« Back to main help
PE-iLAB
- Help - Software
1. Introduction
The PE-iLAB is an educational system consisting of hardware and software to
teach students the basic operation of switching converters as well as their
digital control. The software (interface) is explained in this help file.
2. General Controls
The general controls are always visible and can be accessed independent of
the currently selected tab. They include:
- Status message display
- Combo box of available COM ports
- "Run" button
- "Stop/Reset" button
- "Demo mode" check box
- "Enable moving averaging" check box
- "Always Log data" check box
- "Receiving" and "Sending" labels
2.1. Connecting to hardware
The software will automatically detect all the available COM ports on the
computer and try to connect to the first one. If that fails, the user can
manually select the COM port where the hardware is connected to. The combo
box for that is located at the bottom left of the interface. Once the
connection to the hardware was successful, that combo box won't be accessible
anymore and the background color of the "Receiving" label will be red.
2.2. Running and Stopping the converter
Clicking the "Run" button starts the converter with the currently selected
options (Open or Closed Loop, Connected or Demo mode) and values. Stopping
the converter can be done by clicking the "Stop/Reset" button or hitting
ESC.
Note: The converter only runs
with the interface. If it is closed, the converter will be stopped in any
case.
2.3. Switching to Demo mode
The interface can also simulate expected values of the converter. In this
case the hardware doesn't need to be connected. Demo mode can be enabled by
checking the "Demo mode" check box. The following extra controls will be
visible:
- Input voltage
- Output current
- Converter efficiency
Demo mode is explained in detail
here.
2.4. Moving averaging
By checking the "Enable moving averaging" check box the interface
will perform a moving average of all the ADC measurements received from the
controller. This will smoothen the display of the values in the
"Measurements" group box but also slow down the display once there are fast
changes of the values.
2.5. Data logging
If the "Always Log data" check box is enabled, the interface will always log
data even if the converter is not running. See "
Data Log
Tab" for more information.
2.6. "Receiving" and "Sending" labels
A red background color of the "Receiving" label shows that the interface
is receiving data (hardware is connected), otherwise the color is grey.
A green background color of the "Sending" label shows that the interface
is sending data, otherwise the color is grey. It will always try to send data
unless it is in Demo mode.
2.7. Status messages
Status messages are displayed on the left of the "Run" button to make using
the software as convenient as possible. The following information is shown in
separate lines:
- General status shows one of following information: converter running,
stopped, operating conditions changed, fault happened
- The number of entries in the data log
- Configuration file loaded or not
- Calibration file loaded and/or whether calibration of the system is
needed
3. Main Interface Tab
The main interface tab has all the controls to run the converter and the
displays to get all the feedback from it. The user can switch between "Open
Loop" and "Closed Loop", set parameters for each mode and watch the
measurements in a table.
3.1. Open Loop
In Open Loop the duty cycle is the only parameter to be changed.
3.2. Closed Loop
In Closed Loop the output voltage has to be set first. The user can select
one of the following controller types:
- P-controller
- PI-controller
- PID-controller
Different gain settings are available and are enabled or disabled depending
on the selected controller type.
3.3. Converter options
- The switching frequency can be changed when the converter is stopped
and is then used once the "Run" button is clicked again
- Synchronous switching can be enabled thus forcing Continuous Conduction
Mode (CCM) mode of the converter under all load conditions, otherwise the
converter will run in Discontinuous Conduction Mode (DCM) if there is
only a light load
Note: The converter fails to run properly in DCM with
very light load due to the driving circuit for the high-side MOSFET. In that
case the output voltage will not stay constant.
3.4. Measurements
The following measurements are shown in a table:
- switching frequency
- output voltage
- input voltage
- output current
- input current
- duty cycle
The following calculations are also displayed in the table:
- input power
- output power
- efficiency
The table also has check boxes to change the update and logging functions.
By default, all values will be updated and logged. But sometimes it is
desirable to analyze only certain values. By unchecking the update check box
of the other values, the values of interest are requested more often which
can help for evaluation. Since the power and efficiency are calculated, they
also won't be updated anymore if the respective voltages or currents are not
updated. Furthermore the user can decide which values to log by checking or
unchecking the "Log" check box. If updating of some values is disabled, but
the user still wants to see if they have changed, the "Request all values at
once" button can be clicked to update all values for one time.
3.5. Demo mode
When Demo mode is enabled, extra controls will be visible to set theoretical
values for input voltage, output current and converter efficiency. In open
loop the assigned duty cycle will determine the output voltage whereas in
closed loop the assigned output voltage will set the duty cycle, both based
on the input voltage. All the calculated outputs will show up in the
"Measurements" table once the "Run" button is clicked.
4. Data Log Tab
When the converter is running, data will be logged. If "Always Log data" is
checked, logging will continue at all times. The state of the "Update check
boxes" in the "Measurements table" determines which data is logged. For
performance issues, the log table will be invisible once logging is active
and becomes visible again after logging is finished. The top of the "Data
Log" tab shows the starting time of the log, a "Store data" button as well as
a "Clear" button. Each log will be stored in a subdirectory called "Logs" if
the "Store data" button is clicked or if the converter is stopped. The first
column shows the time gone by in minutes (min):seconds (sec):milliseconds
(ms) since the log started. A green background color of that column shows
that the converter was running, otherwise it is light-red.
5. Options Tab
"General Options":
- "Fast Timer Update": - it determines how fast data is requested from
the controller
- "Communication Timeout": - the software will try to connect to the
hardware during this time with the selected COM port, if it fails,
another COM port can be selected from the list
- "Clear Log after # of entries": - the log will be stored to a file and
cleared once the number of log entries reaches the specified number
"Warning levels and Protection":
If the converter reaches the specified warning levels, the background of
the related cells in the "Measurements" table will turn red as well as in the
log. The user can also choose to have the converter automatically turned off
from the interface once the warning levels are reached.
The DSP also has an over current protection for the input and output which
triggers at 6A. This protection can be enabled or disabled from the
interface. It is recommended to have it enabled. But for closed loop
experiments where the controller is made unstable it can be disabled to avoid
false triggers.
6. Calibration Tab
The voltage and current sensing circuits for each hardware have slightly
different characteristics. Therefore the interface can be calibrated to show
more accurate measurements of the connected hardware. If no calibration was
done, the interface will use default values and display in the status message area that a calibration is recommended. The
following values can be calibrated:
- Input voltage
- Output voltage
- Input current
- Output current
The calibration steps are: (repeat for each value to calibrate)
- Make sure a multimeter is set up to accurately measure the value for
calibration (see Hardware help)
- Select value to calibrate from the drop-down list
- Adjust it to a suggested "Low" value (suggestion displayed in the
numeric up-down box)
- Enter the exact value from the multimeter into that numeric up-down
box
- Hit the "Acquire" button and don't change the value while the
aquisition is in progress
- Adjust it to a suggested "High" value (suggestion displayed in the
numeric up-down box)
- Enter the exact value from the multimeter into that numeric up-down
box
- Hit the "Acquire" button and don't change the value while the
aquisition is in progress
- Done! The calibration data is stored for that value.
Notes:
- Converter needs to be running to calibrate output voltage, input and
output current
- Disable the "Stop converter, if warning levels reached" check box in
the "Options" tab while calibrating because that protection function
could turn off the converter and make the calibration data invalid
- In addition, a variable load needs to be applied to the converter to
calibrate input and output current
- Current measurements are noisier and therefore more sensitive to
changes in the operating conditions; because of that, separate
calibration data for the input- and output current for each switching
frequency can be generated and used
7. System Log Tab
The system log shows messages with time stamps from the interface since it
was started. This helps to keep track of the history of the converter
including possible faults. There are buttons to clear the log or save it to a
file inside the subdirectory "Logs".
8. Appendix
8.1 Pictures of the Interface


Figure 1: Examples of interface: Left: Main interface tab with converter
running, right: Data Log tab showing measurements after converter is
stopped
8.2 Keyboard shortcuts
- Esc - Stop converter
- Ctrl-Tab - Cycle through tabs
- Tab - Cycle through active controls on current tab page
- Space bar - Change state of active check box
- Up/Down - Small change on slider bars, pre-defined change on numeric
up-down controls
- Page Up/Down - Big change on slider bars
- F1 or Alt-H - Open help file
- Alt-F4 - Close the interface
Note: Starting the converter will focus either the
"output voltage" slider in Closed Loop or the "duty cycle" slider in Open
Loop. Thus after the user clicks the "Run" button, the respective slider can
immediately be changed using the keyboard.
« Top
« Back to main help