Application and Comparison of Pressure Control Strategies to a Series Hybrid Hydraulic Powertrain

In this contribution, different control strategies for application within series hybrid hydraulic powertrain are designed, applied, and discussed. Common aspects of the introduced control strategies are the low-level component-oriented control realization. In contrast to common supervisory control concepts, the low-level control strategies are more accurate because of application of dynamic model of the system instead of static model. The engine on/off control strategy based on compensation of used accumulator power is compared to accumulator depleting strategy, in which demanded power is mainly supplied using accumulator power, as well as smooth engine strategy, in which the maximum power of the engine is bounded. The effect of control parameters on the performance and efficiency of the hybrid power train is investigated. Simulation results confirm the results and show significant improvement of fuel economy by applying engine on/off strategy as well as accumulator depleting strategy. In addition, the performance of the hybrid powertrain is detected highly depend on the driving cycle.