Power Converter Neutral and Ground Fault Detection by Harmonic Injection
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Solution Overview
Problem
Existing power conversion devices fail to detect abnormal connections between the neutral wire or the ground cable, leading to the disconnection of the power supply loop and leakage current, causing instability and damage to the alternating current load.
Innovation Solution
A power conversion device that includes a power conversion circuit, a controller, and conducting wires, using a harmonic signal of a target frequency to detect abnormal connections in the neutral wire or ground cable by measuring voltage amplitude within a specific range, ensuring stable power supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the power conversion device does not include connection detection functionality, then the device structure remains simple, but the power supply stability and security deteriorate due to undetected abnormal connections
Solution Approach 1:
The patent makes the power conversion device multi-functional by integrating both power conversion and connection detection functions into a single system. The controller not only controls the power conversion circuit but also detects abnormal connections in neutral wires and ground cables, eliminating the need for separate detection devices and maintaining structural simplicity while improving reliability
Solution Approach 2:
The patent implements feedback by having the controller continuously monitor voltage amplitudes across capacitors connected to different wires. When the voltage amplitude of a detection signal exceeds a threshold, the controller identifies an abnormal connection and can respond accordingly, creating a closed-loop feedback system that enhances power supply security without adding complex external monitoring equipment
2Reliability
If the power conversion device lacks abnormal connection detection, then the implementation remains simple, but the power supply security deteriorates due to undetected leakage currents
Solution Approach 1:
The controller is designed to perform multiple functions: power conversion control and connection detection. By integrating the detection function into the existing controller, the patent avoids the need for separate detection devices, maintaining ease of manufacture while significantly improving power supply security through leakage current detection
Solution Approach 2:
The power conversion device performs self-diagnosis by using its own controller to detect abnormal connections in its wiring system. The device monitors its own operational status through voltage amplitude measurements, enabling self-service functionality that improves security without requiring external monitoring systems or complex implementation
3Reliability
If connection detection is not implemented, then the device structure remains simple, but the power supply stability deteriorates due to disconnected power supply loops
Solution Approach 1:
The patent integrates connection detection functionality into the existing power conversion device structure. The controller uses the same power conversion circuit and adds detection capabilities by measuring voltage amplitudes across capacitors, making the device multi-functional without requiring separate detection equipment or significantly increasing structural complexity
Solution Approach 2:
The controller implements continuous monitoring of voltage amplitudes across capacitors connected to power supply wires. When abnormal voltage levels indicate disconnected or faulty connections, the controller receives feedback and can take corrective actions, creating a feedback mechanism that maintains power supply stability without complex additional structures
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
The device effectively detects abnormal connections in neutral and ground cables, preventing disconnections and leakage currents, ensuring power supply stability and security, with a simple structure and high reliability.
Implementation Method 1
a power conversion circuit, including at least one first bridge arm
Implementation Method 2
A first end of a first capacitor corresponding to each first bridge arm is connected to a side that is of the first inductor on the first conducting wire and that is away from the first bridge arm. A second end of the first capacitor corresponding to each first bridge arm is connected to a direct current end of the power conversion circuit
Implementation Method 3
A first inductor is connected in series to any one first conducting wire
Data Source
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AI summary
This application provides a power conversion device, including a power conversion circuit, a controller, a first capacitor, a first conducting wire, and a second conducting wire. A first inductor is connected in series to the first conducting wire. An alternating current output of a first bridge arm in the power conversion circuit is connected to the first conducting wire. A first end of the first capacitor is connected to a side of the first inductor. A second end of the first capacitor is connected to a direct current end of the power conversion circuit and the second conducting wire. The first conducting wire is a live wire, and the second conducting wire includes at least one of a neutral wire and a ground cable. The controller injects a harmonic signal of a first target frequency into the first bridge arm in the power conversion circuit. When a voltage amplitude of a voltage signal that is of the first target frequency and that is generated between the first conducting wire and the second conducting wire is within a first target range, the controller outputs information about an abnormal connection of the second conducting wire. In this application, the power conversion device can detect whether the neutral wire or the ground cable is abnormally connected, to ensure power supply stability and security, and is also applicable to various power grid standards and power supply scenarios, and has high reliability.