Onboard Electrical System Insulation Fault Detection
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Solution Overview
Problem
Existing onboard electrical systems for motor vehicles lack a cost-effective method for simultaneously testing insulation faults in both the primary and secondary power supply networks, often requiring separate insulation monitoring devices and increasing complexity and cost.
Innovation Solution
Incorporating a DC-DC converter with a blocking diode and an additional resistor in parallel, allowing a single insulation monitoring device with a measuring resistor associated with the secondary power supply network to detect insulation faults common to both networks by bridging the blocking diode, thus eliminating the need for separate monitoring devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single insulation monitoring device is used for the secondary power supply network with a blocking diode, then the device complexity is reduced, but the ability to detect insulation faults in the primary power supply network is lost
Solution Approach 1:
A measuring resistor is connected in parallel with the blocking diode to act as an intermediary component. This measuring resistor enables the insulation monitoring device on the secondary side to detect insulation faults in the primary power supply network by providing a measurement path through the diode, thus resolving the contradiction between device simplicity and detection capability.
2Reliability
If separate insulation monitoring devices are used for primary and secondary power supply networks, then the insulation fault detection capability is improved, but the device complexity and cost increase
Solution Approach 1:
The insulation monitoring device on the secondary side is designed to perform dual functions: monitoring the secondary power supply network directly and monitoring the primary power supply network indirectly through the measuring resistor connected in parallel with the blocking diode. This multi-functionality eliminates the need for separate monitoring devices while maintaining comprehensive detection capability.
3Reliability
If a blocking diode is used to connect primary and secondary power supply networks, then the electrical isolation is improved, but the ability to measure common insulation faults is reduced
Solution Approach 1:
The measuring resistor serves as an intermediary element that bridges the electrical isolation created by the blocking diode. It provides a controlled measurement path that allows the insulation monitoring device to detect common insulation faults in both power supply networks without compromising the functional electrical isolation required for system operation.
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
This configuration enables simple and cost-effective detection of insulation faults across both power supply networks, reducing hardware complexity and operational costs while maintaining system functionality.
Implementation Method 1
the blocking diode has a forward direction thereof oriented from the primary power supply network toward the secondary power supply network
Implementation Method 2
an insulation monitoring device having a measuring resistor is associated with the secondary power supply network for determining an insulation fault
Data Source
AI summary
An onboard electrical system for a motor vehicle is provided having a primary power supply network and a secondary power supply network electrically connected to the primary power supply network via a DC-DC converter, wherein the primary power supply network and the secondary power supply network are connected to one another via a blocking diode of the DC-DC converter and the blocking diode has a forward direction thereof oriented from the primary power supply network toward the secondary power supply network, and wherein an insulation monitoring device having a measuring resistor is associated with the secondary power supply network for determining an insulation fault. It is provided that an additional resistor is connected in parallel with the blocking diode for bridging thereof, such that an insulation fault common to the primary power supply network and the secondary power supply network can be determined by the insulation monitoring device. A related method for operating an onboard electrical system for a motor vehicle is also provided.