Hybrid Vehicle Mode Change Hysteresis Control
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Solution Overview
Problem
Hybrid electric vehicles experience frequent mode changes between EV and HEV modes due to fluctuating driver demand power, leading to inefficient engine operation and reduced fuel efficiency, as existing solutions like hysteresis lines fail to stabilize mode changes effectively.
Innovation Solution
A method and apparatus that adjust the mode change hysteresis line based on stable demand power levels, raising it when demand is above a threshold and lowering it when demand is below another threshold, to optimize mode changes and prevent frequent HEV mode activations, thereby improving engine efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a hysteresis line is applied to the mode change reference point, then frequent mode changes are prevented, but the demand power fluctuates and causes inefficient engine operation
Solution Approach 1:
The hysteresis line is made dynamically adjustable rather than fixed. The control unit raises the hysteresis line when demand power is stably maintained above a threshold and lowers it when demand power drops below another threshold. This dynamic adjustment allows the system to adapt to changing driving conditions, preventing frequent mode changes during stable high-demand periods while avoiding inefficient engine operation during low-demand periods.
Solution Approach 2:
The key parameter being changed is the hysteresis line level itself. By varying this parameter based on demand power thresholds, the system optimizes the balance between mode change stability and engine efficiency. The parameter changes allow the mode change reference point to adapt to different operating conditions, resolving the contradiction between preventing frequent changes and maintaining efficiency.
2Loss of energy
If the mode change reference point is lowered to prevent inefficient engine operation, then fuel efficiency improves, but frequent mode changes occur when demand power fluctuates
Solution Approach 1:
The system implements feedback control by continuously monitoring demand power and adjusting the hysteresis line accordingly. When demand power is stably above a threshold, the feedback mechanism raises the hysteresis line to prevent frequent mode changes. When demand power drops below another threshold, the feedback lowers the hysteresis line to prevent inefficient engine operation. This feedback loop resolves the contradiction by making the reference point adaptive rather than static.
Solution Approach 2:
The mode change reference point becomes dynamic through the adjustable hysteresis line. Rather than using a fixed low reference point that causes frequent changes during fluctuations, the system dynamically adjusts the reference point based on stable demand power levels, achieving both fuel efficiency and mode change stability.
3Stability of the object's composition
If a fixed hysteresis line is used to stabilize mode changes, then mode stability improves, but it cannot adapt to stable high demand power conditions leading to inefficient engine operation
Solution Approach 1:
The hysteresis line transitions from a fixed value to a dynamic, adjustable parameter. The control unit modifies the hysteresis line level based on whether demand power is stably maintained above or below specific thresholds. This dynamic behavior enables the system to adapt to different demand power conditions while maintaining mode change stability within each condition.
Solution Approach 2:
The system changes the hysteresis line parameter in response to demand power conditions. When demand power is stably high, the parameter is raised to maintain stability. When demand power is low, the parameter is lowered to prevent inefficient operation. This parameter adaptation resolves the contradiction between stability and adaptability.
Data Source
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AI summary
An apparatus and a method are provided for controlling a mode change of a hybrid electric vehicle that change a mode of the hybrid electric vehicle at an optimal reference point of mode change when a demand power of a driver is stably maintained to be greater than a predetermined level. The method includes calculating (S10) a demand power or a demand torque of a driver and determining (S20) whether the demand power or the demand torque is maintained to be equal to or greater than a first predetermined value for a first predetermined time. A mode change hysteresis line is raised (S30) when the demand power or the demand torque is maintained to be equal to or greater than the first predetermined value for the first predetermined time and then a mode change is executed based on the raised mode change hysteresis line.