Abstract
A hydraulic transformer may be looked upon as a type of secondary controlled machine. As other secondarycontrolled machines, hydraulic transformers require closed loop control. High efficiency, as a consequence ofenergy recovery possibilities and good controllability have motivated the use of secondary controlled machines, mainly motors. The hydraulic transformer adds some further attractive properties concerning control of linearloads, i.e. cylinders. However, there are still design issues that have to be improved.
In previous studies of the new Innas Hydraulic Transformer (IHT) concept, the low-speed operating andstart/stop sequences have been found to be the most critical operating conditions. Here losses of stick-slipnature are dominant due to the combination of varying driving torque and small inertia.
In the paper conceptual control strategies are presented. The design is simulated and evaluated concerningthe low-speed operation of the IHT. Basis for the study is a detailed simulation model describing the transformerat a high level of detail and with good agreement between simulations and measurements.
