LLC Converter Auxiliary Winding Switching for Holdup Time
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Solution Overview
Problem
LLC converters face challenges in maintaining output voltage stability when input voltage drops, as they often rely on limited switching frequency adjustments, which can lead to output voltage fluctuations and reduced holdup time due to insufficient gain control capability.
Innovation Solution
The LLC converter incorporates a controller that couples the leakage inductance of the auxiliary winding to the primary or secondary side of the circuit when the input voltage drops below a threshold, enhancing gain control and allowing more electromagnetic energy storage, thereby extending holdup time without the need for additional chokes, and uses a transformer design with air gaps to reduce eddy currents and achieve high efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If switching frequency adjustment is limited to maintain output voltage, then output voltage stability is improved, but holdup time is reduced due to insufficient gain control capability
Solution Approach 1:
The patent applies dynamics by making the magnetizing inductance adjustable through a switchable auxiliary winding. The auxiliary winding can be dynamically connected or disconnected to change the total magnetizing inductance value, allowing the system to adapt to different operating conditions. This dynamic adjustment enables extended holdup time when needed while maintaining voltage stability under normal operation.
Solution Approach 2:
The patent changes the electrical parameter of magnetizing inductance by switching the auxiliary winding. When the auxiliary winding is connected, the total magnetizing inductance increases, which extends the holdup time. This parameter change allows the system to overcome the limitation of fixed inductance and provide variable gain control capability.
2Duration of action of moving object
If additional chokes are added to extend holdup time, then holdup time is improved, but device complexity and cost increase
Solution Approach 1:
The auxiliary winding serves multiple functions: it extends holdup time by increasing magnetizing inductance, provides gain control capability, and utilizes existing transformer structure. By making the auxiliary winding multi-functional, the patent avoids adding separate components like additional chokes, thereby reducing device complexity while achieving the desired holdup time extension.
Solution Approach 2:
The patent merges the holdup time extension function with the existing auxiliary winding structure of the transformer. Instead of adding a separate choke component, the auxiliary winding's magnetizing inductance is utilized and switched to serve the holdup time extension purpose, combining multiple functions into a single integrated solution.
3Volume of moving object
If transformer core size is reduced for compact design, then volume is improved, but eddy current losses increase reducing efficiency
Solution Approach 1:
The patent applies local quality by introducing air gaps at specific locations in the transformer core where they are most effective. The air gaps are strategically placed to reduce eddy current losses in critical areas without requiring a larger overall core size. This localized modification maintains compact volume while improving efficiency by reducing energy losses.
Solution Approach 2:
The patent uses composite magnetic core structures with air gaps incorporated into the core design. The combination of magnetic material and air gaps creates a composite structure that reduces eddy current losses while maintaining a compact size. The air gaps act as non-magnetic elements within the magnetic core, disrupting eddy current paths and reducing energy losses.
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 LLC converter's ability to maintain output voltage stability and extends holdup time by increasing gain control and electromagnetic energy storage, while also reducing costs and maintaining high efficiency through compact transformer designs.
Implementation Method 1
a transformer having a primary winding, a secondary winding, and an auxiliary winding. The primary winding is coupled to a primary side circuit
Implementation Method 2
uses a transformer design with air gaps to reduce eddy currents and achieve high efficiency
Data Source
AI summary
In some embodiments, an inductor-inductor-capacitor (LLC) converter includes a transformer having a primary winding, a secondary winding, and an auxiliary winding. The primary winding is coupled to a primary side circuit and the auxiliary winding has a first winding portion coupled between a first terminal and a middle terminal, and a second winding portion coupled between the middle terminal and a second terminal. The LLC converter further includes a first diode coupled between the first terminal and a first node, a second diode coupled between the second terminal and the first node, and a switch coupled between the first node and a reference voltage terminal. The middle terminal of the auxiliary winding is coupled to the reference voltage terminal.