Parallel Resistor Inductor Current Detector for Power Semiconductor Protection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The use of shunt resistors in power semiconductor device protection circuits results in power loss during normal operation, as current flows through the resistor even when the device is functioning correctly, and this can lead to inaccurate short-circuit detection and increased power loss during short-circuit events.
Innovation Solution
A protection circuit that includes a current detector with a first resistor and an inductor connected in parallel, where one end of each is connected to the power semiconductor device, and the reference potential of the drive circuit is connected to the other end of the resistor and inductor, allowing for reduced power loss and improved short-circuit detection accuracy by comparing the voltage changes across these components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a shunt resistor is used to detect current flow through the power semiconductor device, then short-circuit protection can be achieved, but power loss increases during normal operation
Solution Approach 1:
The current detection function is segmented from the main power path by using a parallel RC circuit connected to the collector terminal. The detection circuit only samples a portion of the current signal through the resistor without forcing all current through a sensing element, thus reducing power loss while maintaining protection capability
Solution Approach 2:
A capacitor is introduced as an intermediary element in parallel with the resistor. During normal operation, the capacitor blocks DC current flow through the resistor, eliminating power loss. During short-circuit events, the capacitor charges quickly and allows the resistor to detect the current surge, thus mediating between continuous power loss prevention and intermittent detection needs
2Reliability
If a shunt resistor is used for current detection, then short-circuit detection can be performed, but detection accuracy decreases due to power loss
Solution Approach 1:
The circuit transitions dynamically between two states: during normal operation, the capacitor remains charged and blocks current through the resistor (low power loss state); during short-circuit events, the capacitor discharges and allows current flow through the resistor (detection state). This dynamic behavior optimizes both power efficiency and detection accuracy at different operational phases
Solution Approach 2:
The capacitor charges and discharges periodically based on the operational state of the power semiconductor device. During normal operation, it maintains a charged state to prevent power loss. Upon detecting a short-circuit condition, it transitions to a discharged state enabling accurate current detection, creating a periodic cycle between power-saving and detection modes
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
This configuration reduces power loss during normal operation and enhances short-circuit detection accuracy by increasing the detection voltage, preventing false alarms and protecting the power semiconductor device from damage.
Implementation Method 1
a current detector which includes a first resistor and an inductor connected in parallel
Implementation Method 2
the detection circuit detects the short-circuit condition of the power semiconductor device by comparing a voltage of the one terminal of the power semiconductor device, which changes as a function of current flow through the first resistor and the inductor, with a short-circuit detection voltage
Data Source
AI summary
A power semiconductor device protection circuit includes: a drive circuit that drives a power semiconductor device; a current detector which includes a first resistor and an inductor connected in parallel; and a detection circuit that detects a short-circuit condition of the power semiconductor device. One end of the first resistor and one end of the inductor are connected to one terminal of the power semiconductor device. The detection circuit detects the short-circuit condition of the power semiconductor device by comparing a voltage of the one terminal of the power semiconductor device, which changes as a function of current flow through the first resistor and the inductor, with a short-circuit detection voltage. A reference potential of the drive circuit is connected to the other end of the first resistor and the other end of the inductor.