Power Rectifier Gate Voltage Control for Short Circuit Management
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Solution Overview
Problem
Three-phase power rectifiers face issues with asymmetric short circuit currents during branch faults, leading to critical torque changes in electric motors or generators, and existing methods fail to prevent desaturation and destruction of power semiconductor elements.
Innovation Solution
The method involves detecting collector-emitter voltage and current rates to determine if a short circuit is present, and if so, increasing the gate-emitter voltage of affected power semiconductor elements to allow higher current flow without desaturation, enabling symmetrical short circuit currents and preventing element destruction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the other power semiconductor element in a branch is switched off to avoid destruction, then additional element destruction is prevented, but asymmetric short circuit currents continue to flow causing critical torque changes
Solution Approach 1:
The patent changes the gate-emitter voltage parameter of the power semiconductor elements. By increasing the gate-emitter voltage above the normal operating level, the affected power semiconductor element can conduct higher short circuit currents without desaturation, enabling symmetric current flow while maintaining element integrity
Solution Approach 2:
The patent dynamically adjusts the gate-emitter voltage based on the detected fault condition. The control device monitors collector-emitter voltage and collector current rates, and dynamically increases the gate-emitter voltage when a short circuit is detected, allowing the system to adapt its behavior to the fault condition
2Reliability
If the gate-emitter voltage is increased to allow higher current flow, then desaturation and element destruction are prevented, but the system must detect and respond to short circuit conditions
Solution Approach 1:
The patent implements a feedback mechanism where the control device continuously monitors the collector-emitter voltage and collector current of the power semiconductor elements. When the rate of change of these parameters indicates a short circuit condition, the control device responds by increasing the gate-emitter voltage, creating a closed-loop control system that automatically adapts to fault conditions
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 approach allows for the detection and management of branch short circuits, preventing desaturation and subsequent destruction of power semiconductor elements, resulting in reduced torque changes and maintaining rectifier functionality.
Implementation Method 1
the control device 20 increases the gate-emitter voltage of at least one of the power semiconductor elements 14
Implementation Method 2
the collector current I C (t) and the collector-emitter voltage V CE (t) are detected for at least one of the power semiconductor elements 14
Data Source
Figure 1~2
Figure 3A~3C
AI summary
Disclosed herein is a method for operating an electrical power rectifier (10). The power rectifier (10) comprises at least two branches (11, 12, 13) that are connected in parallel to each other, each of said branches comprising at least two power semiconductor elements (14', 14") that are connected in series. The collector-emitter voltage Vce(t) and/or the collector current Ic(t) of one of the power semiconductor elements (14', 14") is detected by means of the method. Furthermore, it is determined whether at least one of the following conditions is met: dVCE(t)/dt < (dVCE/dt)crit and/or dIC(t)/dt < (dIC/dt)crit and or IC(t_ent) < ICcrit. If at least one of the aforementioned conditions has been met, the gate-emitter voltage of at least one of the power semiconductor elements (14', 14") is increased.