Isolated DC/DC Converter with Dynamic Transformer Ratio
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Solution Overview
Problem
Isolated DC/DC converters face challenges in maintaining efficiency and reducing voltage stress on rectifier diodes due to varying duty cycles, especially in vehicle applications where input voltage fluctuations are significant, leading to inefficiencies and design complexities.
Innovation Solution
A voltage conversion device comprising two interleaved DC/DC converters with a regulation circuit that maintains a constant duty cycle over a first input-output range and allows duty cycle modification over a second range, enabling efficient voltage regulation without significant duty cycle variation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the duty cycle is varied to regulate output voltage when input voltage varies, then the output voltage can be maintained at a desired value, but the voltage stress on rectifier diodes becomes significant and efficiency varies greatly
Solution Approach 1:
The patent applies dynamics by making the transformer turns ratio adjustable rather than fixed. The converter can dynamically switch between different transformation ratios (e.g., 1:1, 2:1, 4:1) to adapt to varying input voltage conditions. This dynamic adjustment allows the system to maintain optimal operating conditions across a wide input voltage range while keeping the duty cycle within a safe range (e.g., 20%-80%) to avoid excessive voltage stress on rectifier diodes.
2Measurement precision
If the duty cycle is varied to regulate output voltage, then the output voltage can be maintained, but the output current ripples vary greatly causing efficiency to vary
Solution Approach 1:
The patent uses dynamic adjustment of the transformer turns ratio to maintain stable efficiency. By switching between different transformation ratios based on input voltage conditions, the system keeps the duty cycle within an optimal range (e.g., 20%-80%), which stabilizes output current ripples and maintains high efficiency across varying operating conditions.
3Object-affected harmful factors
If different transformation ratios are used for two transformers to limit voltage stress on rectifier diodes, then diode stress is reduced, but the design becomes complex because transformers cannot be identical
Solution Approach 1:
The patent applies segmentation by dividing the power conversion function into multiple stages with different transformation ratios. Instead of using two identical transformers with complex winding configurations, the system uses separate transformer circuits (e.g., first transformer with 1:1 ratio, second transformer with 2:1 ratio) that can be independently designed and optimized. This modular approach simplifies the overall design while achieving the goal of limiting voltage stress on rectifier diodes.
4Loss of energy
If the duty cycle is kept constant to maintain high efficiency, then efficiency is improved, but the ability to regulate output voltage over a wide input voltage range is limited
Solution Approach 1:
The patent resolves this contradiction by dynamically switching between different transformation ratios based on the input voltage level. When the input voltage is within a certain range, the converter uses a first transformation ratio (e.g., 1:1) with a constant duty cycle for high efficiency. When the input voltage exceeds this range, the converter switches to a second transformation ratio (e.g., 2:1 or 4:1) to maintain proper voltage levels while keeping the duty cycle constant, thus extending the adaptability to wide input voltage ranges without sacrificing efficiency.
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 allows for stable and efficient voltage conversion across varying input voltages, reducing voltage stress on diodes and maintaining high efficiency by keeping the duty cycle constant within a specific range, thereby enhancing the performance of isolated DC/DC converters in vehicle applications.
Implementation Method 1
The converter comprises two switches, arranged as a half-bridge, which are connected at their midpoint to a branch which comprises two transformers in series. The switches control the transmission of energy through the transformers to obtain a conversion of an input voltage of the converter into an output voltage.
Data Source
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AI summary
The invention relates to a voltage converter (1) comprising an isolated DC/DC converter circuit (3) and a control circuit (2) for controlling the input voltage of the isolated DC/DC converter circuit (3), in which the control circuit (2) and the isolated DC/DC converter circuit (3) are configured such that: in a first input-output operation range of the converter (1), the control circuit (2) controls the output voltage (Vout) of the isolated DC/DC converter circuit (3) by modifying the voltage supplied to the isolated DC/DC converter circuit (3), the duty factor of the isolated DC/DC converter circuit (3) remaining substantially equal to a first value; and, in a second input-output operation range of the converter (1), the isolated DC/DC converter circuit (3) controls the output voltage (Vout) thereof by modifying the duty factor thereof.