Bidirectional AC/DC H-Bridge Converter Eliminates Diodes
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Solution Overview
Problem
Conventional AC/DC converters are bulky, costly, and inefficient due to the presence of diodes and low-pass filtering stages, which also limit their miniaturization and reversibility, especially when used with active DC loads.
Innovation Solution
The proposed AC/DC converter design eliminates the rectifying stage and low-pass filtering stage, utilizing a first and second H bridge configuration with bidirectional switches and a transformer, along with a control circuit that switches at frequencies greater than 1 MHz, allowing for high-frequency operation and reversibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional rectifying stage with diodes and low-pass filtering stage is used, then the converter structure is simple and reliable, but the converter becomes bulky, costly, and inefficient
Solution Approach 1:
The patent removes the rectifying stage with diodes and the low-pass filtering stage from the conventional converter structure. By extracting these components, the invention eliminates their associated losses and reduces overall complexity while maintaining conversion functionality through the H-bridge circuit alone
Solution Approach 2:
The H-bridge circuit is designed to perform multiple functions: it acts as both the rectifying stage and the power conversion stage simultaneously. This multi-functional approach eliminates the need for separate rectifying and filtering components, reducing both complexity and energy losses
2Volume of stationary object
If the switching frequency is limited to a few hundreds of kHz to reduce switching losses, then switching losses are minimized, but the isolation transformer size cannot be reduced
Solution Approach 1:
The patent changes the switching frequency parameter from conventional hundreds of kHz to greater than 1 MHz. This parameter change enables significant reduction of the isolation transformer size while the optimized H-bridge circuit and bidirectional switches minimize switching losses at the higher frequency
3Loss of energy
If a rectifying stage with diodes is used, then the converter structure is straightforward, but the converter efficiency is significantly limited
Solution Approach 1:
The patent extracts and removes the rectifying stage with diodes from the converter structure. By eliminating this stage, the invention removes the efficiency limitations imposed by diode voltage drops and switching losses, achieving significantly higher converter efficiency
Solution Approach 2:
The patent replaces the mechanical/diode-based rectifying system with an electronic H-bridge switching system. This substitution allows for more efficient power conversion by using controlled switches instead of passive diodes, reducing energy losses
4Adaptability or versatility
If conventional converter architecture with rectifying and filtering stages is used, then the converter is simple to implement, but reversibility cannot be achieved
Solution Approach 1:
The H-bridge circuit and bidirectional switches are designed to operate in multiple modes: forward conversion (AC to DC) and reverse conversion (DC to AC). This multi-functionality enables reversibility without requiring separate converter structures, maintaining simplicity while achieving versatility
Solution Approach 2:
The patent enables the converter to operate in reverse by inverting the power flow direction. The same H-bridge circuit that converts AC to DC can convert DC to AC by reversing the switching sequence, achieving reversibility through operational inversion rather than structural modification
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 significantly reduces switching losses, minimizes the size of the isolation transformer, and enables reversibility, leading to a more efficient and compact AC/DC converter.
Implementation Method 1
a transformer comprising a primary winding and a secondary winding, magnetically coupled, first and second ends of the primary winding being respectively coupled to first and second output nodes of the first bridge
Data Source
AI summary
An AC/DC converter including: an H bridge; an inductance in series with an input of the bridge; an inductance in series with an output of the bridge; and a circuit capable of controlling the bridge alternately to a first configuration where first and second diagonals of the bridge are respectively conductive and non-conductive, and to a second complementary configuration, the circuit being capable, during a phase of transition between the first and second configurations, of: turning on a first switch of the second diagonal; turning off a first switch of the first diagonal when the current flowing through this switch takes a zero value; turning on the second switch of the second diagonal; and turning off the second switch of the first diagonal when the current flowing through this switch takes a zero value.