Hybrid Vehicle Motor Torque Limit Control for Engine Estimation Error
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Solution Overview
Problem
Conventional hybrid vehicles experience deviations in actual output torque of the electric motor due to discrepancies between estimated and actual engine output torque, leading to unintended acceleration or deceleration states.
Innovation Solution
A hybrid vehicle system that includes an engine, electric motor, battery, and a controller that sets upper and lower torque limits for the electric motor based on operational conditions to maintain a permissible range, controlling the electric motor's output torque within these limits to align with driver requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the controller controls the electric motor based on the difference between the torque command and the estimated output torque of the engine, then the control system is simple and easy to implement, but the actual output torque of the electric motor deviates from the actually required motor torque when the estimated output torque deviates from the actual output torque of the engine
Solution Approach 1:
The controller dynamically adjusts the torque command for the electric motor based on real-time operational conditions (vehicle speed, accelerator pedal position, engine load). This dynamic adjustment compensates for deviations in estimated engine torque and ensures the actual motor torque matches driver requirements, resolving the contradiction between simple control and accurate torque delivery
Solution Approach 2:
The controller changes the torque command parameter within a calculated range (from lower limit torque to upper limit torque) based on operational conditions. This parameter adjustment allows the system to maintain reliable torque control despite uncertainties in engine torque estimation, achieving both simplicity and accuracy
2Device complexity
If the controller sets a fixed torque command for the electric motor, then the control logic is simple, but the acceleration state and deceleration state of the hybrid vehicle become unintended by the driver when engine torque estimation deviates
Solution Approach 1:
The controller implements dynamic torque command adjustment based on operational conditions including vehicle speed, accelerator pedal position, and engine load. This dynamic approach ensures that the electric motor torque adapts to driver intentions and vehicle state, maintaining natural acceleration and deceleration characteristics while keeping control logic relatively simple
Solution Approach 2:
The controller uses feedback from operational conditions (vehicle speed, accelerator pedal position, engine load) to continuously adjust the torque command range. This feedback mechanism ensures the electric motor torque aligns with driver intent and vehicle state, preventing unintended acceleration or deceleration while maintaining manageable control complexity
Data Source
AI summary
A hybrid vehicle of the present disclosure includes an engine connectable to a drive shaft, an electric motor connectable to the drive shaft, a battery that exchanges electric power with the electric motor, and a controller that sets an upper limit torque and a lower limit torque of the electric motor such that a difference between a torque command indicating a torque to be output to the drive shaft and an actual torque output to the drive shaft is within an allowable range based on an operational condition of the hybrid vehicle, and controls the electric motor to output a torque based on a difference between the torque command and an estimated output torque of the engine within a range from the lower limit torque to the upper limit torque.