LLC Power Converter Control for Wider Inverse Gain Range
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Solution Overview
Problem
Current power converters with LLC resonant circuits have a narrow gain conversion range when operating inversely, due to small inductance in the resonant inductor and limited participation of the excitation inductor, leading to restricted voltage regulation and switching frequency ranges, which is not effectively addressed by existing solutions that increase costs and occupy more space.
Innovation Solution
A power converter design that includes a primary side circuit, a secondary side circuit, and a transformer, where the controller controls the secondary side circuit to operate in a control cycle that is equal to or longer than the resonance cycle, with switching frequencies less than or equal to the resonance frequency, allowing for increased gain conversion range without adding hardware, and utilizing phase shift processing to reduce energy transmission duration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the resonant inductor in the LLC resonant circuit has a small inductance to enable miniaturization and high frequency operation, then the power converter can be compact and high-frequency, but the gain conversion range becomes narrow when operating inversely
Solution Approach 1:
The patent applies dynamics by making the operating frequency variable and adjustable. The controller dynamically adjusts the operating frequency within a range that includes the resonance frequency, allowing the system to adapt to different gain requirements during inverse operation. This dynamic frequency adjustment enables the converter to achieve a wider gain conversion range while maintaining the compact resonant inductor design.
2Device complexity
If the excitation inductor does not participate in resonance during inverse operation to simplify the circuit, then the circuit structure remains simple, but the switching frequency range and voltage regulation range become limited
Solution Approach 1:
The patent applies universality by designing the excitation inductor to serve multiple functions. During forward operation, it provides excitation current to the resonant circuit. During inverse operation, it continues to participate in the resonant process, enabling the circuit to achieve both voltage boost and frequency regulation functions without requiring additional components. This multi-functional design expands the switching frequency range while keeping the circuit structure simple.
3Adaptability or versatility
If additional resonant capacitors or resonant inductors are added to increase the gain conversion range during inverse operation, then the gain conversion range increases, but the cost and occupied space increase
Solution Approach 1:
The patent applies parameter changes by adjusting the operating frequency parameter rather than changing the physical structure or adding components. By varying the operating frequency within and around the resonance frequency, the system achieves different gain values and expands the gain conversion range. This parameter-based approach avoids the need for additional resonant capacitors or inductors, thereby maintaining a compact design with reduced occupied space and lower cost.
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 design enhances the gain conversion range of the power converter when operating inversely, reduces switch currents and switching losses, and prevents switch damage, all while maintaining cost-effectiveness and compactness.
Implementation Method 1
an inductor-inductor-capacitor (LLC) resonant circuit is usually used in a power converter, and the LLC resonant circuit can reduce a component loss in the power converter
Implementation Method 2
The transformer is configured to supply the electric energy to the primary side circuit
Data Source
AI summary
A power converter includes a primary side circuit, a secondary side circuit, a transformer, and a controller. A primary side of the transformer is connected to the primary side circuit, and a secondary side of the transformer is connected to the secondary side circuit. The primary side circuit includes a resonant circuit. The secondary side circuit is configured to supply electric energy to the transformer. The transformer is configured to supply the electric energy to the primary side circuit. The primary side circuit is configured to convert the electric energy. The controller is connected to the secondary side circuit, and is configured to control, in a control cycle, the secondary side circuit to supply the electric energy to the transformer. Duration of the control cycle is greater than or equal to duration of a resonance cycle of the resonant circuit.