Resonant DC-DC Converter Charge Mode Control
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Solution Overview
Problem
Resonant DC-DC converters experience unlinear power gain near resonance frequency, leading to design challenges in feedback loop stability and efficiency, especially under varying load conditions.
Innovation Solution
A modified feedback control system is introduced, where the second feedback circuit connects to the input terminal of the control circuit through a capacitor and resistor, influencing the switching frequency based on the voltage across the transformer, allowing for charge mode operation at high loads and frequency mode at low loads, ensuring linear power conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If resonant DC-DC converter operates near resonance frequency, then power conversion efficiency is improved, but linearity of power gain deteriorates
Solution Approach 1:
The patent implements dynamic switching between two operating modes (frequency mode and charge mode) based on load conditions. The control circuit automatically transitions between these modes to maintain optimal performance, making the system adaptive rather than static. This resolves the contradiction by allowing the system to operate near resonance for efficiency when needed while switching to charge mode when linearity is prioritized.
Solution Approach 2:
The patent changes the control parameter from pure frequency control to a hybrid approach that includes charge control. By introducing a second feedback circuit that controls the charge/discharge of the resonant capacitor, the system can adjust the operating point dynamically. This parameter change enables the system to maintain both high efficiency and linearity under varying load conditions.
2Device complexity
If frequency mode control is used, then device complexity is reduced, but output stability under varying load deteriorates
Solution Approach 1:
The patent segments the control function into two distinct circuits: a first feedback circuit for frequency mode control and a second feedback circuit for charge mode control. Each circuit handles specific aspects of the control, with the second circuit activated under varying load conditions. This segmentation allows the system to maintain simplicity while adding stability enhancement only when needed.
Solution Approach 2:
The patent introduces a second feedback circuit that provides additional feedback control based on the voltage across the transformer. This feedback mechanism monitors the operating conditions and adjusts the charge/discharge of the resonant capacitor accordingly, improving output stability under varying load without significantly increasing overall system complexity.
3Manufacturing precision
If charge mode control is implemented, then linearity of power conversion is improved, but device complexity increases
Solution Approach 1:
The patent merges the frequency control function and charge control function into a unified control system. The second feedback circuit is integrated with the existing resonant converter architecture, sharing common components such as the resonant capacitor and control circuitry. This merging approach implements charge mode control while minimizing the increase in device complexity through resource sharing.
4Speed
If switching frequency is increased, then response speed to load changes is improved, but stability near resonance frequency deteriorates
Solution Approach 1:
The patent implements dynamic adaptation of the control mode based on the operating point and load conditions. When operating near resonance frequency, the system can switch to charge mode control which provides better stability while maintaining adequate response speed. This dynamic adaptation resolves the contradiction by allowing high response speed when stable and providing stability enhancement when needed.
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 stabilizes output voltage and current with fast response to load changes, maintaining high linearity across all load conditions by combining frequency and charge mode control, preventing start-up issues and stability problems.
Implementation Method 1
A modified feedback control system is introduced, where the second feedback circuit connects to the input terminal of the control circuit through a capacitor and resistor, influencing the switching frequency based on the voltage across the transformer
Implementation Method 2
a serial resonance converter containing at least two serial coupled semiconductor switches having a common output terminal connected to at least one first coil which coil can be a part of a transformer
Implementation Method 3
resonant DC-DC converters experience unlinear power gain near resonance frequency
Data Source
AI summary
An apparatus and a method for converting power from a power input to an DC output voltage or current, which apparatus has a serial resonance converter, where a first feedback circuit is connected from the output terminal to an error amplifier, where the apparatus further has a second feedback circuit with at least one first resistor that is connected to a coil and to ground, which second feed back circuit connects the line between the first resistor and the coil and towards an inverting integrator, the output of which is connected through a second capacitor to a second input at a control circuit. As a result, the oscillating frequency is under influence of a signal that depends on the voltage generated in the resistor connected in serial to the coil or transformer.