Multi-Stage Power Converter Pre-Regulator Voltage Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
LLC resonant converters face efficiency challenges due to voltage drops caused by resistive components, which disrupt critically discontinuous conduction mode and prevent zero current switching when adjusting switching frequency to compensate for these drops.
Innovation Solution
A multi-stage power converter system that includes a pre-regulator circuit and an LLC resonant converter, where the control circuit adjusts the regulated output voltage of the pre-regulator as a function of the output current of the LLC resonant converter, maintaining a substantially fixed switching frequency equal to the resonant frequency to ensure zero current switching and optimal efficiency across varying load conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If switching frequency is adjusted to compensate for voltage drops caused by resistive components, then output voltage regulation is improved, but zero current switching is lost and efficiency deteriorates
Solution Approach 1:
The pre-regulator circuit adjusts the input voltage to the LLC resonant converter in advance, compensating for voltage drops caused by resistive components before they affect the output. This preliminary adjustment maintains the switching frequency at the resonant frequency, preserving zero current switching and high efficiency while ensuring proper output voltage regulation.
2Stability of the object's composition
If LLC resonant converter is designed to operate in critically discontinuous conduction mode at fixed load condition, then switching frequency remains stable, but efficiency deteriorates under varying load conditions
Solution Approach 1:
The pre-regulator circuit dynamically adjusts the input voltage to the LLC resonant converter based on varying load conditions. This dynamic adjustment compensates for changes in voltage drops caused by resistive components under different loads, maintaining critical discontinuous conduction mode and high efficiency across the full load range while keeping switching frequency stable at the resonant frequency.
3Device complexity
If pre-regulator circuit provides fixed regulated output voltage, then circuit operation is simplified, but RMS ripple current increases and capacitor lifespan decreases
Solution Approach 1:
The pre-regulator circuit changes its output voltage parameter dynamically based on load conditions, specifically adjusting the voltage to compensate for resistive drops in the LLC resonant converter. This parameter adjustment reduces RMS ripple current through the output capacitors, extending their lifespan while maintaining relatively simple circuit operation through a single-stage architecture.
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 maintains zero current switching and optimal efficiency of the LLC resonant converter across different load conditions, reducing RMS ripple current and extending the lifespan of output capacitors, while providing higher efficiency compared to fixed input voltage scenarios.
Implementation Method 1
the switching frequency of the power switches is substantially equal to the resonant frequency of the resonant elements
Data Source
AI summary
A multi-stage power converter includes a pre-regulator circuit configured to provide a regulated output voltage, at least one DC/DC converter, and a control circuit coupled to the pre-regulator circuit and the DC/DC converter. The DC/DC converter is configured to provide an output voltage and an output current to a load. The DC/DC converter includes an input, an output, and at least one power switch. The input of the DC/DC converter is coupled to the pre-regulator circuit. The control circuit is configured to regulate the output voltage of the DC/DC converter and vary the regulated output voltage of the pre-regulator circuit as a function of the output current of the DC/DC converter.