Hybrid Vehicle Mode Switching Control Method
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Solution Overview
Problem
Hybrid electric vehicles face frequent mode switching and inappropriate mode maintenance due to fixed switching conditions, which affect fuel efficiency and drivability, particularly when battery state of charge is high or during non-driving states like coasting.
Innovation Solution
A mode switching method where a hybrid controller determines reference on-power and off-power thresholds, along with minimum and maximum powers, to dynamically control transitions between electric vehicle (EV) and hybrid electric vehicle (HEV) modes, preventing frequent switching and unnecessary mode maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If fixed switching conditions with hysteresis power are used to prevent frequent mode switching, then mode stability is improved, but the system cannot adapt to different battery states and may unnecessarily maintain HEV mode during coasting or when SOC is high
Solution Approach 1:
The patent applies dynamics by making the mode switching conditions variable rather than fixed. The on-power and off-power thresholds are dynamically adjusted based on battery SOC and driving state. When SOC is high, the on-power threshold is increased to prevent unnecessary HEV mode entry. During coasting or APS-off states, the off-power threshold is adjusted to allow EV mode transitions even at higher power levels. This dynamic adjustment resolves the contradiction by maintaining stability through consistent adjustment logic while adapting to different operational contexts.
Solution Approach 2:
The patent changes the parameters of mode switching conditions based on operational state. Specifically, the on-power and off-power thresholds are modified according to battery SOC levels and driving state (accelerator pedal position, coasting detection). When SOC exceeds a reference value, the on-power threshold is raised. During coasting or APS-off states with high SOC, the off-power threshold is also adjusted. This parameter change approach allows the system to maintain stable switching behavior while adapting to varying battery states and driving conditions.
2Ease of operation
If hysteresis power is lowered to guide switching to EV mode from HEV mode, then EV mode transition is improved, but frequent switching may occur when driver requested power fluctuates near the threshold
Solution Approach 1:
The patent applies dynamics by making the hysteresis power variable rather than fixed. The effective hysteresis is dynamically adjusted based on driving state. During coasting or APS-off states with high SOC, the system allows easier transition to EV mode by adjusting the off-power threshold. During normal driving, the hysteresis is maintained at appropriate levels to prevent frequent switching. This dynamic adjustment resolves the contradiction by providing easy EV transition when appropriate while maintaining stability during normal operation.
3Loss of energy
If on-power threshold is raised to prevent HEV mode entry when SOC is high, then fuel efficiency is improved, but the system may fail to respond adequately when driver requested power increases
Solution Approach 1:
The patent applies dynamics by making the on-power threshold variable based on battery SOC and driving state. When SOC is high and the vehicle is in coasting or APS-off state, the raised on-power threshold prevents unnecessary HEV mode entry, improving fuel efficiency. However, when driver requested power increases beyond certain thresholds or when SOC decreases, the threshold is adjusted to allow HEV mode entry, ensuring adequate power delivery responsiveness. This dynamic adjustment resolves the contradiction by optimizing fuel efficiency when appropriate while maintaining power delivery capability when needed.
Data Source
AI summary
A mode switching method of a hybrid vehicle includes: determining a reference on-power as a reference for switching from a first mode to a second mode and a reference off-power as a reference for switching from the second mode to the first mode; determining a minimum on-power, a minimum off-power, and a maximum off-power; and determining a final on-power and a final off-power using the reference on-power, the reference off-power, the minimum on-power, the minimum off-power, and the maximum off-power.