AC-DC Converter With Four-Quadrant Switch for Wide Voltage Range
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Solution Overview
Problem
Conventional power electronics systems face limitations in providing a wide range of output voltages and operating at high frequencies, particularly in applications like power factor correction, where they require higher DC output voltages than peak AC input voltages or result in high current distortion.
Innovation Solution
The development of an AC-DC converter using a single-ended primary inductor converter (SEPIC) topology with a four-quadrant switch and bidirectional devices, allowing for regulation of DC output voltage across a wide range and enabling continuous input current with low distortion, utilizing components like gallium nitride (GaN) for high-frequency operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional boost topology is used for PFC, then DC output voltage can be regulated above peak AC input voltage, but output voltage range is limited and cannot go below peak AC input voltage
Solution Approach 1:
The converter is divided into two independent half-bridge legs, each capable of operating in buck or boost mode. This segmentation allows the circuit to achieve both buck and boost functionality without requiring a single complex topology, thereby expanding the output voltage range while managing complexity through modular design
Solution Approach 2:
Each half-bridge leg is designed to perform multiple functions: it can operate in boost mode to generate output voltage above peak AC input, or in buck mode to generate output voltage below peak AC input. This multi-functionality eliminates the need for separate circuits for different voltage regulation modes, achieving versatility without proportional complexity increase
2Device complexity
If conventional flyback topology is used for PFC, then circuit complexity is reduced, but input current distortion increases
Solution Approach 1:
The inductors in each half-bridge leg are designed to maintain continuous current flow during switching operations. This continuous current action prevents the discontinuous current patterns that cause distortion in conventional flyback topologies, achieving low distortion while maintaining relatively simple circuit structure
Solution Approach 2:
The capacitor connected between the midpoints of the two half-bridge legs acts as an intermediary energy storage element. It smooths current transitions and provides a stable reference point, enabling continuous current operation and reducing input current distortion without significantly increasing circuit complexity
3Productivity
If high switching frequency is implemented, then converter size is reduced, but voltage stress on switches increases
Solution Approach 1:
The voltage stress is segmented and distributed across multiple switches in the half-bridge configuration. Each switch only needs to block a portion of the total voltage, allowing the use of lower-voltage-rated switches that can operate at higher frequencies, thereby achieving high switching frequency while managing voltage stress requirements
Solution Approach 2:
The patent employs GaN (gallium nitride) semiconductor devices which combine high breakdown voltage capability with high-frequency switching characteristics. This composite material approach allows the switches to simultaneously handle high voltage stress and operate at high switching frequencies, resolving the trade-off between these two parameters
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 solution enables the AC-DC converter to regulate DC output voltage across a wide range, including voltages higher or lower than the peak AC input, while maintaining low current distortion and supporting high-frequency operation, thus improving upon conventional boost and flyback topologies.
Implementation Method 1
a coupled inductor operable to receive an AC input voltage and having first and second outputs coupled to respective first and second nodes
Implementation Method 2
utilizing components like gallium nitride (GaN) for high-frequency operation
Data Source
AI summary
An electrical circuit includes an input for an AC input voltage coupled to a first inductive element with first and second outputs coupled to respective first and second nodes, and a four-quadrant (4-Q) switch coupled between the first and second nodes. A capacitor is coupled between the first node and a third node, a second inductive element is coupled between the third node and the second node, and a first bidirectional device and a first diode are coupled in series between a positive output node and a negative output node. A first output of the second inductive element is coupled between the first bidirectional device and the first diode. A second bidirectional device and a second diode are coupled in series between the positive output node and the negative output node. A second output of the second inductive element is coupled between the second bidirectional device and the second diode.