## 1 Introduction  
Under global energy crisis and increasingly serious environmental pollution, electrification has become one of the important development trends of construction machinery [1]. As important construction machinery, the electrification research and production of loaders have become the power point of manufacturers [2, 3]. In the working process, the loader whose own mass is large needs to start and stop frequently. This makes it contain a lot of braking energy. However, the traditional loader does not have a power motor and battery, and it cannot recover the braking energy, which will be wasted during braking. Meanwhile, electric loaders can recover braking energy because they have motors and batteries themselves [4]. For the braking energy recovery, [PERSON] et al. proposed a combined braking system which includes the hydraulic regenerative braking system, the electro-hydraulic braking system, and the power coordinate module with a simplified structure that is energy saving. The simulation results showed that the accumulator capacity and battery initial SOC are the key factors that affect the energy recovery efficiency, and the initial braking speed is the key point that affects the total energy [5]. [PERSON] et al. proposed a dual-mode regenerative braking control strategy which unified the closed-loop control of regenerative current and the torque. This control strategy can ensure charging safety, regeneration efficiency, and ride comfort when the battery SOC is high or the battery temperature is too high or too low [6]. There are also other research studies on braking energy recovery for electric vehicles, while there are fewer that study electric loaders. Although the walking motor of the electric loader can perform regenerative braking and recovery energy, the regenerative braking torque of the motor cannot meet the braking requirements and ensure the braking safety under various working conditions. Then, the braking system of the electric loader is generally an electro-hydraulic composite braking system. However, due to the different characteristics between the regenerative braking system and the traditional hydraulic braking system, the coordination control between the two will be much more complicated than that of the traditional hydraulic braking system. Generally, the recognition of the driver's braking intention is used as the basis for the distribution of the electro-hydraulic composite braking system. In terms of a regenerative braking control strategy, the main objective of the control strategy based on torque distribution is to make the driving wheel more involved in the braking process and improve the energy recovery efficiency from the perspective of energy recovery. For braking stability, the braking torque distribution of the front and rear wheels is placed on the ideal braking force curve to maximize the road adhesion coefficient. For braking comfort, when the system braking modes switch between motor regenerative braking and hydraulic braking, the change of torque and response are coordinated as far as possible to improve the braking comfort. [PERSON] et al. analyzed the energy consumption and recovery performance of six different powertrain architectures for hydrogen fuel-cell electric vehicles. They analyzed the effects of the regenerative electronic stability control (RESC) system to compare the energy consumption performance of powertrain architectures. They found that an RESC system added to the in-wheel motor layout can recover more energy [7]. [PERSON] et al. tracked the front brake to calculate the rear brake force when the front brake force was only controlled by the brake pedal. The front and rear brake forces of the vehicle were placed on the ideal I curve, regenerative braking torque acted on the rear wheel, and the insufficient part was supplemented by the hydraulic braking system controlled by the solenoid valve [8].