Variable-Inductance Converter Control for Fixed-Frequency Soft Switching
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Solution Overview
Problem
Traditional methods of achieving soft-switching control in AC/DC Power Factor Correction (PFC) rectifiers and DC/DC converters face challenges such as increased electromagnetic interference (EMI) and difficulty in paralleling, due to the need to vary switching frequency.
Innovation Solution
An AC/DC converter system that includes an inductance control system to modify the inductance of filter inductors, maintaining a constant switching frequency while enabling soft switching of switches independent of AC and load variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If switching frequency is varied to achieve soft-switching control, then soft-switching is maintained, but electromagnetic interference increases and paralleling becomes difficult
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the inductance value of the filter inductor based on operating conditions (input voltage, load current) to maintain soft-switching at a fixed switching frequency. This resolves the contradiction by changing the inductance parameter instead of the frequency parameter, thereby eliminating EMI while preserving soft-switching benefits
2Reliability
If switching frequency is varied to achieve soft-switching control, then soft-switching is maintained, but paralleling becomes difficult
Solution Approach 1:
The patent changes the inductance parameter dynamically while keeping switching frequency fixed, enabling easy paralleling of multiple converter units. Since all units operate at the same fixed frequency, synchronization and paralleling become straightforward while soft-switching is maintained through adaptive inductance adjustment
3Object-affected harmful factors
If fixed switching frequency is used, then electromagnetic interference and paralleling issues are reduced, but soft-switching control becomes difficult under varying AC and load conditions
Solution Approach 1:
The patent implements dynamics by making the filter inductor value adjustable and adaptive to changing operating conditions. The control system dynamically modifies inductance based on input voltage and load current variations, enabling soft-switching to be maintained across different operating points while keeping switching frequency fixed
Solution Approach 2:
The patent employs feedback control where the control system continuously monitors operating conditions (input voltage, load current) and adjusts the filter inductor value accordingly. This closed-loop feedback mechanism ensures soft-switching is maintained under varying conditions while operating at a fixed switching frequency
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 solution effectively reduces electromagnetic interference and simplifies paralleling of converters by maintaining a constant switching frequency, enhancing the efficiency and flexibility of the converter system.
Implementation Method 1
The one or more control inductors can be coupled with the one or more filter inductors to apply a magnetic field to the one or more filter inductors to modify the inductance of the one or more filter inductors
Implementation Method 2
The one or more filter inductors can include a core. The one or more control inductors can be configured to modify a magnetic permeability of the core thereby modifying the inductance of the one or more filter inductors
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
An AC/DC converter (100, 200) can include an alternating current (AC) source (102, 202) configured to output AC, one or more AC lines (104a-104b) electrically connected to the AC source to conduct the AC, a conversion circuit (106, 206) operatively electrically connected to the one or more AC lines to receive AC, one or more filter inductors (108, 208a-208c) electrically connected to at least one of the one or more AC lines, and an inductance control system (110, 210) operatively connected to the one or more filter inductors to modify the inductance of the one or more filter inductors. A DC/DC converter (500) can include a direct current (DC) source configured to output DC, one or more DC lines electrically connected to the DC source to conduct the DC, a non-resonant DC/DC conversion circuit operatively electrically connected to the one or more DC lines to receive DC, one or more filter inductors (508, 708) electrically connected to at least one of the one or more DC lines, and an inductance control system (512, 712) operatively connected to the one or more filter inductors to modify the inductance of the one or more filter inductors to maintain a constant switching frequency while maintaining soft switching of the one or more switches independent of variations in the DC and/or a load connected to the non-resonant DC/DC conversion circuit. The non-resonant DC/DC conversion circuit can be configured for DC/DC conversion. The non-resonant DC/DC conversion circuit can include one or more switches configured to be controlled for DC/DC conversion.