Resonant Inverter Phase Modulation for Stable High-Frequency Control
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Solution Overview
Problem
Existing resonant converters face challenges in maintaining high power factor correction, especially at high frequencies, due to instability issues and noise sensitivity in threshold-based control schemes.
Innovation Solution
A resonant inverter employing a phase modulation scheme with a phase control circuit, including a phase locked loop, to control the switch network based on phase differences between the resonant tank voltage and phase signal, suitable for frequencies up to tens of MHz, using low-cost ICs and minimal external circuitry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If threshold-based control schemes are used in resonant converters, then the converter can operate at high frequencies, but the control becomes unstable and sensitive to noise
Solution Approach 1:
The patent changes the control parameter from threshold-based switching to phase difference-based modulation. By controlling the phase difference between the resonant tank voltage and the switching signal instead of using fixed voltage/current thresholds, the system achieves stable control at high frequencies while being less sensitive to noise and parameter variations.
Solution Approach 2:
The patent implements a feedback mechanism where the phase difference between the resonant tank voltage and the switching signal is continuously measured and used to adjust the switching control. This closed-loop phase control ensures stability at high operating frequencies by automatically compensating for disturbances and maintaining optimal switching timing.
2Ease of operation
If threshold sensing is implemented for control, then the converter can regulate output, but the circuit complexity increases
Solution Approach 1:
The patent extracts and eliminates the complex threshold sensing circuitry from the system. Instead of using multiple threshold comparators and complex logic circuits to detect switching instants, the invention uses a simplified phase detection approach that only requires measuring the phase difference between two signals, significantly reducing circuit complexity while maintaining output regulation capability.
Solution Approach 2:
The patent replaces the mechanical/electronic threshold sensing mechanism with a phase-based control mechanism. By substituting the complex threshold detection system with a simpler phase difference measurement and modulation system, the patent achieves output regulation with reduced circuit complexity and fewer components.
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 provides stable and efficient power factor correction across high frequencies, reducing noise sensitivity and control instabilities, enabling high power factor operation without the need for complex threshold sensing.
Implementation Method 1
resonant converters having a series or parallel resonant circuit are well known. For example, resonant LLC converters are well known for use within LED drivers.
Implementation Method 2
A resonant inverter employing a phase modulation scheme with a phase control circuit, including a phase locked loop, to control the switch network based on phase differences
Data Source
AI summary
A resonant inverter has a switch network from which a phase signal is provided representing the phase of the switching signal. A resonant tank circuit is coupled to the first switch network output and provides a feedback signal comprising a resonance voltage across a circuit element of the resonant tank circuit. A reference current to be drawn from the input node is set and a reference phase is set based on the reference current. The switching signal for the switch network is controlled based on a phase difference between the resonance voltage and the phase signal, and based on the reference phase. This resonant inverter employs a phase modulation scheme as the control scheme for the switch network of a resonant inverter. This approach is suited for high and very high frequency operation of resonant converters, for example up to tens of MHz.