Predictive SOC Control for Plug-in Hybrid Vehicle Powertrain
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Solution Overview
Problem
In plug-in hybrid vehicles, the existing control systems unnecessarily switch to HV operation when the battery's SOC falls below a threshold, increasing the cost per unit distance due to excessive use of the electric power generation system.
Innovation Solution
A control system that uses an electronic control unit to predict the SOC of the battery and continue EV operation if the predicted SOC remains above a certain threshold, switching to HV operation only when necessary to prevent excessive battery depletion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the HV operation is simply started when the SOC of the battery falls below the threshold value, then the battery is charged from the electric power generation system and the SOC of the battery rises, but the cost required for the vehicle to run by a unit distance increases
Solution Approach 1:
The electronic control unit performs preliminary calculation of the EVSOC predicted value based on current battery capacity, consumption rate, and remaining distance before making the operation switch decision. This preliminary assessment allows the system to anticipate future SOC levels and make informed decisions about when to switch from EV operation to HV operation, avoiding unnecessary HV operation when EV operation can suffice.
Solution Approach 2:
The control system dynamically adjusts the operation mode based on real-time conditions including current SOC, calculated EVSOC predicted value, and threshold comparisons. The system transitions from a static threshold-based control to a dynamic predictive control that adapts to varying battery capacity, consumption rates, and travel distances, optimizing the balance between reliability and energy cost.
2Use of energy by moving object
If the EV operation is continued until the SOC becomes excessively low, then the cost per unit distance is reduced, but the battery may be depleted below safe operating levels
Solution Approach 1:
The electronic control unit continuously monitors the current SOC level and compares it against the calculated EVSOC predicted value and the second threshold value. This feedback mechanism ensures that when the predicted SOC would fall below the safe threshold, the system automatically switches to HV operation to recharge the battery, preventing depletion while minimizing unnecessary HV operation.
3Device complexity
If a simple threshold-based control is used, then the control system is simple, but the cost efficiency deteriorates due to excessive HV operation
Solution Approach 1:
The system introduces a new calculated parameter (EVSOC predicted value) derived from existing parameters (battery capacity, consumption rate, remaining distance) to enhance decision-making. This parameter change allows the system to evaluate future SOC levels without adding complex hardware, maintaining control system simplicity while improving cost efficiency through predictive operation mode selection.
Data Source
AI summary
A control system includes a motor-generator, an electric power generation system, and a battery. An EV operation, in which the electric motor is operated while the electric power generation system is stopped, is performed, when an SOC of the battery is higher than a first value, and an HV operation, in which the electric motor is operated while the electric power generation system is operated, is performed, when the SOC is lower than the first value. At the time of the EV operation, in response to a predicted value of the SOC being equal to or higher than a second set value which is lower than the first set value, the EV operation is continued even if the SOC falls below the first value. The predicted value is a predicted value of the SOC assuming continuation of the EV operation from a current location to a destination.