Load-Based Isolated Converter Switching for Saturation Control
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Solution Overview
Problem
High-frequency transformer isolated converters face magnetic saturation issues when load changes suddenly, leading to excessive unidirectional excitation changes, which conventional methods address by increasing switching frequency, resulting in significant switching losses and heat dissipation problems.
Innovation Solution
A control device that adjusts the switching frequency of the isolated converter based on load percentage thresholds, using a comparison module to determine if the load is within preset ranges, adjusting the frequency to prevent magnetic saturation and manage temperature, with the ability to increase or decrease frequency gradually through a time delay circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the switching frequency is increased to prevent magnetic saturation during sudden heavy load, then the magnetic saturation problem is solved, but the switching loss increases significantly
Solution Approach 1:
The patent applies dynamics by making the switching frequency adjustable rather than fixed. The control device dynamically changes the switching frequency based on real-time detection of transformer excitation state and load conditions. When excitation is low, frequency increases to prevent saturation; when excitation is sufficient, frequency decreases to reduce switching losses. This dynamic adaptation resolves the contradiction between reliability and energy loss.
Solution Approach 2:
The patent changes the parameter of switching frequency based on operating conditions. By detecting the excitation state of the transformer and load percentage, the system adjusts the switching frequency parameter to optimal values. This parameter change strategy allows the system to prevent magnetic saturation when needed while minimizing switching losses during normal operation, directly resolving the technical contradiction.
2Speed
If the switching frequency is increased to respond to sudden load changes, then the response speed improves, but the temperature rise increases due to higher switching losses
Solution Approach 1:
The system dynamically adjusts switching frequency based on real-time excitation detection. During sudden load changes, frequency increases rapidly to maintain response speed. During steady-state operation, frequency decreases to reduce switching losses and temperature rise. This dynamic behavior resolves the contradiction between response speed and temperature control.
Solution Approach 2:
The patent implements feedback control by continuously detecting the excitation state of the transformer and comparing it with preset thresholds. Based on this feedback, the control device adjusts the switching frequency accordingly. This closed-loop feedback mechanism ensures rapid response to load changes while preventing excessive temperature rise through intelligent frequency management.
3Reliability
If a fixed high switching frequency is used to prevent magnetic saturation, then the reliability improves, but the switching loss and heat dissipation cost increase
Solution Approach 1:
The patent changes the switching frequency parameter from a fixed high value to a dynamically adjusted value based on actual operating conditions. By detecting excitation state and load percentage, the system uses high frequency only when necessary to prevent saturation, and lowers frequency during normal operation to minimize switching losses and heat dissipation, resolving the contradiction between reliability and energy efficiency.
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
Effectively prevents magnetic saturation and manages temperature rise in isolated converters, reducing switching losses and heat dissipation costs by dynamically adjusting switching frequency according to load conditions.
Implementation Method 1
high-frequency transformer isolated converters
Implementation Method 2
increasing the switching frequency may increase the switching loss significantly
Implementation Method 3
the excessive unidirectional excitation change may easily cause a magnetic induction intensity of the transformer to be greater than a maximum allowable operation value, and then cause the magnetic saturation of the transformer
Data Source
AI summary
The present invention provides a control device for an isolated converter, including a comparison module, which receives a load percentage of the isolated converter, compares the load percentage with a first preset threshold and a second preset threshold, and outputs a comparison result; and an adjustment module, which receives the comparison result and adjusts a switching frequency of a switching transistor of the isolated converter based on the comparison result, wherein when the load percentage is not greater than the first preset threshold value, the switching frequency is set to a first frequency value to prevent magnetic saturation of a transformer of the isolated converter, and when the load percentage is greater than the second preset threshold value and in a stable state, the switching frequency is set to a second frequency value, so that the temperature of the isolated converter does not exceed the maximum allowable temperature, wherein the first preset threshold is less than or equal to the second preset threshold, and the first frequency value is greater than the second frequency value.