Advanced control algorithms for compact and highly efficient displacement-controlled multi-actuator and hydraulic hybrid systems
Environmental awareness, emission restrictions, production costs and operating expenses of mobile fluid power systems have provided a large incentive for the investigation of novel and more efficient fluid power technologies for decades. These factors have driven fluid power technology advancements in the earth-moving sector where displacement-controlled (DC) actuation and hydraulic hybrid architectures have emerged as highly efficient choices for the next generation hydraulic systems. Industry and academia have recognized the need for these technologies as well as the challenges for their implementation and commercialization. At the Maha fluid power research center, highly efficient DC actuation with pump switching has demonstrated that, when coupled with novel hydraulic hybrid drives and under certain applications, the prime mover’s power can be downsized by up to 50% leading to substantial energy savings. In this dissertation, challenges related to the actuator and supervisory-level controls for DC machines with pump switching and hydraulic hybrids are studied and implementable solutions are proposed for the first time. On the actuator-level linear robust controllers and an adaptive robust controller are utilized to assess the performance of a secondary-controlled hydraulic hybrid drive, which is subjected to large and rapidly changing inertial and external load dynamics as well as varying pressure nets. Also on the actuator-level, feedforward strategies for the realization of DC actuation with pump switching are put forward, studied and tested in two different experimental platforms, leading to smooth actuator transitions. On the supervisory level, the challenge to manage multi-actuator systems with pump switching is addressed through the use of a priority-based algorithm. An instantaneous optimization algorithm is formulated and coupled with a novel electronic anti-stall control for the power management of the prime mover in hydraulic hybrid DC multi-actuator systems. Finally, a feedforward controller is developed based on the power distribution of this new class of hydraulic hybrid systems to enable prime mover downsizing for cases where the DC actuation savings and cyclical machine operation allow. Ultimately, the control algorithms derived in this dissertation bring the technology a step closer to the predicted savings while emulating traditional or superior operability at reduced cost.
Ivantysynova, Purdue University.
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