Rectifier Circuit Synchronous MOSFETs Self-Driven Driver
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Solution Overview
Problem
In power supplies using bridge rectifiers, the voltage drops across bridge diodes result in losses, which can be mitigated by incorporating MOSFETs, but existing solutions often require complex control circuits and high circuit complexity.
Innovation Solution
A rectifier circuit design that includes MOSFETs in parallel with diodes and a self-driven driver circuit to control the MOSFETs' switching operations based on AC input voltage half-cycles, allowing them to operate as high-side floating synchronous rectifiers without external control signals, thereby reducing diode voltage drops and improving efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If MOSFETs are added in parallel with diodes to reduce voltage drops, then conversion efficiency is improved, but circuit complexity increases due to complex control circuits
Solution Approach 1:
The driver circuit is implemented as a self-driven circuit that automatically generates the necessary gate drive signals for the MOSFETs using the existing AC input voltage and circuit node voltages. The circuit uses the inherent voltage differences during different half-cycles to control the MOSFET switching without requiring external control signals, making the system self-sufficient and reducing overall complexity.
Solution Approach 2:
The self-driven driver circuit performs multiple functions: it generates gate drive signals for both MOSFETs, provides voltage level shifting, and ensures proper timing coordination between the MOSFETs. By consolidating these functions into a single integrated driver circuit, the design reduces the need for separate control components while maintaining efficient MOSFET operation.
2Productivity
If MOSFETs are used as synchronous rectifiers, then conversion efficiency is enhanced, but control complexity increases due to need for external control signals
Solution Approach 1:
The driver circuit automatically generates the required gate drive signals by utilizing the existing voltage differences between circuit nodes during different half-cycles of the AC input. The circuit inherently knows when to switch each MOSFET on and off based on the instantaneous voltage polarities, eliminating the need for external control signals while maintaining synchronized rectification operation.
Solution Approach 2:
The self-driven driver circuit continuously monitors the voltage conditions at its input terminals and automatically adjusts the gate drive signals accordingly. The circuit uses the voltage feedback from the AC input and circuit nodes to determine the appropriate switching state, creating a closed-loop control system that adapts to changing input conditions without external intervention.
3Device complexity
If self-driven driver circuit is implemented, then circuit is simplified, but control precision must be maintained during discontinuous current operations
Solution Approach 1:
The self-driven driver circuit maintains control precision during discontinuous current operations by continuously monitoring the voltage differences between its input terminals. Even when current is discontinuous, the circuit uses the instantaneous voltage polarities to generate appropriate gate drive signals, ensuring reliable MOSFET switching without requiring complex control logic or external synchronization signals.
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 design reduces power losses across diode drops, simplifies the circuit, and enhances conversion efficiency while maintaining cost-effectiveness, particularly during discontinuous current operations and at half load conditions.
Implementation Method 1
controlling switching operation of the first MOSFET and the second MOSFET during corresponding half-cycles of the AC input voltage according to a line frequency and polarity of the AC input voltage, to operate the first MOSFET and the second MOSFET as high-side floating synchronous rectifiers
Implementation Method 2
the bridge diodes introduce voltage drops and associated losses. Some power supplies use a metal-oxide semiconductor field-effect transistor (MOSFET) bridge across the existing bridge rectifier to reduce the losses associated with bridge diode voltage drops
Data Source
AI summary
A rectifier circuit for a power supply includes a diode bridge, a first metal-oxide-semiconductor field-effect transistor (MOSFET) and a second MOSFET each coupled in parallel with corresponding diodes of the diode bridge to reduce losses associated with bridge diode voltage drops and increase conversion efficiency. A self-driven driver circuit is coupled for controlling switching operation of the first MOSFET and the second MOSFET to operate the first MOSFET and the second MOSFET as high-side floating synchronous rectifiers. Methods of supplying power via a rectifier circuit of a power supply are also described.