3.1.3. Hydraulic Pump's Interference in Target Trajectory

The torque consumed by the hydraulic pump will also lead to the genset operation points deviating from the pre-set target trajectory for torque interference. Most previous studies have ignored the hydraulic pump torque and its interference effect [8–10,50,51], which will finally cause a decrease of the genset efficiency and increase of fuel consumption.

### *3.2. Development of the ASPF Strategy*

An ASPF control strategy is proposed here to provide a comprehensive solution to these problems. Through this strategy, the demand power signal is divided into the trend part and the fluctuation part to make the genset output smooth and stable, and the supercapacitor supply the output power fluctuation. Therefore, the transient fuel consumption and the deviation from the target trajectory can be reduced. Meanwhile, when there is torque consumption of the hydraulic pump in the working system, the optimal efficiency working points of the genset are found for control to avoid interference. The structure and development process are presented below.

**Figure 6.** Effect of different changes of the genset's output power on the engine operating points: (**a**) 50 and (**b**) 5 kW/s power change.

**(b)** 

### 3.2.1. Structure of the ASPF Strategy

The structure of proposed ASPF control strategy is shown as Figure 7. It employs two critical steps, including a fuzzy adaptive filter and optimal efficiency control of the genset module, to solve the problems above and improve the power following control strategy. Utilizing the computed demand power of the drive system as the input, and introducing state of charge (*SOC*) and pressure feedback, the strategy outputs the engine target speed and generator target torque to the subcomponent controller. Energy distribution between the genset and the supercapacitor can be completed through determining the genset output power.
