Charge Depleting Mode Shift Control for Plug-in Hybrid Vehicles
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Solution Overview
Problem
In plug-in hybrid vehicles, the charge depleting mode fails to minimize fuel consumption during shift-speed changes, as existing systems do not adequately consider motor and transmission efficiencies, leading to inefficient energy use.
Innovation Solution
A control apparatus and method that determines shift-speed by calculating system efficiency using transmission and motor efficiencies, and compares it with mechanical loss rates to optimize shift-speed changes, ensuring that the vehicle operates in the most efficient mode based on battery state of charge and required torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If shift-speed is determined according to engine efficiency only (conventional method), then the control system is simple, but fuel consumption is not minimized in charge depleting mode
Solution Approach 1:
The patent changes the efficiency parameter from engine efficiency only to system efficiency that incorporates both motor efficiency and transmission efficiency. This parameter expansion allows the system to optimize for fuel consumption in charge depleting mode by considering the actual energy flow path through the motor and transmission, rather than relying solely on engine efficiency maps that are irrelevant when the engine is off.
2Loss of energy
If shift-speed changes are performed without considering mechanical loss rates, then the shifting control is simple, but energy loss during shifting increases
Solution Approach 1:
The patent introduces feedback control by calculating mechanical loss rates associated with shift-speed changes and using this information to determine whether to execute the shift. The system compares the efficiency gain from shifting against the mechanical loss that would occur during the shift event, creating a feedback loop that prevents unnecessary shifts and minimizes energy loss while maintaining relatively simple control logic.
3Loss of energy
If the vehicle operates without optimizing shift-speed in charge depleting mode, then the control logic is simple, but system efficiency deteriorates
Solution Approach 1:
The patent applies dynamics by making the shift-speed determination adaptive to the operating mode. In charge depleting mode, the system dynamically calculates system efficiency using motor and transmission efficiency data to determine optimal shift points. In charge sustaining mode, it reverts to conventional engine efficiency-based control. This dynamic adaptation optimizes system efficiency in charge depleting mode while maintaining simplicity in other modes.
Data Source
AI summary
A charge depleting mode control apparatus of a plug-in hybrid vehicle includes a driving information detector, a mode determining unit, a shift-speed determining unit, a shift determining unit. The driving information detector detects driving information of a vehicle. The mode determining unit determines whether a charge depleting (CD) mode is entered by using a state of charge (SOC) of a battery provided from the driving information detector. The shift-speed determining unit determines a target shift-speed when the mode determining unit determines to enter the CD mode. The shift determining unit determines whether to change the shift-speed determined by the shift-speed determining unit. The shift-speed is determined by using transmission efficiency and motor efficiency when the plug-in hybrid vehicle drives in the CD mode, such that fuel consumption is reduced and performance is improved.