Hybrid Vehicle Battery Over Discharge Prevention Controller
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Solution Overview
Problem
Hybrid electric vehicles face battery discharge issues when the engine clutch slips, leading to a battery charge disable state and reduced drivability, especially on uphill roads where frequent slippage occurs, causing the battery State of Charge (SOC) to drop below a certain level, which can prevent the vehicle from running on engine power alone.
Innovation Solution
A controller method that detects road gradients and engine clutch states to implement torque reserve control, preventing battery discharge when the SOC is below a certain threshold during engine clutch slip on uphill roads, using a combination of road gradient, clutch driving state, and battery SOC to maintain the SOC level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the engine clutch operates in Slip state to switch between EV mode and HEV mode, then the vehicle can flexibly switch power sources, but the battery enters charge disable state and SOC drops below certain level
Solution Approach 1:
The controller performs preliminary action by detecting the Slip state of the engine clutch before the battery SOC drops below the threshold, and preemptively controls the engine torque to prevent over-discharge. This advance detection and control ensures the battery maintains adequate charge while allowing clutch slip operation for power source switching.
Solution Approach 2:
The controller continuously monitors the battery SOC level and engine clutch state, using feedback from these sensors to dynamically adjust engine torque output. When the clutch is in Slip state and SOC approaches the threshold, the feedback mechanism triggers torque reserve control to prevent further discharge, resolving the contradiction between clutch flexibility and battery reliability.
2Adaptability or versatility
If the engine clutch slips frequently on uphill roads, then the vehicle can maintain power source switching capability, but the battery SOC drops below certain level causing driving disablement
Solution Approach 1:
The controller detects uphill road conditions combined with engine clutch Slip state and preemptively applies torque reserve control before the battery SOC drops below the threshold. This preliminary intervention prevents the vehicle from entering a disabled state while maintaining the ability to switch power sources on demanding uphill terrain.
Solution Approach 2:
The controller applies preliminary anti-action by opposing the natural discharge tendency of the battery during frequent clutch slip on uphill roads. Through torque reserve control, the system counteracts the discharge effect before it can cause driving disablement, preserving both power source switching capability and vehicle drivability.
3Use of energy by moving object
If the battery SOC is allowed to discharge freely during engine operation, then the battery can provide necessary power, but the SOC drops below certain level causing hybrid vehicle driving to be disabled
Solution Approach 1:
The controller dynamically changes the torque parameter based on battery SOC level and engine clutch state. When SOC approaches the threshold during Slip state operation, the torque parameter is adjusted to reserve capacity, preventing the battery from discharging into the disabled range while still providing necessary power for hybrid operation.
Solution Approach 2:
The system employs dynamic control where the engine torque output is continuously adjusted based on real-time monitoring of battery SOC and clutch state. This dynamic response allows the battery to discharge freely when adequate charge remains, while automatically applying torque reserve control when SOC approaches critical levels, maintaining hybrid vehicle operability throughout the discharge cycle.
Data Source
AI summary
A method for preventing over discharge of a battery includes steps of: detecting a gradient of a road on which a vehicle is running by a controller, when a battery is discharged under a state that an engine of the running vehicle is operated, detecting a clutch driving state of an engine clutch, which connects or disconnects the engine and an electric motor, after detecting the road gradient, detecting a SOC (State of Charge) of the battery after detecting the clutch driving state of the engine clutch, and carrying out a torque reserve control allowing more torque to be reserved in the engine, using a combination of the road gradient, the clutch driving state, and the battery SOC, such that the battery SOC is not lowered below a certain amount.