Vehicle Power Supply Precharge Failure Diagnosis
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Solution Overview
Problem
The power supply system in vehicles faces challenges in precharging capacitors at system start time due to disconnections in the power lines, which existing systems struggle to diagnose accurately, leading to inefficiencies and potential damage.
Innovation Solution
A power supply system that includes a precharge circuit within the system main relay, using the accumulator's DC power to precharge capacitors and employing a control device to diagnose failure locations based on changes in common voltage during precharge control, specifically identifying disconnections by analyzing voltage changes across the accumulator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the precharge circuit is used to pre-charge the capacitor at system start time, then the capacitor is properly charged before power line connection, but the system cannot accurately diagnose the location of disconnection failures
Solution Approach 1:
The control device monitors the common voltage of the accumulator during precharge control and uses this feedback information to diagnose failure locations. By observing how the common voltage changes when precharging fails, the system can determine whether the disconnection occurred on the positive electrode side or negative electrode side of the power line, thereby resolving the diagnosis difficulty while maintaining precharging reliability
Solution Approach 2:
The common voltage of the accumulator serves as an intermediary parameter that links the precharge operation to the failure diagnosis function. Instead of directly detecting disconnection points, the system uses the common voltage change as an indirect indicator to infer the location of failures, enabling accurate diagnosis without interfering with the precharge circuit operation
2Measurement precision
If multiple diagnostic parameters are used to identify failure locations, then the diagnosis accuracy is improved, but the system complexity increases
Solution Approach 1:
The invention extracts and utilizes an existing parameter (common voltage of the accumulator) that is already present in the power supply system for dual purposes: both for normal operation control and for failure diagnosis. By taking out this existing parameter and applying it to diagnosis, the system achieves accurate failure location identification without adding complex diagnostic hardware or multiple additional sensors
Solution Approach 2:
The common voltage parameter serves multiple functions: it is used for normal power supply control and simultaneously for failure location diagnosis. This multi-functionality allows the system to maintain high measurement precision for diagnosis while avoiding the complexity increase that would result from adding dedicated diagnostic components
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
Effectively diagnoses and identifies the location of failures during precharging, enabling targeted repairs and ensuring proper capacitor precharging, thus enhancing system reliability and efficiency.
Implementation Method 1
a smoothing capacitor mounted, to the power line
Data Source
AI summary
There is provided a power supply system that is mounted on a vehicle and that comprises an accumulator connected with a power line via a system main relay including a precharge circuit; a smoothing capacitor mounted to the power line; and a power converter configured to use a DC power from the power line and supply an AC power to an electric load. When a precharge control that uses the precharge circuit to pre-charge the capacitor at a system start time fails in pre-charging the capacitor, the power supply system diagnoses a place of a failure, based on a change in common voltage of the accumulator during the precharge control.