Bi-Directional DC-DC Converter Fault Isolation in Vehicle Power Supply
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Solution Overview
Problem
Conventional in-vehicle power supply systems can detect failures but fail to accurately identify the specific component causing the failure within the DC-DC converter, leading to potential secondary failures and increased complexity in diagnosis.
Innovation Solution
The in-vehicle power supply system incorporates a controller that performs a series of failure determination operations, including short-circuit and open-circuit checks for input and output switches, and a bidirectional conversion circuit to stop voltage conversion operations when thresholds are exceeded, allowing for precise identification of faulty components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional failure detection is used in in-vehicle power supply systems, then failure detection capability is provided, but the specific location of failure within the DC-DC converter cannot be accurately identified
Solution Approach 1:
The failure detection process is segmented into three distinct determination operations: first determining whether the output switch has failure, second determining whether the conversion circuit has failure, and third determining whether the input switch has failure. This segmentation allows precise identification of the specific faulty component within the DC-DC converter rather than merely detecting that a failure has occurred.
2Reliability
If failure detection is performed without stopping voltage conversion operations, then continuous power supply is maintained, but secondary failures may occur and accurate diagnosis is difficult
Solution Approach 1:
The controller instructs the input switch and output switch to switch to the disconnected state before performing failure determination operations. This preliminary action of disconnecting switches prevents secondary failures during diagnosis while enabling accurate identification of the faulty component through subsequent voltage measurements.
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 enables easy and accurate identification of the failing component within the DC-DC converter, preventing secondary failures and simplifying fault diagnosis, while ensuring safety by disconnecting switches during failure detection.
Implementation Method 1
a DC-DC converter including a conversion circuit having a high-voltage terminal and a low-voltage terminal
Data Source
AI summary
An in-vehicle power supply system includes a high-voltage direct-current (DC) power supply, a low-voltage storage battery, a DC-DC converter, and a controller. The DC-DC converter includes a conversion circuit including a high-voltage terminal and a low-voltage terminal, an input switch connected between the high-voltage DC power supply and the high-voltage terminal, and an output switch connected between the low-voltage terminal and the low-voltage storage battery. The controller is configured to, after detecting that a current flowing through the conversion circuit exceeds a predetermined current threshold or that a charge voltage of the low-voltage storage battery exceeds a predetermined voltage threshold, execute a failure determination of the DC-DC converter after instructing the conversion circuit to stop a voltage conversion operation, causing the input switch to switch to the disconnected state, and instructing the output switch to switch to the disconnected state. The controller is configured to, in the failure determination execute a first determination operation including an output short-circuit failure determination, an output open-circuit failure determination, and an input short-circuit failure determination. If determining, in the first determination operation, that the output switch does not have failure, controller is configured to execute a second determination operation of determining whether or not the conversion circuit has failure. If determining, in the second determination operation, that the conversion circuit does not have failure, the controller is configured to execute a third determination operation of determining whether or not the input switch has failure. The in-vehicle power supply device determines the location of failure easily.