Switching Control Circuit for Synchronous Rectifier Frequency Adaptation
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Solution Overview
Problem
Existing switching control circuits for power converters are limited by the response time of phase lock circuits, restricting the maximum operation frequency and speed of synchronous rectifiers.
Innovation Solution
A switching control circuit with an input circuit and clock generator that reduces the pulse width of the switching signal before changing from low to high frequency, allowing the circuit to operate at high frequencies without synchronous rectifier limitations, using a logic circuit, clock generator, and micro-stepping circuit to modulate and adjust the switching signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a phase lock circuit is used to detect the switching waveform and predict the turn-on time of the SR transistor, then the synchronous rectifier can operate, but the response time is limited which restricts the maximum operation frequency
Solution Approach 1:
The patent applies preliminary action by detecting the primary side waveform in advance and using it to predictively control the secondary side synchronous rectifier timing. The controller detects the switching waveform from the primary winding and generates control signals for the SR transistor before the actual switching event occurs on the secondary side, eliminating the need for slow phase lock circuits to detect and synchronize with the secondary waveform in real-time.
2Productivity
If the switching frequency is increased to improve power converter performance, then productivity increases, but the synchronous rectifier cannot operate properly due to response time limitations
Solution Approach 1:
The patent implements feedback by continuously monitoring the primary side switching waveform and using this information to adjust and optimize the secondary side synchronous rectifier control. The controller uses the detected primary waveform characteristics to generate appropriate control signals for the SR transistor, creating a closed-loop system that adapts to varying operating conditions and maintains reliable operation across different frequency ranges.
Data Source
AI summary
A switching control circuit of a power converter according to the present invention comprises an input circuit and a clock generator. The input circuit is coupled to receive a feedback signal for generating a switching signal. The clock generator generates a clock signal to determine a switching frequency of the switching signal. The feedback signal is correlated to an output of the power converter. The switching signal is coupled to switch a transformer of the power converter for regulating the output of the power converter. The pulse width of the switching signal is reduced before the switching frequency of the switching signal is changed from a low frequency to a high frequency.