Bidirectional ICN AC-DC Converter for Soft Switching and Reactive Power
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Solution Overview
Problem
Conventional AC-DC power converters face limitations in efficiency and power density due to their two-stage architecture, and typical Impedance Control Network (ICN) converter designs are primarily unidirectional, struggling with soft switching in the rectification stage, especially in bidirectional and AC-DC power conversion applications.
Innovation Solution
A bidirectional AC-DC converter design incorporating a first and second half-bridge inverter circuit, an impedance control network, an isolation transformer, and a second rectifier circuit, with an inductive element for zero voltage switching, and a controller to manage phase shift angles, enabling soft switching and reactive power capability across a wide range of operating conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a two-stage architecture (PFC stage + isolated DC-DC stage) is used for grid-attached converters, then power factor correction and voltage regulation are achieved, but efficiency and power density are limited
Solution Approach 1:
The patent merges the PFC stage and DC-DC stage into a single integrated AC-DC converter stage, eliminating the need for separate conversion stages. This single-stage architecture achieves both power factor correction and voltage regulation simultaneously, thereby improving efficiency and power density while reducing overall device complexity compared to two-stage approaches
2Loss of energy
If typical ICN converter designs are used for unidirectional AC-DC power conversion, then soft switching is achieved in the inverter stage, but soft switching cannot be maintained in the rectifier stage
Solution Approach 1:
The patent designs the ICN converter with universal functionality to operate in both forward (AC-DC) and reverse (DC-AC) modes while maintaining soft switching in both the inverter and rectifier stages. The converter topology and control strategy are specifically designed to ensure that soft switching conditions are met regardless of power flow direction, thereby achieving both low switching losses and bidirectional adaptability
3Productivity
If conventional ICN converter designs are used, then single-stage power conversion is achieved, but reactive power capability and grid-forming capability are insufficient
Solution Approach 1:
The patent implements dynamic control of the ICN converter to provide reactive power capability and grid-forming functionality. The converter can dynamically adjust its operating characteristics, power factor, and voltage regulation based on grid conditions and load requirements, enabling it to provide both active and reactive power support while maintaining efficient single-stage power conversion
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 ensures high-efficiency, bidirectional AC-DC conversion with soft-switching of transistors, maintaining efficiency and power density while supporting reactive power and advanced grid-forming capabilities.
Implementation Method 1
an inductive element established across the pair of second terminals of the isolation transformer. The inductive element may include an inductance selected to produce zero voltage switching of the first, second, and third plurality of transistors
Data Source
AI summary
A bidirectional converter includes a first rectifier circuit, a first and second half-bridge inverter circuits, an isolation transformer, a second rectifier circuit, and a network coupled between the half-bridge inverter circuits and the isolation transformer. The network forms an impedance control network (ICN) when the bidirectional converter is operated in a forward operation mode and forms a resistance compression network (RCN) when the bidirectional converter is operated in a reverse operation mode. The bidirectional converter also includes an inductive element established across terminals of the isolation transformer. The inductance of the inductive element, the differential reactance of the network, and the turns ratio of the isolation transformer are determined to ensure zero voltage switching of the high frequency transistors of the bidirectional converter. Additionally, zero voltage switching is promoted by controlling the phase shift between the first and second half-bridge inverter circuits and between legs of the second rectifier circuit.