DC-AC Converter Pulse Control for Transformer Saturation
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Solution Overview
Problem
Existing DC power supplies for large power capacities face challenges in reducing electromagnetic noise due to voltage/current harmonics without causing magnetic saturation of insulating transformers, especially when using single-pulse-driven DC-DC converters.
Innovation Solution
The solution involves controlling the pulse turn-on duration of the output voltage signal waveform in a DC-AC power conversion circuit based on the DC voltage source and changing the switching period according to a predetermined time-series signal, using a control device that generates gate signals for the half-bridge converter to manage the pulse turn-on and turn-off durations effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-pulse-driven DC-DC converter is used to reduce circuit complexity, then device complexity is reduced, but electromagnetic noise increases due to integral multiple harmonics of switching frequency
Solution Approach 1:
The patent applies dynamic frequency modulation by randomly varying the switching frequency within a predetermined range. This dynamic adjustment transforms the fixed-frequency single-pulse-driven converter into a system where the switching frequency changes over time, effectively spreading electromagnetic noise across a broader frequency spectrum and reducing peak noise levels while maintaining circuit simplicity.
Solution Approach 2:
The patent changes the switching frequency parameter dynamically by introducing random variation within a predetermined range. This parameter change approach modifies the operational characteristics of the converter without altering the basic circuit topology, thereby reducing electromagnetic noise while preserving the simplicity of the single-pulse-driven architecture.
2Object-generated harmful factors
If switching frequency is increased above audible range to reduce noise, then electromagnetic noise is reduced, but magnetic saturation occurs in the insulating transformer
Solution Approach 1:
The patent employs dynamic frequency modulation where the switching frequency is randomly varied within a predetermined range rather than operating at a fixed high frequency. This dynamic approach allows the system to operate at lower average frequencies that avoid magnetic saturation while still effectively spreading electromagnetic noise across a broader frequency spectrum, thus resolving the contradiction between noise reduction and transformer reliability.
Solution Approach 2:
The patent modifies the switching frequency parameter by introducing random variation within a predetermined range, enabling the system to operate at lower effective frequencies that prevent magnetic saturation in the insulating transformer. This parameter change strategy maintains noise reduction effectiveness while ensuring transformer reliability.
3Object-generated harmful factors
If pulse width modulation is applied to reduce harmonics, then electromagnetic noise is reduced, but control complexity increases
Solution Approach 1:
The patent implements a simplified dynamic control approach by randomly varying the switching frequency within a predetermined range rather than employing complex pulse width modulation. This dynamic frequency modulation achieves harmonic reduction and electromagnetic noise mitigation with significantly lower control complexity, as it requires only random number generation and frequency adjustment without the need for complex modulation algorithms.
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
This approach effectively reduces electromagnetic noise by spreading the spectra of transformer primary and DC output currents, preventing magnetic saturation of the insulating transformer and achieving significant noise reduction.
Implementation Method 1
a primary circuit to generate an alternating-current (AC) voltage from a DC voltage, then supplies the AC voltage to a secondary circuit via an insulating transformer
Implementation Method 2
rectifies the AC voltage into another DC voltage
Data Source
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AI summary
Disclosed is a DC-DC converter using an insulating transformer, the converter including means that reduces/mitigates electromagnetic noise due to voltage/current harmonics, without magnetically saturating the insulating transformer. In order to realize the above, a DC power supply of this invention is constructed so that a pulse turn-on duration in an output voltage waveform of a DC-AC power conversion circuit is controlled to a value corresponding to a DC voltage of a DC voltage source, and so that a switching period in the output voltage waveform of the DC-AC power conversion circuit changes in accordance with a predetermined time-series signal.