EV Power Supply Switching Control for Safe Sub-Device Transition
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Solution Overview
Problem
In power supply systems for electrically powered vehicles with a main power storage device and multiple sub power storage devices, the process of switching between sub power storage devices to optimize energy use and prevent short-circuits is challenging, requiring careful control to avoid equipment failure and excessive charging/discharging.
Innovation Solution
A power supply system with a main power storage device, multiple sub power storage devices, and a shared voltage converter, utilizing a switching control device that includes a determination unit, step-up-voltage instruction, and power limiter units to gradually adjust power limits and switch connections, ensuring safe and efficient switching by stepping up voltage and managing power limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If sub power storage devices are switched sequentially to increase travel distance, then EV travelable distance is improved, but risk of short-circuit and equipment failure increases during switching
Solution Approach 1:
The control device performs preliminary actions before switching: it determines the voltage of the connection target sub power storage device, compares it with the converter output voltage, and only permits switching when the converter voltage is higher. This preliminary voltage verification prevents short-circuits and equipment failure while enabling sequential switching to extend travel distance.
Solution Approach 2:
The control device continuously monitors the voltage of the converter and each sub power storage device, using this feedback information to make intelligent switching decisions. By comparing real-time voltage measurements, the system ensures safe switching conditions are met before connecting sub power storage devices, thereby maintaining reliability while extending EV travelable distance.
2Device complexity
If a shared converter is used for multiple sub power storage devices, then device complexity is reduced, but control difficulty during switching increases
Solution Approach 1:
A single converter is designed to serve multiple sub power storage devices universally. The control device manages the switching between different sub power storage devices by comparing their voltages with the converter output voltage, enabling one converter to perform multiple functions while maintaining simplified device structure.
Solution Approach 2:
The control device monitors voltage parameters of the converter and each sub power storage device, using parameter comparisons to control switching. By changing the connection state based on voltage parameter differences, the system manages switching control complexity while maintaining a shared converter configuration.
3Reliability
If voltage comparison control is implemented before switching, then switching safety is improved, but control process time increases
Solution Approach 1:
The control device performs voltage comparison as a preliminary check before permitting switching. By determining the connection target sub power storage device voltage and comparing it with the converter output voltage in advance, the system ensures switching safety is improved while the time loss is minimized through efficient voltage measurement and comparison.
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 allows for safe and efficient switching between sub power storage devices, preventing short-circuits and excessive charging/discharging, thereby extending the vehicle's travel distance on stored energy while maintaining system stability.
Implementation Method 1
a first voltage converter provided between the electric power feeding line and the main power storage device, and converting voltage bidirectionally therebetween
Implementation Method 2
a second voltage converter provided between the plurality of sub power storage devices and the electric power feeding line, and converting voltage bidirectionally between one of the plurality of sub power storage devices and the electric power feeding line
Data Source
Figure 1
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Figure 4~5
AI summary
A power supply system includes a main power storage device (BA) and a plurality of sub power storage devices (BB1, BB2). A converter (12B) is connected to selected one of the sub power storage devices (BB1, BB2) to convert voltage between the selected sub power storage device and an electric power feeding line (PL2) bidirectionally. When a request for switching the selected sub power storage devices in use is generated, a converter (12A) steps up voltage on the electric power feeding line (PL2) to a predetermined voltage, and thereafter a process for switching relays (SR1, SRIG, SR2. SR2G) is performed. The predetermined voltage is higher than any of a voltage output from the main power storage device (BA) and a voltage output from a sub power storage device to be newly connected to the converter (12B). Further, during the process for switching connection of the relays, upper limits on electric power input/output to/from the selected sub power storage device are set to 0.