Resonant Converter VCO Control for Overshoot Reduction
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Solution Overview
Problem
Resonant converters face challenges in maintaining stable output voltage and current due to complex poles and high Q transfer functions, leading to overshooting when responding to changing input line or output load conditions.
Innovation Solution
The implementation of a voltage-controlled oscillator (VCO) and frequency divider in the control apparatus of resonant converters, which modulates pulse frequencies based on operating conditions to equalize switch duty cycles and adjust gain automatically, reducing overshoot by splitting complex poles into real poles for improved transient response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If resonant converter uses complex poles and high Q transfer functions for power conversion, then power conversion efficiency is improved, but output voltage and current overshoot when responding to changing operating conditions
Solution Approach 1:
The patent applies preliminary action by detecting inductor current and anticipating overshoot conditions before they occur. The controller proactively adjusts switching frequency based on detected current levels, preventing overshoot rather than reacting to it after the fact. This is evident in the method where the controller increases switching frequency when inductor current exceeds a threshold, thereby preemptively stabilizing output voltage and current.
Solution Approach 2:
The patent implements feedback control by continuously monitoring inductor current and using this information to dynamically adjust switching frequency. The controller establishes a feedback loop where output current detection informs frequency modulation, creating a closed-loop control system that maintains stability while preserving the high Q transfer function characteristics for efficient power conversion.
2Speed
If resonant converter responds quickly to changing input line or output load conditions, then responsiveness is improved, but output voltage and current overshoot increases
Solution Approach 1:
The patent applies dynamics by making the switching frequency variable rather than fixed. The controller dynamically adjusts frequency based on real-time inductor current detection, allowing the system to optimize between fast response and overshoot prevention. The switching frequency modulates between a first frequency (faster response) and second frequency (slower response) depending on operating conditions, enabling adaptive behavior that balances speed and stability.
Solution Approach 2:
The patent implements parameter changes by varying the switching frequency parameter in response to detected inductor current levels. When current exceeds a threshold indicating potential overshoot, the controller changes the frequency parameter to a lower value, thereby slowing the response to prevent harmful overshoot while maintaining fast response when conditions permit.
3Adaptability or versatility
If resonant converter uses frequency modulation to control output, then control flexibility is improved, but switch duty cycle imbalance occurs
Solution Approach 1:
The patent applies asymmetry by introducing a frequency divider that creates asymmetric pulse generation for the two switches. Instead of symmetric duty cycles, the system uses asymmetric frequency division to ensure that one switch operates at a divided frequency while the other maintains the original frequency, thereby balancing power delivery and preventing duty cycle imbalance while preserving control flexibility.
Solution Approach 2:
The patent introduces a frequency divider as an intermediary component between the controller and the switches. This intermediary element processes the control signal to generate appropriate duty cycles for both switches, mediating the frequency modulation to ensure balanced operation. The frequency divider acts as a buffer that translates flexible frequency control into balanced switch operation.
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 input current and output voltage overshoot without direct line voltage sensing, enhancing the transient response and stability of resonant converters under varying conditions.
Implementation Method 1
a voltage-controlled oscillator (VCO) configured to provide a first pulse train having a first frequency, and to modulate the first frequency responsive to the first information
Implementation Method 2
a frequency divider configured to provide a second pulse train to the output, the second pulse train having a second frequency lower than the first frequency
Implementation Method 3
Resonant converters can be used to convert power from voltage source to direct current (DC) voltage and current
Data Source
AI summary
This document discusses, among other things, apparatus and methods for controlling a converter. In an example, a voltage-controlled oscillator (VCO) can be configured to provide a first pulse train to control the converter. The frequency of the first pulse train of the VCO can be modulated using information indicative of an operating condition of the converter to maintain a desired DC voltage at an output. In an example, the VCO can include a frequency divider configured to provide a second pulse train to the output using information from the first pulse train.