Resonant Bi-Directional Power Converter for High-Frequency Reliability
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Solution Overview
Problem
High power converters used in electrical traction systems face challenges such as high failure rates due to cosmic rays, thermal cycling, and high audible noise, particularly in applications like public transport, where traditional silicon-based components are inadequate for long-term reliability and efficiency.
Innovation Solution
A boost or buck power converter design featuring a primary switching arrangement with higher dynamical switching losses than a secondary arrangement, connected by a resonant unit, which improves efficiency, reliability, and reduces size and noise, while allowing for increased switching frequency and reduced electromagnetic interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If higher voltage breakdown voltage components are used to improve reliability against cosmic rays, then MTBF improves, but switching frequency must be reduced which increases system size and weight
Solution Approach 1:
The patent divides the power converter into two separate power stages: a first power stage with voltage breakdown voltage matched to the semiconductor components, and a second power stage with different voltage breakdown voltage. This segmentation allows each stage to operate at optimal voltage levels, enabling the use of lower voltage-rated (and thus lower frequency) semiconductors in the first stage while maintaining overall system reliability and reducing the need for heavy shielding or oversized components.
Solution Approach 2:
The patent changes the voltage parameter across different stages of the power converter. By configuring the first power stage with voltage breakdown voltage adapted to the semiconductor components and the second power stage with different voltage breakdown voltage, the system can operate at higher frequencies without requiring excessive voltage margins, thereby reducing component size and weight while maintaining reliability.
2Loss of energy
If higher switching frequency is used to reduce system size, then power losses decrease, but thermal cycling stress increases reducing component lifetime
Solution Approach 1:
The patent segments the power conversion function into two stages with different switching frequencies and voltage levels. The first power stage operates at a frequency adapted to the semiconductor components' voltage breakdown characteristics, while the second stage handles the remaining conversion. This allows the system to achieve high overall switching frequency for reduced losses while keeping individual component stress within acceptable limits for extended lifetime.
Solution Approach 2:
The patent implements dynamic operation where the two power stages can operate independently at optimally different frequencies. This dynamic segmentation allows the system to adjust the switching frequency of each stage based on component capabilities, achieving high efficiency without subjecting individual components to excessive thermal cycling stress.
3Productivity
If quick charge cycles are implemented for energy storage systems, then productivity improves, but thermal stress from rapid heating and cooling increases reducing system reliability
Solution Approach 1:
The patent divides the power handling into two stages, where the first power stage can operate at higher frequencies during quick charge cycles. This segmentation allows rapid energy transfer to the energy storage system while distributing thermal stress across two stages rather than one, reducing peak thermal cycling stress on individual components and maintaining reliability during high-productivity operations.
4Device complexity
If single power stage converter is used, then device complexity is low, but audible noise from magnetostriction effect increases
Solution Approach 1:
The patent segments the power conversion into two stages with different switching frequencies. The first power stage operates at a frequency that avoids the magnetostriction resonance frequency of the magnetic elements, thereby eliminating audible noise. Although this increases device complexity compared to a single stage, the segmentation enables noise cancellation by operating above the resonance frequency where magnetostriction effects are negligible.
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 design enhances the lifetime and reliability of the power converter, reduces size and audible noise, and increases switching frequency, thereby improving the overall performance and efficiency of energy storage systems in high-power applications.
Implementation Method 1
a resonant unit (150) connecting said at least one primary switching unit (131, 135) and said at least one secondary switching unit (171, 175)
Data Source
AI summary
The present invention relates to a bi-directional power converter (100) for converting an input voltage into an output voltage. The bi-directional power converter (100) may comprise a primary switching unit having a primary switching frequency and a secondary switching unit having a secondary switching frequency: the primary switching frequency being lower than the secondary switching frequency.