Multi-Stage Rectifier Transmission Device for Asynchronous Networks
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Solution Overview
Problem
Current energy transmission devices, such as transformers, face limitations including the inability to dynamically control power flows, high material requirements, significant losses during idling, and the inability to couple asynchronous networks, with DC voltage intermediate circuits being prone to failures and voltage fluctuations.
Innovation Solution
A transmission device utilizing multi-phase multi-stage power converters connected via a multi-phase transformer, with a control device to dynamically adjust energy transmission according to a target specification, eliminating the need for a DC link and enabling electrical isolation and dynamic control of power flows between multi-phase energy networks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a transformer is used for energy transmission between two electrical three-phase networks, then the two networks are coupled in a galvanically isolated manner, but no dynamic control of the power flows is possible
Solution Approach 1:
The patent replaces the static transformer with dynamic power converters that can actively control power flow. The converters use semiconductor switches to modulate the power transmission in real-time, enabling dynamic adjustment of power flow magnitude and direction while maintaining galvanic isolation through the transformer coupling.
Solution Approach 2:
The invention changes the operating parameters by introducing high-frequency switching operation. The power converters switch at frequencies much higher than the grid frequency, enabling precise control of power flow while the transformer operates at this elevated frequency to provide isolation. This parameter change from grid frequency to high-frequency switching enables both isolation and dynamic control.
2Loss of energy
If a transformer is used for energy transmission, then energy can be transmitted between networks, but a large amount of material is required and there are considerable losses when the machine is idling
Solution Approach 1:
The patent employs periodic high-frequency switching action in the power converters. The converters operate in discrete switching cycles, allowing them to be turned off or operate at minimal power when no energy transmission is needed, eliminating continuous idling losses. The periodic switching enables control to be applied only when power flow is required.
Solution Approach 2:
The invention extracts the active control function from the passive transformer. The transformer is reduced to providing only galvanic isolation, while the power converters handle all active power transmission and control functions. This separation allows the transformer to be smaller and eliminates the need for a large idle transformer to maintain control capability.
3Reliability
If a DC voltage intermediate circuit is used to control power flow, then asynchronous three-phase networks can be coupled, but at least one DC voltage intermediate circuit is required which has a large number of power semiconductors, significantly increasing the probability of failure
Solution Approach 1:
The patent segments the power conversion function into multiple independent converter modules connected through the transformer. Each converter handles a portion of the power flow, and the transformer provides galvanic isolation between the segments. This segmentation reduces the number of semiconductors in each module, improving reliability while maintaining the ability to couple asynchronous networks.
Solution Approach 2:
The invention uses the transformer as an intermediary element between the two three-phase networks. The transformer provides galvanic isolation and enables asynchronous operation without requiring a DC voltage intermediate circuit. The high-frequency switching converters on each side independently control power flow to and from the transformer, eliminating the need for a DC link and its associated semiconductors.
4Ease of operation
If a DC voltage intermediate circuit is used, then power flow control is achieved, but sharp rise in voltage occurs which is not desirable
Solution Approach 1:
The patent uses dynamic high-frequency switching control in the power converters to manage voltage levels. The converters continuously adjust their switching duty cycles to maintain stable voltage output, preventing sharp voltage rises. The galvanic isolation provided by the transformer further protects against voltage transients propagating between networks.
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
Enables efficient, dynamic control of power flows between electrical energy networks, reducing material requirements and losses, and allowing for the coupling of asynchronous networks while avoiding the drawbacks of DC voltage intermediate circuits.
Implementation Method 1
The transmission device has multi-phase multi-stage power converters, which are each connected to one of the energy networks (at their supply connections) and to each other via a first multi-phase transformer
Data Source
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Figure 5~7
AI summary
The invention relates to a transmission device (2a, 2b, 2c, 2d, 2e) for energy transmission between multiple electrical energy networks (1a, 1b, 1c), each providing a multi-phase connection voltage at a network frequency for electrical energy supply. The transmission device (2a, 2b, 2c, 2d, 2e) comprises multi-phase multi-stage rectifiers (7a, 7b, 7c) and a control device (5), which adjusts the transmission of energy into at least one energy-receiving energy network (1a, 1b, 1c) according to an input (SW) by controlling the multi-stage rectifiers (7a, 7b, 7c). The multi-stage rectifiers (7a, 7b, 7c) are each connected to one of the energy networks (1a, 1b, 1c) and to one another via at least one multi-phase transformer (8a, 8b, 8c). Electrical energy flows via the transformer (8a, 8b, 8c) at a predefined transmission frequency from at least one energy-emitting energy network (1a, 1b, 1c) into at least one energy-receiving energy network (1a, 1b, 1c), wherein the transmission frequency is, in particular, multiple times the network frequency.