Synchronous Rectification Circuit Integrating Transistors and Control
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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 synchronous rectification, integrating the transistors and control circuitry into a single chip for reduced size and increased efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If rectifier diodes are used in a rectifier bridge, then the device structure is simple and cost is low, but power loss is large and power efficiency is reduced
Solution Approach 1:
The patent changes the key parameter from using passive rectifier diodes to using active switching transistors (MOSFETs or IGBTs). This parameter change enables controlled switching operation, reducing conduction losses and improving power efficiency while maintaining a bridge rectifier structure. The switching transistors can be turned on/off synchronously with the AC input waveform, minimizing energy loss during rectification.
Solution Approach 2:
The patent replaces the passive mechanical/electrical rectification mechanism of diodes with an active controlled switching mechanism using transistors. This substitution allows for precise control of the rectification process through gate signals, enabling synchronous rectification that significantly reduces power loss compared to conventional diode-based rectifiers.
2Device complexity
If rectifier diodes are used in a rectifier bridge, then the device structure is simple, but the device size is large
Solution Approach 1:
The patent merges the rectification function and control function into a single integrated chip. The switching transistors and control circuitry are combined in one package, eliminating the need for separate discrete components. This integration significantly reduces the overall device size and footprint while maintaining the rectifier bridge structure, making the power supply more compact and suitable for modern electronics.
3Loss of energy
If synchronous rectification switching transistors are used instead of rectifier diodes, then power efficiency is improved, but control circuit complexity increases
Solution Approach 1:
The patent implements self-service control where the control circuit automatically generates the appropriate gate signals for the switching transistors based on the AC input waveform detection. The system self-regulates the switching timing and duration without requiring external control inputs, simplifying the overall control architecture. This self-service mechanism reduces control complexity while maintaining the power efficiency benefits of synchronous rectification.
Data Source
AI summary
The present disclosure relates to a synchronous rectification circuit. 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.