Isolated DC/DC Converter Mode Switching for Variable Voltage Ratios
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Solution Overview
Problem
Existing isolated DC/DC converters face efficiency losses due to deviations from the ideal transformer turn ratio caused by varying input and output voltages, necessitating complex voltage variation stages that increase converter complexity.
Innovation Solution
A DC/DC power converter with a control circuit that operates in two modes, alternating between different voltage levels at the midpoints of half-bridges to accommodate varying input and output voltages, using a capacitor series and three-phase transformer to maintain efficiency across a range of voltage ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the converter operates with a fixed transformer turn ratio, then efficiency is optimized at the ideal voltage ratio, but efficiency deteriorates when input-output voltage ratio deviates from the turn ratio
Solution Approach 1:
The patent implements dynamic operation by enabling the converter to switch between two distinct operating modes: a first mode for when the voltage ratio matches the transformer turn ratio, and a second mode for when it deviates. This dynamic adaptation allows the converter to maintain optimal efficiency across varying input-output voltage conditions without requiring a fixed turn ratio design.
Solution Approach 2:
The patent changes operational parameters by introducing a second operating mode that activates when the voltage ratio deviates from the turn ratio. This parameter change enables the converter to adjust its behavior based on the voltage ratio condition, thereby maintaining efficiency across different operating conditions without physical modification of the transformer.
2Adaptability or versatility
If a separate voltage variation stage (buck/boost or PFC) is added to handle varying voltages, then adaptability to varying voltage ratios is improved, but device complexity increases
Solution Approach 1:
The patent makes the existing converter structure multi-functional by enabling it to operate in two distinct modes using the same hardware components. The converter can handle both ideal voltage ratio conditions (first mode) and deviated voltage ratio conditions (second mode) without requiring additional dedicated circuits, thereby achieving versatility while avoiding increased complexity.
Solution Approach 2:
The patent introduces a control mechanism that acts as an intermediary to manage the transition between operating modes. This control intermediary determines which mode to activate based on the voltage ratio condition, enabling the converter to adapt to varying voltages without adding complex physical voltage variation stages.
3Loss of energy
If the converter is designed for optimal performance at a specific voltage ratio, then efficiency is maximized at that ratio, but the converter becomes less tolerant of voltage variations
Solution Approach 1:
The patent implements dynamic mode switching that allows the converter to adapt its operation based on the voltage ratio condition. When the voltage ratio matches the turn ratio, the first mode provides optimal efficiency. When it deviates, the second mode activates to maintain acceptable performance, thereby making the converter tolerant of voltage variations while preserving optimal efficiency at the ideal ratio.
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
The converter achieves higher efficiency across a wider range of input-output voltage ratios by optimizing operation through two distinct modes, allowing for balanced capacitor voltages and efficient power conversion.
Implementation Method 1
They typically consist of an input stage, isolation stage, and output stage. The input stage converts the input voltage to an AC voltage, which is then transferred through the isolation stage using a transformer.
Implementation Method 2
a control circuit configured to operate the semiconductor switches (S1 . . . S12) of the half-bridges to create an AC voltage on the primary side of the transformer (55) using a first operating mode and a second operating mode
Implementation Method 3
The output stage then rectifies and possibly filters the received AC voltage to provide the desired output voltage.
Data Source
AI summary
An isolated DC/DC power converter may include: a capacitor series arranged between the primary terminals; three first half-bridges with two semiconductor switches arranged in parallel between the upper primary side DC terminal and the midpoint of the capacitors; three second half-bridges of two semiconductor switches, each connected between the lower primary side terminal and the midpoint of a first half-bridge; a transformer connected to the midpoints of the second half-bridges; a rectifier on the secondary side of the transformer; and a control circuit operating the semiconductor switches using two operating modes. The first includes alternating between two or more voltage levels at the midpoints of the second half-bridges that include the voltages at the primary side DC terminals. The second includes alternating between two voltage levels at the midpoints of the second half-bridges that have a voltage difference of half the voltage between the primary side DC terminals.