Satellite Thrust Balance Adjustment via Discharge Current Control

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Solution Overview

Problem

The existing orbit raising operations for artificial satellites are hindered by the accumulation of angular momentum in reaction wheels, which limits the duration of thruster firing and necessitates temporary suspension of orbit raising to release this momentum, thereby increasing the time required to reach a target orbit.

Innovation Solution

An artificial satellite equipped with a plurality of thrusters, an angular momentum detection apparatus, and a satellite controller that adjusts the thrust of specific thrusters based on detected angular momentum to maintain balance, preventing excessive accumulation in the reaction wheel.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If multiple electric thrusters simultaneously fire to perform orbit raising, then the orbit raising speed is improved, but angular momentum accumulates in the reaction wheel requiring periodic unloading which increases total time

Engineering Contradiction:
Improveorbit raising speedVSAvoidtotal orbit raising time
Core Design Contradiction:
SpeedVSLoss of time

Solution Approach 1:

The invention changes the operating parameters of individual thrusters by adjusting their discharge currents to compensate for thrust variations. The satellite controller monitors actual thrust deviations and modifies the discharge current of each thruster accordingly, transforming the system from fixed-parameter operation to adaptive parameter control, thereby eliminating angular momentum accumulation while maintaining continuous orbit raising

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention implements a feedback control mechanism where the satellite controller continuously monitors the thrust output of each thruster, detects deviations from the target thrust, and adjusts the discharge current of affected thrusters in real-time. This closed-loop feedback system ensures that thrust variations are corrected dynamically, preventing angular momentum accumulation and enabling continuous uninterrupted orbit raising operations

Inventive Principle:
Principle #23Feedback

2Reliability

If thruster thrust variations occur due to individual differences or distance variations from center of gravity, then angular momentum is generated, but the reaction wheel has limited capacity to absorb it

Engineering Contradiction:
Improveattitude control reliabilityVSAvoidangular momentum management complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The invention performs preliminary thrust balance adjustment by proactively modifying the discharge currents of thrusters before angular momentum accumulation becomes problematic. The satellite controller calculates required current adjustments based on detected thrust variations and applies them in advance, preventing the buildup of angular momentum that would otherwise require reactive unloading operations

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The invention compensates for individual thruster differences and position variations by dynamically adjusting the discharge current parameter of each thruster. This parameter modification equalizes the effective thrust contribution from each thruster, eliminating the root cause of angular momentum generation while maintaining simple reaction wheel operation

Inventive Principle:
Principle #35Parameter changes

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 approach allows for continuous thruster operation, reducing the frequency of unloading and the time needed to achieve orbit by maintaining balanced thrust among thrusters, thus shortening the overall orbit raising process.

Implementation Method 1

an angular momentum detection apparatus to detect an angular momentum that is generated in the artificial satellite

Methodology Applied
Scientific EffectAngular momentum: Angular Momentum

Implementation Method 2

Each electric thruster ionizes xenon gas that is a propellant and accelerates the ionized xenon in a strong electric field, thereby obtaining a thrust as a reaction force

Methodology Applied
Scientific EffectIonization: Ionisation

Implementation Method 3

Each electric thruster ionizes xenon gas that is a propellant and accelerates the ionized xenon in a strong electric field, thereby obtaining a thrust as a reaction force

Methodology Applied
Scientific EffectElectromagnetic propulsion: Electromagnetic Propulsion

Data Source

PatentEP3476749B1Artificial satellite and thrust balance adjustment method
Publication Date: 2021.11.17 MITSUBISHI ELECTRIC CORP
  • EP3476749B1 patent drawingFigure 1
  • EP3476749B1 patent drawingFigure 2
  • EP3476749B1 patent drawingFigure 3

AI summary

A reaction wheel (110) detects an angular momentum. A satellite controller (120) selects a target thruster based on the detected angular momentum. A power supply apparatus (130) changes adjustment electric power for the target thruster. A flow rate adjustment apparatus (140) supplies a propellant to the target thruster at a flow rate corresponding to the adjustment electric power. This changes a thrust of the target thruster. When a discharge current of the target thruster does not become a target current, the power supply apparatus further changes the adjustment electric power for the target thruster.