Macroscale Electrostatic Rotating Machines and Drives: A Review and Multiplicative Gain Performance Strategy

Abstract

The development of electrostatic rotating machines for macroscale power conversion has been largely sidestepped, given the uncertainty of its capabilities and place in the technological hierarchy. This article reviews prior and present works in macroscale electrostatic rotating machinery and identifies the relevant machine types, their limitations, and strategies for performance improvement. The separately excited synchronous electrostatic machine presents the greatest opportunity for competitive macroscale category-two machinery, and a strategy of multiplicative gains is established. The strategy spans machine modeling, optimization, gap media (gases, liquids, and vacuum), gap maintenance, advanced manufacturing techniques, and power electronic drives/control. Ultimately, the product of innovation gains across all these areas reveals that macroscale electrostatic machinery is possible and potentially competitive with magnetic machinery for specific areas, including position and hold, low-speed direct drive, and high-voltage utility generation applications.

Sensorless Control of Separately Excited Synchronous Electrostatic Machines

“…The machine model for a nonsalient SEM in the stationary reference frame is given in (1). The dq-axis stationary reference frame back MMF is shown in (2) and (3).…”

“…F LUID-FILLED synchronous electrostatic machines (SEMs) have the potential to power applications requiring low-speed high torque with very low losses. Torque density improvements using dielectric liquids, advanced manufacturing techniques, and electrode optimization have demonstrated torque densities that are comparable with electromagnetic machines [1]. SEMs operate at a medium-voltage level, which creates a challenge for power electronics and control, as there is no off-the-shelf drive available for controlling the machine.…”

The trajectory monitoring method of hydrodynamic suspension bearing based on laser-ranging technology

“…Rotating machines have been widely used in various industrial applications [1][2][3][4], i.e. turbines, pumps, compressors, and engines.…”

“…For a typical rotor system consisting of a hydrodynamic bearing to provide loading capacity and other shaft segments for workload access, the step axis is often utilised, and it is convenient to monitor the movement of the rotor by arranging displacement sensors targeting the connecting shaft segments [13,22]. Nevertheless, when applied to electromechanical systems, hydrodynamic bearings often work in scenarios with variable solid electromagnetic fields [3,22,23], which might cause electromagnetic interference to the sensors. Furthermore, with the trend of high integration and miniaturisation of devices [1,24], the size of the shafting is becoming increasingly smaller, and arranging displacement sensors is more challenging.…”

A Medium-Voltage Current Source Inverter for Synchronous Electrostatic Drives

“…However, due to the comparably low torque density, electromagnetic counterparts have been the machines of choice for general-purpose applications. To improve the torque density gap, research has focused on increasing the surface area, utilizing a liquid optimized for field breakdown, permittivity and viscosity, and embracing high pole counts and medium voltage designs [5]. This has culminated in a threephase separately excited synchronous electrostatic machine (SEM) that is competitive with air cooled modern electromagnetic machines in torque density and has order of magnitude lower electrical loss [5].…”