Split-Phase PWM Inverter With Multi-Frequency Switching
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Solution Overview
Problem
Generating a split-phase signal, such as a 240V RMS signal, results in high power dissipation due to the need for high-frequency switching in power inverters, which increases thermal requirements and costs.
Innovation Solution
A power conversion circuit with a first, second, and third leg, where the first leg switches at a high frequency to generate a first signal, the second leg switches at a lower frequency to generate a second signal, and the third leg is controlled by a neutral leg signal to generate a third signal, allowing the second leg to operate at a lower frequency and reducing power dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the power inverter switches at high frequencies to generate a split-phase signal, then the signal generation is achieved, but power dissipation increases
Solution Approach 1:
The power inverter is divided into three separate legs (first leg, second leg, and third leg), each capable of independent switching at different frequencies. This segmentation allows the second leg to operate at a lower frequency while the first and third legs operate at higher frequencies, thereby reducing overall power dissipation while maintaining split-phase signal generation capability.
2Temperature
If the power inverter switches at high frequencies, then the split-phase signal is generated, but thermal requirements increase
Solution Approach 1:
By segmenting the inverter into three legs with different switching frequencies, the thermal load is distributed and reduced. The second leg operates at a lower frequency specifically to minimize heat generation, while the other legs maintain high-frequency operation for signal integrity.
Solution Approach 2:
The switching frequency parameter is changed for different legs of the inverter. The second leg uses a lower switching frequency compared to the first and third legs, which directly reduces the thermal requirements and power dissipation while maintaining the overall split-phase signal generation function.
3Ease of manufacture
If the second leg switches at a lower frequency, then power dissipation is reduced, but device cost decreases
Solution Approach 1:
The switching frequency parameter for the second leg is reduced, which allows the use of less costly switching devices that cannot operate at high frequencies. This parameter change achieves both cost reduction and power dissipation reduction simultaneously.
Data Source
AI summary
Methods, circuits, and devices for power conversion are disclosed. In some embodiments, the device comprises a circuit comprising a first, second, and third leg. Each leg may comprise two switches. The first leg is switched at a first frequency to generate a first signal, and the second leg is switched at a second frequency lower than the first frequency to generate a second signal. The third leg is switched by a neutral leg control signal to generate a third signal. The circuit generates an output power signal (e.g., a split-phase power signal) based on the first signal, second signal, and the third signal.