Battery Equalization Circuit With Filtered Peak Overcurrent Detection
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Solution Overview
Problem
Existing active equalizing circuits for battery cells face challenges in achieving accurate overcurrent protection due to high frequency noise interference, leading to inefficient circuit design and increased costs.
Innovation Solution
An energy transfer circuit with an inductor, cell selection circuit, clamp circuit, current detection circuit, and overcurrent detection circuit, utilizing a low-pass filter to band-limit detection values and a threshold for precise overcurrent protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a low-pass filter is installed in front of the overcurrent detection circuit to suppress high frequency noise, then noise suppression is improved, but the ability to capture true peak current value deteriorates
Solution Approach 1:
The patent introduces a peak detection circuit as an intermediary component between the low-pass filter and the overcurrent detection circuit. This peak detection circuit captures the peak current value from the filtered signal, effectively mediating between the noise suppression function of the low-pass filter and the peak detection requirement. The peak detection circuit uses a hold capacitor and comparison circuitry to extract peak values from the smoothed waveform, resolving the contradiction by adding a specialized intermediate stage that recovers peak information that would otherwise be lost in the filtering process.
2Reliability
If a large time constant is designed for the low-pass filter to prevent false detection, then noise suppression is improved, but the performance utilization of the inductor deteriorates due to excessive design margin
Solution Approach 1:
The patent segments the signal processing function into two distinct stages: a low-pass filter stage for noise suppression and a peak detection stage for accurate peak capture. By dividing the overall function, the system can use a smaller time constant in the low-pass filter (improving inductor utilization and response speed) while still achieving reliable overcurrent protection through the subsequent peak detection circuit that identifies true peaks despite the reduced filtering aggressiveness. This segmentation allows each stage to be optimized for its specific purpose without compromising the other.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables highly accurate overcurrent protection at an appropriate circuit scale and cost, optimizing the performance of the inductor and reducing waste in the circuit design.
Implementation Method 1
an energy transfer circuit including an inductor L1, a cell selection circuit 11 provided between n cells C1 to C4 connected in series, where n is an integer of 2 or more, and the inductor L1 and capable of conducting both ends of a selected cell including any one of the n cells C1 to C4 or a plurality of cells connected in series, and both ends of the inductor L1
Implementation Method 2
a low-pass filter 15 configured to band-limit a detection value detected by the current detection circuit
Data Source
AI summary
Cell selection circuit is provided between n cells connected in series, where n is an integer of 2 or more, and inductor, and is provided at both ends of the selected cell and both ends of inductor can be conductive. Clamp circuit includes at least one clamp switch for forming a closed loop including inductor in a state where cell selection circuit does not select any cells. Current detection circuit detects the value of the current flowing through inductor. Low-pass filter band-limits the detection value. Overcurrent detection circuit activates the protection of inductor when the band-limited detection value exceeds the threshold.