Battery Management System Frequency-Adaptive Current Measurement
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Solution Overview
Problem
Existing energy storage systems face measurement errors in alternating discharge current, leading to inaccuracies in calculating state of charge (SOC) and state of health (SOH) of batteries, which affects efficient charging and discharging processes.
Innovation Solution
An energy storage system that calculates measurement times based on the frequency of the discharge current, allowing precise measurement and control of battery charging and discharging by determining initial sampling times and period lengths, thereby accurately calculating SOC and SOH.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If discharge current is measured at regular intervals (e.g., every 3 ms), then the measurement process is simple and easy to implement, but measurement errors occur due to misalignment with the alternating current frequency
Solution Approach 1:
The measurement system transitions from static regular interval measurement to dynamic frequency-adaptive measurement. The battery management system continuously monitors the frequency of alternating discharge current and adjusts measurement timing accordingly, making the measurement interval variable rather than fixed. This dynamic adjustment ensures measurement points always align with the actual current waveform characteristics, eliminating measurement errors while maintaining implementation feasibility.
Solution Approach 2:
The measurement interval parameter is changed from a fixed value (e.g., 3 ms) to a variable value determined by the detected frequency of alternating discharge current. By calculating the period of the alternating current and setting measurement intervals based on this period, the system adapts the measurement parameter to match the actual operating conditions, thereby improving measurement accuracy without complicating the overall system architecture.
2Measurement precision
If measurement times are calculated based on frequency of alternating discharge current, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The battery management system performs self-measurement of the alternating discharge current frequency and automatically adjusts its own measurement timing based on this self-diagnosed information. The system uses its existing computational resources to detect the frequency, calculate the appropriate measurement interval, and schedule measurements accordingly, without requiring external control devices or additional hardware complexity. This self-service approach improves measurement precision while minimizing increases in device complexity.
3Ease of operation
If regular interval measurement is used, then the control system is simple to operate, but SOC and SOH calculations become inaccurate
Solution Approach 1:
The system implements a feedback mechanism where the measured frequency of alternating discharge current is fed back to adjust the measurement timing. The battery management system continuously monitors the current frequency, compares it with the current measurement interval setting, and adjusts the measurement timing to maintain alignment with the actual current waveform. This feedback loop ensures accurate SOC and SOH calculations while keeping the control logic relatively simple, as it builds upon existing measurement infrastructure.
Data Source
AI summary
There are provided an energy storage system and a method for driving the energy storage system, which can exactly measure discharge current by calculating measurement times of the discharge current according to the frequency of the discharge current. An energy storage system includes a battery rack, a battery management system configured to control charging and discharging of the battery rack, and a power conversion system configured to supply discharge current of the battery rack as an alternating current having a frequency to the battery management system. The battery management system is further configured to calculate measurement times of the discharge current, measure the discharge current at the calculated measurement times, and control the charging and discharging of the battery rack based on the measured discharge currents.