Switching Controller Rectifier Off-Time Adjustment
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Solution Overview
Problem
Existing switching converters experience large variations in output current due to fixed off-time of the rectifier, leading to inefficiencies and potential damage from variations in input or output voltage.
Innovation Solution
A controller with an over voltage protection circuit and timing circuit that adjusts the off-time of the rectifier inversely with the input voltage, reducing peak-to-peak ripple current variations and implementing dynamic regulation to prevent damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the off time of the rectifier is fixed, then the control is simple, but the output current varies greatly when input voltage or output voltage changes
Solution Approach 1:
The patent applies dynamics by making the off-time of the rectifier variable rather than fixed. The off-time is dynamically adjusted based on the input voltage level - specifically, the off-time is extended when the input voltage is high and reduced when the input voltage is low. This dynamic adjustment compensates for voltage variations and maintains stable output current, resolving the contradiction between simple fixed-time control and stable output current under varying conditions.
2Stability of the object's composition
If the off time is extended to reduce ripple current, then the peak-to-peak ripple current variation decreases, but the rectifier off time becomes too long at high input voltage
Solution Approach 1:
The patent applies parameter changes by adjusting the off-time parameter based on the input voltage parameter. When input voltage is high, the off-time is extended to reduce the peak-to-peak ripple current variation. When input voltage is low, the off-time is reduced to prevent excessive delay. This conditional parameter adjustment resolves the contradiction between reducing ripple current variation and maintaining appropriate rectifier off-time across different operating conditions.
Data Source
AI summary
A switching controller having an over voltage protection circuit is disclosed. The over voltage protection circuit detects whether the output voltage is higher than an over voltage threshold and turns on the rectifier when the output voltage is higher than an over voltage threshold. The over voltage protection circuit detects whether a current flowing through a rectifier is lower than a negative current limit and further turns off the rectifier for a time period when the current flowing through the rectifier is lower than the negative current limit. The off time period varies inversely with the input voltage.