Dual Battery Power Supply System for Cold Start Thermal Management
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Solution Overview
Problem
Existing electric vehicle power supply systems take time to achieve desired power output performance at cold start due to decreased power output from electrical storage devices, such as batteries, in low temperature environments.
Innovation Solution
A power supply system with a first and second electrical storage device, where the second device has a higher output-weight density and lower energy-weight density, and smaller heat capacity, is used. The system executes power pass control to transfer power between devices until initial conditions are met, then shifts to second priority control, where the second device is discharged preferentially to rapidly raise its temperature and ensure power output performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If power is transferred between electrical storage devices to raise temperatures at cold start, then power output performance is improved, but startup time increases
Solution Approach 1:
The electrical storage system is divided into two distinct devices: a first electrical storage device with larger heat capacity for stable power supply, and a second electrical storage device with smaller heat capacity for rapid temperature rise. This segmentation allows each device to fulfill different functional roles, resolving the contradiction between reliable power output and quick startup response.
Solution Approach 2:
The control device executes power pass control before normal operation to preliminarily raise the temperature of the second electrical storage device. By performing this preliminary heating action before the vehicle actually needs to travel, the system ensures that when startup is required, the second device is already warmed up and can immediately provide power without delay.
2Device complexity
If a single electrical storage device is used, then system complexity is reduced, but power output performance at cold start deteriorates
Solution Approach 1:
Different parts of the electrical storage system are given different local qualities: the first electrical storage device has larger heat capacity suited for stable, sustained power supply, while the second electrical storage device has smaller heat capacity optimized for rapid temperature response. This local differentiation of properties allows the system to achieve high power output performance at cold start without excessive overall complexity.
Solution Approach 2:
The electrical storage system uses a composite configuration of two different electrical storage devices with complementary characteristics. Similar to how composite materials combine different materials to achieve superior properties, this composite electrical storage system combines devices with different heat capacities to achieve both rapid warm-up capability and sustained power output, resolving the contradiction between simple structure and high performance.
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 configuration quickly raises the temperature of the second electrical storage device, ensuring rapid power output performance, and subsequently improves the first device's performance by charging the second device with excess power, thus enhancing overall system efficiency and reducing startup time in cold conditions.
Implementation Method 1
the temperatures of the first and second electrical storage devices are raised by heat generated by charging and discharging
Data Source
AI summary
A power supply system includes: a capacitive first battery; an output-type second battery having a smaller heat capacity than the first battery; a voltage converter that converts a voltage between first and second power circuits; a power converter that converts power between the first power circuit and a drive motor; and a power controller that operates the voltage converter and the power converter. The power controller is configured to: after a start of operation, execute a power pass control under which power is transferred between the first and second batteries, until a total output upper limit Ptot_max of all the batteries exceeds a travelable threshold value Pready1; and subsequent to the power pass control, execute a second priority control under which the second battery is discharged in preference to the first battery, until a first output upper limit P1_max of the first battery exceeds a margin traveling threshold value Pready2.