Archive | Software

Manual Control via the push button

Back to the HVPS User Interface

If you want to control manually the output of the HVPS using the push button located on the board or on the enclosure, use the following configuration:

Configuration to control the output with the push button

  1. Switching source set to button.
  2. Voltage control mode: internal regulated control (this leads to accurate output voltage, according to the calibration file of the HVPS). You can change voltage control mode (4) only if the voltage set point (5) is 0V, and the source output (1) is off. It should be kept on regulated except for very specific applications.
  3. Set the desired voltage with either the knob control(3a), or the digital control (3b).

There are two different behaviour for the push button: latching (switch mode) or non-latching (push-button mode). The button behaviour can be set using the HVPS option button (red square in image below), and then selecting latching or non-latching mode using the Button behaviour control (blue rectangle in image below).

Behaviour of the push button

Latching (switch) mode:

In this mode, the button on the PCB (s1) or on the enclosure panel acts like a switch: the state of the output (on at the programmed voltage/off) can be toggled by pressing and releasing the button. Press and release once to turn the output on. Press and release again to turn the output off.

Non-latching (push-button) mode:

In this mode, the output is on when the button is pressed, and off when it is released. You need to keep the button pressed to keep the output on.

The two different behaviour are illustrated in the figure below.

 

Button behaviour in non-latching (left) and latching (right) modes

When the output is controlled manually using the button (switching source set to button as illustrated in the first image above with 1.), the GUI doesn’t know if the output voltage is on or off. Consequently, and as a safety precaution, the GUI HV indicator will be permanently turned on to warn the user that high voltage can potentially be present at the HVPS output. The onboard red HV LED (d3) however indicates the true state of the output.  It will indicate whether the input is on or off, which is especially useful when the button mode is set to latching.

When the output is controlled manually using the button (switching source set to button as illustrated in the first image above with 1.), the main controls of the GUI On/Off, as well as DC/Switching/Waveform have no effect. The signal is directly controlled by the button.

Finite number of switching cycles

Back to the HVPS User Interface

To produce a finite number of cycles (burst of pulses), use the following configuration:

Configuration to generate a finite number of switching cycles

  1. Source output : either on or off (see text below).
  2. Switching mode: Switching.
  3. Switching source: internal timer.
  4. Voltage control mode: internal regulated control (this leads to accurate output voltage, according to the calibration file of the HVPS). You can change voltage control mode (4) only if the voltage set point (5) is 0V, and the source output (1) is off. It should be kept on regulated except for very specific applications.
  5. Set the desired voltage with either the knob control(5a), or the digital control (5b)
  6. Set the desired frequency in Hz. The frequency range is 0.001 Hz to >1kHz.
  7. Place this button on the right.
  8. Enter the number of cycles that you want to make (maximum value: 65535)
  9. Allows to restart a series of cycles

If the button (1) is on, a series of cycles is being made, and you can follow the progression on the Current HVPS parameters part of the interface. Once the series of pulses has been made, the HVPS turns off, and button (1) reflects this by being set to the off state. There are 3 ways to restart a new series of pulses once the HVPS has finished the previous series:

  • By pressing on button (9)
  • By pressing on button (1) to re-enable the output
  • By pressing the push button (s1) on the HVPS enclosure. Unlike the two previous methods, the user interface is not aware if a new series of cycles is started using the button. The interface will not change state to reflect that the output is enabled again, but the high voltage LED D3 on the PCB should be blinking again (or be solid red if frequency is high). Consequently, it is recommended that you use one of the two methods above to restart the pulses. However, the button is the only way to restart a series of pulses when the HVPS is used without a computer.

While a series of pulses is being made (button (1) is on), pressing on button (1) to turn the output off pauses the generation of pulses (0V at the output). When you press (1) again, the HVPS resumes the burst of pulses where it was paused. You can also press on your keyboard space bar if the interface window has the focus to toggle the state of button (1).

If you change the number of pulses in control (8) while the HVPS is producing a burst of pulses, the counter will restart from 0 up to your newly defined value.

Continuous Switching mode

Back to the HVPS User Interface

To generate a continuous square wave, switching between 0V and a user-defined voltage at a user-defined frequency, use the following configuration:

Continuous switching configuration

  1. Source output on (default setting when starting the interface).
  2. Switching mode: Switching.
  3. Switching source: internal timer
  4. Voltage control mode: internal regulated control (this leads to accurate output voltage, according to the calibration file of the HVPS). You can change voltage control mode (4) only if the voltage set point (5) is 0V, and the source output (1) is off. It should be kept on regulated except for very specific applications.
  5. Set the desired voltage with either the knob control(5a), or the digital control (5b).
  6. Set the desired frequency in Hz. The frequency range is 0.001 Hz to >1kHz.
  7. Place this button on “infinity” to have continuous switching (default setting when starting the interface.)

Button (1) allows to easily turn the HVPS on/off, i.e. to toggle the output voltage between the voltage defined in (5) and 0V. You can also press on your keyboard space bar if the interface window has the focus to toggle the state of button (1).

DC voltage output

Back to the HVPS User Interface

To generate a constant output voltage, use the following configuration:

Configuration for DC voltage output

  1. Source output on (default setting when starting the interface).
  2. Switching mode: DC mode (default setting when starting the interface).
  3. Switching source: internal timer.
  4. Voltage control mode: internal regulated control (this leads to accurate output voltage, according to the calibration file of the HVPS). You can change voltage control mode (4) only if the voltage set point (5) is 0V, and the source output (1) is off. It should be kept on regulated except for very specific applications.
  5. Set the desired voltage with either the knob control (5a), or the digital control (5b).

Button (1) allows to easily turn the HVPS on/off, i.e. to toggle the output voltage between the voltage defined in (5) and 0V. You can also press on your keyboard space bar if the interface window has the focus to toggle the state of button (1).

In addition to these settings, the 6VDC power jack must be plugged in, and the high voltage enable switch (s2) must be in position 1 in order to have high voltage at the output.

Limit the output voltage

Back to the HVPS User Interface

Limit the output of the HVPS

When sensitive devices are connected to the output of a HVPS, such as a dielectric elastomer actuator, it can be desirable to limit the output voltage of the HVPS to prevent against a wrong manipulation on the front panel. This can be done on the HVPS options dialogue, which you can access by clicking the tool button at the top right of the interface (red rectangle).

In the displayed dialogue box, enter the voltage limit into the Safety limit box (blue rectangle), and click on close (green rectangle).

Then, as illustrated on the figure below, when the user enters a voltage set point (green square) higher than the limit, the HVPS limits the set point to the safety value (blue square). The field is blinking to attract the user’s attention to the fact that the chosen set point is not being respected. The feedback voltage (red square) shows that the output voltage is indeed limited to the defined value.

Effect of the voltage safety limit

When you define a limiting voltage, it will be enforced the next time you change the voltage set point. For example if the HVPS has a set point of 4kV with no safety limit, and a safety limit is then defined at 3kV, the output voltage will not drop to 3kV. However, next time you change the voltage set point (for example going from 4kV to 3.9 kV), the limit is enforced, and the output voltage drops to 3kV.

Connection and context help

up one level to HVPS User Interface

1 Connection to the HVPS

Connect the HVPS to the 6VDC power adapter and to a computer with the USB cable (refer to setting up the HVPS).

Open HVPS_interface_vx.x.exe (for PC) or OSX_HVPS_interface_vx.x.app (for mac). If it fails to open, or if the HVPS doesn’t appear in the interface, please be sure you have all the required drivers and software components (see Interface installation and prerequisites).

  • If no HVPS is connected to the computer, a small connection box shows that no HVPS is available (see picture below, left)). You can hot-plug your HVPS if you forgot to do so before launching the interface. If your HVPS is plugged in, but the interface says No HVPS available, be sure you have all the required drivers and software components (see Interface installation and prerequisites).
  • If more than one HVPS are connected, the connection box displays a drop-down list of available HVPS (picture below, right). You can select the one you want and then press on the Connect button. It is possible to connect to more than one
    HVPS simultaneously.

    Left: connection box displayed if no HVPS is connected/recognized. Right: connection box displayed if more than one HVPS are connected.

  • If a single HVPS is connected to the computer, the connection dialogue box is not shown, and communication is automatically initiated with the connected device.

If you forget to plug the power adapter, a dialogue box pops up to remind you to do so. Plug the 6VDC adapter and close the dialogue box.

Reminder that the Power adapter must be used

The following screenshot shows the interface once the communication with two HVPS is established. The connection dialogue on the left shows no HVPS to connect to, as communication has already been established with the two HVPS connected to the computer. Pressing the disconnect button on the interface of each HVPS (bottom right) makes it possible to close the communication with this unit and makes it available again in the connection dialogue. Pressing the Stop button of the connection dialogue closes all open interfaces.

Interface with two HVPS connected

The left part of the interface are the controls to change the settings of the HVPS. The central part, named current HVPS parameters indicates the current setting of the HVPS. Changing a control on the left side should be matched by a change of the indicator on the right side, showing that the HVPS has correctly accepted your command. The commands are accessible at all time. For example, you can set the frequency, even when the HVPS is in DC mode. It has no direct effect, but when you change to switching operation, the frequency that you previously entered is applied. The indicators on the current HVPS parameters part of the interface are greyed out when the HVPS is in a mode in which this particular indicator is not applicable. For example, in DC mode, the indicators Frequency and Cycles are disabled.

2 Context help

The description of the controls and indicators of the interface is included in the program itself. Hovering the mouse over a field displays a short tooltip. For a more detailed explanation, the help button located at the bottom right of the interface displays a help window with additional explanation on the different elements.

Context help

3 On/Off buttons

There are two on/off buttons:

  1. The hardware on/off switch (or high voltage enable) (Switch S2 on the PCB) which directly acts on the high voltage DC/DC converter. It is a purely mechanical switch: when it is in the position 0, it is physically impossible to have high voltage at the output of the HVPS. The switch should be on 0 when the HVPS is manipulated, or to connect a device to the output leads. Once everything is connected, you can safely place this switch on position 1.
  2. The GUI on/off button located at the top left of the interface. Pressing this button makes it possible to quickly change from no output, to the programmed output (DC, square signal, …). Pressing the space bar when the interface window has the focus toggles the state of this button, allowing the user to quickly turn the HVPS on/off by one keyboard key press. This is a software button. In case of a communication problem with the HVPS, or other unforeseen event, the output may not reflect the position of this switch. Consequently, even if this button is on the off position, you must also place the hardware switch S2 (High Voltage enable) on 0 before manipulating the output leads.

This means that to have high voltage at the output of the HVPS, 4 conditions must be met:

  1. The 6 VDC power jack must be plugged
  2. The hardware switch s2 must be in position 1
  3. The software on/off switch must be on
  4. A voltage set point higher than 0 must be defined

PID tuning

It is assumed that you have connected a configured HVPS to the calibration setup described on the automatic calibration and characterisation page.

The voltage of the HVPS is controlled with a PID regulator. Defaults parameters are defined in the config.ini file for the 5 models of HVPS described on this website (5kV, 3kV, 2kV, 1.2kV, and 500V) and stored into the HVPS when you perform the initial configuration. The parameters are chosen with an emphasis on avoiding voltage overshoots (which can be fatal to Dielectric Elastomer Actuators), rather than on speed. The default parameters can be fine-tuned to you liking.

  • On the HVPS option dialogue box, press the PID Tuning button.
  • To perform a test, enter a value for each coefficient (the default values are the current settings stored on the HVPS) and then press the start button.
  • The test takes a few seconds. At the end, you should see a curve on the two graphic indicators

    The test is done at from 0% to 100% (High amplitude step) and from 0% to 20% (Low amplitude step) of the maximum voltage output. An panel matching the colour of the curve gives indications on the rise time and overshoot of the steps. These parameters are automatically calculated by LabVIEW and are not always logical.
  • You can repeat tests by changing the parameters Kp, Ki, and Kd and press on the Test button. Up to 5 different tests can be displayed simultaneously on the graphs, which makes it possible to compare different settings.
  • In the examples above, the blue and red tests are not good, as they lead to voltage overshoot. The green is fine, albeit slower.
  • The selector wheel on the bottom right allows you to choose which of the 5 displayed test you want to keep and gives the possibility to store the values of the parameters Kp, Ki, and Kd in the HVPS.
    Pressing the Save button:

    • Saves the PID values of the test selected with the wheel selector “PID test to keep” to the SHVPS EEPROM.
    • Saves the data (graph and numerical results) to the excel file
    • Closes the window.

    Pressing the Cancel button:

    • Restores the initial PID value of the HVPS (i.e. the value that were used when the PID testing window was first opened)
    • Doesn’t save any result to the excel file
    • Closes the window.

Automatic voltage calibration

It is assumed that you have connected a configured HVPS to the calibration setup described on the automatic calibration and characterisation page.

  • On the HVPS option dialogue box, press the Voltage Calibration button (yellow rectangle)
  • Check that the probe indicated in (1) corresponds to the probe you are using for the calibration. If this is not the case, you need to press cancel (3), and edit line 2 of the config.ini file to point to the probe you are using (refer to section 2.2 of the automatic calibration and characterisation page).
  • Be sure that the high voltage enable switch (s2) of the HVPS is in the on position
  • Start the calibration process by pressing start (2). Alternatively you can can cancel the process (3), which will close the window.
  • The true (measured) output voltage of the HVPS is plotted as a function of the voltage the HVPS reads on (5). This takes about 1 minute. Once the process has finished, correction factors will be calculated, and indicator (6) shows the error between the voltage read by the HVPS and the measured voltage after calibration (so this should ideally be 0, but nothing is perfect in this world).
  • Indicator (7) shows the current calibration factor stored in the board. If you have just reset the board to default settings, the second and 0 order terms should be 0, and the first order term should be the default value as described in column c1 of the resistor ratio table.
  • Indicator (8) shows the new calibration factors obtained by linear regression on the acquired data (5). It is a second order polynomial of the form c2 x^2 + c1 x + c0. The three indicators corresponds to the parameters c2, c1, and c0 stored in the HVPS
  • Button (9) allows you to toggle between quadratic and linear correction (in the latter case, c2 is forced to be 0). You can see the effect on the error (6) when you change from linear to quadratic.
  • Check box (10) allows you to turn on or off the offset of the correction. If unchecked, c0 is forced to 0. The impact can be seen on the error on (6). Usually, you have much better accuracy with a quadratic fitting with offset enabled (default settings).
  • To keep the new calibration values you just obtained, click on (11). This option is greyed out until the calibration process is over.
  • Click on (12) to discard the new calibration values and keep the previous values shown on (7). This option is greyed out until the calibration process is over.
  • The program waits until you press either (11) or (12). You must choose one of these two options for the program to continue

  • A new calibration is performed, this time in closed-loop mode, using the selected calibration values. For a range of voltage set points between 5% and 95% of the board rated voltage, the voltage read by the HVPS and the true (measured) voltage are plotted on graph (13). Ideally, this graph should show two superposed straight lines with equation y=x.
  • The graph (14) displays the error between the HVPS read voltage (white) and the measured voltage (red) as a function of the desired set point. The white curve should be close to 0 (within +/- 0.2 percent of the board rating). The red curve shows the real error between the voltage the user sets and the true output voltage of the HVPS. It should be within +/- 0.5% of the board voltage rating).
  • Once the measurement is finished, the button (15) is enabled. Pressing on it allows to close the window and go back to the main interface. The calibration value you selected is saved in the HVPS memory, and a file with the calibration data is saved in the support directory.

Interface installation and prerequisites

You need to install the drivers for the micro-controller if you haven’t done it yet.

1 Version table

SHVPS firmwareMHVPS firmwareGUIPCBVersion summary
91.52.9v4b2, v4b3, v6b1Improved python interface and python library of functions
81.42.8v4b2, v4b3, v6b1python interface. Standalone version with battery.
71.32.7, 2.7.1v4b2, v4b3, v6b1Initial release of the PetapicoVoltron project

It is important to match the version of the firmware running on the SHVPS microcontroller to the PCB board version, and then the GUI version to the firmware of the HVPS. The table above lists the compatible version. Be sure to download the correct versions

2 PC

  • Copy the folder Windows installer from the download page to your computer, taking care to download to the interface version adapted to your board/firmware. Please refer to the version table above.
  • Launch the installer. By default the interface files are installed in the folder c:\HVPS_interface.
  • Once the installation is finished, launch HVPS_interface_vx.x.exe which will be located in the folder created during the installation. An entry is also created in the windows launch menu for convenience.

3 PC: Update to newer version

If you want to install a newer version of the interface on a computer that already has a version of the interface, you can run the installer of the new version.

If you are using the library in one of your projects (see below), you will need to replace the old version of the library file by the new one. There should be nothing to change in your programs.

4 Mac

The Mac version of the user interface is provided for convenience and is not guaranteed to work perfectly. We do not provide support for the Mac version of the interface. One known issue is that dialogue boxes tend to pop up behind the main window, and remain hidden to the user, unless the main window is moved.

If you don’t have Labview for Mac installed on your computer, you need to install the LabView Runtime Engine. You also need to install NI-VISA for Mac. You’ll find links to the NI website for these two components on the download page, alongside the OSX app.

Once these two components are installed,  copy OSX_HVPS_interface_vx.x.zip to your computer. Unzip the archive into your application folder and launch it from there.