Synchronization Rectification Device With Voltage-Division Capacitor
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Solution Overview
Problem
Conventional synchronization rectifiers in power supplies experience high conduction loss, heat dissipation issues, and short capacitor life due to the use of diodes, leading to low efficiency and short warranty periods, especially when dealing with high power requirements such as in lamp applications.
Innovation Solution
A synchronization rectification device utilizing a voltage-controlled switch module with a voltage-division capacitor to detect secondary voltage, incorporating an NMOSFET or other transistors, and a rectification controller to manage the rectification switch, reducing conduction loss and improving efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If diodes are used as synchronization rectifiers, then the circuit structure is simple, but the conduction loss is high and heat dissipation is poor
Solution Approach 1:
The patent changes the rectification element from diode to synchronous rectification circuit with controllable switches, transforming the conduction characteristics from fixed voltage drop to controllable low-resistance state, thereby reducing conduction loss while managing complexity through integrated control
2Device complexity
If diodes are used as synchronization rectifiers, then the circuit structure is simple, but the efficiency is low
Solution Approach 1:
The patent transforms the rectification mechanism from passive diode conduction to active synchronous switching, where controllable switches operate in low-resistance state during conduction, significantly improving output efficiency despite increased circuit complexity
3Device complexity
If diodes are used as synchronization rectifiers, then the circuit structure is simple, but the capacitor life is short
Solution Approach 1:
The patent changes the conduction mechanism from high-voltage-drop diode rectification to low-voltage-drop synchronous rectification, reducing stress and heat generation on output capacitors, thereby extending capacitor life and reliability
4Loss of energy
If the first resistor value is increased to reduce voltage drop loss, then the conduction loss is reduced, but the IC difficultly detects the drain voltage
Solution Approach 1:
The patent introduces a sampling circuit with voltage division and buffering as an intermediary between the high-voltage node and the IC detection input, enabling accurate voltage detection without being constrained by resistor value choices for loss reduction
5Temperature
If parallel diodes are used to distribute heat, then the heat dissipation is improved, but the current distribution is non-uniform
Solution Approach 1:
The patent employs synchronous rectification with control circuitry that monitors and adjusts switch conduction based on current feedback, achieving uniform current distribution across parallel paths while maintaining effective heat dissipation
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution significantly enhances output efficiency, extends the warranty period of power supply components, and achieves precise synchronization rectification by minimizing conduction losses and ensuring reliable capacitor performance.
Implementation Method 1
the voltage-controlled switch module has a voltage-division capacitor, and receives a secondary voltage generated by the secondary side
Implementation Method 2
The rectification switch is connected between the secondary side and the output capacitor. The voltage-controlled switch module connected with the secondary side has a voltage-division capacitor, and receives a secondary voltage generated by the secondary side
Data Source
AI summary
A synchronization rectification device is connected with a secondary side of a transformer of a power supply and an output capacitor. The synchronization rectification device includes a rectification switch, a voltage-controlled switch module and a rectification controller. The rectification switch is connected between the secondary side and the output capacitor. The voltage-controlled switch module connected with the secondary side has a voltage-division capacitor and receives a secondary voltage generated by the secondary side. The rectification controller is connected with the rectification switch and the voltage-controlled switch module. When the secondary voltage rises to a switching voltage value below a first voltage value, the rectification controller controls the rectification switch to be turned off. After the rectification switch is turned off, the voltage-controlled switch module is turned off, and the voltage-division capacitor receives the secondary voltage.