LLC Resonant Converter Signal Sensing via Buffered Primary Port
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Solution Overview
Problem
Conventional resonant converters, particularly LLC converters, face challenges in effectively sensing and controlling resonant circuit signals, which affects their efficiency and performance in converting high voltage AC power to regulated DC power for electronic devices.
Innovation Solution
The implementation of a buffer circuit coupled with a resonant transformer to provide a buffered primary port signal that includes comprehensive information about input voltage and power, used in conjunction with a sense interface circuit to generate a scaled replica of the primary port signal, enabling enhanced control and power conversion in LLC converters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional sensing methods are used in resonant converters, then the device complexity is reduced, but the measurement precision of resonant circuit signals deteriorates
Solution Approach 1:
The patent introduces an auxiliary winding on the resonant transformer as an intermediary element. This auxiliary winding senses the resonant circuit signals indirectly through magnetic coupling, avoiding the need for direct electrical connection to the high-voltage resonant circuit. The sensed signal is then processed through a sense amplifier and voltage divider to achieve accurate measurement while maintaining electrical isolation and reducing complexity of the high-voltage sensing circuitry.
Solution Approach 2:
The patent replaces direct electrical sensing mechanisms with magnetic field-based sensing through the auxiliary winding. Instead of using voltage dividers or current sensors directly in the high-voltage circuit, the system uses electromagnetic induction to transfer signal information from the resonant circuit to a low-voltage sensing circuit, thereby improving measurement precision while reducing the complexity of high-voltage signal handling.
2Loss of energy
If zero-voltage switching control is implemented in LLC converters, then the loss of energy is reduced, but the control difficulty increases due to challenging signal sensing
Solution Approach 1:
The patent implements a feedback control mechanism where the auxiliary winding continuously senses the resonant circuit voltage and current information. This sensed signal is amplified and processed to generate feedback signals that are used to control the switching timing of the power stage. The feedback loop enables precise zero-voltage switching control by providing real-time information about the resonant circuit state, thereby reducing switching losses while maintaining manageable control complexity through automated control based on sensed signals.
3Productivity
If comprehensive signal information is obtained from the primary port, then the productivity of power conversion is improved, but the device complexity increases due to additional buffer and sense circuits
Solution Approach 1:
The patent designs the auxiliary winding to serve multiple functions simultaneously: it senses voltage information, provides isolation between primary and secondary sides, and generates signals for both control and protection functions. The buffer circuit and sense amplifier are designed to process multiple types of signal information (voltage, current, power) from a single sensing element, thereby improving power conversion productivity through comprehensive signal utilization while minimizing the increase in device complexity through multi-functional component design.
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 improves the control and efficiency of LLC converters by providing accurate and comprehensive signal information for power regulation, leading to better zero-voltage switching and reduced harmonic content, thus enhancing the overall performance and reliability of power conversion.
Implementation Method 1
a resonant transformer to provide a buffered primary port signal
Implementation Method 2
a buffer circuit coupled in parallel with or across the resonant circuit input port to provide a buffered primary port signal
Data Source
AI summary
Apparatus and methods for sensing resonant circuit signals to enhance control in a resonant converter are described herein. A buffer circuit coupled in parallel with or across a resonant component (e.g., a transformer) input port avails a buffered primary port signal for use in resonant conversion. The buffered primary port signal is a comprehensive signal including information relating to both input voltage and input power; and it may be used to advantageously enhance switching and power conversion in an inductor-inductor capacitor (LLC) converter. Additionally, the LLC converter uses a sense interface circuit to provide a scaled replica of the buffered primary port signal. In one example the scaled replica can advantageously be used with a secondary side controller to control output power based on the comprehensive information contained within the buffered primary port signal.