Phase-Locked Active Rectifier for Variable-Frequency Harmonics
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Solution Overview
Problem
Aerospace applications face challenges with active rectifiers due to high, variable fundamental frequencies, leading to excessive weight and size requirements for harmonic filtering, as existing solutions struggle to efficiently manage harmonics within strict aerospace specifications.
Innovation Solution
A phase locked active rectifier system that detects the fundamental frequency and sets the switching rate to an integer multiple of it, specifically using multipliers like 15, 21, or 27, to reduce attenuation requirements and minimize filtering needs, thereby reducing the weight and size of components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing active rectifiers use harmonic filtering for high, variable fundamental frequencies, then rectification performance is maintained, but weight and size increase significantly
Solution Approach 1:
The patent applies dynamics by making the switching frequency variable rather than fixed. The switching controller dynamically adjusts the switching frequency of the active rectifier to track an integer multiple of the variable fundamental frequency from the generator, allowing the system to maintain optimal performance across different operating conditions without requiring heavy, fixed-frequency filtering components
Solution Approach 2:
The patent changes the parameter of switching frequency from a fixed value to a variable parameter that is locked to an integer multiple of the fundamental frequency. This parameter change allows the active rectifier to adapt to varying generator frequencies, eliminating the need for heavy harmonic filtering components designed for fixed-frequency operation
2Reliability
If existing active rectifiers use harmonic filtering for high, variable fundamental frequencies, then rectification performance is maintained, but component size increases
Solution Approach 1:
The switching controller dynamically adjusts the switching frequency to track an integer multiple of the variable fundamental frequency, enabling the active rectifier to maintain optimal rectification performance across different operating conditions without requiring large, fixed-frequency filtering components
Solution Approach 2:
By changing the switching frequency parameter from fixed to variable and locking it to an integer multiple of the fundamental frequency, the system achieves adaptive performance that eliminates the need for large filtering components
3Ease of operation
If fixed frequency active rectifiers are used, then moderate switching frequency is easier to achieve, but they perform poorly with high, variable fundamental frequencies
Solution Approach 1:
The system transitions from static fixed-frequency operation to dynamic variable-frequency operation. The switching controller continuously adjusts the switching frequency to maintain an integer multiple relationship with the fundamental frequency, ensuring both ease of control and high rectification performance across varying operating conditions
Solution Approach 2:
The switching controller uses feedback from the detected fundamental frequency to dynamically adjust the switching frequency. By detecting the fundamental frequency and locking the switching frequency to an integer multiple, the system creates a closed-loop control mechanism that maintains optimal performance without complex manual tuning
Data Source
AI summary
A power distribution system includes a variable frequency alternating current (AC) generator, an active rectifier electrically connected to the variable frequency AC generator such that AC power output from the variable frequency AC generator is rectified by the active rectifier, and a switching controller configured to detect a fundamental frequency of the AC power output and lock an active switch rate of the active rectifier to an integer multiple of the fundamental frequency.