Polyphase Power Converter Redundancy Control for Faulty Subsystems
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Solution Overview
Problem
Existing power converters with distributed energy stores face challenges in maintaining symmetry conditions and preventing harmonic and DC voltage components when one or more subsystems fail, leading to potential system shutdowns and increased stress on semiconductor switches.
Innovation Solution
The method involves controlling the terminal voltages of undisturbed subsystems in faulty phase modules to match the capacitor voltage, ensuring all output voltages are symmetrical, and offsetting switching times of control signals to maintain the amplitude profile of fundamental components, thereby maintaining symmetry and reducing stress on semiconductor switches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a subsystem fails in a phase module, then redundancy allows continued operation, but asymmetry and harmonic voltage components arise that can cause system shutdown
Solution Approach 1:
The patent deliberately introduces asymmetry in the control of undisturbed subsystems by switching them off in specific valve arms (upper or lower) based on the position of the failed subsystem. This controlled asymmetry compensates for the fault condition and eliminates the harmful harmonic and DC voltage components that would otherwise cause system shutdown.
Solution Approach 2:
The control method changes the switching parameters of undisturbed subsystems dynamically based on the fault condition. By adjusting which undisturbed subsystems are switched off in each valve arm according to the failed subsystem's position, the system maintains symmetry in output voltages while accommodating the fault.
2Stability of the object's composition
If undisturbed subsystems are switched off to maintain symmetry, then output voltage symmetry is improved, but the number of active subsystems decreases
Solution Approach 1:
The patent applies local quality by selectively switching off undisturbed subsystems only in specific valve arms (upper or lower) depending on the position of the failed subsystem. This localized control approach maintains overall output voltage symmetry while minimizing the number of inactive subsystems, thereby preserving productivity.
3Reliability
If the converter operates with faulty subsystems, then redundancy is utilized, but stress on semiconductor switches increases
Solution Approach 1:
The patent converts the harmful effect of subsystem failure into a beneficial control strategy. By detecting the failed subsystem's position and systematically switching off corresponding undisturbed subsystems in specific valve arms, the method eliminates harmful voltage components while maintaining balanced stress distribution on remaining semiconductor switches.
Data Source
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AI summary
The invention relates to a method for controlling a power converter having at least two phase modules, which each have an upper and a lower valve branch, each having at least three series-connected two-pole subsystems, in the event of failure of at least one subsystem of a valve branch of a phase module. According to the invention, the valve branch (Tl, , T6) with the failed subsystem (10) is determined, and in each case a subsystem (10) of a valve branch (Tl, , T6), which corresponds to the faulty valve branch (Tl, , T6), of any fault-free phase module (100) is driven such that its terminal voltages (UX21) are in each case zero. A polyphase power converter with distributed energy stores (9) is therefore operated with redundancy.