AC/DC Converter Switching Leg Layout for Lower Switching Loss
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Solution Overview
Problem
Conventional power converters using hard switching techniques experience high switching losses, which reduce energy conversion efficiency, especially at high switching frequencies, and require costly designs to mitigate these losses.
Innovation Solution
The development of an AC/DC converter circuit with a switching leg configuration that dynamically and statically blocks voltages using multiple switches in series, along with auxiliary switches, to reduce switching losses and improve efficiency by alternating between ON and OFF states at different frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If hard switching is used in power converters, then the converter can operate at high switching frequencies, but switching losses increase and energy conversion efficiency decreases
Solution Approach 1:
The switching leg is divided into multiple switches (first switch, second switch, third switch) connected in series. Each switch handles a portion of the voltage blocking, allowing for more granular control of the switching process. This segmentation enables soft switching techniques where switches are turned on/off at different times, reducing simultaneous voltage-current overlap and minimizing switching losses while maintaining high switching frequency operation.
2Strength
If multiple switches are connected in series to increase voltage blocking capacity, then the voltage handling capability increases, but the device complexity and synchronization requirements increase
Solution Approach 1:
A controller acts as an intermediary to manage the switching operations of multiple switches. The controller generates control signals that coordinate the switching of individual switches in the series connection, enabling complex switching patterns (such as alternating between different switch combinations) without requiring complex external synchronization. This centralized control simplifies the overall system architecture while achieving the desired voltage blocking capacity and soft switching performance.
Data Source
Figure 1A~1B
Figure 2A~2D
Figure 2E
AI summary
An apparatus includes a first switch leg connected between a first input terminal and a first output terminal, the first switch leg comprising serially connected switches. The apparatus also includes a second switch leg connected between a second input terminal and the first output terminal, the second switch leg comprising serially connected switches. The apparatus further includes a third switch leg connected between an input voltage midpoint and the first output terminal. A controller controls the first switch leg, the second switch leg and the third switch leg, wherein the controller is configured to disable the second switch leg for a first time period and alternately enable the first switch leg and the third switch leg during the first time period, and to disable the first switch leg for a second time period and to alternately enable the second leg and the third leg during the second time period.