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

Abstract

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.

Development of an electric oil pump control algorithm for an automatic-transmission-based hybrid electric vehicle considering the gear shift characteristics

“…The pump torque cannot be measured but can be estimated from the feedback on the EOP speed, the input voltage and the input current in equation (4). Figure 6 shows the efficiency h e of the EOP electrical units.…”

Electric oil pump design of hybrid continuously variable transmission

“…The most common oil supply solution for CVT is using MOP or MOP plus an auxiliary EOP, for the pressure and flow rate needed for CVT are very high. However, as mentioned in the study [15, 18], the EOP can increase transmission efficiency. Therefore, it is worthwhile to develop an EOP for CVT and conduct‐related research on it.…”

“…Sungkyunkwan University and Hyundai-Kia did the research of using EOP on an AT-based hybrid transmission [14][15][16]. The oil pump motor is a sensor-controlled brushless DC motor.…”

Dynamic Analysis and Control of an Automatic Transmission for Start-Stop Function and Efficiency Improvement

“…However, these studies did not consider an approach for determining the size of the EOP and MOP to derive optimal efficiency. An EOP control algorithm was proposed to reduce energy consumption [8]. In [9], a control method that can keep the powertrain closed when an engine is being restarted to minimize the starting delay was proposed; however, in this control method, the starting delay was minimized at the expense of the starting smoothness.…”