Development and Control of an Electric Oil Pump for Automatic Transmission-Based Hybrid Electric Vehicle

Yoo

et al. 2018

Energies

Self Cite

Abstract:What is the best number of gear steps for parallel type hybrid electric vehicles (HEVs) and what are the pros and cons of the power split type HEV compared to the parallel type have been interesting issues in the development of HEVs. In this study, a comparative analysis was performed to evaluate the fuel economy potential of a parallel HEV and a power split type HEV. First, the fuel economy potential of the parallel HEV was investigated for the number of gear steps. Four-speed, six-speed, and eight-speed automatic transmissions (ATs) and a continuously variable transmission (CVT) were selected, and their drivetrain losses were considered in the dynamic programming (DP). It was found from DP results that the power electronics system (PE) loss decreased because the magnitude of the motor load leveling power decreased as the number of gear steps increased. On the other hand, the drivetrain losses including the electric oil pump (EOP) loss increased with increasing gear step. The improvement rate from the 4-speed to the 6-speed was the greatest, while it decreased for the higher gear step. The fuel economy of the CVT HEV was rather low due to the large EOP loss in spite of the reduced PE loss. In addition, the powertrain characteristics of the parallel HEV were compared with the power split type HEV. In the power split type HEV, the PE loss was almost double compared to that of the parallel HEV because two large capacity motor-generators were used. However, the drivetrain loss and EOP loss of the power split type HEV were found to be much smaller due to its relatively simple architecture. It is expected that the power characteristics of the parallel and power split type HEVs obtained from the DP results can be used in the development of HEV systems.

Section: Electric Oil Pumpmentioning

confidence: 99%

A Study on the Fuel Economy Potential of Parallel and Power Split Type Hybrid Electric Vehicles

Yoo

et al. 2018

Energies

Self Cite

“…In addition, a check valve was installed to prevent reverse flow of the hydraulic pressure generated in the MOP to the EOP. 16,17 Line pressure response for the ATF temperature ATF properties Figure 3 shows the physical property test results for the ATF that were used for the six-speed AT in the hybrid vehicle. As shown in Figure 3, the increase in the ATF temperature reduced the density, the kinematic viscosity and the viscosity.…”

Section: Electric Oil Pump Systemmentioning

confidence: 99%

“…16 The EOP and the algorithm were applied to the AMESim hydraulic performance simulator to examine the line response characteristic of the hydraulic control system, and the energy-saving effect of the algorithm was demonstrated by comparing it with other control EOP system algorithms. 16 In this study, a new technology for the control of the EOP for a six-speed AT-based HEV is proposed. The new technology estimates the viscosity factor (VF) which corresponds to the load torque without having to measure the ATF temperature.…”

Section: Introductionmentioning

confidence: 99%

Power-based control of an electric oil pump for an automatic-transmission-based hybrid electric vehicle

Song

Proceedings of the Institution of Mechanical Engineers, Part D:

et al. 2012

Self Cite

A power-based control algorithm for an electric oil pump for a six-speed automatic-transmission-based hybrid electric vehicle was proposed. The new technology estimates the viscosity factor without having to measure the temperature of the automatic transmission fluid and controls the electric oil pump based on the required power. The viscosity factor was determined on a three-dimensional (3D) map by measuring the steady-state line pressure and the power and speed of the electric oil pump. Using the viscosity factor, the electric oil pump was controlled to supply the target line pressure according to the command power that was determined from the 3D viscosity factor-line pressure-power map. To save energy, multi-stage control was suggested which was based on low power, high power and medium power, according to the driving conditions of the vehicle. The test results showed that the proposed control method based on the electric oil pump power properly followed the target line pressure regardless of the change in the temperature of the automatic transmission fluid. In addition, when the line pressure changed owing to the additional flow rate consumption, e.g. during engine clutch engagement, the power-based control method easily followed the line pressure using only the target power, without needing to set the driving speed of the electric oil pump for each temperature. It was also found that control based on the electric oil pump power could save the driving power of the electric oil pump, unlike the situation with speed-based control, considering the product deviations.

Advances in Mechanical Engineering

“…11 Some control algorithms are developed for the EOP control of a twopump system. [12][13][14] They try to reduce the energy consumption of the two-pump system. High-efficiency EOP and MOP have also been developed and applied in automatic transmissions.…”

Section: Introductionmentioning

confidence: 99%

A method of applying two-pump system in automatic transmissions for energy conservation

Dong

Liu

et al. 2015

In order to improve the hydraulic efficiency, modern automatic transmissions tend to apply electric oil pump in their hydraulic system. The electric oil pump can support the mechanical oil pump for cooling, lubrication, and maintaining the line pressure at low engine speeds. In addition, the start-stop function can be realized by means of the electric oil pump; thus, the fuel consumption can be further reduced. This article proposes a method of applying two-pump system (one electric oil pump and one mechanical oil pump) in automatic transmissions based on the forward driving simulation. A mathematical model for calculating the transmission power loss is developed. The power loss transfers to heat which requires oil flow for cooling and lubrication. A leakage model is developed to calculate the leakage of the hydraulic system. In order to satisfy the flow requirement, a flow-based control strategy for the electric oil pump is developed. Simulation results of different driving cycles show that there is a best combination of the size of electric oil pump and the size of mechanical oil pump with respect to the optimal energy conservation. Besides, the two-pump system can also satisfy the requirement of the start-stop function. This research is extremely valuable for the forward design of a twopump system in automatic transmissions with respect to energy conservation and start-stop function.