Hybrid Vehicle Engine Control for SOC Threshold Management
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Solution Overview
Problem
Hybrid vehicles face discomfort and inefficiency when the internal combustion engine operates during vehicle stops to charge the power storage device, as frequent start-stop cycles occur, and charging at low power states is inefficient.
Innovation Solution
A control system that adjusts the start and stop conditions of the internal combustion engine based on the charged state of the power storage device, using threshold values to minimize engine operation duration during vehicle stops and optimize charging, with different settings for running and non-running modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the internal combustion engine operates during vehicle stop to charge the power storage device, then the charged state of the power storage device is recovered, but user discomfort increases due to frequent start-stop cycles
Solution Approach 1:
The patent applies dynamics by making the engine control strategy adaptable to different driving conditions. The control device dynamically adjusts engine start/stop decisions based on detected vehicle state (running vs. stopped) and power storage device charged state, transitioning between different control modes to balance charging needs with user comfort
Solution Approach 2:
The patent changes control parameters (engine start/stop conditions) based on the vehicle's operational state. When the vehicle is running, the control device permits engine operation for charging even at lower SOC thresholds, whereas when stopped, it maintains higher SOC thresholds to avoid frequent cycling, thereby adapting parameters to operational context
2Reliability
If the internal combustion engine operates at low power state during vehicle stop for charging, then the power storage device is charged, but charging efficiency decreases
Solution Approach 1:
The control device changes the operational parameters of the engine based on vehicle state. When running, the engine can operate at higher power states with better efficiency for charging. When stopped, the control device raises the SOC threshold to minimize operation duration, accepting lower efficiency only when necessary
3Reliability
If the engine start condition is set to allow frequent charging, then the power storage device charged state is maintained, but the number of start-stop cycles increases causing user discomfort
Solution Approach 1:
The control device dynamically adjusts the engine start condition threshold based on vehicle state. When the vehicle is stopped, it sets a higher SOC threshold (e.g., 50%) compared to when running (e.g., 30%), making the start condition less likely to be met during stops and thereby reducing the frequency of engine cycles
Solution Approach 2:
The patent changes the critical parameter (SOC threshold for engine start) based on operational context. By raising this threshold when the vehicle is stopped, the control device reduces the number of times the engine needs to start, thereby reducing total operation duration and improving user comfort
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
The system reduces user discomfort by minimizing engine operation during stops while maintaining power storage device charge levels, improving efficiency by optimizing engine operation based on selected vehicle modes.
Implementation Method 1
The at least one motor has an electric power generation function in which the motor is driven by the internal combustion engine to supply electric power to the power storage device
Data Source
AI summary
A motor generator and a power converter are driven by an engine, to supply electric power to a power storage device. ECU causes the engine to start if SOC of the power storage device falls below a first threshold value, and causes the engine to stop if SOC exceeds a second threshold value which is larger than the first threshold value. In the case where a running range has been selected when the vehicle stops, ECU causes the engine to stop if SOC exceeds a third threshold value which is larger than the first threshold value and smaller than the second threshold value. In the case where a non-running range has been selected, ECU causes the engine to stop if SOC exceeds the second threshold value.