Resonant Power Converter Switching to Limit EMI Noise
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing power converters that convert DC power to AC power using soft switching techniques often experience increased radiation noise, which can lead to electromagnetic interference (EMI) issues.
Innovation Solution
The power converter incorporates a bidirectional switch, a resonant capacitor, a resonant inductor, a regenerative element, and a limiter to control the voltage variation rate, thereby reducing radiation noise during soft switching operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If soft switching is implemented in the power converter, then switching losses are reduced, but radiation noise increases
Solution Approach 1:
A bidirectional switch is introduced as an intermediary component between the main switching elements and the resonant circuit. This bidirectional switch controls the charging and discharging of the resonant capacitor, mediating the interaction between the switching operations and the resonant oscillations, thereby enabling soft switching while controlling voltage variation rates to reduce radiation noise
Solution Approach 2:
The patent changes the voltage variation rate parameter by using the bidirectional switch to control the charging/discharging timing of the resonant capacitor. By adjusting when the bidirectional switch turns on/off, the voltage across the main switching elements changes more gradually, reducing high-frequency noise while maintaining soft switching benefits
2Speed
If the voltage variation rate is not limited, then switching speed is maintained, but electromagnetic interference increases
Solution Approach 1:
The bidirectional switch operates in periodic cycles, alternately charging and discharging the resonant capacitor at specific timing intervals. This periodic action creates controlled voltage transitions that maintain switching functionality while limiting the rate of voltage change to reduce electromagnetic interference
Solution Approach 2:
The resonant capacitor is charged beforehand through the bidirectional switch before the main switching elements operate. This pre-charging creates a cushioning effect that softens the voltage transitions, reducing the abrupt voltage changes that cause electromagnetic interference while maintaining adequate switching speed
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 proposed solution effectively limits the absolute value of the voltage variation rate, reducing radiation noise and electromagnetic interference, thus enhancing the converter's performance and reliability.
Implementation Method 1
The auxiliary circuit includes two capacitors, a coil (resonant inductor), and a bidirectional switch. When making soft switching of the first switching element and the second switching element
Implementation Method 2
The limiter limits an absolute value of a voltage variation rate of a voltage applied between the first and second terminals of the bidirectional switch to a threshold value or less
Data Source
AI summary
In a bidirectional switch of a power converter, a first terminal thereof is connected to a connection node between a first switching element and a second switching element. A resonant capacitor is connected between the first terminal of the bidirectional switch and a second DC terminal. A resonant inductor is connected to a second terminal of the bidirectional switch. A regenerative element is connected between the resonant inductor and the second DC terminal. A first control unit controls the first switching element and the second switching element. A second control unit controls the bidirectional switch. A limiter limits the absolute value of a voltage variation rate of a voltage applied between the first and second terminals of the bidirectional switch to a threshold value or less.