Avionics Fan Controller Using Rectified Sinusoidal Modulation
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Solution Overview
Problem
Existing cooling fan controllers for avionics equipment are costly, complex, and produce significant electromagnetic interference (EMI), making them unsuitable for compact applications.
Innovation Solution
A compact AC load controller using a fixed frequency controlled boost converter to provide a rectified sinusoidal modulation of a DC link to a power bridge, eliminating the need for pulse width modulation and reducing EMI, while maintaining efficient operation of AC motors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If PWM controllers are used to control AC motors, then speed control capability is improved, but device complexity and EMI increase
Solution Approach 1:
The patent extracts and eliminates the PWM control circuitry from the AC motor controller, replacing it with a simpler fixed-frequency square wave controller. This removes the complex modulation functions while retaining basic speed control through fixed-frequency operation, directly resolving the contradiction between adaptability and device complexity.
Solution Approach 2:
The patent replaces expensive, complex PWM controller hardware with a simpler, less expensive fixed-frequency controller that uses minimal circuitry. The solution accepts reduced control flexibility in exchange for significant simplification of the control device, aligning with the principle of using simpler components when full functionality is not required.
2Adaptability or versatility
If PWM controllers are used to control AC motors, then speed control capability is improved, but EMI increases
Solution Approach 1:
The patent removes the PWM switching circuitry that generates EMI, replacing it with a fixed-frequency square wave controller. This extraction of the problematic PWM components eliminates the source of electromagnetic interference while maintaining sufficient control capability for the application.
Solution Approach 2:
The patent converts the harmful EMI generated by PWM switching into a beneficial simplified control approach. By using fixed-frequency square wave control instead of PWM, the solution eliminates EMI problems entirely while still achieving effective motor control, turning a harmful characteristic into a design advantage.
3Volume of moving object
If compact form factor is required for avionics applications, then device size is reduced, but circuitry complexity increases
Solution Approach 1:
The patent extracts and removes unnecessary control circuitry from the controller design, retaining only the essential fixed-frequency square wave generation and power switching components. This reduction in circuitry enables a compact form factor while actually decreasing rather than increasing complexity.
Solution Approach 2:
The patent uses minimal, simple circuitry components to achieve compact controller design. By replacing complex PWM control hardware with basic fixed-frequency control circuitry, the solution achieves small size without the penalty of increased complexity, effectively using simpler components to meet space constraints.
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 reduces the size and EMI of the controller, enhancing cost-effectiveness and operational efficiency, and minimizes motor heating and premature failure by eliminating harmonic interactions, while also providing effective noise cancellation through synchronized motor operation.
Implementation Method 1
A fixed frequency controlled boost convertor to provide a rectified sinusoidal modulation of a DC link
Implementation Method 2
an AC load which sees a single phase sinusoidal voltage from said power bridge
Data Source
AI summary
A system is disclosed which utilizes a non-pulse width modulated signal, which provides a fully rectified sinusoidal modulated DC link to a single phase AC motor to emulate a variable single phase AC power line. The system provides for reduced EMI and reduced size when compared to a controller with a PWM drive signal.