Antiparallel Switch Diode Protection Circuit
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing protection devices for electrical overcurrent in photovoltaic systems face challenges in activation speed and output preservation, with known solutions causing voltage drops, increased costs, or inefficiencies in short-circuit protection.
Innovation Solution
A protection device with a second electronic switch connected in antiparallel to the diode, capable of switching under controller command, along with current measurement and control means to manage overcurrent, preserving branch output and improving activation speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an impedance is connected serially between phase output and electrical network to limit short-circuit current, then diode protection is improved, but voltage drop at phase outputs increases and inverter apparent power must be overdimensioned
Solution Approach 1:
The protection function is segmented from the main inverter circuit by using a separate parallel branch containing the second electronic switch. This allows protection to be provided without inserting impedance into the main current path, thus avoiding voltage drops while still limiting fault current through the dedicated protection branch.
Solution Approach 2:
The second electronic switch acts as an intermediary protection element that can rapidly intervene to block fault current from reaching the diode. By placing this switch in parallel with the diode and controlling it independently, the system provides fast protection without the need for series impedance that would cause continuous voltage drops.
2Reliability
If a diode is connected serially between photovoltaic module output and inverter input to protect against reverse current, then diode protection response time is improved, but input voltage drops and overall output deteriorates
Solution Approach 1:
Instead of placing the protection element in series with the main current path (which would block normal operation), the second electronic switch is placed in parallel with the diode. This inverted configuration allows the protection element to remain inactive during normal operation and only engage when needed, thus protecting the diode without affecting overall system output.
Solution Approach 2:
The control means continuously monitors current conditions and prepares the second electronic switch for immediate activation. When overcurrent is detected, the switch is rapidly activated in parallel with the diode, providing preliminary protection action that prevents diode damage before fault conditions can propagate, without interrupting normal power flow.
3Reliability
If fuses are used in the protection device connected serially between phase output and electrical network, then overcurrent protection is provided, but operating costs increase due to high temperature requirements and fuse replacement
Solution Approach 1:
The passive mechanical fuse system is replaced with an active electronic protection system using controllable electronic switches. This substitution eliminates the need for thermal-magnetic fuse elements that require high temperatures to operate, allowing for lower operating costs and easier maintenance through electronic control rather than mechanical replacement.
Solution Approach 2:
The protection mechanism changes from thermal-based (fuses requiring high temperature to melt) to electronic-based (controllable switches that can be activated instantaneously). This parameter change from thermal to electronic control allows for rapid response without the cost and complexity of high-temperature fuse specifications and replacement procedures.
4Speed
If the inverter is too slow to open the electrical circuit when input voltage decreases abruptly, then response time is insufficient, but diode breaking is prevented
Solution Approach 1:
The control means continuously monitors current conditions and prepares the second electronic switch for immediate activation. When overcurrent is detected, the switch is rapidly activated in parallel with the diode, providing preliminary protection action that prevents diode damage before fault conditions can propagate, without interrupting normal power flow.
Solution Approach 2:
The control means implements feedback control by continuously monitoring current conditions and immediately responding by activating the second electronic switch when overcurrent is detected. This closed-loop feedback system ensures rapid response times that exceed the capabilities of passive protection devices, providing reliable diode protection through active control.
Data Source
AI summary
This device protects at least one electronic switching branch of an electrical conversion system against an overcurrent, each branch comprising two switching half-branches serially connected at an intermediate terminal, at least one half-branch including a switching member, each switching member comprising a first controllable switch and a diode connected in antiparallel to the first switch. The protection device includes, for each switching branch, at least one second controllable switch, each second switch being connected to the intermediate terminal or to an electrode of said diode in antiparallel to the first switch, each second switch being able to switch, under action of a controller, from an on state to an off state to protect said diode from the overcurrent, means for measuring a magnitude relative to a current able to circulate in each diode, and means for controlling each second switch, based on the measured magnitude.