Bidirectional Resonant Tank Circuit With Equal Forward and Reverse Gain
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Solution Overview
Problem
Existing bidirectional DC-DC converters with symmetrical resonant tank circuits face challenges in achieving equal gains in both forward and reverse modes due to structural asymmetry, particularly when space and cost constraints limit the inclusion of inductance on the secondary side of the transformer.
Innovation Solution
The primary circuit includes a primary inductance and capacitance in series, with a winding ratio of N = Lm + (L1^2)/Lm, and the secondary circuit has no inductance, with a capacitance of C2 = C1/N^2, ensuring equal forward and reverse gains at the resonant frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a symmetrical resonant tank circuit is used with inductance on both primary and secondary sides, then the forward and reverse gains are similar, but the number of components increases and space requirements increase
Solution Approach 1:
The patent applies asymmetry by removing the secondary inductance component while adjusting the transformer winding ratio to compensate. The primary circuit retains inductance L1 and capacitance C1, while the secondary circuit has only capacitance C2. The transformer winding ratio N is specifically designed to achieve equal forward and reverse gains despite this asymmetric configuration, thus simplifying the overall device while maintaining operational symmetry.
Solution Approach 2:
The patent changes the transformer winding ratio parameter to compensate for the removed secondary inductance. By optimizing the winding ratio N, the circuit achieves equal forward and reverse gains at the resonant frequency without requiring symmetric inductance components on both sides. This parameter adjustment allows the circuit to maintain bidirectional control simplicity with fewer components.
2Device complexity
If the secondary inductance is removed to reduce component count, then the circuit becomes asymmetric, but the forward and reverse gains can still be equalized through transformer ratio adjustment
Solution Approach 1:
The patent deliberately creates an asymmetric circuit configuration by removing the secondary inductance while using transformer winding ratio adjustment to achieve symmetric operational characteristics. The primary side has inductance L1 and capacitance C1, while the secondary side has only capacitance C2, yet the forward gain equals the reverse gain at resonance through proper winding ratio selection.
Solution Approach 2:
The transformer winding ratio N is adjusted as a compensating parameter to maintain equal forward and reverse gains despite the asymmetric component configuration. This parameter change allows the circuit to achieve control symmetry in operation while having structural asymmetry in components.
3Ease of operation
If the winding ratio is adjusted to achieve equal forward and reverse gains, then the gain symmetry is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The patent uses the transformer winding ratio as a tunable parameter to achieve equal forward and reverse gains. By adjusting this parameter, the circuit compensates for component tolerances and achieves gain symmetry. The winding ratio serves as a calibration parameter that can be optimized during manufacturing to account for variations in other components.
Solution Approach 2:
The patent implies a feedback mechanism where the transformer winding ratio is adjusted based on the measured forward and reverse gains to achieve equality. This feedback approach allows manufacturing tolerances in individual components to be compensated through winding ratio optimization, reducing the overall precision requirements for each component.
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 results in a nearly symmetrical resonant tank circuit with equal forward and reverse gains, simplifying control and improving operational efficiency by minimizing power losses and thermal issues.
Implementation Method 1
a transformer comprising primary and secondary windings magnetically coupled
Implementation Method 2
the transformer and the primary and secondary circuits have, at a resonant frequency, a forward gain, respectively a reverse gain, essentially independent of the primary load, respectively the secondary load
Data Source
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AI summary
The resonant tank circuit (102) comprises: a transformer (T); a primary circuit (M1); and a secondary circuit (M2); wherein the transformer (T) and the primary and secondary circuits (M1, M2) are designed to operate in a forward mode and in a reverse mode; and wherein the transformer (T) and the primary and secondary circuits (M1, M2) have, at a resonant frequency (FR), a forward gain (GF (FR)), respectively a reverse gain (GR (FR) ), essentially independent of the load, when operating in the forward mode, respectively the reverse mode.The primary and secondary circuits (M1, M2) are different one from another and the forward gain (GF (FR) ) and the reverse gain (GR (FR) ) at the resonant frequency (FR) are essentially equal to one another, notably to within 5%.