Resonant Converter Voltage Compensation Circuit Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Resonant LLC converters face stability issues and audio noise at low output voltages due to the need to switch between Vcap and Ipeak control methods, resulting in complex design requirements and potential instability, especially when output power levels are varying.
Innovation Solution
A resonant converter with a voltage compensation circuit that generates a periodic compensation voltage signal, allowing the control circuit to end conduction intervals based on derived voltage levels and the compensation signal, ensuring stable operation across a full range of power output levels without mode switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mode switching between Vcap and Ipeak control methods is implemented, then stability at low output voltages can be improved, but device complexity and design requirements increase
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the voltage levels (VcapH and VcapL) used as reference thresholds for control based on the output voltage level. When output voltage is high, conventional Vcap control levels are used; when output voltage drops below a threshold, the control levels are switched to Ipeak-based levels. This parameter adaptation allows the system to maintain stability across different operating conditions without requiring fundamentally different control architectures.
Solution Approach 2:
The patent implements dynamics by making the control method adaptive rather than static. The control system continuously monitors the output voltage and dynamically switches between two control modes (Vcap control and Ipeak control) based on the operating condition. This dynamic adaptation allows the converter to respond appropriately to changing load conditions and maintain stability at both high and low output voltages without manual intervention or complex fixed control logic.
2Reliability
If mode switching between control methods is implemented, then low voltage stability can be improved, but audio noise and instability may increase
Solution Approach 1:
The patent changes the control parameter thresholds based on output voltage level. By switching from Vcap control levels to Ipeak control levels when voltage drops below a threshold, the system avoids the audio noise and instability that would result from forcing Vcap control at low voltages. The parameter change ensures that the control method matches the operating conditions, preventing harmful effects.
Solution Approach 2:
The patent uses feedback by continuously monitoring the output voltage and using this information to determine which control mode to employ. The control system measures the actual output voltage and compares it against a threshold to decide whether to use Vcap control or Ipeak control. This feedback mechanism ensures that the appropriate control method is selected in real-time, preventing audio noise and instability by avoiding inappropriate control mode operation.
3Adaptability or versatility
If resonant converter operates at varying power levels, then adaptability is improved, but stability and audio noise performance deteriorate
Solution Approach 1:
The patent applies dynamics by implementing a dynamic control mode selection mechanism that adapts to varying power levels. The system automatically transitions between Vcap control and Ipeak control based on the current operating point, allowing it to maintain stability across the full power range. This dynamic adaptation enables the converter to handle both high and low power levels effectively without sacrificing stability or generating audio noise.
Solution Approach 2:
The patent changes control parameters (voltage thresholds and control method selection) based on the power level and output voltage conditions. At high power levels, Vcap control parameters are used; at low power levels, Ipeak control parameters are activated. This parameter adaptation allows the converter to maintain optimal performance and stability across varying power levels, resolving the contradiction between adaptability and stability.
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
The solution provides stable output current over a wide range of power levels, eliminating the need for mode switching and reducing instability and audio noise, thereby simplifying the design and improving converter performance.
Implementation Method 1
resonant converters are of interest due to their high efficiency and small size... One particular type of resonant converter is a resonant LLC converter, in which a capacitor and two inductors form a resonant circuit
Implementation Method 2
A transformer and secondary rectifier circuit 3 provides a DC output voltage Vo across output terminals 4
Data Source
AI summary
A resonant converter (10) comprising a voltage compensation circuit (72, 73) configured to generate a periodic compensation voltage signal (Vslopecompens) at a switching frequency of the converter such that conduction intervals (31, 32) are ended according to first and second voltage levels in combination with the periodic compensation signal.