Capacitive-Isolated Power Converter for High Step-Down Output
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Solution Overview
Problem
Existing power conversion devices face challenges in further decreasing the output voltage while maintaining insulation between primary and secondary circuits, particularly in applications requiring high voltage conversion for vehicles.
Innovation Solution
A power conversion device with a secondary-side circuit that includes series-connected coils and diodes, along with capacitive isolation using first and second capacitors, to manage voltage and current effectively, allowing for increased step-down ratios and reduced current requirements in switching elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If capacitive isolation is used between primary and secondary circuits, then insulation is achieved, but the output voltage cannot be decreased further
Solution Approach 1:
The secondary-side circuit is divided into two separate legs (first leg with first coil and first diode, second leg with second coil and second diode), each connected to different connection lines. This segmentation allows independent optimization of each leg's voltage and current characteristics, enabling further voltage reduction while maintaining insulation through the capacitors.
Solution Approach 2:
The patent introduces a new dimensional approach by connecting the coils and diodes in series within each leg, and cross-connecting them through wires between output ends. This creates a multi-dimensional current path structure that enables voltage reduction beyond the limitations of conventional capacitive isolation.
2Power
If higher step-down ratios are required, then current requirements in switching elements increase, but this leads to higher losses and reduced efficiency
Solution Approach 1:
By dividing the secondary-side circuit into two legs with separate coils and diodes, the total current is distributed across multiple paths. Each switching element handles only a portion of the total current, reducing individual element losses while achieving the required overall power conversion.
Solution Approach 2:
The patent combines multiple coils and diodes in a parallel-leg configuration where their contributions are merged at the output. This merging allows the system to achieve high step-down ratios through collective action of multiple components, with each component operating at lower current levels and thus lower losses.
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 device achieves efficient voltage reduction and insulation between circuits, reducing current demands on switching elements and enhancing power conversion efficiency, particularly suitable for vehicles with high-voltage and low-voltage battery systems.
Implementation Method 1
The primary-side circuit and the secondary-side circuit are insulated from each other by a first capacitor and a second capacitor
Implementation Method 2
The first leg includes a first coil and a first diode that are connected in series to each other. The second leg includes a second coil and a second diode that are connected in series to each other
Implementation Method 3
The first leg includes a first coil and a first diode that are connected in series to each other. The second leg includes a second coil and a second diode that are connected in series to each other
Data Source
AI summary
A power conversion device includes a primary-side circuit, a first connection line and a second connection line, a first capacitor provided on the first connection line, a second capacitor provided on the second connection line, a secondary-side circuit. The secondary-side circuit includes a first leg and a second leg. The first leg includes a first coil and a first diode, which are connected in series to each other. The second leg includes a second coil and a second diode, which are connected in series to each other. An anode terminal of the first diode and an anode terminal of the second diode are electrically connected to a negative one of the two output ends. A cathode terminal of the first diode is electrically connected to the first coil. A cathode terminal of the second diode is electrically connected to the second coil.