Adaptive Equivalent Consumption Minimization Strategy for Off-Road Hydraulic Hybrid Vehicles: A Cycle-to-Cycle Optimization Approach

The energy management strategy is the key factor for hybrid vehicles since it determines how efficiently the engine power is transferred to the wheels. As a local-optimal and implementable strategy, the equivalent consumption minimization strategy is of great research interest. The equivalent factor and the gain coefficient of penalty function are two important parameters in the strategy that need to be determined in advance. It is challenging to choose these parameters to achieve minimum fuel consumption in different on-road driving cycles. For some off-road vehicles, such as wheel loaders, the loading cycle is highly repetitive. This brings a great opportunity to optimize these parameters cycle-to-cycle. In this study, an adaptive equivalent consumption minimization strategy is applied to a series hydraulic hybrid wheel loader. A cycle-to-cycle tuning scheme is developed where the equivalent factor and the gain coefficient of penalty function are optimized through repetitive loading cycles. The potential with parameter optimization in different loading cycles is identified. Results show a fuel-saving with the cycle-to-cycle optimization method of up to 6.36% in a 57 s loading cycle.