Plant Modeling and Performance ... - MATLAB & Simulink · Plant Modeling and Performance Analysis...
Transcript of Plant Modeling and Performance ... - MATLAB & Simulink · Plant Modeling and Performance Analysis...
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Plant Modeling and Performance
Analysis of Electro Mechanical
Actuation System for Fire Shut-off Valve
By H K Pavan Kumar Kollipara
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Agenda
Objective
Challenges
Introduction
Problem Statement
Plant Modeling
Performance Analysis
Validation using Analytics
Conclusions & Recommendations
References
Appendix
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Objective
To develop the plant model & study the performance of
the Electro-Mechanical Actuation System to operate
Fire Shut-off Valve
Critical performance parameters under study are:
– Operation time
Time taken by the valve to reach its desired position, since start of the
operation
– Close position error
Difference between the desired and the actual position after power shut-off
and the valve comes to rest
– Power supply demand
To understand the peak and steady-state requirements
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Challenges
Operation time and the Close position error are two
contradictory requirements of the system
Meeting operation time and the close position error
simultaneously across wide range of operating
temperatures is a big challenge in designing this
system
Hence it becomes critical to study the dynamics of the
system at various operating temperatures
Due to absence of the controller the performance of this
system is majorly determined by its inertia
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Introduction
Fire Shut-off Valve (FSOV) has to be installed between
hydraulic fluid reservoir and the hydraulic system of the
aircraft
In case of fire accidents in the aircraft, the valve should
stop the fluid supply to the hydraulic system
Eaton has come up with an Electro-Mechanical
Actuation System to operate this FSOV, which is as
shown in fig.1.
Fig.1 System Schematic
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Analyze the dynamic behavior of the Eaton’s system to operate the FSOV
Verify the following requirements – Allowable error in Close position : ±1%
– Operation time: Max. 1.5 sec, at -6.6oC to 110oC and 18 Vdc
Max. 5 sec, at -55oC to -6.6oC and 28 Vdc
– Maximum duration the power supply requirements can exceed 30W is, 100ms
Provide recommendations to improve the design
Problem Statement
Non-linear dynamic equations are solved numerically
using MATLAB/SIMULINK
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Plant Modeling
Assumptions in Plant modeling
– Neglected Gear Backlash effects
– Neglected damping inside the gearbox
– Temperature effects on Motor Mechanical damping coefficient
is not accounted for
– Temperature effects on mass MI of Rotor and the Gears are
neglected
– Shaft is assumed to be perfectly rigid
Plant model is developed based on the mentioned
assumptions
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Plant Modeling
Motor Dynamics [1]
Gear Train Kinematics
System Dynamics [2]
Eq. (4) and (16) are solved simultaneously using
MATLAB/SIMULINK, to predict the system performance
System Dynamics
On normalizing (15) can be re-written as follows
Where,
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Plant Modeling
Control Flow Diagram Input Parameters
Control flow diagram represents the way plant model is
developed in SIMULINK
Parameter Units
Jeqv Kg-m2
beqv N-m-sec
Tfeqv N-m
0eK Volts/RPM
0tK
Oz-in/Amp
0R Ohms
L Henry
B /deg.C
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Performance Analysis
System responses are verified against the design requirements
Normalized Angular Displacement Power Supply Demand
@ -
55
oC
, 2
8V
@ -5
5oC
, 28
V
@ 2
5oC
, 1
8V
@ 2
5oC
, 18
V
max: 1.01
min: 0.99
max:1.01
min: 0.99
Y=1.05
Y=1.06
0.92 secs
0.56 secs
0.035 secs
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Performance Analysis
Close Position error (%) Operation time (s)
Time duration for which the power supply
requirements exceeded 30W (ms)
Provided design recommendations based on simulation
predictions, to meet the performance requirements
Voltage
(V)
Temperature (deg. C)
-55 25 110
18 x 0.92 1.15
28 0.56 0.54 x
Voltage
(V)
Temperature (deg. C)
-55 25 110
18 x 0 0
28 35 0 x
Voltage
(V)
Temperature (deg. C)
-55 25 110
18 x 5.2 4.5
28 6.1 12.2 x
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Validation using Analytics
Validated simulation predictions using analytics, as the
study is carried out prior to prototype development
Normalized Angular Acceleration Normalized Angular Velocity
Normalized Angular Displacement
Operating Temperature: 25oC
Supply Voltage: 28V
to
tf
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Validation using Analytics
Considering initial time as the instant the power supply
is cut-off (t0=0.545s) and final instant as the moment
complete system came to rest (tf=0.69s)
Simulation results (acceleration & close position error)
are verified using following equations
Simulation Analytics
Y 27.5 27.5
Y 0.12 0.088
~25% variation in close position error is due to the fact that the
deceleration does not remain constant throughout, as assumed in
analytical calculations.
𝑌 𝑓2 − 𝑌 0
2 = 2𝑌0 𝑌
𝑌0 =1
𝐽𝑒𝑞𝑣𝜃𝑐𝑑(𝑇𝑀 − 𝑏𝑒𝑞𝑣𝑌0 𝜃𝑐𝑑 − 𝑇𝑓𝑒𝑞𝑣
)
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Conclusions & Recommendations
Valve will switch from Open to Close position in desired operation of time, at all operating conditions
The valve is travelling beyond the desired close position due to Inertia effects of the gear train
Close position error is observed to be higher than the acceptable value, at all operating conditions
Motor armature resistance & the damping coefficients are very high and hence operating at very low efficiencies in the desired operating range
Selecting a motor with low armature resistance and increased damping in the system could help in meeting the CTQ’s in Operation time as well as the Close position error simultaneously
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References
[1 ] R H. Welch Jr., G W. Younkin, “How Temperature Affects a
Servomotor's Electrical and Mechanical Time Constants,” Industry
Applications Conference, 37th IAS Annual Meeting, October 13-18,
2002.
[2] A.Tewari, “Translational Motion of Aerospace Vehicles,”
Atmospheric and Space Flight Dynamics, Birkhäuser Boston,
2007, ch.4, sec.4.4, pp.86.
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Appendix
Nomenclature
𝜃𝑐𝑑 − 𝑑𝑒𝑠𝑖𝑟𝑒𝑑 𝑝𝑜𝑠𝑖𝑡𝑖𝑜𝑛 𝑜𝑓 𝑡ℎ𝑒 𝑣𝑎𝑙𝑣𝑒