Modeling a variable speed drive for positive displacement pump

Abstract

Positive displacement pumps are critical to applications ranging from drug delivery to water jet cutters. The reciprocating motion of these pumps means that their output inevitably pulses at the rate proportional to the speed of the drive. However, if the constant speed drive, traditionally employed in PD pumps, is replaced by one that can dynamically vary speed and torque the possibility of controlling the form of the output pulses arises. To enable such a system this paper reports the modeling of a drive train connected to a Positive Displacement Pump. The drive train comprises a internal combustion engine to generate rotary power, a gearbox transmission to enable changes in the speed-torque ratio and a hydrodynamic coupling in between the two to accommodate flexible power flow. The behavior of the swept pumping volume is generated from a parametric model derived from a CFD analysis. The result demonstrates that there is a significant difference in the flow predicted by models that use average, rather than instantaneous speeds

Hydraulic vs. Electric: A Review of Actuation Systems in Offshore Drilling Equipment

“…However, what still might occur at low speeds and high static heads, is that pumps run at efficiencies that are far from the optimum. Therefore, adjusting the flow rate and total head within the best efficiency region of the pump by using appropriate induction motor control strategies becomes a challenge (Josifovic et al, 2014). Additional design factors such as serial or parallel connections of pumps and motors have to be considered to achieve the best possible system performance (Neufeld et al, 2014).…”