Synchronous Rectification Circuit for Electronic Transformer Efficiency
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Solution Overview
Problem
Conventional switching power supplies using rectifier bridges suffer from high power loss and low efficiency due to the large size and forward conduction characteristics of diodes, which hinder efficient AC to DC conversion.
Innovation Solution
A synchronous rectification circuit utilizing switching transistors instead of diodes, controlled by a switching control circuit to achieve efficient AC to DC conversion in an electronic transformer, reducing power loss and increasing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If rectifier diodes are used in a rectifier bridge, then the circuit structure is simple and cost is low, but power loss is large and power efficiency is low
Solution Approach 1:
The patent changes the key parameter from using passive rectifier diodes to using active transistor switches (MOSFETs or IGBTs) that can be controlled to conduct during specific phases. This parameter change enables synchronous rectification where the switching transistors are turned on during their respective conduction periods, reducing forward voltage drop and power loss compared to conventional diode rectification
Solution Approach 2:
The patent implements a control circuit that detects the polarity of the input voltage and generates appropriate drive signals for the switching transistors. This feedback mechanism ensures that the transistors are turned on at the correct times (when their body diodes would naturally conduct), enabling synchronous rectification and improving power efficiency while maintaining reliable operation
2Area of stationary object
If rectifier diodes are used in a rectifier bridge, then the circuit is simple, but the size is large
Solution Approach 1:
The patent merges the rectification function with the switching control function into an integrated circuit. The control circuit and switching transistors are integrated onto a single chip, combining multiple functions (voltage detection, signal processing, and power switching) that would traditionally require separate components. This integration significantly reduces the overall circuit size while managing the increased functional complexity through systematic design
3Productivity
If synchronous rectification switching transistors are used instead of rectifier diodes, then power efficiency is improved, but device complexity increases
Solution Approach 1:
The control circuit is designed to automatically detect voltage polarity and generate appropriate drive signals without requiring external control or complex timing circuits. The system essentially controls itself by monitoring its own operating conditions (input voltage polarity) and adjusting the switching transistor states accordingly, which simplifies the control architecture while maintaining high efficiency
Data Source
AI summary
The present disclosure relates to a synchronous rectification circuit adapted to an electronic transformer. Operation states of four transistor switches in the synchronous rectification circuit are adjusted in accordance with a detected input voltage signal of the synchronous rectification circuit to achieve synchronous rectification. Moreover, the transistor switches in a rectifier bridge and a switching control circuit are all integrated into a single chip to have an increased integration level, a reduced chip size, and high efficiency. The present disclosure also relates to a switching power supply comprising the above synchronous rectification circuit.