Switching Power Supply Auxiliary Coil Voltage Selection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional switching power supplies face issues with output voltage switching affecting the supply voltage for the control circuit, leading to reduced margins for overvoltage protection and undervoltage-lockout thresholds, and increased component complexity when trying to maintain a constant supply voltage.
Innovation Solution
A switching power supply design with a center-tapped auxiliary coil generating multiple supply voltages, allowing a supply voltage switching circuit to select between them based on output voltage states, ensuring the control circuit operates within stable voltage ranges while maintaining overvoltage and undervoltage protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the output voltage is switched according to load state to reduce power consumption, then power consumption decreases, but the supply voltage for the control circuit changes, reducing the margin for overvoltage protection and undervoltage-lockout thresholds
Solution Approach 1:
The auxiliary coil is divided into two separate winding sections: a first auxiliary coil winding and a second auxiliary coil winding. Each winding generates a different supply voltage level when rectified and smoothed. This segmentation allows the system to provide multiple discrete supply voltage options (higher supply voltage and lower supply voltage) to the control circuit, enabling selection of appropriate voltage levels for different operating conditions while maintaining adequate margins for protection thresholds.
2Stability of the object's composition
If a constant-voltage circuit is added to maintain constant supply voltage, then supply voltage stability improves, but device complexity increases
Solution Approach 1:
The system dynamically switches between different supply voltage sources based on the output voltage state. When the output voltage is in a first state, the control circuit receives the higher supply voltage from the first auxiliary coil winding; when the output voltage is in a second state, the control circuit receives the lower supply voltage from the second auxiliary coil winding. This dynamic switching approach maintains supply voltage stability within acceptable ranges for each operating mode without requiring complex constant-voltage regulation circuits.
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 design keeps the supply voltage for the control circuit constant, maintaining sufficient margins and stability, reducing component complexity, and ensuring stable operation with overvoltage and undervoltage protection features, even during output voltage switching.
Implementation Method 1
a supply voltage generation circuit that rectifies and smoothes voltages induced in an auxiliary coil provided in the transformer to generate a plurality of supply voltages
Implementation Method 2
an output circuit that rectifies and smoothes a voltage induced in a secondary coil of the transformer to obtain an output voltage
Data Source
AI summary
A switching power supply includes a switching element that turns ON and OFF a current flowing through a primary coil of a transformer to which a DC input voltage is applied, an output circuit that rectifies and smooths a voltage induced in a secondary coil of the transformer T to generate a prescribed output voltage, and a control circuit that uses feedback control to turn the switching element ON and OFF according to a feedback voltage obtained from the detected output voltage. The switching power supply also includes a supply voltage generation circuit that rectifies and smoothes a voltage induced in an auxiliary coil of the transformer to generate a plurality of supply voltages, an output voltage switching circuit that switches the output voltage according to a magnitude of a load to which the output voltage is supplied, and a supply voltage switching circuit that selects one of the supply voltages according to changes to the output voltage and supplies that supply voltage to the control circuit.