Aircraft Window Heating Regulated DC Voltage Control
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Solution Overview
Problem
Current aircraft windshield heating systems using AC or DC electrical systems face issues with temperature control, particularly in DC systems, where ON-OFF or Pulse Width Modulation (PWM) methods can cause optical diffraction due to temperature gradients and generate excessive electromagnetic interference.
Innovation Solution
A DC voltage with variable level is delivered to the heater using a controller with embedded temperature sensors, power contactors, and a high-frequency PWM signal to maintain constant heater temperature, minimizing interference and diffraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If ON-OFF or PWM methods are used to control heater temperature in DC electrical systems, then heating control is achieved, but optical diffraction occurs due to temperature gradients
Solution Approach 1:
The patent applies periodic action by using a high-frequency PWM signal to switch the power contactors, delivering power in rapid pulses rather than continuous or simple ON-OFF cycles. This high-frequency periodic switching allows the heater temperature to remain relatively constant between pulses, minimizing temperature gradients and the resulting optical diffraction while still achieving effective heating control.
Solution Approach 2:
The patent implements dynamics by using embedded temperature sensors that continuously monitor heater temperature and dynamically adjust the PWM duty cycle in real-time. This dynamic control ensures the heater maintains a stable temperature profile, preventing the temperature gradients that cause optical diffraction while adapting to changing thermal conditions.
2Temperature
If PWM methods are used to control heater temperature, then heating control is achieved, but excessive electromagnetic interference is generated
Solution Approach 1:
The patent uses power contactors as intermediaries between the PWM control signal and the heater element. These contactors switch the high-power DC voltage to the heater in response to PWM signals, isolating the sensitive electronic control circuitry from the high-power switching transients and reducing electromagnetic interference generation at the source.
Solution Approach 2:
The patent replaces direct electronic PWM switching of the heater element with a mechanical/electromechanical approach using power contactors. This substitution moves the high-power switching to isolated contactor switches rather than solid-state switches directly connected to the heater, reducing electromagnetic interference in the control electronics while maintaining effective heating control.
3Reliability
If separate circuits for pilot and co-pilot are used, then visibility in case of malfunction is ensured, but system complexity increases
Solution Approach 1:
The patent applies segmentation by providing separate heating circuits and control channels for the pilot and co-pilot windshields. This segmentation ensures that a malfunction in one circuit does not affect the other, maintaining visibility assurance while using a standardized controller design that minimizes overall system complexity through modular architecture.
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
This solution effectively controls windshield temperature, reducing optical diffraction and electromagnetic interference, while ensuring stable and efficient heating performance.
Implementation Method 1
heating elements are often placed on the inside of the outer glass ply 118
Implementation Method 2
A DC voltage with variable level is delivered to the heater using a controller with embedded temperature sensors, power contactors, and a high-frequency PWM signal
Data Source
AI summary
The example non-limiting technology herein provides an alternative way to control window heater temperature by delivering to the heater a DC voltage with variable level.