Transformer Rectifier Circuit Eliminates Auxiliary Windings
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Solution Overview
Problem
Existing power conversion devices face challenges in reducing loss and size due to the complexity and increased size caused by the addition of auxiliary windings for rectification, particularly when using MOS-FETs driven by inversion signals from auxiliary windings.
Innovation Solution
A power conversion device configuration that includes AC voltage input, a transformer with rectifying elements such as MOS-FETs and diodes connected in parallel, where the control terminal of the switch element is connected to the primary side of the transformer, eliminating the need for auxiliary windings and reducing voltage drop losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If an auxiliary winding is added to the converter transformer and MOS-FET is driven using inversion signal from auxiliary winding, then loss in rectifying circuit is reduced, but circuit complexity increases and device size increases
Solution Approach 1:
The patent extracts and eliminates the auxiliary winding from the transformer structure. Instead of using the auxiliary winding to generate inversion signals for MOS-FET drive, the invention directly connects the MOS-FET control terminals to the primary side terminals, thereby simplifying the circuit while maintaining the low-loss rectification function.
Solution Approach 2:
The primary side terminals of the transformer are made to serve dual functions: both power transmission and signal generation for MOS-FET drive. By connecting the control terminals of MOS-FETs directly to the primary side terminals, the same terminals that carry power also provide the drive signals, eliminating the need for separate auxiliary windings.
2Loss of energy
If an auxiliary winding is added to the converter transformer, then loss in rectifying circuit is reduced, but device size increases
Solution Approach 1:
The auxiliary winding is completely removed from the transformer structure. The invention achieves space savings by eliminating this additional component while maintaining the low-loss rectification performance through direct connection of MOS-FET control terminals to the primary side terminals.
3Device complexity
If diode is used in rectifying circuit, then circuit simplicity is maintained, but voltage drop loss is generated
Solution Approach 1:
The patent changes the key parameter of the rectifying element from diode to MOS-FET. This parameter change transforms the rectifying mechanism from passive diode rectification to active MOS-FET switching rectification, which has significantly lower on-resistance and voltage drop, thereby reducing power loss while maintaining circuit simplicity through direct terminal connections.
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 configuration achieves efficient rectification with reduced loss and space savings by using MOS-FETs with lower ON-resistance than diodes, while preventing overvoltage application to control terminals, thereby simplifying the circuit and reducing component count.
Implementation Method 1
a transformer that has a primary-side terminal pair and a secondary-side terminal pair and the primary-side terminal pair is connected to the AC voltage input unit
Implementation Method 2
one or a plurality of rectifying elements that have first terminals and second terminals and cause electric current to flow to the second terminals from the first terminals
Data Source
AI summary
A power conversion device includes a step-down-type transformer and a bridge circuit that rectifies output voltage of the transformer and supplies the rectified output voltage to a load. The bridge circuit is connected to a secondary winding of the transformer and includes MOS-FETs connected in series and diodes connected in series. A gate of the MOS-FET is connected to one end of a primary winding of the transformer with a capacitor interposed therebetween and a gate of the MOS-FET is connected to the other end of the primary winding of the transformer with a capacitor interposed therebetween. With this, a power conversion device and a wireless power transmission system that can achieve space saving and reduce loss in a rectifying element are provided.