Dual-Resonant Converter Current Shaping With Harmonic Injection
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Solution Overview
Problem
Conventional resonant converters face inefficiencies in power delivery due to high conduction losses and RMS current values, as they rely on a single resonant frequency for both the primary and secondary tank circuits, limiting their ability to effectively shape the resonant tank current.
Innovation Solution
The introduction of a secondary resonant tank circuit with a higher resonant frequency that injects odd order harmonics into the primary resonant tank circuit, allowing for the shaping of the resonant tank current to more closely approximate a square wave, thereby reducing conduction losses and improving energy efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single resonant frequency is used for both primary and secondary tank circuits, then the converter structure is simple, but conduction losses and RMS current values are high
Solution Approach 1:
The patent divides the resonant frequency control into two independent segments: a primary resonant frequency (f_pr) for the primary tank circuit and a secondary resonant frequency (f_sr) for the secondary tank circuit. This segmentation allows each circuit to operate at its optimized frequency, reducing overall conduction losses while maintaining structural simplicity through independent frequency control.
Solution Approach 2:
The patent changes the operating parameters by introducing two distinct resonant frequencies instead of one. The primary tank circuit operates at f_pr while the secondary tank circuit operates at f_sr, where f_sr is typically higher than f_pr. This parameter change enables optimization of current waveforms and reduction of RMS current values, thereby reducing conduction losses.
2Device complexity
If a single resonant frequency is used for both primary and secondary tank circuits, then the circuit design is simple, but the ability to shape resonant tank current is limited
Solution Approach 1:
The patent segments the current shaping function into two independent control mechanisms: the primary tank circuit shaped by f_pr and the secondary tank circuit shaped by f_sr. This segmentation provides versatile current shaping capability, allowing independent optimization of current waveforms in each tank circuit while keeping the overall circuit design relatively simple.
Solution Approach 2:
The patent introduces dynamic control by allowing the two tank circuits to operate at different resonant frequencies that can be independently adjusted. This dynamic approach enables flexible current shaping to achieve desired waveform characteristics (such as square wave approximation) while maintaining simple circuit topology through independent frequency control.
3Adaptability or versatility
If higher resonant frequency is used in secondary tank circuit, then odd order harmonics are effectively injected to shape current, but the frequency control becomes more complex
Solution Approach 1:
The patent employs self-service frequency control where each tank circuit naturally resonates at its designated frequency (f_pr for primary, f_sr for secondary) through proper component selection (inductors and capacitors). The circuits self-regulate their operating frequencies based on their resonant characteristics, eliminating the need for complex external frequency control mechanisms while achieving effective current shaping through odd order harmonic injection.
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 configuration lowers the RMS value of the resonant tank current and reduces conduction losses, enhancing energy efficiency by effectively controlling the output voltage through the manipulation of resonant frequencies.
Implementation Method 1
The resonant tank current induces a current in a secondary winding of the transformer
Implementation Method 2
the secondary tank circuit has a resonant frequency that is higher than a resonant frequency of the primary resonant tank circuit. The secondary resonant tank circuit injects an odd order harmonic of the operating frequency of the resonant converter to the primary resonant tank circuit
Data Source
AI summary
A resonant converter has a primary resonant tank circuit and a secondary resonant tank circuit. An inverter circuit converts an input DC voltage received by the resonant converter at an input voltage node to a pulsating signal that is fed to the primary resonant tank circuit to generate a resonant tank current that flows through a primary winding of a transformer. The resonant tank current induces current in a secondary winding of the transformer. The induced current is rectified by a rectifier and the rectified signal is filtered by an output capacitor to generate an output DC voltage at an output voltage node. The secondary resonant tank circuit is disposed between the input voltage node and the output voltage node to inject odd order harmonics of the operating frequency to the primary tank circuit to shape the resonant tank current.