Insulation Fault Detection Bridge for High Voltage DC Systems
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Solution Overview
Problem
Existing insulation fault detection devices for DC voltage electrical systems in vehicles are inadequate for anticipating insulation failures under critical conditions, such as high potential differences between terminals and ground, and they consume significant electrical power, impacting vehicle autonomy.
Innovation Solution
A bridge assembly with controlled switches and a detection circuit that selectively connects to the DC voltage source and mechanical ground, using a capacitor and resistive load to measure current and determine insulation fault resistance, allowing for fault detection with minimal electrical consumption and at high voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If known insulation fault detection devices are used, then insulation faults can be detected, but they cannot anticipate insulation failure under critical conditions (high potential difference between terminal and ground)
Solution Approach 1:
The detection device dynamically adjusts its operating voltage to match the actual potential difference between the DC terminal and ground, rather than using a fixed test voltage. This allows the device to adapt to critical conditions where high potential differences exist, enabling reliable detection under varying operational scenarios including charging states.
Solution Approach 2:
The invention changes the detection parameter from a fixed test voltage to a variable voltage that corresponds to the actual operational potential difference. By measuring and adapting to the real voltage condition, the device can accurately detect insulation faults under critical conditions that previous fixed-voltage devices could not handle.
2Reliability
If traditional insulation fault detection devices are used, then faults can be detected, but electrical consumption is significant, impacting vehicle autonomy
Solution Approach 1:
The detection device performs insulation fault detection periodically rather than continuously, significantly reducing electrical consumption while maintaining effective monitoring. The control unit activates the detection circuit at scheduled intervals, allowing the vehicle to maintain autonomy while still detecting insulation faults reliably.
Solution Approach 2:
The detection device utilizes the vehicle's existing electrical system components and potential differences for detection, rather than requiring separate dedicated power sources for continuous testing. This self-service approach minimizes additional electrical consumption while maintaining detection capability.
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 insulation fault detection with reduced electrical consumption, capable of operating at high potentials and during critical conditions, ensuring user safety and maintaining vehicle autonomy.
Implementation Method 1
A capacitor 421 and a resistive load 422 are connected between nodes 462 and 464 in the fifth branch... determine insulation fault resistance
Data Source
AI summary
The invention relates to a device comprising a bridge assembly including: first to fourth nodes (461, 462, 463, 464), the first and third nodes being connected to a direct voltage source; a first branch connecting the first and second nodes; a second branch connecting the second and third nodes; a third branch connecting the first and fourth nodes; a fourth branch connecting the third and fourth nodes; a fifth branch connecting the second and fourth nodes and comprising a capacitor (421) connected between the second and fourth nodes; a circuit (40) controlling the switches in order successively to a) close the switches in order to charge the capacitor, and b) keep one switch closed and the other switches open; a measuring circuit (431) measuring the current flowing through the capacitor (421); and a circuit (43) determining the magnitude of an insulation fault according to a current measured during step (b).