Ultra Linear Switching Rectifier High Power Factor AC-DC Conversion
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Solution Overview
Problem
Current AC/DC converters face challenges in achieving high power quality with low harmonic distortions and efficient voltage regulation, particularly in applications like the More Electric Aircraft, where stringent power factor and harmonic limits are required, while also needing to consider weight, cost, complexity, and electromagnetic compatibility.
Innovation Solution
The Ultra Linear Switching Rectifier (ULSR) is a unidirectional three-phase three-switch pulse-width modulation rectifier with integrated buck-boost converter, offering high power factor (>99.9%) and low total harmonic distortion (<0.5%) across a wide range of frequencies and voltage conversion ratios, featuring a simple and robust analog fixed-frequency PWM controller for regulated output voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If passive AC/DC conversion with diode pairs is used, then the structure is simple, but current harmonics are substantial and power quality deteriorates
Solution Approach 1:
The patent applies active power factor correction to convert the harmful effect of current harmonics into beneficial sinusoidal current waveforms. The PFC circuit actively shapes the input current to follow the voltage waveform, transforming what would be harmonic-distorted current into clean sinusoidal current, thereby eliminating pollution to the power system while maintaining simple converter structure.
Solution Approach 2:
The patent changes the operating parameters of the converter by implementing active control mechanisms that dynamically adjust the switching patterns and control signals. This enables the converter to maintain high power factor and low harmonic distortion across varying load conditions and input voltages, resolving the contradiction between structural simplicity and power quality.
2Object-generated harmful factors
If multi-phase transformers are employed to reduce current harmonics, then harmonic distortion decreases, but device complexity and weight increase
Solution Approach 1:
The patent extracts the harmonic reduction function from the transformer structure itself and implements it separately through an active PFC circuit. Instead of using complex multi-phase transformers to achieve harmonic reduction, the solution separates the rectification function from the harmonic correction function, allowing simple diode-based rectification combined with active control to achieve both simplicity and low harmonic distortion.
Solution Approach 2:
The patent replaces the mechanical/physical solution of multi-phase transformers with an electronic control-based solution. The active PFC circuit uses electronic switching and control signals to achieve harmonic reduction, substituting the need for complex physical transformer structures with a more compact and controllable electronic system.
3Object-generated harmful factors
If active power factor correction is implemented, then power quality improves, but device complexity and cost increase
Solution Approach 1:
The patent merges the PFC function with the main converter circuit by using the same switching devices and control infrastructure for both rectification and power factor correction. This integration eliminates the need for separate PFC hardware, reducing overall device complexity and cost while maintaining the benefits of active power factor correction and low harmonic distortion.
Solution Approach 2:
The patent designs the converter circuit to perform multiple functions simultaneously - rectification, voltage regulation, and power factor correction - using a unified circuit architecture. The switching devices and control system serve dual purposes, making the PFC functionality inherent to the converter design rather than an add-on, thereby reducing complexity and cost.
4Stability of the object's composition
If voltage regulation is added to AC/DC converters, then output stability improves, but device complexity and weight increase
Solution Approach 1:
The patent combines voltage regulation functionality with the main converter circuit by using the same switching devices and control infrastructure. The control system dynamically adjusts the switching patterns to maintain stable output voltage, integrating regulation into the existing circuit rather than adding separate regulation hardware, thereby improving stability without significantly increasing complexity or weight.
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
ULSR provides efficient 3-phase AC-to-DC conversion with high power quality, low complexity, and robust operation under various conditions, including unbalanced mains and failures, with flexible cooling options and component technologies, while maintaining low EMI emissions and high reliability.
Implementation Method 1
unidirectional three-phase three-switch pulse-width modulation rectifier
Data Source
AI summary
The present invention relates to methods and corresponding apparatus for AC to DC conversion, including 3-phase AC to DC conversion, with high power quality, for example, high power factor and low harmonic distortions. The invention further relates to methods and corresponding apparatus for regulation and control of said AC to DC conversion.