Parallel Converter Paths for UPS Emission Cancellation
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Solution Overview
Problem
Traditional online UPS systems require large and expensive filters to reduce lower frequency emissions, which is inefficient and costly, especially in applications where conducted emissions need to be limited below 150 kHz.
Innovation Solution
A front-end converter with two parallel converter paths, where one path generates a low-frequency current signal and the other path generates a high-frequency current signal that is amplitude modulated to cancel out the low-frequency signal, reducing the need for bulky filters by using smaller components and achieving efficient Power Factor Correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If traditional single converter path is used, then Power Factor Correction is achieved, but large and expensive filters are required to reduce lower frequency emissions
Solution Approach 1:
The single converter path is divided into two parallel converter paths. The first converter path operates at a lower frequency and the second converter path operates at a higher frequency (multiple of the first frequency). This segmentation allows each path to handle specific frequency ranges, reducing the burden on filtering components and enabling the use of smaller, less expensive filters while still achieving effective emission reduction.
Solution Approach 2:
The invention changes the operating frequency parameter by introducing a second converter path that operates at a higher frequency (a multiple of the first frequency). This frequency multiplication allows the system to shift emissions to higher frequencies where smaller filters are effective, and the amplitude modulation of the second path cancels out low-frequency emissions from the first path.
2Object-generated harmful factors
If larger filters are used to reduce emissions, then conducted emissions are limited, but system cost and size increase
Solution Approach 1:
By segmenting the converter into two parallel paths with different operating frequencies, the system can address different frequency ranges of emissions separately. The first path handles fundamental frequency emissions while the second path handles harmonics and provides cancellation at low frequencies. This segmentation enables the use of smaller filters that would be insufficient for a single high-power path but are adequate when distributed across two paths.
Solution Approach 2:
The invention converts the potentially harmful low-frequency emissions from the first converter path into a beneficial cancellation mechanism. By amplitude modulating the second converter path at a multiple of the first frequency, the system creates current signals that destructively interfere with the low-frequency emissions, effectively converting what would be harmful emissions into a self-cancelling pattern.
3Object-generated harmful factors
If single converter path is used, then system simplicity is maintained, but emission reduction efficiency is poor
Solution Approach 1:
The converter is segmented into two parallel paths with distinct frequency operations. The first path operates at frequency f and the second path operates at frequency nf (where n is an integer multiple). This segmentation enables targeted emission reduction at different frequency ranges, with the second path specifically designed to cancel low-frequency emissions through amplitude modulation, thereby improving overall emission reduction efficiency.
Solution Approach 2:
The second converter path employs periodic amplitude modulation at a frequency that is a multiple of the first path's frequency. This periodic action creates a cancellation pattern that systematically reduces emissions across the frequency spectrum, particularly effective at eliminating low-frequency components through destructive interference of current signals.
Data Source
AI summary
According to one aspect, embodiments herein provide a UPS comprising a UPS input configured to be coupled to an AC power source and to receive input AC power, an interface configured to be coupled to a DC power source and to receive backup DC power, a UPS output configured to provide output power derived from at least one of the input AC power and the backup DC power to a load, a converter comprising a converter input coupled to the UPS input, a converter output, a first converter path coupled between the converter input and the converter output, and a second converter path coupled between the converter input and the converter output, and a controller configured to operate the first converter path and the second converter path to convert the input AC power into DC power and provide the DC power to the converter output.