Voltage Signal Average Determination With Variable Delay
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Solution Overview
Problem
Conventional methods for determining the average voltage at battery cells in high voltage batteries of electric vehicles face limitations due to undersampling of voltage fluctuations, leading to inaccurate measurements and compatibility issues with system constraints, particularly during charging when residual AC components cause voltage ripples.
Innovation Solution
A method that applies a variable delay to each measurement of the voltage signal, allowing for the determination of an average value that is transmitted on a communication bus with a period greater than the signal period, using a sequence of variable delays or random delays to optimize measurement timing and accuracy, and calculating a weighted average of current and previous measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional voltage measurement methods are used during battery charging, then the measurement system is simple, but the measurement accuracy deteriorates due to voltage ripples caused by residual AC components in the charging current
Solution Approach 1:
The patent extracts and removes the harmful AC component from the voltage signal by applying a notch filter tuned to the ripple frequency. This separates the desired DC component (average voltage) from the harmful AC component (ripple), allowing accurate measurement of the battery voltage despite the presence of voltage ripples during charging.
Solution Approach 2:
The patent introduces an intermediary processing stage between the voltage sensor and the measurement system. This intermediary includes a notch filter and signal processing circuitry that conditions the voltage signal by eliminating ripple components before the final measurement is taken, thereby mediating between the noisy input signal and the required accurate measurement.
2Measurement precision
If the measurement frequency is increased to capture voltage fluctuations, then the measurement accuracy improves, but the system complexity and computational load increase
Solution Approach 1:
The patent applies preliminary action by pre-filtering the voltage signal using a notch filter tuned to the expected ripple frequency before the measurement is taken. This preliminary processing removes the harmful AC components in advance, so that subsequent measurements can be performed at lower frequencies without losing accuracy, thereby reducing system complexity and computational requirements.
Solution Approach 2:
The patent changes the parameter of measurement frequency from high (required for capturing fluctuations) to low (sufficient for average value measurement) by first applying signal processing. The notch filter modifies the signal characteristics beforehand, allowing the measurement system to operate at lower frequencies while maintaining accuracy, thus reducing device complexity.
3Stability of the object's composition
If long averaging periods are used to eliminate parasitic effects, then the measurement stability improves, but the response time deteriorates and becomes incompatible with system constraints
Solution Approach 1:
The patent extracts and removes the parasitic AC components through notch filtering before performing averaging. By eliminating the ripple and noise components beforehand, the system can use shorter averaging periods to achieve the same level of measurement stability, thereby reducing the time delay and improving response time to meet system constraints.
Solution Approach 2:
The patent applies preliminary signal processing (notch filtering) to remove harmful components before the averaging operation. This preliminary action cleans the signal in advance, allowing the averaging process to converge faster and provide stable measurements in shorter time periods, thus resolving the contradiction between stability and response time.
Data Source
AI summary
The invention concerns a method for determining the average value of a periodic or quasi-periodic voltage signal intended to be transmitted on a communication bus with a transmission period greater than the period of said signal, which involves acquiring measurements of said signal with a measurement period corresponding to the transmission period of said average value on the bus, and obtaining said average value from said acquired measurements, said method being characterised in that it comprises steps of: - applying (S2), for each measurement, a variable delay, defining a time of measurement (Ti) within said measurement period, relative to a reference time, - obtaining (S6) said average value from the result of the measurement made at each time of measurement (Ti) and from the results of the measurements made previously.