Vehicle Start-Stop Thermal Protection via Virtual Temperature Estimation
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Solution Overview
Problem
Existing automatic start/stop systems for vehicles face challenges in accurately predicting and preventing overheating of the starter-alternator, leading to potential system unavailability and increased costs due to imprecise temperature estimation methods.
Innovation Solution
A method that estimates the current temperature of the electronic power module and stator of the alternator-starter using a combination of real temperature measurements and rotation speed values, with parameters from thermal characteristic tables, to inhibit restarts before thermal limits are reached, thereby protecting the system without significant cost increases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If temperature sensors are installed at the switching transistors to accurately measure temperature, then temperature measurement precision is improved, but manufacturing cost increases
Solution Approach 1:
The patent introduces a thermal model as an intermediary that translates easily measurable parameters (ambient temperature, water temperature, rotation speed) into accurate estimates of internal component temperatures. This mediator allows the system to achieve precise temperature monitoring without directly installing sensors at the critical switching transistors, thus resolving the contradiction between measurement precision and manufacturing cost.
Solution Approach 2:
The patent creates a virtual thermal model that copies and simulates the thermal behavior of the power electronic module. Instead of physically measuring temperature at multiple critical points, the system uses a computational model that replicates thermal conditions based on readily available sensor data and operational parameters, achieving accurate temperature estimation without the cost of extensive physical sensor deployment.
2Ease of manufacture
If existing sensors are used to calculate temperature by thermal radiation model, then manufacturing cost is reduced, but temperature estimation precision deteriorates
Solution Approach 1:
The patent performs preliminary calculations during the design phase to establish accurate thermal models and lookup tables that correlate easily measurable parameters with internal temperatures. By pre-computing thermal characteristics and storing them in memory, the system achieves precise real-time temperature estimation using simple sensor readings, thus improving precision without increasing manufacturing cost.
Solution Approach 2:
The patent transforms the temperature measurement problem by changing from direct physical measurement to indirect estimation through a sophisticated computational model. The system uses multiple parameters (ambient temperature, water temperature, rotation speed, operational mode) and processes them through thermal models and lookup tables to derive accurate temperature estimates, thereby achieving high precision through parameter transformation rather than direct measurement.
3Reliability
If the restart function is inhibited when estimated temperature exceeds threshold, then thermal protection is improved, but system availability deteriorates
Solution Approach 1:
The patent implements dynamic temperature threshold management where the inhibition threshold is not fixed but adapts based on real-time conditions such as cooling system status, ambient temperature, and operational history. This dynamic approach allows the system to maintain reliable thermal protection while minimizing unnecessary inhibitions, thus resolving the contradiction between thermal protection reliability and system availability by making the protection mechanism adaptive rather than static.
4Measurement precision
If multiple temperature sensors are installed for accurate temperature monitoring, then temperature measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent replaces the mechanical sensor system with a computational thermal model. Instead of installing multiple physical temperature sensors throughout the power electronic module, the system uses a virtual thermal model that calculates internal temperatures based on easily measurable external parameters and operational data. This substitution eliminates the complexity of installing and managing multiple sensors while maintaining accurate temperature monitoring through mathematical modeling.
Data Source
AI summary
The automatic start/stop system comprises an alternator-starter, an electronic power module and control means that include a control module controlling the electronic power module and an electronic control unit. The control module exchanges information representative of an operating status of the vehicle with the electronic control unit. The method is of the kind in which the control means make a first estimate of a first current temperature (Th_Leadframe) of the electronic power module and determine the inhibition of the restart function when this first estimate is higher than a predetermined first temperature (ThInverterMax). According to the invention, the control means make this first estimate of the first current temperature on the basis of at least one actual measurement (TChip) of the temperature of the control module.