Balanced-Current Circuit for Bifilar Winding Coil Wireless Power Transfer
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Solution Overview
Problem
In wireless power transfer systems with multiple-winding coils, unbalanced currents in each winding prevent the full utilization of improved current-carrying capacity due to practical differences in coil parameters.
Innovation Solution
A balanced-current circuit structure for bifilar winding coils, incorporating a compensation capacitor array and controlled voltage sources, where the capacitance of each compensation capacitor is determined by specific formulas based on self-inductance and mutual inductance to achieve current balance between the two windings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a multiple-winding scheme is adopted to improve current-carrying capacity, then the current-carrying capacity of the coil is improved, but unbalanced current in each winding occurs due to practical winding differences
Solution Approach 1:
The patent divides the compensation system into separate segments for each winding. Instead of using a single centralized compensation capacitor for the entire multiple-winding coil, the invention applies individual compensation capacitors (C1, C2, ..., Cn) to each winding respectively. This segmentation allows independent adjustment of compensation parameters for each winding, thereby addressing the current imbalance caused by manufacturing variations in coil parameters.
Solution Approach 2:
The patent applies local quality by allowing each winding to have its own specific compensation capacitor value tailored to its individual characteristics. The compensation capacitor for each winding is calculated based on its specific self-inductance and mutual inductance parameters, ensuring that each winding receives customized compensation rather than a uniform approach. This local optimization enables current balance across all windings despite manufacturing variations.
2Device complexity
If centralized series compensation is used, then the circuit structure is simple, but current imbalance between windings cannot be eliminated
Solution Approach 1:
The patent transitions from a centralized series compensation structure to a segmented independent compensation structure. Each winding is equipped with its own compensation capacitor connected in series, allowing independent current control for each winding. This segmentation resolves the current balance issue while maintaining reasonable circuit complexity through modular design.
Solution Approach 2:
The patent employs parameter changes by calculating and setting different compensation capacitor values for each winding based on their specific electrical parameters (self-inductance L and mutual inductance M). The compensation capacitor value for each winding is determined by the formula C = 1/(ω²(L±M)), where the parameters are adjusted individually to achieve current balance across all windings.
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 solution ensures approximately equal currents in both windings, eliminating the current imbalance issue and maximizing the current-carrying capacity of bifilar winding coils, thereby enhancing their practical application in wireless power transfer.
Implementation Method 1
configuring compensation capacitors in a compensation capacitor array to the two coils in the bifilar winding coil respectively
Implementation Method 2
measuring self-inductance of a first coil and a second coil respectively, wherein L1 and L2 represent the self-inductance of the first coil and the second coil respectively
Implementation Method 3
measuring mutual inductance between the two coils in the bifilar winding coil, wherein M12 represents the mutual inductance between the first coil and the second coil
Data Source
AI summary
The disclosure provides a balanced-current circuit structure and a parameter design method for a bifilar winding coil of wireless power transfer. The disclosure relates to the technical field of magnetic coupling wireless power transfer. The circuit includes a bifilar winding coil, a compensation capacitor array and a controlled voltage source array. The bifilar winding coil includes a first coil and a second coil, the compensation capacitor array includes a first compensation capacitor and a second compensation capacitor, and the controlled voltage source array includes a first controlled voltage source and a second controlled voltage source. Compared with the existing centralized series compensation scheme, the scheme proposed by the disclosure can realize the currents in two windings of the bifilar winding coil being basically the same, so as to eliminate the current imbalance problem existing in the traditional compensation mode, thereby fully exerting the current-carrying capacity of the bifilar winding coil, and improving the practicability of the bifilar winding coil in practical applications.