Power Conversion Device Frequency Control Pattern
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Solution Overview
Problem
Existing power conversion devices face challenges in effectively reducing electromagnetic noise over a wide frequency band while minimizing the increase in switching frequency variation width and preventing excessively prolonged duration times for each switching frequency, particularly in the AM band, which leads to increased calculation load and potential current ripple issues.
Innovation Solution
A power conversion device that employs a control device with a pattern generation unit to generate a frequency change pattern using 2n switching frequencies, determined by adding or subtracting a second frequency from n first frequencies, ensuring that the middle value between shifted frequencies does not overlap with other frequencies, and a controller that synchronizes carrier wave changes with upper or lower peaks to manage switching operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the variation width of switching frequency is increased to reduce electromagnetic noise in the AM band, then the noise decreasing effect is improved, but the calculation load of high-frequency switching control increases
Solution Approach 1:
The frequency change pattern is segmented into multiple discrete frequency values (2n switching frequencies) rather than using a continuous wide variation. This segmentation allows the patent to achieve noise reduction across a wide frequency band while keeping each individual frequency value manageable for calculation processing.
Solution Approach 2:
The patent changes the switching frequency parameter among 2n discrete values in a systematic pattern. By controlling the frequency to switch among these predetermined values rather than allowing continuous variation, the patent achieves wide frequency band noise reduction while maintaining manageable calculation complexity.
2Stability of the object's composition
If the duration time for each switching frequency is prolonged to suppress current ripple, then the stability is improved, but the responsiveness to frequency changes deteriorates
Solution Approach 1:
The patent implements periodic switching among 2n frequency values in a predetermined pattern. This periodic action allows the system to maintain stable operation at each frequency (suppressing current ripple) while systematically transitioning through all frequency values, ensuring both stability and responsiveness.
Solution Approach 2:
The patent dynamically adjusts the switching frequency among 2n discrete values in a controlled manner. The frequency is changed at optimal timing points (carrier wave peaks or valleys), creating a dynamic system that balances current ripple suppression with responsive frequency switching.
3Object-affected harmful factors
If a frequency change pattern with multiple switching frequencies is used to reduce electromagnetic noise, then the noise decreasing effect is improved, but the device complexity increases
Solution Approach 1:
The frequency change pattern is segmented into 2n discrete frequency values generated through systematic operations (adding/subtracting frequencies). This segmentation approach reduces control system complexity compared to continuous frequency variation, as the controller only needs to select from predetermined discrete values.
Solution Approach 2:
The frequency determination unit generates the 2n switching frequencies systematically using n first frequencies and a second frequency through addition and subtraction operations. This self-generating approach reduces device complexity by eliminating the need for external frequency generation circuits.
Data Source
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AI summary
A control device (20) for controlling switching elements (2, 3) in a power conversion circuit (1) includes a pattern generation unit (20) for generating a frequency change pattern (25), and a controller (22). Using n first frequencies fc and a second frequency fdef smaller than the smallest one of differences between the n first frequencies fc, the pattern generation unit (20) determines a shift order of the 2n switching frequencies f determined by adding/subtracting the second frequency fdef to/from the first frequencies fc, such that the middle value between two switching frequencies f before and after shifting does not overlap the value of each switching frequency f, thereby generating a frequency change pattern (25). The controller (22) generates a control signal G for each switching element (2, 3) by using the 2n switching frequencies f for respective different duration times in accordance with the frequency change pattern (25).