Hybrid Vehicle Engine Speed Control Trajectory Smoothing
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Solution Overview
Problem
In hybrid vehicles, the rapid increase or decrease in engine rotational speed due to the higher responsiveness of the electric motor to the accelerator pedal position leads to an uncomfortable acceleration and deceleration feel for the driver, differing from the intended experience, especially in series hybrid vehicles where the engine is used for power generation.
Innovation Solution
A control method that stores the timing of significant changes in target driving force and calculates an estimated trajectory for engine rotational speed, allowing the engine speed to be controlled based on this trajectory, even when the engine start timing changes due to battery output power, thereby smoothing the rotational speed changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the electric motor's rotational speed is determined responsively to the accelerator pedal position, then the responsiveness to driver input is improved, but the engine rotational speed changes rapidly causing uncomfortable acceleration and deceleration feel
Solution Approach 1:
The control device calculates an estimated trajectory of engine rotational speed in advance based on the amount or factor of change in target driving force. By preparing this trajectory beforehand and storing the timing when change thresholds are exceeded, the system can smoothly guide the engine speed along the pre-calculated path, preventing sudden uncomfortable changes while maintaining responsive acceleration and deceleration behavior.
2Power
If the engine start timing is changed due to battery output power availability, then the power supply to the electric motor is improved, but the engine rotational speed deviates from the ideal trajectory causing uncomfortable feeling
Solution Approach 1:
The control device continuously monitors the actual engine rotational speed and compares it with the pre-calculated estimated trajectory. When the engine starts at different timing due to battery power availability, the feedback mechanism detects the deviation and adjusts the control to guide the engine speed back toward the ideal trajectory, maintaining stability and preventing uncomfortable sensations for the driver.
Data Source
AI summary
A control method for a hybrid vehicle (1) is provided. The hybrid vehicle includes an electric motor (13) that drives the vehicle to travel, a generator (12) that supplies power to the electric motor, and an engine (11) that drives the generator. The control method includes storing the timing at which an amount or factor of change in target driving force (Fd) for the vehicle becomes a predetermined threshold or more, calculating an estimated trajectory of the rotational speed of the engine in accordance with the amount or factor of change in the target driving force, and when an increase request for power generation is issued to the engine at different timing than the timing, controlling the rotational speed of the engine on the basis of the calculated estimated trajectory.