Aircraft Window Shade Backup Circuit Using Supercapacitor Power
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Solution Overview
Problem
Existing electrically operated aircraft window shades become inoperable during a power loss, and connecting them to the aircraft emergency power system increases power demand, leading to weight and cost issues.
Innovation Solution
A supercapacitor bank and charge/discharge circuit are integrated with a control circuit to provide emergency power to the window shades, using stored energy when main power fails, without relying on the emergency power system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electric window shades are connected to the aircraft emergency power system, then the window shades remain operational during power outages, but the power demand on the emergency power system increases, requiring larger batteries and adding weight
Solution Approach 1:
The emergency power system is segmented into individual units, with each window shade having its own dedicated supercapacitor backup power source. This segmentation allows each unit to be independently powered during outages without requiring a centralized emergency power system to support all shades, thereby reducing the overall weight and power capacity requirements of the emergency power infrastructure.
Solution Approach 2:
A supercapacitor bank serves as an intermediary energy storage device between the main aircraft power system and the window shade motor. The supercapacitor charges during normal operation and discharges to power the window shade during emergencies, acting as a buffer that eliminates the need for the window shade system to draw directly from the aircraft's emergency power system.
2Reliability
If a mechanical override system is added to allow manual operation of electric window shades, then the window shades can be operated during power loss, but the system complexity increases
Solution Approach 1:
The mechanical override system is replaced with an electrical solution using a supercapacitor bank and control circuitry. The supercapacitor provides electrical energy to power the motor during outages, eliminating the need for mechanical cranking mechanisms and associated mechanical components, thereby reducing system complexity while maintaining operational reliability.
3Duration of action of moving object
If the supercapacitor bank is charged to high voltage, then more energy is stored for longer operation during emergencies, but the risk of voltage spikes and damage to connected electronics increases
Solution Approach 1:
A voltage clamping circuit with TVS diodes is implemented to protect downstream electronics from voltage spikes. The TVS diodes clamp excessive voltage to safe levels, providing beforehand protection against voltage surges that could damage the motor or control electronics during supercapacitor discharge.
Solution Approach 2:
The system employs a boost converter circuit that efficiently converts the supercapacitor voltage to the appropriate operating voltage for the window shade motor. This parameter transformation allows the supercapacitor to be charged to high voltage for maximum energy storage while the converter ensures the motor receives a stable, appropriate voltage, preventing damage from voltage fluctuations.
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
Ensures the window shades remain operational during power outages without overburdening the emergency power system, reducing weight and cost by using supercapacitors that can be efficiently charged and discharged.
Implementation Method 1
A voltage source circuit is coupled to a supercapacitor bank. The voltage source circuit is configured to store charge in the supercapacitor bank when a voltage level from a main power source is above a preselected threshold voltage level and to provide a voltage to operate a window shade when the voltage level from the main power source falls below the preselected threshold voltage level.
Implementation Method 2
there is further included a charge and discharge circuit coupled between the supercapacitor bank and a voltage feed line (an output) to the electrically controlled aircraft device
Data Source
AI summary
An emergency backup power source for an electrically controlled and motorized window shade unit includes an input power switch, and charge and discharge control circuit, and a supercapacitor bank. During normal operation a nominal voltage level from a main power source of the aircraft is provided directly to the window shade unit through the input power switch, and the supercapacitor bank is charged. The input voltage is monitored by the emergency backup power source, which controls the input power switch. When the input voltage drops below a threshold level, the input power switch is opened and the charge and discharge circuit operates to provide an emergency output voltage to the window shade unit from the supercapacitor bank so that the window shade can be fully opened or closed, as is required.