Parallel Inverter Coupling Coils for Voltage Drop Reduction
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Solution Overview
Problem
Existing conversion systems are not modular and generate significant line voltage drops due to high common mode inductance between phases, making it difficult to add inverters in parallel and increasing power losses.
Innovation Solution
The system incorporates N x M second electromagnetic coupling coils, where each coil is connected to the other end of a respective first coil and wound around a distinct core, with the first and second coils generating common mode fluxes in opposite directions to cancel each other out, reducing line voltage drops without increasing inductance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If N polyphase inverters are connected in parallel with N x M first electromagnetic coupling coils wound around N x M distinct cores, then the power output is increased, but the common mode inductance increases causing significant line voltage drops
Solution Approach 1:
The patent combines the first and second coupling coils around the same magnetic core, merging their magnetic paths. This allows the common mode fluxes generated by both coils to interact and cancel each other out, reducing the common mode inductance and associated line voltage drops while maintaining the power output benefits of parallel inverter connection.
Solution Approach 2:
The patent converts the harmful common mode fluxes into a beneficial cancellation effect. By winding both coupling coils around the same core with opposite winding directions, the common mode fluxes that would normally cause voltage drops are transformed into opposing magnetic fields that neutralize each other, turning a harmful effect into a beneficial one.
2Stability of the object's composition
If N polyphase inverters are connected in parallel to improve waveform and power output, then the output voltage waveform is improved, but the system becomes non-modular making it difficult to add more inverters
Solution Approach 1:
The patent segments the coupling mechanism into modular units where each inverter is paired with a magnetic core assembly containing both its first coupling coil and the corresponding second coupling coil. This segmentation allows independent inverters to be added or removed without affecting the overall system architecture, maintaining modularity while improving waveform quality through the coupled coil configuration.
Solution Approach 2:
The magnetic core serves multiple functions: it provides magnetic coupling for both the first and second coupling coils, enables common mode flux cancellation, and maintains a compact modular structure. This multi-functionality allows the same core design to be used across all inverter units, facilitating easy system expansion while maintaining waveform quality.
3Reliability
If first coupling coils are wound around distinct cores to isolate magnetic flux, then differential mode inductance is maintained, but common mode flux cancellation cannot occur
Solution Approach 1:
The patent applies different magnetic coupling configurations to different functional requirements: the first coupling coils are wound around the same core to provide common mode flux cancellation, while the second coupling coils are wound around distinct cores to maintain differential mode inductance. This local differentiation of magnetic path configurations allows both objectives to be achieved simultaneously in different parts of the system.
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 configuration reduces common mode line voltage drops and maintains high differential mode inductance, allowing for modular expansion and efficient power conversion with reduced power losses.
Implementation Method 1
N x M first electromagnetic coupling coils, each being connected by one of its ends to a respective terminal of the M intermediate terminals of one of the N polyphase inverters; N x M magnetic cores, each first electromagnetic coil being wound around a respective core
Implementation Method 2
arranged in such a way that, for each magnetic core, the common mode flux generated by the first coil is in the opposite direction to the flux of common mode generated by the second coil
Implementation Method 3
each first coupling coil and a second coupling coil being wound around the same magnetic core, the first and second coils of the same core corresponding to the same phase of each intermediate alternating current
Data Source
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Figure 3~5
AI summary
This system for converting at least one direct current input into an alternating current output having M phases and delivered to M output terminals (U, V, W) comprises N polyphase inverters (2A, 2B, 2C), connected in parallel, each converting the direct current input into an intermediate alternating current having M phases and delivered to M intermediate terminals (U1 to U3, V1 to V3, W1 to W3); N x M first electromagnetic coupling coils (8), each being connected to a respective intermediate terminal; N x M magnetic cores (10), each first coil (8) being wound around a respective core (10). This system comprises N x M second electromagnetic coupling coils (14), each being connected to a respective first coil (8) and wound around a core (10) distinct from that of the respective first coil (8).The first and second coils (8, 14) of the same core (10) correspond to the same phase and generate opposite common-mode fluxes. Each output terminal (U, V, W) is connected to the second M coils (14) of the same phase.