Inverter Backup Power Architecture for Safe Shutdown Control
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Solution Overview
Problem
Inverters in electric vehicles face challenges in ensuring a safe state during fault conditions, particularly with high-voltage systems, where the risk of DC link capacitors being charged by the electrical machine poses a safety concern, and existing solutions lack robustness in maintaining power supply redundancy.
Innovation Solution
The implementation of an inverter with three supply branches: a high-voltage branch, a low-voltage branch, and a backup supply branch, connected via DC/DC converters, ensuring that the inverter circuit and safety control device can transition to a safe state even in fault conditions by utilizing a backup supply branch that is independently powered from the low-voltage system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single power supply network is used in the inverter, then the device complexity is reduced, but the reliability and functional safety are compromised because faults cannot be isolated and backup power supply is unavailable
Solution Approach 1:
The power supply network is segmented into three independent branches: high-voltage branch (110), low-voltage branch (120), and backup supply branch (130). Each branch can be independently connected or disconnected, allowing fault isolation while maintaining overall system functionality. This segmentation enables the system to achieve functional safety without requiring complete system redundancy.
Solution Approach 2:
The backup supply branch (130) is pre-configured and ready to provide power before any fault occurs. The low-voltage branch (120) is preliminarily connected to both the high-voltage branch via operating DC/DC converter (10) and the backup supply branch via backup supply DC/DC converter (20), establishing redundant power paths in advance so that immediate switchover can occur during emergencies.
2Power
If the high-voltage branch is used exclusively, then the power supply capacity is sufficient for high-power applications, but the safety risk increases due to high touch voltage and potential faults in the high-voltage system
Solution Approach 1:
The low-voltage branch (120) serves as an intermediary power supply that can replace the high-voltage branch (110) during fault conditions. The operating DC/DC converter (10) and backup supply DC/DC converter (20) act as intermediary devices that enable power conversion and isolation between different voltage levels, allowing the system to operate at high voltage when needed while providing a safe low-voltage fallback option.
Solution Approach 2:
The backup supply branch (130) connected through the backup supply DC/DC converter (20) provides beforehand cushioning by being pre-positioned to immediately support the low-voltage branch if the high-voltage branch fails. This prevents complete power loss and ensures safe state transition can occur without interruption to safety-critical functions.
3Adaptability or versatility
If DC/DC converters are used to connect different voltage branches, then power conversion between high and low voltage is enabled, but the device complexity and potential failure points increase
Solution Approach 1:
The voltage conversion function is segmented into two separate DC/DC converters: operating DC/DC converter (10) for primary power conversion and backup supply DC/DC converter (20) for redundancy. Each converter handles a specific function and can be independently controlled, which reduces the complexity of any single converter while providing comprehensive voltage conversion capability across all operating modes.
Solution Approach 2:
Different DC/DC converters are deployed at different locations in the power supply architecture with different functions. The operating DC/DC converter (10) is positioned between high-voltage and low-voltage branches for primary operation, while the backup supply DC/DC converter (20) is positioned between low-voltage branch and backup supply for redundancy. Each converter is optimized for its specific local requirement.
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 significantly enhances functional safety by maintaining power supply redundancy, preventing faults in one branch from affecting others, and allows for a safe state transition during shutdown situations, particularly in high-voltage systems, while being cost-effective and simple to implement.
Implementation Method 1
The high-voltage branch (110) is connected to the low-voltage branch (120) via an operating DC/DC converter (10)
Implementation Method 2
the low-voltage branch (120) is connected to the backup supply branch (130) via a backup supply DC/DC converter (20) that is different from the operating DC/DC converter (10)
Data Source
AI summary
An inverter for controlling an electrical machine, the inverter having a high-voltage branch, a low-voltage branch and a backup supply branch, an operating DC/DC converter, which is connected on the one hand to the high-voltage branch and on the other hand to the low-voltage branch, a backup supply DC/DC converter, which is connected on the one hand to the low-voltage branch and on the other hand to the backup supply branch, and an inverter circuit for connecting the high-voltage branch to AC voltage terminals for the electrical machine. The inverter circuit and a safety control device are supplied with energy from the low-voltage branch and the safety control device may be set up to switch the inverter circuit to a safe state when a shutdown situation occurs, wherein the inverter circuit and the safety control device are supplied or can be supplied with energy from the backup supply branch.