Regulated Hybrid AC-DC Rectifier Harmonic Control
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Solution Overview
Problem
Existing AC-DC conversion technologies, particularly in aircraft applications, face challenges in regulating output voltage and managing harmonic content, leading to inefficiencies and poor power quality due to the limitations of passive rectifiers and the inability to control input power factor.
Innovation Solution
A regulated hybrid AC-DC rectifier system incorporating a 12-pulse inductive current splitter/merger system coupled with a boost stage and a PWM controller, along with a three-phase input filter and notch filters to manage harmonic ripples, ensures a constant DC output voltage and reduced harmonic distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a passive rectifier is used for AC-DC conversion, then the device complexity is reduced, but the output voltage cannot be regulated and harmonic content increases
Solution Approach 1:
The rectifier system is divided into two independent stages: a passive rectification stage for AC-DC conversion and a separate boost regulation stage for output voltage control. This segmentation allows each stage to perform its specialized function optimally while maintaining overall system simplicity.
Solution Approach 2:
A boost converter stage is introduced as an intermediary between the passive rectifier output and the final load. This intermediate stage provides the necessary voltage regulation and harmonic filtering without requiring the passive rectifier itself to be complex.
2Ease of manufacture
If a passive rectifier is used, then manufacturing ease is improved, but harmonic distortion increases and power quality deteriorates
Solution Approach 1:
The passive rectifier's inherent simplicity is preserved while its harmful harmonic output is converted into a controllable parameter by the subsequent boost stage, which actively filters and regulates the output to eliminate harmonics.
Solution Approach 2:
The harmonic distortion problem is extracted and isolated to the boost stage, where it can be addressed through active control and filtering, allowing the passive rectifier to continue operating in its optimal simple configuration.
3Reliability
If active rectifiers are used to regulate output voltage, then voltage regulation is improved, but device complexity and control requirements increase
Solution Approach 1:
The system separates rectification functions from regulation functions, placing them in distinct stages. This segmentation reduces the control complexity of each individual stage while achieving both voltage regulation and simple passive rectification.
Solution Approach 2:
The boost stage provides dynamic voltage regulation capability, allowing the system to adapt output voltage to load requirements while the passive rectifier stage remains static and simple in structure.
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
The solution provides a stable and efficient AC-DC conversion with reduced harmonic distortion, enabling better power quality and voltage regulation, particularly suitable for aircraft systems operating at constant frequencies like 400 Hz.
Implementation Method 1
a three phase input filter configured to regulate the harmonic content of the AC-DC hybrid converter within a desired limit
Implementation Method 2
a notch filter system configured to tune out harmonic ripples at known intervals, such as 11th and 13th order harmonics
Implementation Method 3
The output of the IPT-based passive rectifier may be input to a boost stage
Implementation Method 4
The boost stage may be regulated using a PWM controller. The output of the PWM controller may be coupled to the input of the boost switch. A switching duty of the boost switch may be varied by the PWM controller to maintain a substantially constant DC output voltage
Data Source
AI summary
A regulated hybrid AC-DC rectifier employing a boost stage is disclosed herein. The regulated hybrid AC-DC rectifier comprises a 12 pulse inductive current splitter/merger (CSM) system coupled to a boost stage. The boost stage may be regulated using a PWM controller. The regulated hybrid AC-DC rectifier may further include a three phase input filter configured to regulate the harmonic content of the AC-DC hybrid converter within a desired limit. The regulated hybrid AC-DC rectifier may further comprise a notch filter system configured to tune out harmonic ripples at known intervals, such as 11th and 13th order harmonics.