EV Power Storage Charging Control for Low-Response Chargers
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Solution Overview
Problem
In-vehicle power storage systems face challenges with premature charging cessation due to low response speed of charging devices, leading to decreased followability of current indications and potential overvoltage or overcharge issues.
Innovation Solution
An in-vehicle power storage system that includes a controller to estimate the response speed of the charging device and adjust the current indication accordingly, ensuring the change speed of the current indication does not exceed the response speed, and implementing a limit start time to gradually lower the current indication to prevent overvoltage or overcharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the charging device operates with a low response speed, then the device complexity is reduced, but the followability of the current to the current indication decreases
Solution Approach 1:
The controller performs preliminary actions by estimating the response speed of the charging device before charging begins, and pre-calculating the current indication values that account for this response characteristics. This allows the system to proactively compensate for the low response speed rather than reactively correcting issues after they occur.
Solution Approach 2:
The controller continuously monitors the actual current of the power storage device and compares it with the current indication. Based on this feedback and the estimated response speed, the controller dynamically adjusts the current indication to ensure the actual current follows the desired trajectory, compensating for the charging device's low response speed.
2Loss of time
If the current indication is lowered quickly to prevent overvoltage, then the response time is reduced, but the followability decreases when the charging device has low response speed
Solution Approach 1:
The controller dynamically adjusts the current indication based on the estimated response speed of the charging device. Instead of using a fixed current indication, the system adapts the current profile in real-time, changing the rate of current reduction to match the actual response capabilities of the charging device, thereby maintaining both speed and reliability.
Solution Approach 2:
The system changes the parameters of the current indication based on the estimated response speed. When the response speed is low, the controller modifies the current indication to change more gradually, and when the response speed is higher, it allows for faster changes, thus optimizing both response time and followability under different conditions.
3Ease of operation
If the charging device has low response speed, then the ease of operation is improved, but overvoltage or overcharge may occur due to decreased followability
Solution Approach 1:
The controller applies preliminary anti-action by estimating the response speed and pre-calculating appropriate current indication values that prevent overvoltage or overcharge from occurring in the first place. The system proactively compensates for the low response speed by adjusting the current indication to ensure it never exceeds safe limits, rather than waiting for overvoltage to occur and then correcting it.
4Device complexity
If the current indication is set without considering response speed, then the device complexity is reduced, but the productivity decreases due to premature charging cessation
Solution Approach 1:
The charging device performs self-service by automatically estimating its own response speed during the charging process. The controller uses this self-estimated information to adjust the current indication, allowing the system to optimize its own performance without requiring external intervention or complex pre-programming, thereby improving productivity while maintaining relatively simple device architecture.
Data Source
AI summary
In the event of external charging where a charging device charges a power storage device with electric power from an external electric power source, a current indication for the external charging is transmitted to the charging device. In this case, in the event of the external charging, a response speed of the charging device is estimated based on change of current in the power storage device due to change of the current indication after start of charging, and the current indication is set in consideration of the response speed of the charging device after the response speed of the charging device is estimated.