Hybrid Vehicle Shift Control Torque Prediction
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Solution Overview
Problem
Hybrid electric vehicles face challenges in minimizing fuel efficiency loss during shift intervention due to limitations in power generation capacity and prediction accuracy, leading to reduced engine efficiency and passenger discomfort from torque disconnectness.
Innovation Solution
A method for predicting torque and RPM at shift times, determining if motor-only intervention is feasible, and redistributing torque to minimize engine involvement, using a control system with multiple units to accurately predict and execute shift interventions, thereby optimizing torque distribution between the engine and motor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the electric motor alone performs shift intervention, then fuel efficiency is improved by minimizing engine involvement, but the power generation capacity of the motor is limited and may not satisfy intervention requirements
Solution Approach 1:
The control system predicts the quantity of intervention required before the shift intervention occurs. Based on this prediction, the system determines in advance whether the motor alone can satisfy the intervention requirements, allowing proactive torque redistribution or engine involvement planning to avoid power deficiency during actual intervention
Solution Approach 2:
The system continuously monitors motor RPM, torque, and battery state of charge during shift intervention, comparing actual motor performance against predicted intervention requirements. This feedback loop enables real-time adjustment of intervention strategy, determining whether additional engine torque is needed when motor power becomes insufficient
2Power
If the engine is involved in shift intervention through torque reduction, then intervention capability is improved, but fuel efficiency deteriorates due to engine efficiency loss
Solution Approach 1:
The system implements partial engine involvement only when necessary. By predicting intervention requirements and comparing with motor capability, the engine is engaged at minimal levels (partial action) only for the duration and magnitude needed to satisfy intervention requirements, avoiding excessive engine involvement that would cause unnecessary fuel efficiency loss
Solution Approach 2:
The control system dynamically adjusts engine torque parameters during shift intervention based on predicted requirements and actual vehicle state. By changing torque magnitude and duration parameters precisely, the system achieves sufficient intervention capability while minimizing fuel efficiency deterioration through optimized engine operation parameters
3Speed
If the motor RPM and engine RPM are significantly different, then the engine clutch cannot be closed for simultaneous rotation, but this creates torque disconnectness and passenger discomfort
Solution Approach 1:
The control system predicts motor RPM at shift time and compares it with engine RPM before attempting clutch engagement. This preliminary RPM assessment allows the system to determine in advance whether RPM synchronization conditions are met, preventing clutch engagement attempts that would cause torque disconnectness and passenger discomfort
Solution Approach 2:
The engine clutch acts as an intermediary element that requires RPM synchronization for proper engagement. By monitoring and comparing motor and engine RPM as intermediary parameters, the control system ensures synchronization conditions are satisfied before clutch closure, thereby maintaining torque continuity and passenger comfort during mode transitions
Data Source
AI summary
Disclosed are a hybrid electric vehicle which may minimize fuel efficiency loss by shift intervention, and a method of controlling shift thereof. The method of controlling shift of the hybrid electric vehicle includes predicting torque of an input terminal of a transmission at a shift time, predicting an RPM of a motor at the shift time, predicting a quantity of intervention using the predicted torque of the input terminal of the transmission and the predicted RPM of the motor, determining whether or not intervention using the motor alone at the shift time is feasible based on the predicted quantity of intervention, and executing shift corresponding to a result of the determination.