DC/AC Converter Disconnect Verification via Midpoint Voltage
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing photovoltaic inverter systems require multiple voltage detectors to verify the correct operation of disconnecting means, increasing cost and complexity, while current methods may fail to detect malfunctions effectively, posing safety risks.
Innovation Solution
A system using four voltage detectors to measure voltages between midpoints and the neutral of each phase, along with a reference point, to verify the status of both internal and external disconnecting means in a three-phase DC/AC converter, allowing for efficient verification with reduced detector numbers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If six voltage detectors are used to measure voltages on grid side and between disconnecting means, then verification accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent combines multiple measurement functions into fewer detectors. Specifically, it measures voltages at strategic points (between series disconnecting means and at converter output) to simultaneously verify both disconnecting means operation and converter output status, reducing the total number of detectors needed while maintaining comprehensive verification capability
Solution Approach 2:
The voltage detectors are designed to perform multiple verification functions. The same detectors used to measure voltages for disconnecting means verification also provide information about converter output status and grid connection state, allowing one detector to serve multiple safety verification purposes
2Reliability
If six voltage detectors are used for comprehensive verification, then safety reliability is improved, but manufacturing cost increases
Solution Approach 1:
The patent merges the verification functions into a more compact detector arrangement. By measuring voltages at key intermediate points in the circuit rather than at every possible location, it achieves comprehensive safety verification with fewer components, directly reducing bill of materials cost and assembly complexity
Solution Approach 2:
The system uses the existing voltage signals already present in the circuit during normal operation. The verification process leverages the operational voltages themselves rather than requiring additional excitation sources or test signals, eliminating the need for extra hardware and reducing manufacturing cost
3Measurement precision
If traditional six-detector method is used, then complete verification coverage is achieved, but design simplicity is reduced
Solution Approach 1:
The patent segments the verification process into two key measurement points: the voltage between series disconnecting means and the voltage at converter output. This segmentation allows each detector to focus on a specific functional zone, simplifying the overall design while maintaining complete verification coverage through strategic placement rather than comprehensive monitoring
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Verifying system and method for verifying the disconnecting means of a DC/AC converter which are connected in series through a midpoint (5, 6, 7) in each phase (L1, L2, L3) between the converter (3) and a power grid (4). The system comprises voltage detectors (90, 91, 92, 93) and a control unit (8) communicated with said detectors (90, 91, 92, 93) and configured for determining the status of the disconnecting means (1a, 1b, 1c, 2a, 2b, 2c) depending on said voltages. The detectors comprise a detector (91, 92, 93) associated with each phase (L1, L2, L3) for measuring the voltages (V'L1-N, V'L2-N, V'L3-N) between the corresponding midpoint (5, 6, 7) and the neutral (N) of the power grid (4), and an additional detector (90) for measuring the voltage (V'O-N) between said neutral (N) and a reference point (O) of the converter (3).