Llcc Resonant Converter Impedance Control
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Solution Overview
Problem
Conventional series resonant power converters face limitations in effective power transmission and harmonic control due to decreasing amplitude and increasing passband with load impedance variations, leading to reduced efficiency and increased harmonic inclusion.
Innovation Solution
The introduction of an RCN structure within the primary circuit of the transformer, comprising an inductor Lx in parallel with one winding and a capacitor Cx in parallel with the other, allows for controlled impedance variation and quality factor limitation, enabling extended operational range and improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the load impedance increases, then the quality factor Q decreases rapidly, but the amplitude of current transmitted to secondary decreases and passband widens
Solution Approach 1:
The patent applies dynamics by making the primary circuit impedance adaptive through the parallel LC tank circuit. As load impedance changes, the tank circuit automatically adjusts the primary impedance to maintain stable quality factor, transforming a static circuit into a dynamically responsive system that adapts to varying load conditions.
Solution Approach 2:
The patent changes the impedance parameter of the primary circuit by introducing a parallel LC tank circuit with specific inductance Lx and capacitance Cx. This parameter modification allows the system to control quality factor variation, maintaining it within acceptable ranges despite load impedance changes, thereby resolving the contradiction between quality factor stability and current amplitude transmission.
2Adaptability or versatility
If the passband widens to accommodate load variations, then the selectivity decreases, but harmonics are included in the resonant current
Solution Approach 1:
The patent uses dynamics to maintain stable quality factor across varying load conditions. The parallel LC tank circuit dynamically adjusts the primary circuit impedance to keep the resonant system selective, preventing harmonic inclusion even when operating range is extended to accommodate different load impedances.
Solution Approach 2:
The patent implements a form of feedback through the parallel LC tank circuit that automatically compensates for load impedance variations. The tank circuit responds to changes in load conditions by adjusting the overall impedance, maintaining stable quality factor and selectivity, thereby preventing harmonic distortion without requiring external control mechanisms.
3Reliability
If the quality factor is limited to maintain stability, then the amplitude of transmitted current decreases, but the converter can operate with extended load range
Solution Approach 1:
The patent changes the impedance parameters by introducing a parallel LC tank circuit with carefully selected inductance Lx and capacitance Cx. This parameter modification enables the system to maintain stable quality factor across extended load ranges while preserving adequate current transmission capability, effectively resolving the contradiction between stability and productivity.
Solution Approach 2:
The patent creates a composite circuit structure by combining the series resonant circuit with a parallel LC tank circuit. This composite configuration integrates the benefits of both circuit topologies, achieving stable quality factor characteristics while maintaining effective power transmission capability across varying load conditions.
4Device complexity
If conventional series resonant structure is used, then the design is simple, but the converter size and losses increase with load variations
Solution Approach 1:
The patent applies segmentation by dividing the primary circuit into two functional parts: the series resonant circuit for power transmission and the parallel LC tank circuit for impedance stabilization. This segmentation allows each part to perform its specific function efficiently, maintaining compact converter size while handling load variations without increasing overall complexity significantly.
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 maintains stable amplitude and selectivity across varying load impedances, ensuring quasi-sinusoidal voltages and currents, and facilitates soft switching to reduce losses and electromagnetic disturbances, thereby enhancing efficiency and reducing converter size.
Implementation Method 1
the primary circuit comprises a first winding of N11 turns and a second winding of N12 turns with N11=N12, an inductor Lx in parallel with the first winding, a capacitor of capacitance Cx in parallel with the second winding. This innovative solution makes it possible to control the variation of the impedance of the primary circuit in order to be able to limit the quality factor Q.
Implementation Method 2
In a conventional resonant structure, operation is ensured at the resonance frequency or for a close frequency. Under these conditions and for a sufficiently large selectivity, the current in the structure is of sinusoidal form.
Data Source
Figure 1~2
Figure 3~4a
Figure 4b~5
AI summary
series resonant circuit power converter (100) comprising: - an inverter (1), - a series LC resonant circuit, - a transformer (T1) comprising a primary circuit (2) and a secondary circuit (3), and - means (4) for controlling the inverter, the inverter being connected to the series LC resonant circuit which is intended to be connected to an output load (Rout) through the transformer (T1), characterized in that the primary circuit (2) comprises a first winding of N11 turns and a second winding of N12 turns with N11=N12, an inductance (Lx) in parallel with the first winding, a capacitor of capacitance Cx in parallel with the second winding.