Isolated Converter Frequency Control for Saturation and Heat Limits
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Solution Overview
Problem
High-frequency transformer-based isolated converters experience magnetic saturation and increased switching loss when load changes suddenly, leading to temperature rise and operational instability.
Innovation Solution
A control device and method that adjusts switching frequency based on load measurement, using a time delay circuit and microcontroller to gradually decrease frequency when load exceeds a threshold, preventing magnetic saturation and reducing switching loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the switching frequency is increased to prevent magnetic saturation when load changes suddenly, then the transformer saturation is avoided, but the switching loss significantly increases
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 the transformer is near saturation risk, the frequency is increased; when stable operation is achieved, the frequency is reduced to minimize switching losses.
Solution Approach 2:
The patent changes the switching frequency parameter adaptively based on operating conditions. The control device monitors transformer excitation and load changes, then adjusts the switching frequency parameter accordingly - increasing it temporarily during transient states to prevent saturation, and decreasing it during stable states to reduce switching loss.
2Productivity
If the duty cycle is suddenly increased from very small to very large when heavy load is applied, then the load demand is met, but the transformer becomes magnetically saturated
Solution Approach 1:
The patent applies preliminary action by detecting load changes before they cause transformer saturation. The control device continuously monitors the transformer excitation state and anticipates saturation risk by detecting rapid load increases, then proactively adjusts the switching frequency and duty cycle to prevent saturation before it occurs.
Solution Approach 2:
The patent implements feedback control by continuously detecting the transformer excitation state and load conditions, then using this information to adjust the switching frequency and duty cycle. The control device receives feedback about the transformer's magnetic state and modifies its operation accordingly to maintain safe operating margins.
Data Source
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AI summary
The present invention provides a control device for an isolated converter. The control device includes: a comparison module, for receiving a load amount of the isolated converter, comparing the load amount with a first pre-configured threshold and a second pre-configured threshold, and outputting a comparison result; and an adjustment module, for receiving the comparison result and adjusting a switching frequency of a switching transistor of the isolated converter on the basis of the comparison result. When the load amount is not greater than the first pre-configured threshold, the switching frequency is configured to be a first frequency value so as to prevent a transformer of the isolated converter from being magnetically saturated. When the load amount is greater than the second pre-configured threshold and is in a steady state, the switching frequency is configured to be a second frequency value so that a temperature of the isolated converter does not exceed a maximum allowable temperature. The first pre-configured threshold is less than or equal to the second pre-configured threshold. The first frequency value is greater than the second frequency value.