Semiconductor Switch Protection Circuit Using Charge Integration
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Solution Overview
Problem
Conventional overvoltage protection devices for semiconductor switches, such as those using avalanche or Zener diodes, face challenges in quickly and reliably detecting overvoltages at high switching speeds due to their capacitive properties, which can affect response voltage and behavior.
Innovation Solution
A protection device for semiconductor switches that includes a capacitive component, an integrator, and a comparison device to determine and compare the charge in the capacitive component with a preset limit value, allowing for timely and effective control of the semiconductor switch to prevent overvoltage damage, utilizing components like diodes or capacitors to account for capacitive properties and synchronize integration with control signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If avalanche diodes are used for overvoltage detection, then overvoltage protection is provided, but the capacitive properties of the diodes affect response voltage and behavior at high switching speeds
Solution Approach 1:
The patent introduces a capacitive component as an intermediary element between the semiconductor switch and the overvoltage detection circuit. This capacitive component serves as a mediator that stores charge information and enables the detection circuit to sense overvoltage conditions without being directly affected by the high-speed switching transients that would otherwise interfere with the detection accuracy.
Solution Approach 2:
The patent replaces the direct voltage sensing approach (which would be affected by capacitive effects at high speeds) with a charge integration approach. By integrating the charging current into a capacitive component and evaluating the accumulated charge, the system substitutes a temporal integration mechanism for direct instantaneous voltage measurement, thereby eliminating the adverse effects of capacitive properties on response behavior.
2Reliability
If conventional overvoltage protection devices are used, then protection is provided, but detection is not quick or reliable at high switching speeds
Solution Approach 1:
The patent implements preliminary action by continuously charging the capacitive component during normal operation, so that when an overvoltage event occurs, the charge already accumulated in the capacitive component can be quickly evaluated. This pre-charging process ensures that the detection system is prepared in advance, eliminating detection delays that would occur with systems needing to respond from scratch during high-speed switching events.
Solution Approach 2:
The patent substitutes direct voltage comparison with charge evaluation. By integrating the charging current into the capacitive component over time and then evaluating the accumulated charge quantity, the system replaces instantaneous voltage measurement with a temporal integration process. This substitution allows the system to filter out high-frequency switching noise and provide reliable detection even at high switching speeds.
3Measurement precision
If the capacitive properties of avalanche diodes are considered, then accurate detection is possible, but response voltage and response behavior are negatively affected
Solution Approach 1:
The patent introduces a separate capacitive component as an intermediary that decouples the detection function from the switching circuit. This intermediary capacitive element accumulates charge proportional to the voltage stress on the semiconductor switch without being directly subjected to the high-speed switching transients, thereby maintaining measurement precision while preserving response speed.
Solution Approach 2:
The patent replaces direct voltage sensing through capacitive diodes with charge integration through a dedicated capacitive component. By substituting the sensing mechanism from direct capacitive voltage division to charge accumulation and evaluation, the system achieves both precise overvoltage detection and fast response, as the integration process naturally filters high-frequency noise while maintaining sensitivity to voltage changes.
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 quick and reliable detection of overvoltages at high switching speeds, preventing damage by allowing for precise control of the semiconductor switch when charge exceeds a set limit, ensuring effective overvoltage protection both in rapid and steady-state conditions.
Implementation Method 1
A protection device for a semiconductor switch having a capacitive component, an integrator and a comparison device. The integrator is designed to integrate a charging current into the capacitive component.
Data Source
AI summary
The invention relates to a protection for a semi-conductor switch against over voltages. A capacitive element is provided on an inlet connection of the semi-conductor switch. The load amount, which flows into said capacitive element, is integrated in order to trigger a protection function when a threshold value is exceeded.