Battery Charge Transfer Calculation With Unsynchronized AFE Clocks
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Solution Overview
Problem
Existing battery management systems face challenges in accurately determining charge transfer due to clock signal drift and synchronization issues between analog front-end circuits and host microcontrollers, leading to inaccuracies in current measurements and power consumption inefficiencies.
Innovation Solution
The system employs an analog front-end (AFE) circuit with an unsynchronized clock signal to measure average current values, which are then communicated to a host microcontroller for time value determination, ensuring compliance with functional safety standards and reducing power consumption by offloading timing tasks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If synchronized clock signals are used between AFE circuit and host microcontroller, then measurement accuracy is improved, but device complexity and power consumption increase
Solution Approach 1:
The system divides the measurement function into two independent parts: the AFE circuit measures current using its own clock signal, while the host microcontroller measures time duration using its own clock signal. These segmented measurements are then combined through multiplication to calculate charge transfer, eliminating the need for synchronized clocks while maintaining measurement accuracy.
Solution Approach 2:
The patent introduces an intermediary calculation method where the product of average current (from AFE) and time duration (from host microcontroller) is used to determine charge transfer. This intermediary approach allows the two unsynchronized clock systems to work together without direct synchronization, resolving the contradiction between measurement precision and device complexity.
2Device complexity
If the host microcontroller handles all timing and measurement tasks, then device complexity is reduced, but power consumption increases
Solution Approach 1:
The system segments the computational workload: the AFE circuit's current measurement module handles current sampling and average calculation, while the host microcontroller handles time duration measurement. This segmentation allows both components to operate independently with unsynchronized clocks, reducing overall system complexity while distributing power consumption efficiently.
Solution Approach 2:
The AFE circuit performs self-service by independently measuring current and calculating average current values using its own clock signal, without requiring the host microcontroller to manage its timing. This self-service capability reduces the host microcontroller's workload and enables independent operation with unsynchronized clocks, lowering overall power consumption.
3Use of energy by moving object
If the AFE circuit uses its own unsynchronized clock signal, then power consumption is reduced, but measurement accuracy deteriorates
Solution Approach 1:
The patent uses an intermediary calculation approach where the AFE circuit's average current measurement (taken at its own clock speed) is multiplied by the host microcontroller's time duration measurement. This intermediary multiplication method allows the AFE to operate independently with its own unsynchronized clock while still achieving accurate charge transfer measurements through the combined product.
Solution Approach 2:
The system changes the measurement parameters by separating current measurement (performed by AFE over a sampling period) from time measurement (performed by host microcontroller). By changing from a synchronized time-stamping approach to an average-current-times-duration approach, the system allows unsynchronized clocks while maintaining measurement accuracy.
Data Source
AI summary
A battery management system can include a host microcontroller, which can be operated in accordance with a first clock signal, and an analog front end (AFE) circuit, where the AFE circuit can be operated in accordance with a second clock signal that can be unsynchronized with the first clock signal. The AFE circuit can include an input which can be configured to receive a representation of a battery current associated with one or more cells in a battery system. The AFE circuit can also include current measurement circuitry, included in or coupled to the AFE circuit, which can be configured to generate an average current value representative of an average of the battery current for a specified time period. The host microcontroller can be configured to determine a time value representative of a duration of the specified time period, and determine, based on the indication of the average current value, a current transfer value of the battery current during the specified time period.