Parallel DC/DC Converter Bridges Using Split Resonant Impedance
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Solution Overview
Problem
In high-current applications, achieving homogeneous distribution of losses among parallel semiconductor switches is challenging due to parasitics, inhomogeneous temperatures, and semiconductor properties, especially at fast switching speeds, making it difficult to efficiently handle large currents in DC/DC converters used in distributed energy systems.
Innovation Solution
A DC/DC converter design with a plurality of converter bridges connected in parallel, each connected to a transformer via different impedance elements, optimizing current distribution through split resonant capacitors or inductors, which act as partial resonant components, independent of power module parasitics and semiconductor characteristics, preventing circulating currents and allowing for efficient operation with off-the-shelf semiconductor switches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a large number of semiconductor switches are connected in parallel to handle large currents, then the current handling capability is improved, but the homogeneous distribution of losses becomes difficult to achieve due to parasitics, inhomogeneous temperatures, and semiconductor properties
Solution Approach 1:
The patent introduces an intermediary current balancing circuit that acts as a mediator between the parallel semiconductor switches. This circuit measures the current through each switch and adjusts the gate driving signals to compensate for current imbalances caused by parasitics and temperature variations, thereby achieving homogeneous loss distribution while maintaining high current handling capability
Solution Approach 2:
The patent implements a feedback mechanism where the actual current through each semiconductor switch is measured and fed back to the control system. The control system then adjusts the switching signals to balance the current distribution, creating a closed-loop system that continuously maintains homogeneous loss distribution despite variations in parasitics and temperature
2Loss of energy
If pre-selection and dedicated gate driver technology are used to balance currents, then the current distribution homogeneity is improved, but the device complexity and manufacturing effort increase
Solution Approach 1:
The patent enables the parallel semiconductor switch system to self-balance its current distribution through an automated control mechanism. The system independently measures its own current imbalances and adjusts its gate driving signals accordingly, eliminating the need for complex external pre-selection processes and dedicated balancing hardware, thus reducing device complexity while maintaining current homogeneity
3Power
If the number of semiconductor chips is increased to handle larger currents, then the power handling capacity is improved, but the current balancing becomes increasingly difficult
Solution Approach 1:
The patent introduces a centralized current balancing circuit that acts as an intermediary between all parallel semiconductor chips. This circuit systematically monitors and adjusts the current through each chip regardless of the total number of chips, making the balancing process scalable and maintaining ease of operation even as power handling capacity increases with additional chips
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 design ensures stable and homogeneous current distribution without additional balancing efforts, reduces losses, and enables efficient operation with wide bandgap semiconductor switches at high currents, increasing the maximum power handling capacity of medium frequency transformers while simplifying the realization of resonant and dual active bridge converters.
Implementation Method 1
A DC/DC converter design with a plurality of converter bridges connected in parallel, each connected to a transformer via different impedance elements, optimizing current distribution through split resonant capacitors or inductors, which act as partial resonant components
Data Source
AI summary
A DC/DC converter which includes a first DC link, the first DC link can be a first DC link capacitor; a first plurality of N>1 converter bridges connected in parallel to the first DC link; and a transformer, the transformer can be a medium frequency transformer. The transformer includes a primary side and a secondary side, the primary side including at least one primary winding. The converter further includes a first plurality of N impedance elements, for each converter bridge, a respective impedance element of the first plurality of impedance elements is connected between the converter bridge and the at least one primary winding.