# A Low Energy Consumption Solar Tracker based in Parallel Kinematics

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13 Νοε 2013 (πριν από 4 χρόνια και 8 μήνες)

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Introduction
Description of the Mechanism
Operational Mode for Low Energy Consumption
Design of the Mechanism
Conclusions
A Low Energy Consumption Solar Tracker
based in Parallel Kinematics
O.Altuzarra,I.Seras,E.Macho,J.Aginaga
Universidad del País Vasco - Euskal Herriko Unibestritatea
Department of Mechanical Engineering,Bilbao
Romansy,Paris,June 2012
Introduction
Description of the Mechanism
Operational Mode for Low Energy Consumption
Design of the Mechanism
Conclusions
Outline
1
Introduction
2
Description of the Mechanism
3
Operational Mode for Low Energy Consumption
4
Design of the Mechanism
5
Conclusions
2/19
Introduction
Description of the Mechanism
Operational Mode for Low Energy Consumption
Design of the Mechanism
Conclusions
Introduction
Solar Trackers are mechanisms
with two rotational degrees of
freedom.
The rotational requirement is
very high:90

elevation,180

east to west.
There is a 50%surplus of energy
obtained with such device.
Standard facilities move panels
every 20 minutes or so.
Continuous tracking is a key
point for Concentrated
Photovoltaics Technology.
3/19
Introduction
Description of the Mechanism
Operational Mode for Low Energy Consumption
Design of the Mechanism
Conclusions
Motivation
Problem Statement
How can we obtain a continuous tracking with a minimum
energy cost,minimum actuators,and maximal photovoltaic
surface?
Objectives
Find an alternative mechanism based in parallel
kinematics to increase photovoltaic surface.
Find a way to reduce the actuation to the minimum.
Find an operational mode to reduce the energy cost of
tracking.
4/19
Introduction
Description of the Mechanism
Operational Mode for Low Energy Consumption
Design of the Mechanism
Conclusions
Description of the Mechanism
Two P
RRR kinematic chains,
i = 1,2.
Two P
RRS kinematic chains,
i = 3,4.
The middle line of the moving
platform is a planar mechanism
on the XZ plane.
Reference point P has a ﬁxed
coordinate Y = 0.
Revolute joints avoid any rotation
of the moving platform about the
direction of its perpendicular
j ×(c
1
−p).
5/19
Introduction
Description of the Mechanism
Operational Mode for Low Energy Consumption
Design of the Mechanism
Conclusions
Description of the Mechanism2
Principal Screws are:
^
\$
p,1
=
￿
0
i
￿
^
\$
p,2
=
￿
0
k
￿
^
\$
p,3
=
￿
j
c
1
×j
￿
^
\$
p,4
=
￿
c
1
−p
0
￿
Wrench sustained by platform:
^
\$
r,1
=
￿
j
0
￿
^
\$
r,2
=
￿
0
j ×c
1
−p
￿
Dimensioning has been done for
workspace optimization.
6/19
Introduction
Description of the Mechanism
Operational Mode for Low Energy Consumption
Design of the Mechanism
Conclusions
Description of the Mechanism3
P
RRR kinematic chains,i = 1,2.
P
RRS kinematic chains,i = 3,4.
Mechanism doubled for a better
constraint.
7/19
Introduction
Description of the Mechanism
Operational Mode for Low Energy Consumption
Design of the Mechanism
Conclusions
Kinematic Analysis
Constraints:
_
p ∙ j = 0 ω ∙ [j ×(a
1
−p)] = 0
Output variables:
_
p =
_
xi +
_
zk
ω =
_
θj +
_
ψ
c
1
−p
r
Restriction Jacobian:
_
x =
￿
ω
_
p
￿
=
￿
c
1
−p
r
j 0 0
0 0 i k
￿

_
ψ
_
θ
_
x
_
z

= J
r
_
s
8/19
Introduction
Description of the Mechanism
Operational Mode for Low Energy Consumption
Design of the Mechanism
Conclusions
Kinematic Analysis
Loop Closure equations:
(c
i
−b
i
) = p +R(c
i
−p) −a
i
−(b
i
−a
i
),i = 1,...,4
Differentiation:
ω
i
×(c
i
−b
i
) =
_
p +ω ×(c
i
−p) − _ρ
i
k
Eliminate Passive variables:

i
[(c
i
−b
i
) ∙ k] = (c
i
−b
i
) ∙ _p +ω ∙ [(c
i
−p) ×(c
i
−b
i
)]
Jacobian equation:
J
x
J
r
_
s = J
q
_
q
9/19
Introduction
Description of the Mechanism
Operational Mode for Low Energy Consumption
Design of the Mechanism
Conclusions
Operational Mode of the Mechanism
Operation:
Raise the panel at night.
Place in position for
sunrise releasing brakes.
Drop the panel
controlling brakes.
Drop completely in case
of strong winds.
Dimensions:
Height:9 meters
Diameter:10 meters
Weight:2000 kilograms
10/19
Introduction
Description of the Mechanism
Operational Mode for Low Energy Consumption
Design of the Mechanism
Conclusions
Design of the Mechanism:Sliding lengths
11/19
Introduction
Description of the Mechanism
Operational Mode for Low Energy Consumption
Design of the Mechanism
Conclusions
Design of the Mechanism:Sliding lengths
12/19
Introduction
Description of the Mechanism
Operational Mode for Low Energy Consumption
Design of the Mechanism
Conclusions
Design of the Mechanism:Angle with guides
13/19
Introduction
Description of the Mechanism
Operational Mode for Low Energy Consumption
Design of the Mechanism
Conclusions
Design of the Mechanism:Angle with guides
14/19
Introduction
Description of the Mechanism
Operational Mode for Low Energy Consumption
Design of the Mechanism
Conclusions
Design of the Mechanism:Angles with platform
15/19
Introduction
Description of the Mechanism
Operational Mode for Low Energy Consumption
Design of the Mechanism
Conclusions
Design of the Mechanism:Checking performance
P
RRR kinematic chains,i = 1,2
16/19
Introduction
Description of the Mechanism
Operational Mode for Low Energy Consumption
Design of the Mechanism
Conclusions
Design of the Mechanism:Checking performance
P
RRS kinematic chains,i = 3,4
17/19
Introduction
Description of the Mechanism
Operational Mode for Low Energy Consumption
Design of the Mechanism
Conclusions
Conclusions
A new 4 DoF parallel
mechanism.
A very high rotational
capability.
Parasitic motions to be
carefully considered.
Combine Kinematic and
Dynamic optimization.
18/19
Introduction
Description of the Mechanism
Operational Mode for Low Energy Consumption
Design of the Mechanism
Conclusions
A Low Energy
Consumption Solar
Tracker based in
Parallel Kinematics
O.Altuzarra,I.Seras,E.
Macho,J.Aginaga
Universidad del País Vasco - Euskal
Herriko Unibestritatea
Department of Mechanical
Engineering,Bilbao
19/19