Resonant Inverter Phase Modulation for Stable MHz Operation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing resonant converters face challenges in maintaining high power factor, especially at high frequencies, due to instability issues and noise sensitivity in threshold-based control schemes, making them impractical above 0.5MHz.
Innovation Solution
A resonant inverter employing a phase modulation scheme with a phase control circuit, including a phase locked loop and PID filter, to control the switch network based on phase differences between the resonant tank voltage and phase signal, allowing for stable operation up to tens of MHz without requiring extensive 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 system becomes unstable and noise-sensitive above 0.5MHz
Solution Approach 1:
The patent changes the control parameter from threshold-based switching to phase-based modulation. By controlling the phase angle of the resonant current relative to the switching signal, the system achieves stable operation at high frequencies without the instability and noise sensitivity inherent in threshold-based schemes. This parameter transformation enables reliable operation above 0.5MHz.
2Reliability
If phase modulation with phase locked loop and PID filter is implemented, then control stability improves, but device complexity increases
Solution Approach 1:
The patent implements a feedback control system using a phase locked loop that continuously monitors the phase relationship between the resonant current and switching signal. The PID filter processes this phase information to generate appropriate control signals, creating a closed-loop system that maintains stability while managing the complexity through systematic feedback mechanisms.
Solution Approach 2:
The phase locked loop acts as an intermediary between the switching signal and the resonant tank circuit. It translates phase difference information into control actions, mediating the interaction between the control system and the power conversion process, thereby simplifying the overall control architecture despite the added components.
3Reliability
If power factor correction is implemented in a dedicated pre-regulator circuit, then power factor improves, but the system requires dual-stage configuration increasing complexity
Solution Approach 1:
The patent merges the power factor correction function with the main resonant converter by controlling the phase of the resonant current to be in phase with the input voltage. This single-stage approach combines what would traditionally require separate pre-regulator and converter stages, reducing system complexity while maintaining high power factor through phase-controlled current draw from the input.
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 and conversion control at high frequencies, reducing noise sensitivity and maintaining high power factor without the need for complex threshold sensing, enabling effective operation in high-frequency resonant converters.
Implementation Method 1
a resonant tank circuit coupled to the switch network output, wherein the resonant tank circuit adapted to provide a feedback signal comprising a resonance voltage across a circuit element of the resonant tank circuit
Data Source
Figure 1~3
Figure 4~5
Figure 6~8
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.