Battery Pack Charge Current Sensing for Variable AC Frequencies
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Solution Overview
Problem
Existing battery management systems face challenges in accurately measuring sinusoidal waveform charge currents due to mismatched sampling frequencies and varying AC frequencies, leading to mismeasurement and reduced accuracy.
Innovation Solution
A battery pack and measurement system that adjusts sampling times based on recognized frequencies of the sinusoidal waveform charge current, using a processor to determine the correct sampling frequency and adjust accordingly to ensure accurate measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the BMS uses a fixed current measurement cycle (e.g., 25 ms), then the measurement process is simple and deterministic, but the measurement accuracy deteriorates when the measurement cycle does not align with the charge current cycle (e.g., 8.3 ms for sinusoidal charging)
Solution Approach 1:
The patent applies dynamics by making the measurement cycle adjustable rather than fixed. The BMS dynamically adapts its measurement cycle to match the charge current cycle based on detected charging patterns. When sinusoidal charging is detected, the measurement cycle is adjusted to 8.3ms (or multiples thereof) to align with the charge current frequency, ensuring accurate measurements at critical points in the charging waveform.
Solution Approach 2:
The patent changes the measurement cycle parameter from a fixed value (e.g., 25ms) to an adaptive value that can be set to 8.3ms or its multiples based on the detected charge current frequency. This parameter change allows the system to optimize measurement accuracy for different charging modes by adjusting the timing of current measurements to coincide with peak charging current points.
2Measurement precision
If the BMS performs current measurement at fixed intervals, then the measurement process is straightforward, but continuous mismeasurement occurs when the measurement timing consistently hits peak or trough points of the sinusoidal waveform
Solution Approach 1:
The system dynamically adjusts the measurement cycle to match the charge current cycle (8.3ms for sinusoidal charging). By synchronizing the measurement timing with the charging waveform, the BMS ensures measurements are taken at appropriate points in the cycle rather than consistently at peaks or troughs, improving both accuracy and reliability of charge current detection.
3Adaptability or versatility
If the BMS assumes a fixed charge current frequency, then the measurement process is simplified, but accurate measurement cannot be ensured when different AC frequencies are used in different countries
Solution Approach 1:
The patent implements universality by designing a measurement system that can automatically adapt to different charge current frequencies (e.g., 100Hz or 120Hz corresponding to different AC frequencies). The BMS detects the actual charge current frequency and adjusts its measurement cycle accordingly, making the system universally applicable across different countries and charging standards without requiring manual configuration.
Solution Approach 2:
The system changes the measurement cycle parameter based on the detected charge current frequency. When 100Hz charging is detected, the measurement cycle is set to 10ms; when 120Hz is detected, it's set to 8.3ms. This dynamic parameter adjustment enables the BMS to maintain measurement accuracy across different frequency standards used in various countries.
Data Source
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AI summary
Disclosed are a battery pack, a method of measuring a charge current of the same, and a charge current measurement system, which enable accurate measurement of a sinusoidal waveform charge current using a charger adapted to charge the battery pack with the sinusoidal waveform charge current. The battery pack includes: a battery module including a plurality of battery cells; a current measurement module measuring a charge current supplied to the battery module; and a processor. Upon detecting connection of a charger to the battery pack, the processor sets a frequency of a sinusoidal waveform charge current supplied from the charger to the battery module to a first frequency, recognizes the frequency of the charge current based on a charge current value measured through a current measurement module according to a first number of sampling times for one cycle set to the first frequency, and adjusts the number of sampling times for one cycle based on the recognized frequency of the charge current.