Active Filtered Rectifier for High-Quality Aircraft DC Power
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Solution Overview
Problem
Existing electrical power systems in aircraft face challenges in achieving high-quality DC output with reduced cost and complexity, as passive diode-bridge rectifiers produce lower quality DC voltage, while active devices increase system complexity and cost, and conventional filters are bulky and lossy, optimized for a narrow range of operating parameters.
Innovation Solution
An electrical power system incorporating a diode-bridge rectifier with an active filter circuit, controlled by a controller to manage the switching operation of power semiconductor switches, effectively filtering harmonics in the DC output, utilizing a rotary electrical machine with trapezoidal or quasi-trapezoidal voltage output and an active filter circuit with parallel or series-connected active bridge circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a passive diode-bridge rectifier is used, then system cost and complexity are reduced, but DC output quality deteriorates with higher harmonic content
Solution Approach 1:
The rectifier system is segmented into two independent parts: a passive diode-bridge rectifier for basic rectification and a separate active filter circuit for harmonic compensation. This segmentation allows each component to be optimized independently - the diode bridge maintains simplicity while the active filter independently improves output quality by injecting counter-phase harmonic currents.
Solution Approach 2:
An active filter circuit acts as an intermediary between the passive rectifier and the DC load. This intermediary component captures harmonic distortions from the rectifier output and actively compensates them through controlled power semiconductor switches, thereby improving DC output quality without requiring the rectifier itself to be complex.
2Manufacturing precision
If first- and second-order voltage filters (R-L-C) are used, then DC output quality is improved, but system mass and energy losses increase
Solution Approach 1:
The patent replaces traditional passive mechanical R-L-C filter components with an active electronic filter system using power semiconductor switches (MOSFETs or IGBTs). This substitution eliminates the need for bulky inductors and capacitors, significantly reducing filter mass while maintaining effective harmonic filtering through electronic control and switching operations.
Solution Approach 2:
The active filter circuit dynamically changes its operating parameters (switching frequency, duty cycle, and circuit configuration) to adapt to different operating conditions and harmonic content. This allows the filter to maintain optimal performance across varying loads and frequencies without requiring oversized components designed for worst-case scenarios, thereby reducing overall system mass.
3Manufacturing precision
If conventional R-L-C filters are used, then harmonic filtering is achieved, but adaptability to different operating parameters is limited
Solution Approach 1:
The active filter circuit employs dynamic control through power semiconductor switches that can be rapidly switched on and off according to real-time harmonic detection. The filter's impedance, switching frequency, and control parameters are continuously adjusted based on operating conditions, enabling effective harmonic filtering across a wide range of frequencies and load conditions unlike static R-L-C filters.
Solution Approach 2:
The system incorporates feedback mechanisms where the output voltage quality is continuously monitored and used to adjust the active filter's switching control. This closed-loop feedback enables the filter to automatically adapt to changing operating parameters, load conditions, and harmonic content, maintaining optimal filtering performance across diverse operating scenarios.
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 system achieves improved DC output quality with reduced size and mass, enabling efficient harmonic filtering and adaptable frequency response, thereby optimizing the electrical power system for various operating conditions.
Implementation Method 1
an active filter circuit comprising a plurality of power semiconductor switches connected in a bridge configuration between first and second output terminals
Implementation Method 2
a controller configured to control a switching operation of the plurality of power semiconductor switches of the active filter circuit to control an output voltage
Data Source
Figure 1~2
Figure 3
Figure 4(a)~4(d)
AI summary
An electrical power system 10, comprising: a rotary electrical machine 12 configured to output AC; a diode-bridge rectifier 13 having an AC input connected to the electrical machine 12 and a DC output (DC+, DC-); an active filter circuit 14 comprising a plurality of power semiconductor switches 141L-H, 142L-H connected in a bridge configuration between first and second output terminals 14out, the first and second output terminals 14out connected to the DC output (DC+, DC-) of the diode-bridge rectifier 13; and a controller 15 configured to control a switching operation of the plurality of power semiconductor switches 141L-H, 142L-H of the active filter circuit 14 to control an output voltage Vfilt across the first and second output terminals 14out of the active filter circuit 14.