Shaft Generator Voltage Link Converter Short-Circuit Control
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Solution Overview
Problem
Existing shaft generator systems with voltage intermediate circuit converters face challenges in dynamically limiting mains short circuits and maintaining harmonic limits due to limited switching frequencies of IGBTs, requiring complex filter designs and additional components like duplex chokes and transformers, which are space-constrained on ships.
Innovation Solution
A shaft generator system with a voltage link converter featuring distributed energy stores allows for adaptable output voltage and high switching frequencies using low-voltage IGBTs, eliminating the need for duplex chokes and transformers, and enabling dynamic short-circuit management without switching off during overcurrents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a voltage intermediate circuit converter with IGBTs is used, then frequency and voltage decoupling is achieved, but the switching frequency is limited and harmonic limits cannot be maintained
Solution Approach 1:
The voltage intermediate circuit converter is segmented into multiple series-connected IGBT modules, each capable of independent high-frequency switching. This segmentation allows the system to achieve both frequency decoupling and maintain harmonic limits through coordinated high-speed switching of individual modules.
Solution Approach 2:
The system employs dynamic control of the IGBT switching operations, where the switching frequency and timing are continuously adjusted based on real-time operational conditions. This dynamic approach enables the converter to maintain harmonic limits while achieving frequency and voltage decoupling across varying load conditions.
2Reliability
If duplex chokes and transformers are added to limit short-circuit currents, then short-circuit protection is improved, but device complexity and space requirements increase
Solution Approach 1:
The patent extracts and eliminates the need for separate duplex chokes and transformers by integrating short-circuit current limiting functionality directly into the voltage intermediate circuit converter through high-frequency IGBT switching control. This extraction reduces device complexity while maintaining short-circuit protection.
Solution Approach 2:
The mechanical/passive short-circuit protection approach using duplex chokes and transformers is replaced with an active electronic control system using IGBTs. The high-frequency switching of IGBTs provides dynamic short-circuit current limiting without requiring additional passive components, thereby reducing system complexity.
3Reliability
If duplex chokes and transformers are installed, then short-circuit currents are limited, but installation space on the ship increases
Solution Approach 1:
The patent merges the functions of duplex chokes, transformers, and frequency converters into a single integrated voltage intermediate circuit converter. This consolidation provides short-circuit protection, frequency decoupling, and voltage regulation in one compact unit, significantly reducing the installation space required on the ship.
Solution Approach 2:
Heavy passive components (duplex chokes and transformers) are replaced with compact active electronic IGBT-based circuitry. The high-frequency switching capability of IGBTs enables effective short-circuit current limiting in a much smaller footprint compared to traditional passive components.
4Speed
If low-voltage IGBTs with high switching frequencies are used, then dynamic control of short-circuit currents is improved, but the system operates outside resonance frequencies requiring filter design changes
Solution Approach 1:
The system operates at high switching frequencies that dynamically vary with operational conditions, deliberately operating outside the resonance frequencies of the ship's electrical network. This dynamic high-frequency operation reduces harmonic content by avoiding resonant amplification, eliminating the need for complex filter designs.
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 ensures high dynamic control of short-circuit currents, meets ship network requirements for short-circuit currents, reduces harmonic content in generator currents, and simplifies filter design by operating outside resonance frequencies, enhancing system reliability and efficiency.
Implementation Method 1
A shaft generator system with a voltage link converter featuring distributed energy stores allows for adaptable output voltage and high switching frequencies using low-voltage IGBTs
Implementation Method 2
voltage link converter featuring distributed energy stores
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The invention relates to a shaft-driven generator system having a shaft-driven generator (18). According to the invention, a voltage source inverter (42) having a network-side inductance is provided, wherein said voltage source inverter (42) has a converter (44, 46) on the generator side and on the network side, which are linked to each other on the direct-voltage side, and wherein the converter (46) on the network side has at least two phase modules, which each have an upper and a lower valve branch (P1, N1, P2, N2, P3, N3), which each have a plurality of two-pole sub-systems (SM1,..., SMn) connected electrically in series, which sub-systems each have a unipolar storage capacitor (CSM), to which a series circuit of two semiconductor switches (S1, S2) that can be switched off is connected electrically in parallel, each semiconductor switch having a diode (D1, D2) connected antiparallel. Thus, a shaft-driven generator system is obtained that has a voltage source inverter (42) as a static frequency converter. By means of the voltage source inverter, the required effects on the network can be complied with and transient operating states controlled.