Transformer Windings Coupling for Power Supply Cross-Regulation
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Solution Overview
Problem
In multiple-output switching power supply devices, cross-regulation issues arise where changes in load on one output affect the stability of another output, leading to voltage regulation deterioration, especially when feedback control is not applied to all outputs, resulting in unstable voltage levels.
Innovation Solution
The implementation of a power supply circuit with a transformer having multiple output windings coupled together, where center taps and cross capacitors are used to balance voltage across outputs, allowing for improved cross-regulation by equalizing the number of turns between windings and connecting them via capacitors to stabilize voltage levels without significant changes to the circuit configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If feedback control is applied to only one output terminal in a multiple-output power supply, then the controlled output voltage is stabilized, but the uncontrolled output terminals exhibit poor voltage regulation and instability
Solution Approach 1:
The patent introduces a dummy load as an intermediary component connected to the uncontrolled output terminal. This dummy load acts as a mediator that absorbs excess energy and provides a minimum load condition, preventing voltage instability without requiring feedback control circuitry on every output terminal. The dummy load enables the uncontrolled terminal to maintain stable voltage by providing a controlled energy dissipation path.
Solution Approach 2:
The patent changes the electrical parameter (load impedance) of the uncontrolled output terminal by connecting a dummy load. This parameter change ensures that the output terminal operates within its stable voltage region even without active feedback control, transforming the terminal's electrical characteristics to achieve better voltage regulation performance.
2Reliability
If a dummy resistor is added to increase load on uncontrolled output terminals, then voltage regulation is improved, but power conversion efficiency deteriorates
Solution Approach 1:
The patent applies partial action by using a dummy load that provides only the minimum necessary load current required for stable operation, rather than a full load. This partial loading approach improves voltage regulation just enough to eliminate instability while minimizing the energy wasted in the dummy load, thus reducing the impact on overall power conversion efficiency compared to heavier dummy loads.
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 effectively stabilizes output voltages across multiple outputs, reducing voltage variations and improving cross-regulation by balancing energy transfer between windings, thereby maintaining stable voltage levels even without feedback control on all terminals.
Implementation Method 1
A capacitor is connected between center taps of a first output winding and a second output winding
Implementation Method 2
a transformer that has a plurality of output windings, the plurality of output windings including first and second output windings that are coupled to each other
Data Source
AI summary
A power supply circuit includes a plurality of output terminals that output voltages (voltages may have the same or different voltage values among the output terminals), and a transformer that has a plurality of output windings. First and second output windings of the plurality of output windings are coupled to each other. The first and second output windings have the same number of turns. First terminals, which have a first polarity, of the first and second output windings are connected to each other via a capacitor. Further, second terminals, which have a second polarity opposite to the first polarity, of the first and second output windings are electrically connected to each other. The second terminals of the first and second output windings may be directly connected to each other.