Modular Multi-Stage Converter for Asynchronous Machine Power Injection
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Solution Overview
Problem
High nominal power rating and cost-intensive full-power converters in synchronous machines restrict the optimization of drive systems in electricity generating installations, and complex four-quadrant converters are required for asynchronous machines to deliver variable frequency three-phase AC current.
Innovation Solution
A modular multi-stage converter in a matrix configuration is used to connect a double-feed asynchronous machine to the AC network, allowing for scalable and cost-effective operation with a lower nominal power rating, generating advantageous stepped AC voltage and reducing thermal stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a full-power converter is used in synchronous machines, then the entire capacity can be transmitted, but the converter becomes cost-intensive and restricts optimization of drive systems
Solution Approach 1:
The converter is divided into multiple switching modules connected in series, where each module handles a portion of the total power. This segmentation allows the system to achieve full-power transmission capability while using smaller, more cost-effective individual modules rather than a single large full-power converter.
2Adaptability or versatility
If a four-quadrant converter is used in asynchronous machines, then variable frequency three-phase AC current can be delivered, but the converter becomes complex to produce
Solution Approach 1:
The four-quadrant converter functionality is achieved through multiple simple switching modules connected in series, where each module contributes to the overall variable frequency capability. This modular approach simplifies production compared to manufacturing a single complex four-quadrant converter, while maintaining the ability to deliver variable frequency three-phase AC current.
3Device complexity
If a modular multi-stage converter with lower nominal power rating is used, then costs are reduced, but the converter must still handle the entire capacity transmission
Solution Approach 1:
Multiple switching modules with lower individual power ratings are connected in series to collectively handle the entire capacity transmission. The series connection allows the voltage and power handling capability to scale up while each individual module remains cost-effective with a lower nominal power rating.
Solution Approach 2:
Multiple switching modules are combined in series to achieve the required total power transmission capability. The combined system of modular units delivers the full capacity transmission needed, while the cost benefits of using lower-rated individual modules are realized.
4Device complexity
If a non-modular converter is used, then the design is simpler, but the converter cannot be adapted to different applications and machines
Solution Approach 1:
The converter is designed as a modular system where identical switching modules can be combined in series to match different power requirements. This segmentation enables the same basic module design to be adapted to various applications and machine sizes, achieving versatility without increasing the complexity of individual module design.
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
The solution enables flexible and cost-effective operation of asynchronous machines by reducing the nominal power rating of converters, allowing for efficient energy injection into AC networks and supporting variable-frequency turbine operation, while minimizing thermal stress and operational costs.
Implementation Method 1
each switching module comprises a power semiconductor circuit and a dedicated energy store
Implementation Method 2
each switching module comprises a power semiconductor circuit and a dedicated energy store
Implementation Method 3
an asynchronous machine which, in generator operation, is configured to inject electrical energy into an AC network
Data Source
AI summary
An arrangement contains an asynchronous machine, which, in generator operation, is configured to feed electric power into an AC network. Accordingly, the asynchronous machine can be dual-fed by a modular multi-stage converter in a matrix configuration. The asynchronous machine has a rotor and the modular multi-stage converter is connected to the rotor of the asynchronous machine.