Asymmetric Half-Bridge Flyback Demagnetization Without Adjustable Capacitors
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Solution Overview
Problem
Conventional asymmetric half bridge flyback converters face challenges in efficiently demagnetizing the transformer at low output voltages, leading to increased demagnetization time and associated losses due to high currents, which requires adjustable capacitors and complex control mechanisms.
Innovation Solution
The implementation of a controller-configured asymmetric half bridge flyback converter with a low-side switching device capable of blocking current flow in both directions, utilizing wide bandgap materials or bidirectional switches to prevent reverse current flow, allowing for efficient discharge of magnetizing energy to the secondary side during the demagnetization phase, thereby eliminating the need for adjustable capacitors and reducing losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the resonant capacitor is varied depending on output voltage to avoid losses due to high currents at low output voltages, then energy efficiency is improved, but device complexity increases due to requiring adjustable capacitors and corresponding control mechanisms
Solution Approach 1:
The low-side switching device automatically blocks reverse current flow during demagnetization phase, enabling the converter to self-regulate demagnetization behavior without external control mechanisms or adjustable capacitors. The device serves its own demagnetization needs through inherent bidirectional blocking capability.
Solution Approach 2:
The patent changes the electrical parameter of the low-side switching device from unidirectional to bidirectional current blocking capability. This parameter change enables the device to actively control current flow direction, allowing efficient demagnetization across varying output voltages without requiring variable capacitors.
2Device complexity
If conventional demagnetization is used at low output voltages, then device simplicity is maintained, but demagnetization time increases and energy losses occur due to high currents
Solution Approach 1:
The low-side switching device automatically blocks reverse current flow during demagnetization phase, enabling the converter to self-regulate demagnetization behavior without external control mechanisms or adjustable capacitors. The device serves its own demagnetization needs through inherent bidirectional blocking capability.
Solution Approach 2:
The patent changes the electrical parameter of the low-side switching device from unidirectional to bidirectional current blocking capability. This parameter change enables the device to actively control current flow direction, allowing efficient demagnetization across varying output voltages without requiring variable capacitors.
3Device complexity
If conventional demagnetization is used at low output voltages, then device simplicity is maintained, but energy losses increase due to high currents during extended demagnetization
Solution Approach 1:
The low-side switching device automatically blocks reverse current flow during demagnetization phase, enabling the converter to self-regulate demagnetization behavior without external control mechanisms or adjustable capacitors. The device serves its own demagnetization needs through inherent bidirectional blocking capability.
Solution Approach 2:
The patent changes the electrical parameter of the low-side switching device from unidirectional to bidirectional current blocking capability. This parameter change enables the device to actively control current flow direction, allowing efficient demagnetization across varying output voltages without requiring variable capacitors.
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 ensures efficient energy transfer to the secondary side, reducing demagnetization time and losses across a range of output voltages without requiring adjustable capacitors, enhancing the converter's efficiency and simplicity.
Implementation Method 1
energy is transferred from an input voltage source to the resonant tank. Then, in a second phase when the switching device parallel to the resonant tank is switched on and the other switching device of the half bridge is switched on, energy is transferred to a secondary side of the transformer
Implementation Method 2
the resonant tank including at least stray inductances of the transformer, in particular of a primary side winding thereof, and a resonant capacitor
Data Source
Figure 1
Figure 2~3A
Figure 3B~3D
AI summary
An asymmetric half bridge flyback converter, comprising a first primary side switching device and a second primary side switching device coupled in series between a supply voltage and a reference potential, a transformer, wherein one end of a primary side winding of the transformer is coupled to a node between the first primary side switching device and the second primary side switching device, a capacitor, wherein a resonant circuit including at least the primary side winding and the capacitor is coupled in parallel to the second primary side switching device, and a controller controlling the switches devices. The second primary side switching device is configured to prevent or reduce current flow in both directions when switched off.