AC/DC Converter With Segmented Isolation Transformer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing AC/DC converters for aircraft electrical systems face inefficiencies due to high distortion in current consumption, leading to heating, electromagnetic radiation, and increased mass and size requirements, particularly when dealing with variable frequency alternators.
Innovation Solution
An AC/DC converter design incorporating a rectifier circuit connected in series with a primary winding of an isolation transformer and a chopping switch controlled by pulse-width modulation, featuring multiple secondary windings for efficient energy transmission and storage, allowing for galvanic isolation and power factor correction in a single stage, minimizing energy waste and overvoltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a BOOST type PFC circuit is used, then power factor correction is achieved, but galvanic isolation is lost requiring additional DC/DC converter increasing weight and size
Solution Approach 1:
The patent combines the PFC function and galvanic isolation function into a single AC/DC converter stage. The converter simultaneously performs power factor correction by shaping the input current waveform and provides galvanic isolation through the isolation transformer, eliminating the need for a separate DC/DC converter and reducing overall system weight.
Solution Approach 2:
The AC/DC converter is designed to perform multiple functions: power factor correction, galvanic isolation, and voltage conversion. By making the converter universal and multi-functional, the patent eliminates the need for separate dedicated circuits for each function, thereby reducing weight and complexity.
2Reliability
If a FLYBACK type PFC circuit is used, then galvanic isolation is provided, but large transformers are required for high powers increasing mass and size
Solution Approach 1:
The patent segments the transformer windings into multiple secondary windings with different configurations (same direction and opposite direction relative to primary winding). This segmentation allows the transformer to handle high power while maintaining compact size by distributing the power handling across multiple winding pairs rather than requiring a single large transformer.
Solution Approach 2:
The patent employs dynamic switching control using pulse-width modulation to control the chopping switch, enabling the converter to adaptively manage power flow and magnetic core energy storage. This dynamic control allows efficient operation across varying power levels without requiring oversized transformers designed for peak power only.
3Reliability
If a FORWARD type circuit is used, then galvanic isolation is achieved, but current cannot be exploited over entire sinusoid reducing efficiency
Solution Approach 1:
The patent segments the secondary side into multiple windings (first and second secondary windings) with different connections. The first secondary winding with same-direction connection handles power transmission during positive half-cycles, while the second secondary winding with opposite-direction connection utilizes energy during negative half-cycles, enabling full-wave utilization of the input sinusoid and improving overall efficiency.
4Device complexity
If simple transformer rectifier is used, then circuit complexity is reduced, but current distortion causes heating and electromagnetic radiation
Solution Approach 1:
The patent introduces dynamic pulse-width modulation control of the chopping switch to actively shape the input current waveform. This dynamic control forces the converter to draw sinusoidal current from the AC source, eliminating current distortion and its associated harmful effects such as heating and electromagnetic radiation, while maintaining relatively simple circuit topology.
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 achieves high efficiency, reduced size and weight, and effective galvanic isolation with power factor correction, ensuring reliable energy transmission and consumption across varying voltage conditions.
Implementation Method 1
an isolation transformer comprising a first secondary winding which has the same direction as the primary winding and which is connected to an output line of the converter via a diode and a filtering coil
Implementation Method 2
connected to an output line of the converter via a diode and a filtering coil
Implementation Method 3
a filtering coil, the line output being connected to an output capacitor
Data Source
Figure 1
AI summary
The invention relates to an AC/DC converter that comprises at the input a rectifying circuit (2) connected in series to the primary winding (5) of an insulation transformer (6) and to a splitting switch (T1) connected to a pulse-width modulation control circuit (10), the insulation transformer including a first secondary winding (7) having a direction identical to that of the primary winding and connected to the output line (8) of the converter via a diode (D4), the output line being connected to an output capacitor (Cout), characterised in that the insulation transformer includes a second secondary winding (9) having a direction opposed to that of the primary winding and connected to the output line via a diode (D2).