EV Motor Mode Control Under Battery SOC Limits
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Solution Overview
Problem
Battery electric vehicles face limitations in driving experience due to state of charge (SOC) constraints, which restrict supplied and regenerative power, hindering the ability to switch between driving modes like a manual transmission vehicle and a normal electric vehicle without spoiling the driving experience.
Innovation Solution
A battery electric vehicle system with an electric motor, accelerator pedal, shifter, mode selector, and control device that adjusts motor output based on SOC, allowing selective driving modes and limiting modes when SOC is out of range to maintain consistent acceleration and deceleration feelings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the driver selects MT mode to drive like a manual transmission vehicle, then the driving experience like MT vehicle is improved, but the SOC may become close to overcharge or overdischarge region causing power limitation that spoils the driving experience
Solution Approach 1:
The control device dynamically switches between MT mode and EV mode based on real-time SOC conditions. When SOC is within the predetermined range, MT mode is enabled for authentic manual transmission driving experience. When SOC approaches overcharge or overdischarge regions, the system automatically transitions to EV mode to maintain power supply stability, thus adapting the driving mode to current battery conditions.
Solution Approach 2:
The control device acts as an intermediary between the driver's mode selection and the actual motor control. Even when the driver selects MT mode, the control device mediates by forcibly switching to EV mode when SOC conditions require it, thereby protecting the battery while maintaining the illusion of driver control through appropriate notifications.
2Reliability
If the supplied power and regenerative power are controlled with reference to SOC, then the battery is protected from overcharge and overdischarge, but the driving experience is spoiled when power is limited due to SOC constraints
Solution Approach 1:
The system dynamically adjusts power control strategy based on SOC levels. When SOC is within the predetermined range, the system allows full MT mode operation with minimal power limitations. When SOC approaches critical thresholds, the system transitions to EV mode with SOC-aware power control, ensuring battery protection while maintaining acceptable driving experience through smooth power delivery.
3Adaptability or versatility
If the driver wants to drive like an MT vehicle with manual operation, then the MT driving experience is improved, but the SOC limitations restrict the accelerator pedal operation and shifter usage
Solution Approach 1:
The control device dynamically adapts the responsiveness of accelerator pedal and shifter operations based on SOC conditions and selected mode. In MT mode with adequate SOC, full operational range is permitted. When SOC becomes critical, the system dynamically restricts operational ranges in EV mode while maintaining the interface elements, allowing the driver to retain control over the interface while experiencing softened power delivery that protects the battery.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables drivers to enjoy both MT and EV driving experiences while minimizing disruptions from SOC limitations, ensuring consistent acceleration and deceleration by controlling motor output based on SOC conditions.
Implementation Method 1
uses as a traction power unit an electric motor configured to run on power supplied from a battery and stores regenerative power in the battery
Data Source
AI summary
A battery electric vehicle includes an accelerator pedal, a shifter, a mode selector, and a control device. The mode selector selects either an EV mode or an MT mode as a control mode for an electric motor according to a mode selection operation by a driver. When the SOC of a battery is within a predetermined range, the control device controls the electric motor in the control mode selected by the mode selector. When the SOC is out of the predetermined range, the control device controls the electric motor in the EV mode regardless of the control mode selected by the mode selector.