Download DC-link Voltage Control using a TI DSP. National Center of

DC-link Voltage Control using
a TI DSP.
National Center of
Research and
Technological
Development (CENIDET)
TI Innovation Challenge 2016 Project Report
Team Leader:
Gabriel Calderón Zavala
[email protected]
Team Members: Team Gabriel Calderón Zavala
Team
[email protected]
Advising Professor:
Rodolfo Amalio Vargas Méndez [email protected]
The penetration of the Wind Energy Conversion Systems (WECS) is connected to
the advancement of power electronics, which has permitted the development of
efficient and low cost WECS in the last decades. A WECS configuration that has great
attention is based on a doubly fed induction generator (DFIG) and a back to back
(B2B) converter, the back to back converter is constituted by a Rotor Side Converter
(RSC) and a Grid Side Converter (GSC).
The GSC control is based in the dq reference frame model. This model gives the
necessary equations to implement the control which is implemented in a TI
TMS320F28335 DSP.
Qty.
List all TI analog IC or
TI processor part
number and URL
1
TMDSDOCK28335TMS320F28335
This TI DSP is used in the acquisition of the sensors
signals and to give the commutation signals to the
IRAM IGBT modules.
3
HCPL2631
Optocouplers used to isolate the control stage from the
power stage. It provides the gate signals from the DSP
to the IRAM module.
3
TL084
It is used to condition the signals from the hall effect
sensors; it is also used to condition the voltage
sensors signals and to implement analog active filters.
1
TL082
It is used to condition the signals from the hall effect
sensors; it is also used to condition the voltage
sensors signals and to implement analog active filters.
1
ISO124
It is used to isolated the DC link voltage stage from the
control stage (TI DSP TMS320F28335).
1.- DFIG configuration system
B2B is constituted by a Rotor Side Converter (RSC), a grid side converter (GSC)
and a capacitive dc bus between both converters, see Fig. 1. In a grid connected
WECS based in a DFIG and a B2B, the RSC controls the transfer of active and
reactive power between the stator of the DFIG and the network, while the GSC
controls the reactive power through the converter and the voltage in the dc bus [1].
Fig. 1. WECS diagram based in a DFIG and a B2B
The DFIG three-phase model of the back to back converter can be written in a dq
arbitrary reference frame [2]:
𝑣𝑑𝑠 = 𝑟𝑠 𝑖𝑑𝑠 − 𝜔𝜆𝑞𝑠 + 𝜆̇𝑑𝑠
𝑣𝑞𝑠 = 𝑟𝑠 𝑖𝑞𝑠 + 𝜔𝜆𝑑𝑠 + 𝜆̇𝑞𝑠
𝑣𝑑𝑟 = 𝑟𝑟 𝑖𝑑𝑟 − (𝜔 − 𝜔𝑟 )𝜆𝑞𝑟 + 𝜆̇𝑑𝑟
𝑣𝑞𝑟 = 𝑟𝑟 𝑖𝑞𝑟 + (𝜔 − 𝜔𝑟 )𝜆𝑑𝑟 + 𝜆̇𝑞𝑟
𝜆𝑑𝑠 = (𝐿𝑙𝑠 + 32𝐿𝑚𝑠 )𝑖𝑑𝑠 + 32𝐿𝑚𝑠 𝑖𝑑𝑟
3
3
3
3
3
3
(1)
𝜆𝑞𝑠 = (𝐿𝑙𝑠 + 2𝐿𝑚𝑠 ) 𝑖𝑞𝑠 + 2𝐿𝑚𝑠 𝑖𝑞𝑟
𝜆𝑑𝑟 = (𝐿𝑙𝑟 + 2𝐿𝑚𝑠 ) 𝑖𝑑𝑟 + 2𝐿𝑚𝑠 𝑖𝑑𝑠
𝜆𝑞𝑟 = (𝐿𝑙𝑟 + 2𝐿𝑚𝑠 ) 𝑖𝑞𝑟 + 2𝐿𝑚𝑠 𝑖𝑞𝑠
where 𝑣𝑑,𝑞𝑠 and 𝑣𝑑,𝑞𝑟 are the stator and rotor voltages in the dq frame; 𝑖𝑑,𝑞𝑠 and 𝑖𝑑,𝑞𝑟
are the stator and rotor currents in the dq frame; 𝜆𝑑,𝑞𝑠 and 𝜆𝑑,𝑞𝑟 are the stator and
rotor flux linkages in the dq frame; 𝑟𝑠 is the stator resistance; 𝑟𝑟 is the rotor resistance;
𝐿𝑙𝑠 is the stator inductance; 𝐿𝑙𝑟 is the rotor inductance; 𝐿𝑚𝑠 is the mutual inductance;
𝜔𝑟 is the rotor speed; and 𝜔 is the angular speed of the reference frame.
2. DC link Controller
The process to design the DC link controller based in vector control is as
follows[3].
*
vdgl
 vds1   Liqg  vds 
*
vqgl
 vqs1   Lidg 
Where
vds1  Ridg  L
didg
dt
vqs1  Riqg  L
(2)
diqg
dt
(3)
The expressions from (3) where used to design the control for the GSC which can be
seen in Fig 2.
Fig. 2. GSC Control schematic.
Meanwhile, the DC link controller design comes from the dq reference frame
formulas and is given by:
C
ducd
3

m1idg
dt
4 2
(4)
From this expression the controller to regulate the dc bus is designed and is in
cascade with the controller in (3).
3.- DC link control Implementation
Now, some images of the dc-link control implementation are showing.
In figure 3 the voltage sources used to energize all the circuits involve in the
implementation are depicted; it worth to mention that TMS320F28335 SCI interface
was used to visualize in real time some important data processed by the DSP.
Fig. 3. Voltage sources and SCI interface.
In figure 4 it can be appreciated all the stages involved to control de dc-link bus voltage.
Fig. 4. Implementation for the dc-link bus voltage control.
4.- Results
After all the analysis realized in relation with the abc model of the GSC, the
reference frame model and the control scheme, it was possible to carry out a real
implementation based mainly on the DSP TMS320F28335. The main objective of the
control was to regulate tha dc-link bus voltage at 80 volts. Figure 5 shows how this
objective control was reached.
Fig. 5. Dc-link bus voltage controlled to 80 volts. (Channel multiplied x10).
5.- Bibliography
[1]
G. Calderón, J. Mina, and A. López, “Modelado y simulación de un Sistema de Conversión de Energía
Eólica de velocidad variable interconectado a la red eléctrica .,” XVI Congreso Latinoamericano de
Control Automático, 2014.
[2]
R. Pena, J. C. Clare, and G. M. Asher, “A doubly fed induction generator using back-to-back PWM
converters supplying an isolated load from a variable speed wind turbine,” IEE Proc. - Electr. Power
Appl., vol. 143, no. 5, p. 380, 1996.
[3]
R. Pena, J. C. Clare, and G. M. Asher, “Doubly fed induction generator using back-to-back PWM
converters and its application to variable-speed wind-energy generation,” IEE Proc. - Electr. Power
Appl., vol. 143, no. 3, p. 231, 1996.