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Evaluating the EVM with GUI
12.6.2
Tuning PID Coefficients for Loop Compensation
When making fine-tuned adjustments to the feedback control loop, knowing how each PID parameter
affects the control loop characteristics without using the complicated equations in
Use
Table 9
and
Figure 40
Control Parameters
K
p
K
K
d
α
T
= 1 / ƒ
s
Increasing f s causes the whole Bode plots to shift to right
Pole 1
K
I
Zero 1
13
Evaluating the EVM with GUI
The collective graphical user interface (GUI) is called TI's Fusion Digital Power Designer (FDPD). The GUI
serves as the interface for several families of TI's digital-control ICs including the UCD31xx family, (such
as UCD3138). The GUI is divided into two main categories, Designer GUI and Device GUI. Each
UCD31xx EVM relates to a particular Designer GUI allowing users to re-tune and re-configure a particular
EVM with existing hardware and firmware. Device GUI relates to the accessing of internal registers and
memories of a particular device.
The UCD3138PSFBEVM-027 is used with the UCD3138CC64EVM-030 control card where the UCD3138
device is placed. The firmware for control is loaded onto UCD3138CC64EVM-030 board through the
Device GUI. The user's guide, Using the UCD3138CC64EVM-030 (SLUU886), describes the GUI
installation. The Designer GUI is installed at the same time as installing the Device GUI.
44
Using the UCD3138PSFBEVM-027
as a quick reference for tuning PID coefficients.
Table 9. Tuning PID Coefficients
Increasing K
pushes up the minimum gain between the two zeros, moving
p
the two zeros apart.
Increasing K
pushes up the integration curve at low frequencies, provides a
i
i
higher low-frequency gain, and moves the first zero to the right.
Increasing K
shifts the second zero left with no impact on the second pole.
d
Increasing α shifts the second pole and the second zero to the right.
Increasing the sampling frequency ƒ
s
K
P
Frequency
Figure 40. Tuning PID Parameters
Copyright © 2013, Texas Instruments Incorporated
Impact on Bode Plot
shifts the whole Bode plot to the right.
s
K
Zero 2
www.ti.com
Table 8
is beneficial.
Pole 2
D
SLUUAK4 – August 2013
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