Switching Power Supply Controller Using Auxiliary Winding Feedback
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Solution Overview
Problem
Existing power supply controller systems face challenges in accurately regulating output voltage and limiting secondary current, often requiring costly optical couplers and auxiliary windings with limited accuracy and current control capabilities.
Innovation Solution
A power supply system that utilizes an auxiliary winding to generate a pseudo current sense signal, allowing for accurate regulation of output voltage without direct connection to the secondary winding, using a switching power supply controller with a current sense resistor and capacitor to form a de-magnetization signal, which is then used to control the switching of a power switch and limit secondary current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an optical coupler is used to sense output voltage and form a feedback signal, then the output voltage regulation is achieved, but the system cost increases
Solution Approach 1:
The patent extracts the feedback sensing function from the secondary side to the primary side by utilizing the auxiliary winding. The controller senses the output voltage indirectly through the auxiliary winding on the primary side, eliminating the need for optical couplers and direct secondary side sensing components, thereby reducing system cost while maintaining regulation accuracy
Solution Approach 2:
The auxiliary winding acts as an intermediary that transfers information about the output voltage from the secondary side to the primary side controller. Instead of directly measuring the output voltage on the secondary side, the controller uses the induced voltage on the auxiliary winding as a mediator to regulate the output, avoiding the need for expensive optical couplers
2Device complexity
If an auxiliary winding is used to control the power supply controller, then the system cost is reduced, but the output voltage regulation accuracy deteriorates to less than ten percent
Solution Approach 1:
The patent implements a feedback mechanism where the controller continuously monitors the voltage on the auxiliary winding and adjusts the duty cycle of the power switch accordingly. This closed-loop feedback ensures that the output voltage is regulated with high accuracy (within five percent) despite using the auxiliary winding for sensing, overcoming the limitation of prior art that achieved less than ten percent accuracy
Solution Approach 2:
The patent changes the operating parameters by sampling the auxiliary winding voltage at specific timing points (when secondary current is zero) and uses these sampled values to dynamically adjust the duty cycle. This parameter-based control approach enables precise regulation accuracy while maintaining the cost benefits of using an auxiliary winding
3Device complexity
If direct connection to the secondary winding is not made, then the system complexity is reduced, but the ability to limit secondary current is lost
Solution Approach 1:
The auxiliary winding serves as an intermediary that provides indirect information about secondary current conditions to the primary side controller. By monitoring the voltage and timing signals from the auxiliary winding, the controller can infer secondary current status and implement current limiting without direct electrical connection to the secondary winding, thus maintaining both low complexity and high reliability
Solution Approach 2:
The patent replaces direct electrical connection (mechanical/electrical contact) with electromagnetic coupling through the auxiliary winding. The controller uses the induced signals on the auxiliary winding to detect and limit secondary current, substituting a non-contact electromagnetic sensing mechanism for direct electrical connection, thereby reducing complexity while preserving current limiting capability
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 approach reduces system costs, improves voltage regulation accuracy, and effectively limits secondary current, achieving precise control of output voltage within a desired range while eliminating the need for optical couplers.
Implementation Method 1
the transformer included an auxiliary winding into which a voltage was induced from the primary side of the transformer
Data Source
AI summary
In one embodiment, a switching controller uses an auxiliary winding voltage of a transformer to form a signal representative of current flow through a secondary winding of the transformer. The controller is configured to limit a current through a secondary winding to a maximum value.