Synchronous Rectifier Circuit Pulse Signal Isolation
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Solution Overview
Problem
Existing synchronous rectifying control circuits for power converters require additional power consumption due to the use of saturable inductors and current-sense devices for both continuous and discontinuous mode operations, which reduces efficiency.
Innovation Solution
A synchronous rectifying circuit that generates pulse signals in response to the rising and falling edges of a switching signal, utilizing an isolation device like a pulse transformer or capacitors to transfer the signal across the transformer, eliminating the need for current sense devices and saturable inductors, and employing integrated synchronous rectifiers with power transistors to regulate the power converter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If synchronous rectifier is applied on secondary side of power transformer, then conversion efficiency is improved, but additional power consumption is caused by saturable inductors and current-sense devices
Solution Approach 1:
The patent extracts and removes the saturable inductor and current-sense device from the synchronous rectifier circuit. By using a simple diode-based rectifier topology without these additional components, the invention eliminates their associated power consumptions while maintaining the core synchronous rectification function through alternative means.
Solution Approach 2:
The patent makes the power transistor serve multiple functions: it acts as both the synchronous rectifier switch and the current sensing element. The body diode of the power transistor provides the rectification path, eliminating the need for separate current-sense devices and reducing overall component count and power consumption.
2Adaptability or versatility
If saturable inductor and current-sense device are used, then synchronous rectifier can operate in both continuous mode and discontinuous mode, but device complexity increases
Solution Approach 1:
The patent removes the saturable inductor and current-sense device from the circuit, significantly reducing component quantity and complexity. The simplified topology uses only essential components (power transistor, diode, capacitor) while maintaining the ability to operate in both continuous and discontinuous modes through proper control circuitry.
Solution Approach 2:
The power transistor's body diode serves as a universal element that provides both rectification and current sensing functions. This multi-functional approach eliminates the need for separate dedicated components for each function, reducing overall device complexity while maintaining operational flexibility across different modes.
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 achieves higher conversion efficiency by reducing power consumption and eliminating the need for additional components, thereby improving the overall performance of the power converter in both continuous and discontinuous modes.
Implementation Method 1
An isolation device, such as a pulse transformer or capacitors, is coupled to the pulse-signal generation circuit to transfer the pulse signal from the primary side of the transformer to the secondary side of the transformer
Data Source
AI summary
A synchronous rectifying circuit is provided for power converter. An integrated synchronous rectifier has a rectifying terminal, a ground terminal a first input terminal and a second input terminal. The rectifying terminal is coupled to secondary side of a transformer. The ground terminal coupled to output of the power converter. A power transistor is connected between the rectifying terminal and the ground terminal. The first input terminal and the second input terminal are coupled to receive a pulse signal for turning on/off the power transistor. A pulse-signal generation circuit includes an input terminal coupled to receive the switching signal for switching the transformer of the power converter. A first output terminal and a second output terminal of the pulse-signal generation circuit generate the pulse signal. An isolation device is coupled between the first input terminal and the second input terminal, and the first output terminal and the second output terminal.