Vehicle Battery SoH Estimation Using External Server Models
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Solution Overview
Problem
Existing battery management systems in electric and hybrid vehicles provide imprecise estimates of the state of health (SoH) due to limited computing capacity and storage, using simplified models that are not tailored to specific vehicle batteries, leading to inaccurate calculations.
Innovation Solution
A method and system that involves connecting the vehicle battery to a load, measuring predefined parameters, and calculating the state of health on an external server using a vehicle-specific battery model based on complex algorithms, incorporating real-time data and laboratory data, which allows for precise estimation of SoH.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If simplified battery models and algorithms are used in the onboard battery management system, then the computing capacity and storage requirements are reduced, but the measurement precision and reliability of state of health estimation deteriorate
Solution Approach 1:
The patent extracts the complex state of health calculation function from the onboard battery management system and relocates it to an external server. The onboard system only collects and transmits battery parameter data, while the external server performs the computationally intensive calculations using complex battery models, thereby resolving the contradiction between limited onboard computing power and the need for precise state of health estimation.
Solution Approach 2:
The patent introduces an external server as an intermediary between the battery management system and the state of health estimation process. This intermediary receives battery parameter data from the vehicle, performs complex calculations using sophisticated battery models, and returns the state of health results, enabling high-precision estimation without burdening the onboard computing resources.
2Measurement precision
If complex battery models with vehicle-specific parameters are used, then the state of health estimation precision improves, but the device complexity and storage requirements increase
Solution Approach 1:
The patent extracts the complex battery models and their associated parameters from the vehicle's onboard systems and stores them externally on a server. This allows the vehicle to use highly detailed, vehicle-specific battery models without increasing onboard device complexity, as the models are maintained and processed externally.
Solution Approach 2:
The patent implements a two-stage modeling approach where a general battery model is first created, then refined with vehicle-specific parameters through adaptation. This allows the system to use complex models tailored to each vehicle's specific battery characteristics while managing complexity through a systematic parameter adjustment process rather than requiring completely unique models for each vehicle.
Data Source
AI summary
A method for ascertaining the state of health of the vehicle battery of an electric vehicle includes charging the vehicle battery and ascertaining specified battery parameters during the charging process, and calculating the state of health of the vehicle battery using a vehicle-specific battery model on the basis of the transmitted battery parameters. A basic battery model, which is based on the vehicle battery type, in the form of an electric equivalent circuit model is first used as the vehicle-specific battery model, wherein the internal resistance and RC elements are ascertained as a function of the cell temperature and the charge state, an open circuit voltage characteristic is ascertained as a function of the charge state, and the cell temperature is ascertained using a thermal model on the basis of the measured battery pack current, EC parameters, the battery module temperature, and the ambient temperature.