Multi-Step SOTC for Resonant Converters
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Solution Overview
Problem
The control of resonant converters, particularly LLC resonant converters, is complex due to the dynamics of the resonant tank, requiring advanced state-trajectory analysis and control methods that are resource-intensive and challenging to implement, especially at high frequencies.
Innovation Solution
A multi-step Simplified Optimal Trajectory Control (SOTC) method that uses only Voltage Output (VO) and Load Current (ILoad) sensing, allowing for a simple control scheme that can be easily extended to high-frequency applications, requiring low controller speed and resources, and facilitating soft start-up, fast load transient response, burst mode operation, and integration with synchronous rectifier (SR) driving.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If state-trajectory control methods based on resonant tank information are used, then control precision is improved, but device complexity increases
Solution Approach 1:
The patent extracts only the essential control parameters (output voltage and load current) from the complex resonant tank system, discarding the need to measure or control all resonant tank variables. This extraction approach maintains adequate control precision while significantly reducing the complexity of sensing and control circuitry.
Solution Approach 2:
Instead of using resonant tank information to directly control the converter, the patent inverts the approach by using output voltage and load current measurements to infer the required control actions. This indirect control method simplifies the control scheme while maintaining effectiveness.
2Measurement precision
If advanced state-trajectory analysis and control methods are used, then control precision is improved, but ease of operation deteriorates
Solution Approach 1:
The patent replaces complex, resource-intensive control algorithms with a simpler control method that uses readily available output voltage and current measurements. This simpler approach is easier to implement and operate while maintaining adequate control precision for practical applications.
3Measurement precision
If resonant tank information-based control is used, then control precision is improved, but productivity decreases due to high resource requirements
Solution Approach 1:
The patent extracts only the minimal necessary measurements (output voltage and load current) that can be obtained with standard, low-speed ADCs. This extraction eliminates the need for high-speed sampling and processing, allowing implementation on low-cost microcontrollers without sacrificing essential control functionality.
Data Source
AI summary
A resonant power converter is disclosed with a driving circuit generating a switching signal connecting power to a resonant tank circuit, with a voltage monitoring circuit measuring a voltage output and a load current. A micro-controller is operable with a control circuit for multiple step sampling with the switching signal at a switching frequency to settle the resonant circuit determined from the voltage output and load current. A fast load transient response at a high frequency with the resonant circuit provides the multiple step sampling to ensure enough time for micro-controller to calculate. Optimal trajectory control facilitates a burst mode of high frequency with the resonant circuit using adaptive multiple step sampling for an on-time to extend the burst operation range. A soft start-up process uses the micro-controller processing in multiple stages.