Single Stage Boost-Asymmetric LLC Converter
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Solution Overview
Problem
Existing AC/DC switching power supplies face challenges in achieving high power factor correction and output voltage regulation efficiently, particularly at low power levels, due to complex and costly double-stage topologies, and single-stage solutions often lack energy storage capability and poor load transient response.
Innovation Solution
A single stage boost-asymmetric LLC topology using pulse width modulation and frequency modulation to control a single main magnetic element, enabling both input current conditioning and output voltage regulation through frequency modulation, while providing energy storage via duty cycle control, with a pair of complementary switches and resonant components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a double stage topology with PFC is used, then power factor correction is improved, but device complexity increases
Solution Approach 1:
The patent combines the PFC function and output voltage regulation into a single integrated LLC resonant converter stage. The LLC tank circuit performs both power factor correction and voltage regulation simultaneously, eliminating the need for separate PFC and DC-DC conversion stages while maintaining high power factor and stable output voltage.
Solution Approach 2:
The LLC resonant converter is designed to perform multiple functions: it provides power factor correction, output voltage regulation, and galvanic isolation all in one stage. The resonant tank components serve dual purposes of achieving soft switching for high efficiency and enabling voltage transformation for regulation.
2Device complexity
If a single stage topology is used, then device complexity is reduced, but energy storage capability deteriorates
Solution Approach 1:
The LLC resonant tank is designed to provide both the resonant operation for soft switching and the energy storage function traditionally provided by separate PFC inductors. The magnetizing inductance of the transformer and the resonant inductor work together to provide energy storage capability while maintaining single-stage operation.
3Device complexity
If a single stage topology is used, then device complexity is reduced, but output voltage regulation deteriorates
Solution Approach 1:
The patent employs dynamic control of the LLC resonant converter by adjusting the switching frequency to regulate the output voltage. The control circuit monitors the output voltage and dynamically adjusts the switching frequency to maintain stable regulation despite variations in input voltage and load conditions, achieving precise voltage control in a single stage.
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 simplifies the design, reduces component count, and achieves efficient power processing with improved output voltage regulation and power factor correction, resulting in a more efficient and cost-effective single-stage AC/DC converter with higher efficiency and reduced complexity.
Implementation Method 1
The resonant inductor, the first resonant capacitor, and the second resonant capacitor form a resonant tank that may operate in resonant mode (LLC)
Implementation Method 2
The high frequency magnetic transformer includes a primary winding and a secondary winding
Data Source
AI summary
An AC/DC power converter utilizing a single stage boost-asymmetric LLC topology is disclosed. The converter uses a combined pulse width modulation (PWM) and frequency modulation (FM) to achieve dual control for a single main magnetic element (transformer). The transformer provides an output voltage regulation throughout the primary-secondary isolation operating in resonant mode (LLC) by means of frequency modulation, while at the same time its magnetizing inductance is conditioning the input current and providing a boosted high voltage for energy storage purpose by means of duty cycle control. A single pair of complementary primary switches is used to drive the primary winding of the transformer in order to achieve both voltage regulation and power conditioning. The secondary side capacitors and the resonant inductor, which may be either integrated into the transformer or external to the transformer, achieve the resonant function of the transformer.