Abnormality Diagnosis Apparatus for Power Supply Precharge Circuit Failures
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Solution Overview
Problem
Existing abnormality diagnosis systems for power supply input circuits fail to diagnose failures such as insufficient precharge voltage, disconnection of the precharge path, and short-circuit failures between capacitor electrodes, leading to erroneous determinations during bidirectional power supply relay failure diagnosis.
Innovation Solution
An abnormality diagnosis apparatus that includes a precharge circuit, precharge voltage detection circuit, inter-relay voltage detection circuit, and a determination section, which diagnoses a shortage of precharge voltage or short-circuit failure between capacitor electrodes in the first step, disconnection failure of the precharge path in the second step, and relay failures in subsequent steps, ensuring accurate diagnosis after normal charging by the precharge circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the precharge circuit is not operated or operates abnormally, then the precharge voltage is insufficient or the capacitor is not charged normally, but the existing diagnosis system cannot detect these failures and makes erroneous determinations during relay failure diagnosis
Solution Approach 1:
The patent applies preliminary action by performing precharge voltage detection and precharge path detection before conducting relay failure diagnosis. The determination section checks whether the capacitor has been charged normally by the precharge circuit before proceeding to relay diagnosis, thereby preventing erroneous determinations and improving diagnosis reliability without significantly increasing system complexity.
2Reliability
If the determination section diagnoses relay failures without checking precharge circuit status first, then the diagnosis process is simpler and faster, but erroneous determinations occur when precharge circuit abnormalities exist
Solution Approach 1:
The patent implements preliminary detection steps that check precharge voltage and precharge path status before relay failure diagnosis. This sequential approach ensures accurate diagnosis by eliminating precharge-related failure modes from consideration before conducting relay diagnosis, thereby preventing erroneous determinations while adding only minimal detection time.
Solution Approach 2:
The patent segments the diagnosis process into distinct stages: precharge voltage detection, precharge path detection, and relay failure diagnosis. Each stage operates independently with clear entry and exit conditions, allowing the system to progress through diagnostic steps efficiently while maintaining high reliability through systematic elimination of failure modes.
3Adaptability or versatility
If the existing diagnosis system assumes normal precharge operation, then the diagnosis logic is simpler, but it cannot diagnose failures such as disconnection of precharge path or short-circuit between capacitor electrodes
Solution Approach 1:
The patent segments the diagnosis coverage into multiple detection functions: precharge voltage detection for detecting insufficient precharge voltage, precharge path detection for detecting disconnection failures, and relay failure diagnosis for detecting relay abnormalities. Each detection function operates independently with specific detection circuits and determination logic, enabling comprehensive failure mode coverage while maintaining clear and manageable system architecture.
Solution Approach 2:
The determination section serves multiple functions: it determines precharge voltage abnormalities, determines precharge path disconnection failures, and determines relay failures based on inter-relay voltage. This multi-functional determination logic enhances diagnosis versatility without requiring separate dedicated circuits for each function, thereby increasing diagnosis coverage while controlling system complexity.
Data Source
AI summary
An abnormality diagnosis apparatus performs: a first step of diagnosing a shortage of precharge voltage or a short-circuit failure between electrodes of a capacitor based on a detection value of a precharge voltage detection circuit in a state where a first relay and a second relay are turned off, and a precharge circuit is operated; a second step of diagnosing, after a normal determination in the first step, a disconnection failure of a precharge path based on the detection value of the precharge voltage detection circuit or a detection value of an inter-relay voltage detection circuit in a state where the first relay and the second relay are turned off, and the precharge circuit is not operated; and a relay failure diagnosis step of diagnosing, after a normal determination in the second step, a short-circuit failure and an open failure of the first relay or the second relay.