Relay Weld Diagnostic Device Using Current Detection
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Solution Overview
Problem
Existing relay welding diagnostic techniques for electric vehicle charging circuits cannot determine if relays are welded without a functional voltage detection circuit.
Innovation Solution
A relay welding diagnostic apparatus that determines relay welding by setting threshold values based on resistance values and comparing peak voltage values, eliminating the need for a voltage detection circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a voltage detection circuit is used to determine relay welding, then relay welding can be detected, but the system cannot determine relay welding when the voltage detection circuit is broken
Solution Approach 1:
The patent introduces an intermediary measurement approach by using a current detector to measure current values instead of directly measuring voltage. This intermediary current measurement allows the system to determine relay welding status without relying on the voltage detection circuit, thereby maintaining reliability even when the voltage detection circuit is broken.
Solution Approach 2:
The patent replaces the voltage detection circuit (electrical measurement system) with a current detection system. By substituting the measurement method from voltage-based to current-based, the system eliminates the dependency on the voltage detection circuit while maintaining the ability to detect relay welding.
2Measurement precision
If voltage detection circuit is used, then relay welding can be determined, but the system fails when voltage detection circuit is broken
Solution Approach 1:
The patent changes the measurement parameter from voltage to current. By measuring current values instead of voltage, the system maintains measurement precision for relay welding detection while improving reliability, as the current detection system remains functional even when the voltage detection circuit is broken.
3Reliability
If threshold value is determined based on resistance values and peak voltage comparison is used, then relay welding can be determined without voltage detection circuit, but additional measurement components are required
Solution Approach 1:
The patent extracts the essential measurement function from the voltage detection circuit by using only the current detector and existing resistors. By taking out the voltage detection dependency and relying solely on current measurement combined with threshold comparison, the system reduces device complexity while maintaining reliability.
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
Enables reliable determination of relay welding without relying on a voltage detection circuit, ensuring effective diagnosis even when the voltage detection circuit is broken.
Implementation Method 1
a signal output circuit that supplies a predetermined voltage to the voltage line
Implementation Method 2
a peak value measurement section that measures a peak value of the voltage supplied to the voltage line from the signal output circuit
Implementation Method 3
a comparison diagnosis section that determines a state of the relay by comparing the peak value with the threshold value, and determines whether the relay is welded on the basis of the state of the relay thus determined and a state set to the relay
Data Source
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AI summary
In relay weld diagnostic device, a threshold value determination unit (104) determines a threshold value on the basis of a resistance value that is set for each of a P-pole-side resistor (24) and an N-pole-side resistor (23) provided to charging equipment. A peak value measuring unit (110) measures the peak value of a voltage supplied to a voltage line by an alternating-current signal output circuit (112). A comparison diagnosis unit (111) assesses the state of a relay (14) on the P-pole side and a relay (15) on the N-pole side by comparing the peak value and the threshold value, and makes a diagnosis as to whether the relays (14), (15) are welded on the basis of the assessed state of the relays (14), (15) and the state in which the relays (14), (15) are controlled.