BMS Voltage Measurement Calibration Across Wide Temperature Ranges
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Solution Overview
Problem
Existing battery management systems (BMS) face challenges in accurately measuring high-voltage battery and inverter voltages due to errors in voltage division and sensing resistors, especially in varying temperature environments, which increases component costs and measurement inaccuracies.
Innovation Solution
A BMS with a voltage measurement module that includes multiple voltage measurement units, switch modules, and a control unit to calculate correction amounts using a diagnostic power source, allowing for precise voltage measurement without high-precision resistance elements, and continuously updating correction factors to account for temperature changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If precision resistance elements are used to reduce measurement error, then measurement precision is improved, but component cost increases
Solution Approach 1:
The patent changes the measurement parameters by introducing temperature as a variable factor. It measures resistance at multiple temperatures and calculates temperature coefficients to compensate for temperature-induced measurement errors, thereby achieving high precision without expensive precision resistors
Solution Approach 2:
The system implements feedback by continuously monitoring temperature and using the measured temperature to adjust voltage measurements through calculated correction factors. The control unit stores and applies temperature-specific correction data to compensate for environmental variations
2Measurement precision
If precision resistance elements are used to reduce measurement error, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The system uses itself to calibrate and correct its measurements. By measuring its own resistance values at different temperatures and calculating its own temperature coefficients, the system achieves self-compensation without requiring external precision reference components
Solution Approach 2:
The patent performs preliminary measurements of resistance values at multiple temperatures during system initialization or calibration phase. These preliminary measurements are used to calculate correction factors that are stored and applied during normal operation, preparing the system in advance for temperature variations
3Temperature
If multiple resistors are connected in series to achieve high voltage measurement, then voltage measurement capability is improved, but measurement precision deteriorates due to cumulative error
Solution Approach 1:
The patent changes the approach from relying on resistor precision to measuring and compensating for actual resistance values. By measuring the actual resistance of each series resistor at operating temperatures and calculating their combined temperature coefficient, the system compensates for cumulative errors without requiring individual resistors to be high-precision components
Data Source
AI summary
Provided are a battery management system (BMS) and a battery system capable of accurately measuring a voltage without using a precise resistance element and reducing an error even when operating in a wide temperature range. Since a correction amount for the resistor included in the voltage measurement module is generated using a diagnostic power source configured independently of the battery system, and a voltage of the circuit included in the battery system is measured by applying the generated correction amount, the voltage may be precisely measured without using a high-precision resistance element. Since a changeover switch operates periodically to generate and apply an updated correction amount according to a changing environment, the voltage may be precisely measured even if it is applied to a system in which the environment continuously changes, such as a driving electric vehicle.