Active Bridge Rectifier Load Shedding Control
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Solution Overview
Problem
Active bridge rectifiers face challenges in managing load shedding events, leading to potential overvoltage damage due to rapid current changes and the need for additional protection strategies that are difficult to implement with existing technologies.
Innovation Solution
A method involving a longer switching time for active switching elements in bridge rectifiers during load shedding, using a voltage signal to gradually change the on-resistance, thereby reducing voltage peaks and dips, and eliminating the need for extensive intermediate circuit capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If switching time is reduced systematically, then switching speed is improved, but voltage peaks occur during load shedding that can damage connected components
Solution Approach 1:
The patent applies dynamics by making the switching time adjustable rather than fixed. During normal operation, the switching time is kept short for high efficiency, while during load shedding events, the switching time is dynamically extended to prevent voltage peaks. This is achieved through control circuitry that detects load shedding conditions and adjusts the switching waveform accordingly, allowing the system to adapt its switching characteristics to different operational states.
2Stability of the object's composition
If intermediate circuit capacitance is provided to maintain voltage during load shedding, then voltage stability is improved, but device complexity increases due to thermal and vibration constraints at generator installation site
Solution Approach 1:
The patent replaces the mechanical/electrical solution of adding physical intermediate circuit capacitance with an electronic control solution. Instead of relying on passive capacitive elements that would require robust mechanical mounting to withstand vibration and thermal conditions, the invention uses active control of the switching elements to synthesize the desired voltage waveform, thereby maintaining voltage stability without the complexity of additional passive components.
3Object-affected harmful factors
If phase short circuits are separated to prevent overvoltage, then overvoltage protection is improved, but rapid current changes occur that lead to voltage peaks
Solution Approach 1:
The patent applies parameter changes by modifying the switching time parameter during load shedding events. When load shedding is detected, the control system extends the switching time of the active switching elements, which gradually changes the on-resistance and current flow. This controlled parameter adjustment prevents both overvoltage damage and the generation of harmful voltage peaks from rapid current 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
This approach effectively prevents overvoltages and undervoltages, reducing electrical power losses and allowing for less robust switching elements, thus avoiding damage to connected components and lowering costs.
Implementation Method 1
using a voltage signal to gradually change the on-resistance
Data Source
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AI summary
A method for driving a bridge rectifier (1) with active switching elements (S) is proposed, in which, during normal operation, at least one of the active switching elements (S) is driven using a voltage signal, the voltage of which is changed from a first voltage value to a second voltage value within at least one switching time, wherein, if load shedding at the bridge rectifier (1) is determined, the at least one switching time is extended by a predefinable period. The invention likewise relates to a corresponding rectifier arrangement and to a computer program product.