Diode Bridge Transient Current Protection for Grid-Connected Inverters
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Solution Overview
Problem
Electrical energy conversion systems connected to the power grid face issues with transient currents caused by overvoltages, which can be lethal to recirculation diodes and switching devices due to high amperage levels, leading to device destruction.
Innovation Solution
A diode bridge is introduced between the power grid and the inverter's power section upstream of the main filtering inductors, acting as an alternative path for transient currents, and optionally combined with common-mode eddy current blocking filters or transient voltage suppressors to protect semiconductor devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If recirculation diodes are used in the inverter circuit, then the inverter can operate normally with switching devices, but the recirculation diodes are vulnerable to destruction by transient currents from grid overvoltages
Solution Approach 1:
A diode bridge is introduced as an intermediary component between the power grid and the inverter circuit. This diode bridge acts as a mediator that intercepts transient currents from grid overvoltages and directs them through a safe path (through the filter capacitor and grid connection) rather than allowing them to flow through the vulnerable recirculation diodes and switching devices.
2Productivity
If the inverter is directly connected to the power grid, then energy conversion efficiency is improved, but transient phenomena on the grid can cause high amplitude currents that destroy semiconductor devices
Solution Approach 1:
The diode bridge is positioned upstream in the circuit, before the transient currents can reach the vulnerable semiconductor devices. This preliminary placement allows the diode bridge to intercept and redirect transient currents before they cause damage, while maintaining the direct grid connection for normal energy conversion operations.
3Adaptability or versatility
If switching devices are used for DC to AC conversion, then the inverter can control output voltage and frequency, but the switching devices are stressed by transient currents during grid transients
Solution Approach 1:
The diode bridge serves as a protective intermediary that shields the switching devices from transient current stress. During normal operation, the switching devices maintain voltage and frequency control functionality, while the diode bridge provides a alternative path for transient currents, reducing the stress on the switching devices.
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 diode bridge and additional filters or suppressors effectively divert transient currents away from recirculation diodes, enhancing the robustness of semiconductor devices and preventing damage during grid transient phenomena.
Implementation Method 1
a diode bridge connected between the power grid and the power section of said inverter, upstream of the main filtering inductors
Data Source
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AI summary
The present invention relates to a transient current and voltage protection device for electrical energy conversion systems connected to the power grid, comprising a diode bridge connected between the power grid and the power section of said inverter, upstream of the main filtering inductors.