilization of a low-cost constant-speed (electric) driver for a variable-speed application.
All of the above plots were taken by analyzing the current to the motor. In a normal situation, the vibration will be monitored and kept on a periodic basis. If the 360 Hz signal is present in the vibration spectrum, it isn’t normally of any concern. If, however, additional unexplained frequencies appear in the vibration spectra, then it would be advisable to take a look at both the current waveform and the current spectrum. In the webpages that follow, some examples of problems discovered in DC drives and motors are presented.”
It started with hydraulic fluid couplings creating slippage with results very little much better than the throttle.
The design of hydraulic clutches then improved and included a torque converter and a superimposed epicyclic drive.
Adjustable Frequency Drives (VFD) were developed and, at the same time, 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 many applications.
