Vehicle Power Path Segmentation for Overcurrent Protection
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Solution Overview
Problem
In vehicles with directly connected rotary electric machines and wheels, failure in the inverter or rotary electric machine leads to overcurrent flow into the battery due to counter electromotive voltage, causing potential overcharge and sudden deceleration, as there is no mechanism to disconnect the motive power transmission path.
Innovation Solution
A vehicle configuration with a power path including a first, second, and third power path, along with switches and a control device to manage these paths, allowing the control device to disconnect the rotary electric machine from the battery and connect an auxiliary machine to prevent overcurrent flow and continue vehicle operation using alternative power sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the rotary electric machine is directly connected to the wheels without a motive power transmission device, then the vehicle structure is simplified and ease of operation is improved, but reliability deteriorates because overcurrent cannot be prevented when failure occurs in the inverter or rotary electric machine
Solution Approach 1:
The power transmission path is segmented into controllable sections using switching elements. The switching element is inserted between the rotary electric machine and the inverter, allowing the system to disconnect the rotary electric machine from the power transmission path when failure occurs, while maintaining the simplified direct connection structure during normal operation
Solution Approach 2:
A switching element is introduced as an intermediary component between the rotary electric machine and the inverter. This intermediary can selectively connect or disconnect the power transmission path, providing a safety mechanism without permanently complicating the direct connection structure
2Reliability
If a motive power transmission device is added to disconnect the power transmission path, then reliability is improved by preventing overcurrent, but device complexity increases
Solution Approach 1:
The power transmission path is divided into controllable segments with switching elements positioned at critical points. This segmentation allows the system to isolate faulty components while maintaining overall system functionality, achieving reliability improvement without requiring a complete complex transmission device
Solution Approach 2:
The switching element is extracted as a separate, independent component that can be added to the existing direct connection system. This extraction allows the safety function to be implemented as a minimal addition rather than requiring a complete redesign of the power transmission system
3Reliability
If the switching element is disposed between the inverter and the rotary electric machine, then reliability is improved by enabling disconnection, but device complexity and manufacturing cost increase
Solution Approach 1:
The switching element serves as an intermediary component that can be integrated into the existing power transmission path between the inverter and rotary electric machine. This positioning allows the switching element to control power flow without requiring major manufacturing changes to the existing system architecture
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
Prevents overcurrent flow from the rotary electric machine to the battery, allowing continued vehicle operation by switching to alternative power sources and ensuring battery protection during system failures.
Implementation Method 1
the permanent magnet type rotary electric machine passively operates as the power generator by receiving rotation force from the outside so as to generate counter electromotive voltage
Data Source
AI summary
Provided is a vehicle capable of suppressing the inflow of an overcurrent from a rotating electrical machine to a battery side as a result of a reverse voltage generated when the rotating electrical machine is operated as an electric power generator. A control device controls a switch disposed between a battery and an inverter to an OFF state if an abnormality is detected in a motor or the inverter. At this time, the control device controls a switch disposed between the battery on the one hand and auxiliary equipment and a motor on the other hand to an ON state, causing the vehicle to continue to run using the motor or an engine.