AC Power Electronic Converter Circuit for Distribution Networks
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Solution Overview
Problem
Traditional AC chopper circuits for urban electricity distribution networks face issues with switching patterns dependent on voltage or current polarity, leading to short-circuiting, floating currents, and inefficiencies, particularly when operating at lower voltages like 230 V, which restricts the capacity and efficiency of power delivery.
Innovation Solution
An AC power electronic converter circuit with two pairs of uni-directional switches arranged in parallel and a bridge connection, along with an inter-phase transformer and LC filter, which eliminates the need for dead-time and snubbers by providing an overlap period for inductor current flow, ensuring stable operation and reducing losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional AC chopper circuits use voltage or current dependent switching patterns, then the circuit can operate at lower voltages like 230 V, but this leads to short-circuiting, floating currents, and requires dead-time and clamping circuits which cause significant losses and distortions
Solution Approach 1:
The invention changes the switching pattern from voltage or current dependent to a fixed sequence pattern, fundamentally altering the operational parameters. This fixed sequence switching eliminates the need for dead-time and clamping circuits, thereby reducing power losses and distortions while maintaining reliable operation at higher voltages
Solution Approach 2:
The invention extracts and removes the dead-time and clamping circuits from the traditional AC chopper design. By eliminating these components through the use of a fixed sequence switching pattern with overlap periods, the circuit achieves reduced power losses without compromising switching reliability
2Ease of manufacture
If electricity is distributed at lower voltage of 230 V, then traditional transformers and meters can be used, but this increases current and results in higher electrical power losses and reduced network capacity
Solution Approach 1:
The invention changes the distribution voltage parameter from the traditional 230 V to a higher voltage of 346 V. This parameter change reduces the current for the same power transmission, thereby reducing electrical power losses and increasing network capacity while the AC chopper converter enables compatibility with existing 230 V end-user equipment
3Productivity
If distributed generation feeds power back into the network, then renewable energy is utilized, but this causes network over-voltages that affect downstream properties
Solution Approach 1:
The AC chopper converter implements feedback control to regulate the voltage at the point of common coupling. By continuously monitoring and adjusting the switching pattern, the device maintains stable voltage levels even when distributed generation feeds power back into the network, preventing over-voltage conditions that would affect downstream properties
Data Source
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AI summary
An alternating current power electronic converter comprises an alternating current chopper circuit including two pairs of switches each switch of a pair connected in series and the two pairs of switches connected in parallel. Each switch of a pair is a uni-directional switch and the uni-directional switches of each pair are arranged in opposing directions and wherein the uni-directional switches of one pair of switches are arranged in an opposing configuration to the uni-directional switches of the other pair of switches. The circuit comprises a bridge connection between the two pairs of switches, the bridge connection being between the uni-directional switches of each pair. the converter further comprising a controller. The controller is configured to control the sequence of operation of the switches, the sequence providing an overlap period whenever one of the uni-directional switches of a pair changes from open to closed and the other uni-directional switch of the pair changes from closed to open. During the overlap period the uni-directional switch that is moving from closed to open remains closed.