Resonant DC-DC Converter With Variable Transformation Ratio
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Solution Overview
Problem
Resonant DC choppers face inefficiencies due to high switching losses and the need for elaborate filtering when operating over a wide range of input and output voltages, as they often stray from the resonance frequency, leading to increased switch-on and switch-off losses and loss of sinusoidal current characteristics.
Innovation Solution
A resonant DC chopper with a transformer unit featuring a variable transformation ratio, achieved through a tap changer or inverter, allows for efficient power transfer by adjusting the transformation ratio to keep operating points close to resonance frequency, reducing semiconductor losses and eliminating the need for filters by maintaining a sinusoidal current characteristic.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If resonant DC chopper is operated over a wide range of input and output voltages, then voltage adaptability is improved, but switching losses increase and efficiency deteriorates
Solution Approach 1:
The patent applies dynamics by making the transformation ratio adjustable through a tap changer on the transformer primary side. This allows the converter to dynamically adapt the transformation ratio based on operating conditions, enabling the resonant circuit to maintain sinusoidal current characteristics and operate efficiently across a wide voltage range without excessive switching losses.
Solution Approach 2:
The patent changes the transformation ratio parameter to resolve the contradiction. By adjusting the transformation ratio via the tap changer, the system can maintain optimal operating points close to resonance frequency across different voltage conditions, thereby reducing switching losses while maintaining wide voltage adaptability.
2Adaptability or versatility
If resonant DC chopper is operated over a wide frequency range, then voltage adaptability is improved, but current sinusoidal characteristic is lost and filtering complexity increases
Solution Approach 1:
The patent uses dynamics by implementing an adjustable transformation ratio through tap changer that responds to operating conditions. This dynamic adjustment ensures the resonant circuit maintains its sinusoidal current characteristic across wide voltage ranges, eliminating the need for complex output filtering while preserving voltage adaptability.
Solution Approach 2:
The transformation ratio parameter is adjusted to maintain the resonant circuit's sinusoidal current characteristic. By changing this parameter adaptively, the system avoids operating in purely capacitive or inductive ranges that would distort the current waveform, thereby simplifying filtering requirements while maintaining wide voltage adaptability.
3Device complexity
If transformation ratio is fixed, then device complexity is reduced, but ability to maintain resonance frequency and reduce switching losses deteriorates
Solution Approach 1:
The patent applies dynamics by implementing an adjustable transformation ratio via tap changer that can be modified based on operating conditions. This dynamic capability allows the system to maintain optimal operating points close to resonance frequency, minimizing switching losses without significantly increasing device complexity.
4Adaptability or versatility
If operating point moves away from resonance frequency, then voltage adaptability is improved, but switching losses increase continuously
Solution Approach 1:
The patent changes the transformation ratio parameter to maintain operating points close to resonance frequency across different voltage conditions. By adjusting this parameter via the tap changer, the system achieves wide voltage adaptability while preventing the continuous increase of switching losses that would occur if operating points moved away from resonance.
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 significantly reduces switching losses and enhances efficiency across a large dynamic range of voltages, maintaining low switch-on and switch-off losses and avoiding undesirable harmonics, thereby improving the overall performance and efficiency of the resonant converter.
Implementation Method 1
the first and the second terminal are galvanically isolated from one another by means of a first transformer
Implementation Method 2
a resonant-switching inverter circuit of a DC chopper, a sinusoidal current is generated which flows through the transformer
Data Source
AI summary
A resonant DC-DC converter includes an inverter circuit, a rectifier circuit and a transformer unit. The inverter circuit is connected to a first terminal of the transformer unit, and the rectifier circuit is connected to a second terminal of the transformer unit. The first and second terminals are galvanically isolated from one another by a first transformer. The transformer unit is configured to adapt a transformation ratio of the transformer unit. The transformer unit has an energy transmission path which includes an inverter and a second transformer, with an input of the energy transmission path being arranged parallel to a primary side of the first transformer and an output of the energy transmission path being arranged in series with the secondary side of the first transformer.