Phase-Offset Switching in Series Converter Modules
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Solution Overview
Problem
Conventional converter systems face challenges in achieving higher effective switching frequencies without increasing actual switching frequencies, leading to larger and more expensive passive components and higher switching losses, while also dealing with electromagnetic interference and efficiency reductions.
Innovation Solution
The implementation of phase-offset switching in series-connected converter modules, where switch control signals are interleaved or offset in phase, effectively increases the switching frequency by summing the outputs of individual modules, allowing for the use of smaller and less expensive components and reduced EMI filters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the actual switching frequency is increased to achieve higher effective switching frequency, then the switching losses increase and electromagnetic interference worsens
Solution Approach 1:
The converter system is divided into multiple converter modules (first converter module, second converter module, etc.) that operate in parallel. Each module switches at a lower individual frequency, but their combined output achieves a higher effective switching frequency through phase-offset control signals. This segmentation allows the system to benefit from high effective switching frequency while avoiding the penalties of high actual switching frequency in individual components.
2Speed
If the actual switching frequency is increased to achieve higher effective switching frequency, then electromagnetic interference increases
Solution Approach 1:
By dividing the converter into multiple modules with phase-offset switching, the electromagnetic interference from each individual module operates at a lower frequency. The segmented approach distributes the EMI across multiple lower-frequency sources rather than concentrating it at a single high frequency, making filtering easier and reducing overall electromagnetic interference.
Solution Approach 2:
The outputs of multiple converter modules are combined to produce the final converter output. When these modules switch with phase offsets, their combined effect creates a higher effective switching frequency at the output while the individual modules generate less EMI. The merging of multiple lower-frequency switching operations achieves the benefits of high-frequency operation without the EMI penalties.
3Ease of manufacture
If smaller passive components are used to reduce cost and size, then the filtering capability decreases
Solution Approach 1:
The converter modules operate with periodic phase-offset switching patterns. This periodic action creates a higher effective switching frequency that naturally reduces output ripple amplitude. The regular interleaved switching of multiple modules produces a more uniform combined output, allowing smaller passive filtering components to achieve the same level of ripple suppression that would require larger components at lower switching frequencies.
Data Source
AI summary
Various examples are directed to electrical converters and systems for operating the same. An electrical converter may comprise a first converter module configured to receive a first direct current (DC) input and provide a first output. The first converter module may comprise a first switch modulated according to a first switch control signal. A second converter module may be configured to receive a second DC input and provide a second output. The second converter module may be connected in series with the first converter module. The second converter module may comprise a second switch modulated according to a second switch control signal. A phase of the first switch control signal may be offset from a phase of the second switch control signal by a first phase offset.