Hybrid Vehicle Torque Control for Engine Stall Prevention
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Solution Overview
Problem
Hybrid vehicles experience engine stalls during battery-less drives due to increased torque requirements, which can disrupt both vehicle operation and auxiliary machinery power supply.
Innovation Solution
The hybrid vehicle employs a control system that adjusts the torque output of the first motor when the engine rotation speed drops below a predetermined threshold, reducing the absolute torque value to prevent engine stalls by autonomously controlling the engine and motors to maintain stable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the torque of the first motor is increased to meet the required torque when the accelerator pedal is pressed down, then the driving force required for the run is improved, but the rotation speed of the engine decreases and may cause an engine stall
Solution Approach 1:
The control device dynamically adjusts the torque output of the first motor based on real-time engine rotation speed feedback. When the engine rotation speed approaches the stall threshold, the control device automatically reduces the torque command to the first motor, creating a dynamic balance between meeting power requirements and preventing engine stall during battery-less drive operation.
2Speed
If the absolute value of the torque of the first motor is increased to suppress engine rotation speed increase, then the engine rotation speed control is improved, but the engine stall occurs due to insufficient engine output
Solution Approach 1:
The control device implements a feedback mechanism that continuously monitors engine rotation speed during battery-less drive. When the rotation speed exceeds the predetermined threshold, the control device adjusts the torque command to the first motor to bring the rotation speed back within the safe range, preventing both excessive speed and subsequent stall conditions.
3Stability of the object's composition
If the torque of the first motor is adjusted to maintain engine rotation speed, then the engine operation stability is improved, but the driving force for the hybrid vehicle is reduced
Solution Approach 1:
The control device changes the torque parameter of the first motor based on the engine rotation speed condition. During battery-less drive, when engine rotation speed approaches the stall threshold, the torque parameter is adjusted to a safer value, prioritizing engine operation stability over maximum driving force output.
Data Source
AI summary
The hybrid vehicle performs battery-less drive control to control an engine such that the engine is autonomously operated at an autonomous operation rotation speed, to control a first motor such that a torque based on a driving force required for a run of the hybrid vehicle is output from the first motor, and to control a second motor such that an electric power by subtracting an auxiliary machinery power from an electric power charged or discharged by the first motor is charged or discharged by the second motor. During the battery-less drive control, when a rotation speed of the engine becomes lower than a first predetermined rotation speed that is lower than the autonomous operation rotation speed, the hybrid vehicle performs torque adjustment control to decrease an absolute value of the torque output from the first motor.