DC Network Inductance Measurement via Controlled Switch Disconnect
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Solution Overview
Problem
Existing methods for measuring inductance in DC networks are inadequate for large-signal disturbances, as they either require high power excitation that disrupts the network or cannot accurately account for non-linear behavior, and existing small-signal measurements fail to extrapolate to large-signal conditions.
Innovation Solution
A large-signal inductance measuring device that includes a disconnecting switch, series circuits with capacitive and diode arrangements, and measuring devices to measure voltage and current changes, allowing for the determination of source-side and load-side inductance separately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If small-signal measurement is used to measure inductance, then the measurement can be performed with low power and without disrupting the network, but the measurement cannot accurately reflect the large-signal behavior and non-linear characteristics of the inductance
Solution Approach 1:
The patent uses periodic switching of the disconnecting switch to generate large-signal disturbances at controlled intervals. This periodic action allows the system to measure inductance under large-signal conditions without requiring continuous high power input, thus resolving the contradiction between low power consumption and accurate large-signal measurement
Solution Approach 2:
The patent performs preliminary measurements using small-signal disturbances to establish baseline characteristics, then uses these results to inform and optimize subsequent large-signal measurements. This preliminary action reduces the overall power requirement while ensuring measurement accuracy
2Measurement precision
If large-signal measurement is performed using resonant circuit excitation, then the inductance can be measured under large-signal conditions, but the power demand becomes very high and the network operation is severely restricted
Solution Approach 1:
The disconnecting switch is operated periodically to generate controlled large-signal disturbances. This periodic operation allows large-signal measurements to be performed intermittently rather than continuously, significantly reducing the average power demand while still obtaining accurate large-signal inductance measurements
Solution Approach 2:
The patent applies large-signal disturbances only partially in time (during measurement intervals) rather than continuously. This partial action provides sufficient data for accurate large-signal inductance measurement while keeping the overall power demand acceptable for network operation
3Loss of information
If the disconnecting switch is used to disconnect the first conductor for measurement, then the source-side and load-side inductance can be determined separately, but the device complexity increases
Solution Approach 1:
The patent segments the inductance measurement into source-side and load-side components by using the disconnecting switch to isolate the first conductor. This segmentation allows independent determination of inductance on each side of the circuit breaker, providing complete information without requiring a single complex measurement system
Solution Approach 2:
The disconnecting switch acts as an intermediary element that enables the separation of measurements. By temporarily disconnecting the first conductor, it mediates between the source and load sides, allowing independent measurement of each side's inductance contribution without requiring direct access to both sides simultaneously
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 accurate and high-speed measurement of inductance in DC networks, facilitating adapted overload protection solutions on both sides of the circuit breaker, suitable for industrial networks and DC charging infrastructure.
Implementation Method 1
a first capacitive arrangement (3) and a first diode arrangement (4), wherein a first end of the first series circuit 3, 4 is electrically connected to the first conductor EL at a source-side side of the disconnecting switch (2), and which is configured such that, after disconnecting the first conductor EL, a first current EST caused by the source-side part of the inductance QTI flows through the first series circuit 3, 4, which current leads to a first change in voltage ESA at the first capacitive arrangement (3)
Data Source
AI summary
Large-signal inductance measuring device for performing a measuring operation for measuring an inductance at an electrical energy supply line arrangement operated with a DC voltage, the large-signal inductance measuring device including: a disconnecting switch for electrically disconnecting the first conductor of the energy supply line arrangement; a first series circuit including a first capacitive arrangement and a first diode arrangement; a first measuring device for measuring a first change in voltage after the first conductor is disconnected; a second series circuit including a second capacitive arrangement and a second diode arrangement; a second measuring device for measuring a second change in voltage after the first conductor is disconnected; a third measuring device for measuring a third current on the first conductor before the first conductor is disconnected; and an evaluation device for evaluating the measured first change in voltage, the measured second change in voltage, and the measured third current.