Vehicle OBC Relay Diagnosis Using Existing Voltage Sensors
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Solution Overview
Problem
Current relay diagnosis techniques in vehicle on-board chargers (OBCs) require additional voltage sensors, increasing costs and complexity, and are limited in their ability to diagnose relays in various operational phases.
Innovation Solution
An apparatus and method for diagnosing relays in OBCs using existing voltage sensors, such as input phase voltage sensors or PFC line voltage sensors, to determine the open or fused states of relays in single-phase, L1-L2 phase, L1-L3 phase, and three-phase operations without adding extra components, by controlling the operation of relays within the relay circuit unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a voltage sensor for relay diagnosis is additionally located, then relay diagnosis capability is improved, but cost increases
Solution Approach 1:
The patent makes existing voltage sensors (input phase voltage sensor or PFC line voltage sensor) perform dual functions: their original control/power identification function and the new relay diagnosis function. By utilizing the measurement capability of these existing sensors to detect voltage drops across relay terminals, the system achieves relay diagnosis without requiring additional dedicated voltage sensors, thereby improving reliability while avoiding increased cost.
2Device complexity
If existing voltage sensors are used for relay diagnosis, then device complexity is reduced, but measurement precision may be insufficient
Solution Approach 1:
The patent introduces an intermediary approach by using the existing voltage sensor measurements in combination with knowledge of the normal voltage characteristics of the OBC system. The diagnosis module compares the measured voltage against expected voltage ranges to infer relay status, effectively using the existing sensor data with enhanced interpretation capability to achieve precise relay diagnosis without requiring dedicated high-precision measurement equipment.
3Adaptability or versatility
If relay diagnosis is performed in multiple phase operations, then adaptability is improved, but device complexity increases
Solution Approach 1:
The patent implements a dynamic diagnosis approach where the diagnosis module adaptively selects and executes different diagnosis algorithms based on the current operational phase of the OBC (single-phase L1, L1-L2 phase, L1-L3 phase, or three-phase operation). The system dynamically adjusts its measurement and evaluation strategy to match the active phase configuration, enabling comprehensive relay diagnosis across all operating modes without requiring separate dedicated diagnosis systems for each phase type.
Data Source
AI summary
The present disclosure relates to techniques for diagnosing a relay in a vehicle on-board charger (OBC), and an apparatus for diagnosing a relay in a vehicle OBC according to an exemplary embodiment may include first to third voltage sensors configured to measure phase-specific voltages for AC inputs to the relay circuit unit, fourth and fifth voltage sensors configured to measure line voltages for AC outputs from the relay circuit unit, and a diagnosis module configured to diagnose the relay circuit unit, based on the phase-specific voltages measured by the first to third voltage sensors and based on the line voltages measured by the fourth and fifth voltage sensors.