Power Supply System for Electric Vehicles with Dynamic Battery Output Limiting
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Solution Overview
Problem
In electric vehicles, when the second electrical storage device's output declines during boost travel, there is a significant deceleration feeling for passengers due to the increased reliance on the second battery's power, leading to a sudden decrease in driving force.
Innovation Solution
A power supply system that limits the second output of the second electrical storage device to a predetermined upper limit, adjusts this limit based on the first output parameter and vehicle speed, and uses a first electrical storage device with lower output weight density and higher energy weight density to reduce deceleration feelings by managing power transfer between the batteries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the second electrical storage device's output is increased to supplement the first battery's declining power capability, then the drive motor's power requirement can be met, but the deceleration feeling for passengers increases significantly when the second battery's output declines
Solution Approach 1:
The control device dynamically adjusts the second output upper limit based on the first output parameter (charge rate). When the first battery's charge rate is high, the second battery can output more power. When the first battery's charge rate is low, the second battery's output is limited to a smaller value, preventing excessive deceleration feeling when the second battery's output declines.
Solution Approach 2:
The control device continuously monitors the first output parameter (charge rate of the first battery) and uses this feedback to adjust the second output upper limit in real-time. This closed-loop control ensures that the second battery's output is appropriately limited based on the first battery's current state, balancing power requirements with passenger comfort.
2Object-affected harmful factors
If the second electrical storage device's output is limited to reduce deceleration feeling, then passenger comfort improves, but the power supply capability during boost travel may be insufficient
Solution Approach 1:
The second output upper limit is not a fixed value but dynamically changes based on the first output parameter. When the first battery has high charge rate, the second battery can provide maximum output for boost travel. When the first battery has low charge rate, the second battery's output is limited. This dynamic adjustment resolves the contradiction by adapting the power limit to current system capabilities.
Solution Approach 2:
The control device changes the parameter of the second output upper limit based on the first output parameter (charge rate). By varying this parameter according to the first battery's state, the system can provide sufficient power when needed while limiting deceleration feeling when the first battery cannot support high power demands.
3Use of energy by moving object
If the first electrical storage device has higher energy weight density to extend cruising distance, then the vehicle's energy efficiency improves, but the output weight density decreases requiring more reliance on the second battery
Solution Approach 1:
The power supply system is segmented into two electrical storage devices with different characteristics: the first battery optimized for energy density (cruising distance) and the second battery optimized for output density (power boost). The control device manages the power distribution between these two segments, using the first battery for baseline power and the second battery for supplemental power during boost travel, resolving the contradiction between energy efficiency and power capability.
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
This approach reduces the deceleration feeling experienced by passengers by limiting the second output and optimizing power distribution, ensuring a smoother ride even when the second battery's output declines, and extends the vehicle's cruising distance.
Implementation Method 1
a first electrical storage device (for example, the first battery B1 described later); a second electrical storage device (for example, the second battery B2 described later)
Data Source
AI summary
A power supply system includes power circuit which connects first and second batteries with a drive motor, and a management ECU which controls transfer of power between the batteries and the drive motor. The management ECU limits the output power of the second battery to no more than a second output upper limit, during combined output travel which drives the drive motor by way of the combined output of the first and second batteries. In addition, the management ECU sets the second output upper limit to a second maximum output of the second battery in the case of the first SOC of the first batter being greater than a remaining amount warning threshold, and sets the second output upper limit to a range extending upper limit which is smaller than the second maximum output, in the case of the first SOC being less than the remaining amount warning threshold.