Hybrid Vehicle Control System for Low SOC and Altitude Stability
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Solution Overview
Problem
Hybrid vehicles face challenges in maintaining optimal operating conditions, particularly in low State Of Charge (SOC) and high altitude conditions, leading to inefficient energy use, excessive battery discharge, and uncomfortable vibrations during uphill driving in HEV mode.
Innovation Solution
A control system for hybrid vehicles that detects driving requests and SOC, adjusts motor and engine operating points based on incline and atmospheric pressure, maintaining low shift speeds and limiting charging to enhance stability and comfort, while prohibiting compensation in low atmospheric pressure to prevent excessive battery discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If engine power is delivered for charging the battery and for driving the vehicle simultaneously in low SOC conditions, then the battery charging requirement is satisfied, but the engine operates in low RPM resulting in bad vibration characteristics with high torque
Solution Approach 1:
The control system dynamically adjusts the shift speed based on real-time operating conditions including SOC level, vehicle speed, and driving mode. In low SOC conditions during HEV mode, the system selectively maintains low shift speed to keep engine RPM low and reduce vibration, while still enabling battery charging through optimized power distribution. This dynamic adjustment resolves the contradiction by making shift speed adaptive rather than fixed.
Solution Approach 2:
The system changes the shift speed parameter based on operating conditions. Specifically, in low SOC conditions during HEV mode, the system maintains low shift speed to reduce vibration while still achieving battery charging through optimized power management. This parameter change allows the system to satisfy charging requirements without suffering from high vibration characteristics.
2Ease of operation
If the motor operating point is compensated to satisfy driver requirements in low atmospheric pressure, then the driver requirements are met, but the real output torque of the engine is lower than optimal resulting in excessive battery discharge
Solution Approach 1:
The control system incorporates feedback from atmospheric pressure sensors and battery SOC monitoring to adjust motor operating point compensation. In low atmospheric pressure conditions, the system moderates compensation to prevent excessive battery discharge, while still meeting driver requirements through coordinated engine-motor power management. This feedback mechanism resolves the contradiction by adapting compensation levels to actual operating conditions.
Solution Approach 2:
The system changes the motor operating point compensation parameter based on atmospheric pressure conditions and battery SOC levels. In low atmospheric pressure, the system reduces compensation magnitude to prevent excessive battery discharge, while maintaining adequate driver requirement satisfaction through optimized power distribution. This parameter adaptation resolves the energy loss issue.
Data Source
AI summary
The present invention relates to a control system and a method for a hybrid vehicle which may optimally control the operating point of a vehicle. A control method for a hybrid vehicle includes detecting driving requests and a state of charge (SOC) of a battery when the vehicle is driving in HEV mode, determining a motor operating point and an engine operating point when the battery is in low SOC state, and compensating the motor operating point and the engine operating point by applying a climbing degree of the vehicle and the atmospheric pressure.