EV Battery Charge Current Control for Accessory Load Compensation
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Solution Overview
Problem
Existing battery charging systems for electric vehicles face inaccuracies in current sensing, leading to under/over current flow due to unawareness of accessory power consumption and varying manufacturer components, which affects the accuracy of target current calculation.
Innovation Solution
Implementing a powertrain controller with feed-forward and feedback current control logic to determine a target current by integrating measured battery current with feed-forward demand current, using a proportional-integral module to adjust and ensure accurate current delivery to the battery, accounting for both reporting and non-reporting accessories.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a target current is calculated based on battery power limits and accessory load demand, then the battery charging speed is improved, but current sensing inaccuracies in different components lead to errors in target current calculation
Solution Approach 1:
The patent implements a feedback mechanism where the powertrain controller continuously monitors the actual current supplied to the battery and compares it with the target current. Based on this feedback, the controller adjusts the charging parameters to compensate for sensing inaccuracies and ensure the battery receives the correct current, thereby resolving the contradiction between charging speed and calculation accuracy.
Solution Approach 2:
The powertrain controller acts as an intermediary between the charger and the battery, managing the current flow and compensating for inaccuracies introduced by different manufacturers' components. It calculates the target current considering accessory loads and adjusts the charging current to account for sensing errors in various components, ensuring accurate current delivery despite measurement variations.
2Loss of time
If the charger provides maximum power to the battery, then charging time is reduced, but the charger lacks awareness of accessory power consumption leading to under/over current flow
Solution Approach 1:
The powertrain controller performs multiple functions: it manages battery charging, monitors accessory power consumption, calculates target current, and adjusts charging parameters. This multi-functionality allows the system to provide maximum charging power while simultaneously accounting for accessory loads, preventing under/over current flow and ensuring reliable current control throughout the charging process.
Solution Approach 2:
The powertrain controller preliminarily calculates the target current by considering both battery charging requirements and accessory power demands before initiating maximum power charging. This preliminary assessment enables the charger to deliver maximum power safely from the start, reducing charging time while maintaining current flow accuracy through pre-computed adjustments for accessory loads.
Data Source
AI summary
A method to charge a vehicle having a battery operable to power an electric traction system includes: connecting the battery (20) to a charger (9), wherein the electric vehicle (10) includes a powertrain controller communicatively connected to the battery (20) and the charger (9) when the battery (20) is connected to the charger (9); and by the charge controller: determine a feed-forward demand current; receive a measured battery current indicative of a current received by the battery (20) from the charger (9); determine a current feedback based on an integral of a difference between the measured battery current and the feed-forward demand current; and determine a target current based on the sum of the feed-forward demand current and the current feedback; and command the charger (9) to supply the target current to the electric vehicle (10).