Aircraft AC Bus Stabilization via DC Power Buffer
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Solution Overview
Problem
In commercial aircraft, the electric system driven mainly by AC power faces instability issues due to voltage fluctuations, leading to weight increases in conventional stabilization methods, such as large resistors or increased AC power generator size, which are inefficient and generate unnecessary heat.
Innovation Solution
An electric system stabilizing system that includes a DC power supply and an AC power supply with a power stabilizing device using a PWM converter and control section to monitor voltage and frequency changes, absorbing regenerative power and supplying transient power, thereby stabilizing the system without increasing weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large-sized resistor is used to consume regenerative power, then voltage increase is addressed, but the weight of the aircraft increases
Solution Approach 1:
A DC power supply is introduced as an intermediary component between the AC power system and the actuator. This DC power supply absorbs regenerative power during braking operations, preventing voltage spikes in the AC system while avoiding the need for large resistors. The DC power supply acts as a buffer that can quickly absorb energy without generating excessive heat or requiring large physical components.
Solution Approach 2:
The invention changes the operating parameters of the power system by introducing bidirectional power flow capability. The DC power supply can both charge from and discharge to the AC system, allowing regenerative power to be reused rather than dissipated. This parameter change enables the system to handle voltage fluctuations without requiring oversized passive components.
2Reliability
If the AC power generator size is increased to address voltage decrease, then voltage stability is improved, but the weight of the aircraft increases
Solution Approach 1:
The DC power supply serves as a mediator that provides transient power support during voltage drops. Instead of oversizing the AC generator, the DC power supply quickly discharges to supplement power during temporary load increases, allowing the AC generator to be sized for average rather than peak demands.
Solution Approach 2:
The DC power supply is pre-charged during normal operation when power demand is low, storing energy in advance. When voltage drops occur due to sudden load increases, the pre-charged DC power supply immediately discharges to compensate, preventing voltage instability without requiring the AC generator to be continuously oversized.
3Loss of energy
If a large-sized heat radiator is incorporated to dissipate heat from the resistor, then regenerative power consumption is achieved, but the weight of the aircraft increases
Solution Approach 1:
Instead of dissipating regenerative power as heat through a resistor and radiator, the invention converts this wasted energy into a useful resource by storing it in the DC power supply. The regenerative power from actuator braking is captured and stored as electrical energy, which can then be reused to power other systems, transforming a harmful heat generation problem into a beneficial energy recovery opportunity.
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 effectively stabilizes the electric system in aircraft driven mainly by AC power without increasing weight, by efficiently managing voltage fluctuations and regenerative power, reducing the need for heavy components and heat generation.
Implementation Method 1
a power converter section including a PWM (Pulse Width Modulation) converter
Implementation Method 2
the DC power supply is configured to absorb regenerative power from the electric device
Implementation Method 3
the power stabilizing control section monitors at least one of a change in a voltage and a change in a frequency in the AC power supply bus
Data Source
AI summary
An electric system of an aircraft includes a power stabilizing device connected to a primary AC bus and a secondary battery. The secondary battery has a rated voltage which allows the secondary battery to absorb regenerative power from a control surface actuator. Based on a voltage and a frequency in the primary AC bus, charging/discharging of the secondary battery is controlled to stabilize the electric system.