Coupled Inductor Output Filter for DC/DC Converter Power Sharing
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Solution Overview
Problem
Existing DC/DC switched mode power supply topologies face challenges in achieving true modularity due to inherent load imbalance issues in paralleled converters, where one module takes over current delivery due to slight voltage differences, requiring complex control algorithms and communication for even power sharing.
Innovation Solution
A coupled inductor output filter topology using a split inductor, main output capacitor, and DC blocking capacitor enables predictable and linear power sharing without inter-module communication, mimicking favorable characteristics of discontinuous conduction mode converters for all load conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional paralleled DC/DC converter modules are used, then modularity and scalability are improved, but load sharing becomes unbalanced due to voltage differences between modules
Solution Approach 1:
The patent introduces an intermediary coupled inductor connected between the output terminals of parallel converter modules. This inductor acts as a mediator that equalizes current distribution by providing a magnetic coupling path that compensates for voltage differences between modules, enabling balanced load sharing without requiring complex control algorithms or communication between modules.
Solution Approach 2:
The patent changes the electrical parameters at the output stage by introducing the coupled inductor with specific inductance values and coupling coefficients. This parameter modification transforms the output characteristics of parallel converters, creating a system where current sharing becomes inherently balanced regardless of individual module voltage variations.
2Reliability
If complex control algorithms and inter-module communication are implemented to achieve even power sharing, then load distribution is improved, but system complexity increases
Solution Approach 1:
The coupled inductor creates a self-regulating system where each converter module automatically adjusts its current contribution based on the magnetic coupling feedback. The system achieves balanced power sharing through inherent physical coupling rather than requiring external control algorithms or communication protocols, making each module self-sufficient in maintaining load balance.
Solution Approach 2:
The patent extracts the complex control and communication requirements from the system by replacing them with a passive coupled inductor. This removal of active control elements simplifies the overall system while maintaining the desired power sharing functionality through passive magnetic coupling.
3Object-affected harmful factors
If standard output filters are used in DC/DC converters, then filtering performance is achieved, but ripple current and frequency response variability increase across different load conditions
Solution Approach 1:
The coupled inductor serves multiple functions simultaneously: it acts as an output filter to reduce ripple current, provides current balancing between parallel modules, and maintains consistent frequency response across varying load conditions. This multi-functionality eliminates the need for separate components and achieves universal performance improvement.
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
Enables true modular operation of DC/DC converters with even current distribution across modules, independent of switching topology, and simplifies control loop implementation by maintaining low ripple DC current and uniform frequency response.
Implementation Method 1
coupled inductor output filter topology
Implementation Method 2
split inductor Lout1 and Lout2
Implementation Method 3
two coupled inductors, Lout1 and Lout2, having a coupling coefficient, k, greater than 0.5
Data Source
AI summary
The present invention is directed to a coupled inductor output filter to be used with DC/DC switched mode power supply topologies. This new output filter changes the inherent power sharing capability of most DC/DC converter topologies, enabling the overall converter to operate as a truly modular block with no inter-module communication required to accomplish power/current sharing on a multi-module configuration. The coupled-inductor output filter uses a split inductor, Lout1 and Lout2, a main output capacitor, Cout, and a DC blocking capacitor, CDC Block.