###### Abstract
This type of electro-hydraulic pump combines a quantitative pump and a variable speed motor, which has the advantages of simple structure, lightweight, low energy loss, and high engineering feasibility while achieving the expected performance. Many scholars have also done much research on the performance analysis of the integrated electric hydraulic pump. [PERSON] et al. studied the energy conversion efficiency of hydraulic motor vane pump [20]. The finite element method is used to analyze the transient electromagnetic field of the three-phase asynchronous motor to obtain the characteristics of the motor starting torque and iron core loss under rated voltage and the magnetic field distribution of the motor. Through theoretical analysis and numerical simulation, the total efficiency of the hydraulic motor vane pump under rated conditions is 63.77%, which  
Figure 4: The integrated electric hydraulic pump designed by Beihang University. Figure 3: RP series rotary pump of Daikin Company, Osaka, Japan. is 1.5% higher than that of the traditional three-stage hydraulic power unit. [PERSON] completed the performance analysis of the motor and the simulation of the temperature field by establishing the motor model and calculating the power loss of the motor vane pump during operation [21]. Through studying the transient process of the oil-immersed motor and the ordinary motor, the iron core loss of the oil-immersed motor is 140 W, and it is lower than the loss of the ordinary motor (150 W) during no-load operation. By changing different inner diameters of the rotor, the motor speed becomes slower when the inner diameter of the motor rotor lamination increases. Considering the temperature field model, the maximum temperature of the motor under the condition of oil cooling is 73.097 \({}^{\circ}\)C which is lower than that of the air cooling, which indicates that oil cooling has a significant effect on the temperature reduction of the hydraulic motor pump. [PERSON] et al. [22] established a simulation model of the internal flow field of the proposed motor axial piston pump. By comparing and analyzing the flow field distribution when the motor speeds were 800 rpm, 1200 rpm, 1500 rpm, and 2000 rpm, respectively, the simulation results reveal that with the increase of rotor speed, the pressure loss in the plunger cavity increases, and the minimum pressure decreases, which makes it easy to produce cavitation in the plunger cavity, resulting in vibration and noise of the motor pump. Therefore, the speed of the motor pump should not be too large. Through the analysis and calculation of the motor loss, the volumetric efficiency, and the mechanical efficiency of the plunger pump, the efficiency of the motor pump is 94.96%, which is higher than that of the traditional \"motor-pump\" (85-90%). In conclusion, the above integrated electric hydraulic pumps adopt the integration of the hydraulic pump into the inner rotor of the electric motor. However, due to the internal space of the motor rotor being very limited, it is necessary to redesign the structure of the rotor or even change the overall structure of the motor to integrate the rotor of the hydraulic pump with the motor rotor, which dramatically increases the complexity. More importantly, when the motor is rotating at high speed, installation and fixation of the magnetic steel installed on the rotor must be considered for permanent magnet inner rotor motors, which will restrict the further integration of the inner rotor motor and the hydraulic pump. Therefore, a novel integrated electric hydraulic vane pump (IEHVP) is proposed in this paper. To obtain the operating characteristics of the proposed IEHVP, theoretical analysis, simulation calculation, and bench test are applied. The main content and innovations of this paper are as follows:  
1. A novel integrated electric hydraulic vane pump that combines an outer rotor brushless DC motor and a balanced vane pump is proposed. 2.