Secondary Controller for Power Converter Voltage Detection
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Solution Overview
Problem
Existing power converter control methods, whether using a primary or secondary controller, face limitations in accurately controlling the turning-on and turning-off of power converters, especially when operating in discontinuous conduction mode (DCM) or continuous conduction mode (CCM), due to indirect detection methods and structural constraints imposed by necessary components like synchronous rectification switches.
Innovation Solution
A secondary controller with a control signal generation circuit that utilizes a secondary-side auxiliary winding to generate a turning-on signal, which is coupled to the primary-side auxiliary winding, allowing the primary controller to turn on the power converter based on voltage changes, thereby bypassing the need for a feedback path through a photo coupler and synchronous rectification switch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a primary controller utilizes an auxiliary winding to indirectly detect output voltage changes, then the control structure is simpler, but the control accuracy deteriorates
Solution Approach 1:
The patent introduces a secondary controller as an intermediary component that directly detects output voltage changes on the secondary side. This secondary controller then transmits control signals back to the primary controller through a feedback path, allowing indirect detection while maintaining high measurement precision. The intermediary resolves the contradiction by separating the detection function (performed directly on secondary side) from the control execution (performed on primary side).
2Measurement precision
If a secondary controller directly detects output voltage changes and controls turning-on/off, then the control accuracy improves, but the power converter is limited to discontinuous conduction mode only
Solution Approach 1:
The patent implements dynamic adaptability by enabling the power converter to operate in multiple conduction modes (discontinuous conduction mode and continuous conduction mode) through the secondary controller's flexible control strategy. The controller dynamically adjusts its operation based on real-time voltage detection, allowing seamless transition between different conduction modes while maintaining high control accuracy through direct voltage change detection.
3Measurement precision
If the secondary controller uses a feedback path with photo coupler and synchronous rectification switch, then the control accuracy improves, but the device complexity and cost increase
Solution Approach 1:
The patent enhances the functionality of existing components to serve multiple purposes. The synchronous rectification switch not only performs rectification but also serves as part of the feedback path for voltage detection. The auxiliary winding on the primary side is utilized to transmit control signals from the secondary side, eliminating the need for separate dedicated feedback components. This multi-functionality reduces device complexity and cost while maintaining control accuracy.
4Measurement precision
If the synchronous rectification switch is made necessary for the feedback path, then the control accuracy improves, but the structural flexibility deteriorates
Solution Approach 1:
The patent inverts the traditional approach by making the auxiliary winding on the primary side serve the feedback function rather than relying solely on the synchronous rectification switch for feedback. The control signal flows from the secondary controller through the auxiliary winding back to the primary side, reversing the conventional feedback direction. This inversion provides structural flexibility while maintaining control accuracy, as the auxiliary winding is already present and can be utilized for signal transmission without adding necessary constraints.
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 enables more accurate and cost-effective control of power converters, allowing them to operate in both DCM and CCM with quicker dynamic responses to output voltage changes, reducing structural limitations and operational costs.
Implementation Method 1
The turning-on signal is coupled to a primary-side auxiliary winding of the power converter through a secondary-side auxiliary winding of the power converter to make the primary-side auxiliary winding generate a voltage
Data Source
AI summary
A secondary controller applied to a secondary side of a power converter includes a control signal generation circuit. The control signal generation circuit is coupled to an output terminal of the secondary side of the power converter for detecting an output voltage of the secondary side and enabling a pulse signal to a signal source of the secondary side of the power converter, wherein the signal source enables a turning-on signal according to the pulse signal. The turning-on signal is coupled to a primary-side auxiliary winding of the power converter through a secondary-side auxiliary winding of the power converter to make the primary-side auxiliary winding generate a voltage, and a primary controller of a primary side of the power converter makes the primary side of the power converter be turned on according to the voltage.