Hybrid Vehicle ISG Torque Control Using Temperature-Based Loss Torque
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Solution Overview
Problem
In hybrid electric vehicles, the inaccuracy in engine loss torque estimation leads to poor torque control precision and unstable engine start conditions, affecting the smooth operation of the integrated starter generator motor (ISG motor).
Innovation Solution
A control method that determines engine start conditions by obtaining engine oil and cooling liquid temperatures, using a correspondence table to calculate work loss torque, and adjusting the ISG motor's torque control based on these values to improve accuracy and smoothness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed loss torque value is used in engine start control, then the control process is simple, but the accuracy of engine start control deteriorates due to the large difference between used loss torque and actual loss torque
Solution Approach 1:
The patent applies dynamics by transitioning from a static fixed loss torque value to a dynamic adaptive loss torque determination method. The loss torque is dynamically adjusted based on real-time engine operating conditions including oil temperature, cooling liquid temperature, and engine speed, allowing the control system to adapt to varying operational states and improve accuracy without excessive complexity
Solution Approach 2:
The patent implements parameter changes by modifying the loss torque parameter based on multiple operating parameters. The loss torque is recalculated according to oil temperature, cooling liquid temperature, and engine speed parameters, enabling the system to account for environmental and operational variations that affect actual loss torque
2Measurement precision
If the loss torque is accurately determined by considering multiple parameters, then the engine start control accuracy is improved, but the device complexity increases due to additional sensors and control logic
Solution Approach 1:
The patent applies universality by making the existing engine control unit perform multiple functions. The ECU not only controls engine operation but also determines loss torque by integrating data from existing sensors (oil temperature sensor, cooling liquid temperature sensor, speed sensor), eliminating the need for separate dedicated hardware while achieving accurate loss torque determination
Solution Approach 2:
The system applies self-service by utilizing the engine's own existing sensors and control infrastructure to determine loss torque. The control unit uses data already being collected for engine operation (temperature, speed parameters) to calculate loss torque, making the system self-sufficient without requiring external or additional specialized components
3Stability of the object's composition
If the ISG motor torque control is adjusted based on accurate loss torque, then the working smoothness of ISG motor is improved, but the control complexity increases
Solution Approach 1:
The patent implements feedback by continuously monitoring engine operating parameters (oil temperature, cooling liquid temperature, engine speed) and using this feedback to adjust the loss torque determination and ISG motor torque control. This closed-loop approach ensures the ISG motor operates smoothly under varying conditions while maintaining manageable control complexity through systematic feedback integration
Data Source
AI summary
A method for controlling engine start of a hybrid electric vehicle, includes: determining whether an engine start condition is satisfied; in response to that the engine start condition is satisfied, obtaining an engine oil temperature and an engine cooling liquid temperature; searching a correspondence according to the engine oil temperature and the cooling liquid temperature, to obtain a work loss torque of an engine, wherein the correspondence comprises engine oil temperatures, cooling liquid temperatures, and loss torques; and controlling an integrated starter generator (ISG) motor of the hybrid electric vehicle according to the work loss torque, to start the engine.