Hydraulic System Control for a Hybrid Continuously Variable Transmission Based on an Electric Oil Pump

Switching between different working modes customarily brings sudden changes in torque and speed, leading to energy wastage for mechatronics‐electro‐hydraulic power coupling electric vehicles. Investigating the effect of vehicle speed thresholds on operating mode switching when working in concert with compound energy sources is timely. Thus, under the constraint of a known reference path, the optimal threshold is determined by weighing the path tracking accuracy and economic performance with the vehicle speed and the accumulator pressure as control variables. Wherein the constraint relationship between the factors is fully elucidated by combining various typical and actual road conditions. The validation results indicate a positive correlation between the starting acceleration capacity and the threshold value for a certain accumulator volume. The optimal speed thresholds under new European driving cycle, China light‐duty vehicle test cycle‐passenger, and actual routes are 4.1, 3.81, and 3.66 m s−1, with state of charge consumption rates of 6.30%, 8.56%, and 4.25%, respectively. More frequent speed switching may lead to excessive hydraulic power wastage, thereby increasing dependence on electrical power. Appropriate threshold setting can effectively enhance path tracking accuracy and hydraulic utilization under unpredictable road conditions. This research may in the future provide theoretical support for the rational control and interconstraint mechanism of energy utilization in hybrid vehicles.

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“…Hence, the vehicle is always in a state of efficient operation under various working conditions. [31][32][33]…”

Section: Working Principle and Driving Model Modelingmentioning

confidence: 99%

Electrohydraulic Power Switching Control for Mechatronics–Electrohydraulic Power Coupling Electric Vehicles Considering Optimal Speed Thresholds

Yang

Zhang²,

Hong

2023

Energy Tech

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“…i~d and i~q is the current of d-q-axes estimated from state observer. E d and E q are the constructed back electromotive forces of d-qaxes, which adopt (20) and (21). Equation 22is the sliding-mode conditional function.…”

Section: Sliding-mode Observermentioning

confidence: 99%

“…The CVT-based P2 hybrid transmission developed here adopts an EOP as the sole source of hydraulic system to meet the flow rate requirements on vehicle launching state, since the MOP is removed. The EOP speed can be adjusted according to the flow rate demand of the hydraulic system, and much of energy consumptions can be reduced compared with MOP for its speed is coupled with engine speed [20]. The research object of this paper is the development of oil pump motor and the research of sensor-less control in EOP.…”

Section: Introductionmentioning

confidence: 99%

Electric oil pump design of hybrid continuously variable transmission

Liu

Zhou

et al. 2019

IET Electric Power Applications

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An electric oil pump (EOP) must be used to supply oil for actuators in the hybrid continuously variable transmission (CVT) on the launch state of vehicle. To develop this EOP, the current CVT-based hybrid schemes and the use of EOP on traditional automatic transmissions are analysed. Permanent magnet synchronous motor (PMSM) type is chosen as the power source of the developed EOP for its advantages of high efficiency and long-life cycle. The PMSM EOP motor is designed and simulated by ANSYS EM. Based on the parameters of the simulation results, the sensor-less speed controller of the EOP is designed. Then, the model of the EOP and its load CVT hydraulic system are established by Simulink and AMEsim, respectively, for joint simulation. The simulation results show that the EOP can respond to the speed command request quickly, and when the load of the hydraulic system changes it also can keep the speed stable. Finally, based on the developed prototype of EOP and hybrid CVT, the correctness of the developed EOP and its sensorless speed controller are verified by bench test.

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“…By optimizing the structure, hydraulic system and clamping force control strategy of CVT, the transmission efficiency can be significantly improved, while quantitatively indicating whether CVT can save energy. In this paper, an ECVT scheme based on the optimization of both speed ratio control and ratio range of variator is proposed, which aims to improve the overall efficiency of powertrain by taking into account factors such as electric oil pump (EOP) and CVT experimental test [29][30][31]. Table I summarizes the advantages and defects of mainstream technical solutions and the proposed ECVT from different dimensions.…”

Section: Introductionmentioning

confidence: 99%

Study on the Design and Speed Ratio Control Strategy of Continuously Variable Transmission for Electric Vehicle

Liu,

Zhou

et al. 2023

IEEE Access

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In order to develop continuously variable transmission (CVT) suited for electric vehicle (EV), a comparative analysis of the transmission used on EV is introduced in this paper. To solve the problems of traditional CVT used for EV, a newly designed electric CVT (ECVT) is proposed. The final drive ratio, speed ratio range of variator and hydraulic system of ECVT are redesigned for improving the transmission efficiency. Considering that the permanent magnet synchronization traction motor (PMSTM) of EV has an ideal driving characteristic (Constant torque at low speed, constant power at high speed) and wider high efficiency area compared with gasoline engine, the speed ratio control strategy of ECVT is studied again for improving the vehicle driving range and better meeting the requirements of driver. Finally, a simulation test system is fabricated for evaluating the battery energy consumption of an EV equipped with ECVT and single-speed transmission (SST) under constant speed and road drive cycle. The simulation results show that the ECVT proposed can extend the endurance mileage of EV at the speed of 20 to 90km/h, and improve the acceleration performance from 0 to 50km/h. The EV equipped with ECVT showed more advantages compared with SST in urban conditions.

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Hydraulic System Control for a Hybrid Continuously Variable Transmission Based on an Electric Oil Pump

Cited by 15 publications

References 12 publications

Electrohydraulic Power Switching Control for Mechatronics–Electrohydraulic Power Coupling Electric Vehicles Considering Optimal Speed Thresholds

Electrohydraulic Power Switching Control for Mechatronics–Electrohydraulic Power Coupling Electric Vehicles Considering Optimal Speed Thresholds

Electric oil pump design of hybrid continuously variable transmission

Study on the Design and Speed Ratio Control Strategy of Continuously Variable Transmission for Electric Vehicle

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