Cascaded Flyback SMPS with Segmented Primary Windings
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Solution Overview
Problem
Switched-mode power supply (SMPS) converters, particularly fly-back converters, face challenges in maintaining efficiency over a wide range of input voltages, reducing ripple in output voltage, and minimizing electromagnetic interference (EMI), while also requiring complex control circuits and high-power dissipation.
Innovation Solution
The implementation of a cascaded fly-back SMPS converter with multiple primary windings sharing a common core, where each primary stage includes a winding connected in series with a switch and a capacitor, allowing for energy recovery from leakage inductance and equalization of voltages across stages, reducing the need for complex control circuits and using low-voltage switching components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a typical fly-back converter with a single primary winding is used, then the design is simple, but efficiency cannot be maintained over a wide range of input voltages and ripple in output voltage cannot be reduced
Solution Approach 1:
The primary winding is divided into multiple segments (first primary winding, second primary winding, etc.) that are connected in series. Each segment can be independently controlled by its own switch, allowing the converter to maintain efficiency across a wide range of input voltages by selectively activating appropriate segments based on the input voltage level.
Solution Approach 2:
The converter dynamically selects which primary winding segments to activate based on the input voltage level. The control circuit adjusts the operating state of each switch independently, enabling the system to adapt to varying input conditions and maintain optimal efficiency across different voltage ranges.
2Ease of manufacture
If a typical fly-back converter with a single primary winding is used, then the design is simple, but ripple in output voltage cannot be reduced
Solution Approach 1:
The primary winding is segmented into multiple independent sections, each with its own switch. This segmentation allows for finer control over the energy transfer process, enabling the control circuit to regulate output voltage more precisely and reduce ripple by adjusting the duty cycle of individual segments.
Solution Approach 2:
The control circuit changes the operating parameters (duty cycle, switching frequency) of each primary winding segment independently to maintain stable output voltage. By adjusting these parameters based on feedback, the system can reduce output voltage ripple while maintaining design simplicity.
3Device complexity
If a typical fly-back converter is used, then design simplicity is maintained, but electromagnetic interference cannot be minimized
Solution Approach 1:
Dividing the primary winding into multiple segments with independent switches allows for distributed switching operations. This segmentation reduces the peak current stress on individual switches and distributes the electromagnetic interference across multiple switching events, thereby minimizing overall EMI while maintaining design simplicity.
4Loss of energy
If complex control circuits are used to maintain efficiency over wide voltage range, then efficiency is improved, but device complexity increases
Solution Approach 1:
The control circuit complexity is managed by segmenting the primary winding into independent sections, each controlled by a simple switch. This modular approach allows the control circuit to maintain efficiency across wide voltage ranges through straightforward selective activation of segments, avoiding the need for overly complex control mechanisms.
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 enhances efficiency, reduces EMI, and allows for the use of smaller, lower-cost components, achieving high power handling capability and efficient AC-DC power conversion in a single stage with improved power factor and reduced ripple.
Implementation Method 1
In a typical fly-back converter, energy is stored in the primary side of the transformer when a switch in series with the primary side of the transformer is closed. When the switch is opened, the energy is transferred to the secondary side
Data Source
AI summary
In accordance with an embodiment, a switched-mode power supply (SMPS) includes a transformer having a plurality of windings sharing a common core and a plurality of primary stages coupled in series. Each of the plurality of primary stages include a winding of the plurality of windings, a switch having a first node coupled to a first terminal of the winding, and a first capacitor coupled between a second terminal of the winding and a second node of the switch.