Insulation Power Supply Feedback via Opposite Polarity Windings
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Solution Overview
Problem
Conventional insulation type switching power supply apparatuses face issues such as increased cost, board area, and reliability concerns due to the use of auxiliary windings and photo-couplers, and require complex circuits like error amplifiers and sample/hold circuits.
Innovation Solution
An insulation type switching power supply apparatus that performs feedback control without an auxiliary winding or photo-coupler, utilizing a transformer with opposite polarity windings, a rectifying-smoothing portion, feedback voltage generation, reference voltage generation, a main comparator, and a switching control portion employing on-time control methods to manage output voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an auxiliary winding and photo-coupler are used for feedback control, then output voltage feedback control is achieved, but device complexity, board area, and cost increase
Solution Approach 1:
The patent extracts and eliminates the auxiliary winding and photo-coupler from the feedback control system. Instead, it uses the main transformer windings and a voltage divider circuit to generate feedback voltage, thereby simplifying the device structure while maintaining feedback control functionality
Solution Approach 2:
The patent makes the main transformer windings serve dual purposes: power transmission and feedback voltage generation. The feedback voltage is obtained by tapping into the main secondary winding through a voltage divider, eliminating the need for separate auxiliary windings and photo-couplers
2Reliability
If conventional feedback circuits (error amplifier, sample/hold circuit) are used, then output voltage control is achieved, but device complexity and board area increase
Solution Approach 1:
The patent removes error amplifiers, sample/hold circuits, and other complex control components from the feedback system. The control is achieved directly through the main comparator by comparing feedback voltage with a reference voltage, eliminating the need for additional control circuits and reducing board area
Solution Approach 2:
The patent changes the control approach from complex analog signal processing to direct voltage comparison. By using the main comparator to compare feedback voltage with reference voltage and generating PWM control signals, the system achieves precise output voltage control with simpler circuitry
3Reliability
If auxiliary winding and photo-coupler are used, then insulation feedback is achieved, but cost and board area increase
Solution Approach 1:
The patent makes the main transformer windings serve dual purposes: power transmission and feedback voltage generation. The feedback voltage is obtained by tapping into the main secondary winding through a voltage divider circuit, eliminating the need for separate auxiliary windings and photo-couplers, thereby reducing component count and manufacturing cost
Solution Approach 2:
The patent creates an electrical copy of the output voltage through the feedback voltage generation circuit. By using resistors to divide the output voltage and generate a scaled-down feedback voltage, the system achieves insulation feedback without requiring expensive photo-couplers or auxiliary windings
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 solution reduces component count, costs, and board area, enhances reliability, and eliminates the need for error amplifiers and sample/hold circuits, achieving efficient and stable feedback control with reduced power consumption.
Implementation Method 1
a transformer that includes a primary winding and a secondary winding that are electromagnetically connected to each other with polarities opposite to each other
Implementation Method 2
a rectifying-smoothing portion that generates an output voltage by rectifying and smoothing an induced voltage
Data Source
AI summary
A power supply apparatus comprises: a transformer that includes primary/secondary windings that are electromagnetically connected to each other with polarities opposite to each other, an output switch that activates/inactivates an electric-current route that extends from an application terminal for an input voltage to a ground terminal via the primary winding a rectifying-smoothing portion that generates an output voltage from an induced voltage, a feedback voltage generation portion that monitors a switch voltage appearing at a connection node between the primary winding and the output switch and generates a feedback voltage in accordance with the output voltage, a reference voltage generation portion that generates a reference voltage, a comparator that compares the feedback voltage and the reference voltage with each other to generate a comparison signal, and a switching control portion that generates an output switch control signal by means of an on-time control method in accordance with the comparison signal.