A comprehensive case study with both hydraulic system designs has increased the know-how of optimal control strategies and modelling demands for both technologies. A handbook and guidelines for arctic environment and operation conditions was established and helped in estimating the temperature effects on the simulated system performance and component material selection. The achieved simulated efficiency rates were 75…90 % with both systems and therefore propose significant improvements compared to traditional hydraulic designs. Based on the promising simulation results, a compact prototype for the pump controlled unit was produced and tested in laboratory environment, verifying the predicted efficiency rate and change of operating point which is a characteristic feature for the studied hydraulic circuit.
For applications which utilize hydraulic systems, the performance and environmental requirements are still not met for a wide range of applications, such as marine machinery. This forces designers to find alternative, more efficient system solutions, which can have complex control and/or unstable behaviour with heavy loading. Also, in hydraulic systems the energy efficiency is more or less a demand for compact design where the total oil volume is minimized and the result can be potential system overheating. Technology surveys and careful modelling and control design with the virtual load model have provided case-specific design rules, optimization of components and more insight about the renewable hydraulic drive technologies.
Surveys of hydraulic system demands in cold and harsh operating conditions have increased arctic design competence. The loading profile based optimization in design has led to prototype testing and near-future commercialization of the pump-controlled compact hydraulic power unit but the digital hydraulic version is currently not yet considered for production. In academic research, the importance of accurate loading profiles has played significant role especially in optimal pump control research. Future studies will concentrate on inverter controlled hydraulic drives and further development of their control concepts.