Hybrid Vehicle Power Supply Device with Removable Current Limiting
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Solution Overview
Problem
In hybrid and electric vehicles, the use of capacitors and secondary batteries as power sources can lead to rush currents when the vehicle is started after maintenance, causing overheating and damage due to excessive current flow, and existing solutions require large, high-impedance current limiting devices to prevent this, increasing the size of the power supply device.
Innovation Solution
A power supply device with a switchable current limiting mechanism using externally removable connection members, where a resistance element is introduced to limit current flow when the power supply voltage is low, preventing rush currents without the need for a large, internal current limiting device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a current limiting device with high impedance is arranged to prevent rush current, then the capacitor can be protected from overheating and damage, but the size of the device increases
Solution Approach 1:
The patent applies a dynamic current limiting approach by using a relay circuit that can switch between different resistance states. The relay circuit includes a first resistance value for limiting rush current during startup, and a second, lower resistance value for normal operation. This dynamic switching allows the system to protect the capacitor from rush current without requiring a permanently high-impedance current limiting device, thus reducing overall device size while maintaining protection capability.
Solution Approach 2:
The patent implements preliminary action by detecting the voltage of the capacitor before startup and determining whether rush current protection is needed. The control device checks if the capacitor voltage is below a threshold value, and only activates the high-impedance relay circuit when necessary. This preliminary detection and conditional activation allows the system to prepare protection measures in advance only when required, avoiding the need for continuously high-impedance current limiting components.
2Reliability
If the capacitor is discharged during maintenance operation, then operation safety is ensured, but rush current flows into the capacitor during next startup
Solution Approach 1:
The patent employs feedback control by continuously monitoring the capacitor voltage and using this information to control the relay circuit. The control device detects the capacitor voltage and provides feedback to determine whether to activate the rush current protection relay. When the capacitor voltage is detected to be below a threshold (indicating the capacitor may be discharged), the control device activates the relay circuit with high impedance to prevent rush current. This feedback mechanism ensures safety during maintenance while automatically preventing rush current during subsequent startup.
Solution Approach 2:
The patent introduces a relay circuit as an intermediary element between the power supply line and the capacitor. This relay circuit acts as a mediator that can be selectively activated to limit current flow. The relay circuit includes resistance elements that serve as an intermediate impedance barrier, allowing the system to safely connect the capacitor to the power supply line only when necessary and with appropriate current limiting, thus preventing rush current while maintaining operational safety.
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
The solution effectively prevents rush currents and reduces the size of the power supply device by using a removable current limiting mechanism, ensuring safe and efficient startup of the vehicle while maintaining a compact device structure.
Implementation Method 1
a resistance element introduced to limit current flow when the power supply voltage is low
Data Source
AI summary
A power storage device is in parallel to a battery, and is connected to a power supply line and a ground line. A service plug internally includes a resistance and is attached to the power storage device for connecting the resistance between contacts of a relay circuit. The service plug is a member independent of an ordinary service plug arranged at the power storage device. When residual charges in the power storage device are substantially zero, an operator appropriately attaches the service plug to the power storage device in place of the ordinary service plug. Accordingly, when the power storage device enters an overdischarged state due to a maintenance or the like of the power storage device, a vehicle system to which the service plug internally having a current limiting device is attached is started so that occurrence of a rush current can be prevented.