A cycle-adaptive control strategy to minimize electricity and battery aging costs of electric-hydraulic hybrid wheel loaders

Electrification is a promising trend for wheel loaders, with their advantages of high efficiency, zero emissions, and low noise. However, wheel loaders experience high instantaneous power and frequent acceleration and deceleration during operation, accelerating battery aging and increasing the annual operating cost. One approach to extending battery lifetime is to employ an electro-hydraulic hybrid drivetrain system to reduce battery usage frequency and charging/discharging currents. In this paper, a cycle-adaptive control strategy is proposed with the combined goal of minimizing electricity and battery aging costs. Dynamic programming is used to determine the optimal power ratio for different speed trajectories. Based on the offline results, the cycle-adaptive control strategy is designed to adjust power distribution based on vehicle position, speed, and average hydraulic pressure of the last cycle. Simulation results indicate that the proposed strategy achieves combined costs comparable to those of dynamic programming and reduces costs by approximately 7 % compared to the universal thermostat control algorithm. Additionally, the paper discusses the impact of electricity prices in different countries and battery prices over various years on electricity consumption and battery degradation, providing design guidelines for implementing the strategy in practice.