Asymmetric Half-Bridge Converter With Uneven Tapped Windings
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Solution Overview
Problem
Existing isolated DC-DC converters with uneven tapped windings suffer from inefficiencies due to peak current increases and operate in discontinuous current mode during light loads, leading to poor load regulation.
Innovation Solution
Implementing a DC-DC converter with uneven tapped windings and a half- or full-bridge arrangement, where the secondary windings have different numbers of turns, and using a voltage divider to set the duty cycle based on the winding turns ratio, thereby reducing peak current and improving load regulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the duty cycle is adjusted to set output voltage or reduce negative current flow, then the voltage across diodes becomes different, but the peak current of inductor increases causing extra losses and decreased efficiency
Solution Approach 1:
The patent applies asymmetry by using unequal tapped windings on the transformer secondary side, where the first and second windings have different numbers of turns (N1 ≠ N2). This asymmetric configuration allows the duty cycle to be set according to the specific formula D = (N1 ± N2) / (2 × Np) while maintaining equal voltage across both diodes during operation, thereby reducing peak current and minimizing energy losses without compromising output voltage control capability
2Reliability
If the rectifying circuit includes a two-diode center-tapped full-wave rectifier, then the converter is more likely to operate in discontinuous current mode during light loads, but this causes poor load regulation
Solution Approach 1:
The patent changes the operational parameters by implementing unequal tapped windings with specific turn ratios that maintain continuous current mode even during light load conditions. The duty cycle control formula D = (N1 ± N2) / (2 × Np) ensures that the converter operates in continuous conduction mode (CCM) rather than discontinuous current mode (DCM), thereby achieving both reliable load regulation and efficient operation across the full load range
3Loss of energy
If the duty cycle is adjusted to reduce negative current flow, then voltage balance is affected, but unequal voltages across diodes increase peak current and reduce efficiency
Solution Approach 1:
The patent implements self-service through the inherent symmetry of the unequal tapped winding configuration combined with the specific duty cycle formula. The circuit automatically maintains equal voltage across both diodes during operation without requiring external voltage balance control mechanisms. The asymmetric winding ratios (N1, N2) together with the duty cycle D = (N1 ± N2) / (2 × Np) create a self-balancing system that reduces peak current and minimizes energy losses while maintaining simplicity
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
The solution reduces peak current losses and maintains efficient operation across varying loads, ensuring improved efficiency and load regulation by avoiding discontinuous current mode.
Implementation Method 1
The first inductor 208 and the second inductor 254 define a transformer. The first inductor 208 and the second inductor 254 are coupled via a magnetic core.
Implementation Method 2
The rectifying circuit 256 is a two-diode, center-tapped, full-wave rectifier that includes a first diode 262, a second diode 264
Data Source
AI summary
A DC-DC converter includes input and output voltage terminals; a transformer including a primary winding, a first secondary winding, and a second secondary winding, the first and the second secondary windings having a different number of turns; a primary circuit connected between the input voltage terminals and the primary winding and including an integrated circuit (IC) including power switches, a switch-output terminal, and a feedback terminal; and a voltage divider connected between the switch-output terminal and the feedback terminal such that a duty cycle of the power switches is set by equation (1):Duty Cycle=S1 turnsS1 turns+S2 turns(1)where S1 turns is a number of turns in the first secondary winding and S2 turns is a number of turns in the second secondary winding; and a secondary circuit connected to the first and the second secondary windings and including a rectifier and the output voltage terminals.