Hybrid Powertrain Control for Acceleration With Smaller Motor and Battery
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Solution Overview
Problem
Existing hybrid vehicle systems face challenges in enhancing acceleration performance while minimizing the size and cost of the electric motor and battery.
Innovation Solution
A vehicle control apparatus that includes an electric motor, a transmission, an engine, and a control system. The control system executes different speed modes and assist modes to optimize the torque and output of the electric motor, switching to a higher power assist mode when the accelerator operation exceeds a certain threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the electric motor size and output are increased to enhance acceleration performance, then the acceleration performance is improved, but the vehicle weight and cost increase
Solution Approach 1:
The patent implements dynamic switching between two speed modes (first speed mode with higher speed ratio and second speed mode with lower speed ratio) based on driving conditions. The control system determines whether to use the engine or electric motor as the primary power source by evaluating accelerator operation amount and vehicle speed, dynamically adjusting the powertrain configuration to optimize acceleration performance while avoiding the need for a continuously large electric motor
Solution Approach 2:
The patent changes the operating parameters of the powertrain system by switching between different speed modes and power sources. The control system adjusts the speed ratio of the transmission and the operating state of the electric motor based on driving conditions, allowing the electric motor to operate efficiently in specific regimes rather than requiring high peak power capability across all conditions
2Power
If the electric motor output is increased to enhance acceleration performance, then the acceleration performance is improved, but the battery size and cost increase
Solution Approach 1:
The system dynamically switches between engine-driven mode and electric motor-driven mode based on real-time driving conditions. By using the engine as the primary power source during cruising and low-speed conditions, and only engaging the electric motor for acceleration assistance or when the engine is not operating, the battery only needs to provide supplemental power rather than serving as the primary energy source, significantly reducing battery size requirements
Solution Approach 2:
The powertrain system is designed with multi-functionality where the engine can operate as the primary power source for both propulsion and electric motor charging, while the electric motor provides auxiliary acceleration support. This dual-power-source configuration allows the battery to serve multiple functions (acceleration assistance, regenerative braking energy storage, and engine start-stop support) without requiring large capacity
3Speed
If the transmission speed ratio is set lower to improve acceleration, then the acceleration performance is improved, but the engine operating efficiency decreases
Solution Approach 1:
The control system dynamically selects between first speed mode (higher speed ratio, engine-efficient) and second speed mode (lower speed ratio, acceleration-optimized) based on driving conditions. During steady-state cruising, the system uses the first speed mode to maintain the engine in its efficient operating range. During acceleration requests, the system switches to the second speed mode with lower speed ratio to improve acceleration performance, and supplements with electric motor power to reduce the penalty on engine efficiency
Data Source
AI summary
A vehicle control apparatus includes an electric motor, an engine, and a control system. The control system executes a first speed mode or a second speed mode as a speed mode of the transmission on the basis of a driving operation performed by a driver, sets a speed ratio on a lower side in the second speed mode than in the first speed mode in a case where an accelerator operation performed by the driver is cancelled, executes a first assist mode or a second assist mode as an assist mode in which the electric motor is brought into a power-running state, and switches the assist mode to the second assist mode in a case where the amount of the accelerator operation is increased greater than a starting threshold while the second speed mode is being executed.