IGBT Overvoltage Protection Circuit with Logic Module
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing circuit arrangements for protecting units from overvoltages in supply networks do not effectively address transient overvoltage events without continuous higher-level control signals, and their response times are inadequate for fast voltage fluctuations.
Innovation Solution
A circuit arrangement featuring a logic module that detects overvoltage events and drives a power semiconductor with an increased gate voltage, utilizing a comparator to rapidly activate the power semiconductor and a thyristor for follow current limiting, with a microcontroller taking over control once activated, and additional TVS diodes for bridging response times and interference suppression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a microcontroller is used to detect and respond to overvoltage events, then the control logic can be implemented, but the response time is too slow for fast transient events
Solution Approach 1:
The control system is segmented into two independent parts: a fast comparator circuit for immediate detection and actuation, and a microcontroller for subsequent monitoring and analysis. The comparator operates autonomously during the critical initial response phase, bypassing the microcontroller's slower processing, while still enabling comprehensive protection functionality through division of labor between fast and intelligent components.
2Ease of operation
If the power semiconductor is driven with normal gate voltage, then continuous control signals are required, but this increases device complexity and prevents autonomous operation
Solution Approach 1:
The protective circuit is designed to be self-activating through the comparator that continuously monitors the voltage and automatically triggers the power semiconductor when overvoltage is detected. The circuit serves itself by having the comparator generate the gate drive signal directly from the voltage condition, eliminating the need for external control systems to continuously monitor and command the protection mechanism.
3Reliability
If the power semiconductor switching edge is not steep, then surge current capacity is insufficient, but increasing gate voltage increases power consumption
Solution Approach 1:
The high gate voltage is applied only periodically during transient overvoltage events rather than continuously. The comparator detects the overvoltage condition and activates the power semiconductor with enhanced gate drive only when needed, then returns to normal operation, thereby achieving surge current capability when required while minimizing average power consumption through event-driven operation.
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 efficient detection and management of transient overvoltage events with rapid response times, ensuring the power semiconductor can handle surge currents and limit follow currents effectively, even without continuous control signals, thereby protecting the unit from voltage spikes.
Implementation Method 1
A TVS diode is connected to the input of the unit against overvoltages, which is connected to the signal input of the microcontroller and the comparator that is also connected there and supplies a trigger signal in the event of breakdown.
Implementation Method 2
In order to enable the power semiconductor used to accept the required surge current, the invention ensures that the power semiconductor is driven with an increased gate voltage of up to 100 V and a correspondingly steep switching edge.
Implementation Method 3
a thyristor is provided at the output terminals, quasi parallel to the power semiconductor, which is connected to the logic module, the logic module activating the thyristor in a time-coordinated manner for the purpose of limiting the follow current.
Data Source
Figure 1
Figure 2
AI summary
The invention relates to a circuit assembly for protecting a unit to be operated from a supply network against overvoltage, comprising an input having a first and a second input connection, which are connected to the supply network, an output A having a first and a second output connection, to which the unit to be protected can be connected, and a protection circuit, which is provided between the first and the second input connections in order to limit the voltage present at the first and the second input connections, wherein the protection circuit has a power semiconductor IGBT and a controller for the power semiconductor. According to the invention, the controller is designed as a driver that detects overvoltage events by means of a logic assembly LB and, in the case of an overvoltage event, activates the power semiconductor IGBT until the overvoltage event has subsided, and for this purpose the power semiconductor IGBT is controlled at an increased gate voltage of up to 100 V with a steep switching edge.