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Three-phase Three-level NPC Converter - 3. Panels
Section Content
3.1. Understanding the Panels
When starting the demo, the panel in Figure 10 below appears first with the default settings.
Figure 10: Start-Up Panel - Inverter Mode Scenario
The panel is to be operated while following the three steps below:
Step 1: Select Scenario
In the upper left corner, the student can select the scenario using the three tabs:
- Inverter Mode
- LC Filter
- Rectifier Mode
Step 2: Change Parameters / Switch Buttons
In the lower left corner, the student can change the control parameters and can switch the control buttons (to enable/disable their associated functions) in the following categories:
- Scope Parameters
- Protection
- DC Source
- Inverter Parameters
- AC Source
Table 3 below summarizes the control parameters, while Table 4 in this page is dedicated for the control buttons.
Step 3: Observe Waveforms
On the right side, the student can observe the waveforms displayed in four scopes.
Additionally, the power flow, the fundamental voltage and total harmonic distortion (THD) for inverter and load are displayed.
More details are given in Tables 5 and 6 in this page.
Control Parameters | Default Value | Interval of Variation |
|---|---|---|
DC Source Vdc (V) | 120 | [90; 160] |
PWM Frequency (Hz) | 3000 | [900; 3000] |
Reference Amplitude/modulation | 0.8 | [0; 0.8] |
AC-source Amplitude (V) | 70 | [0; 100] |
AC-source Frequency (Hz) | 60 | [0; 60] |
AC-source Phase Shift (Deg) | 0 | [-90; 90] |
Table 3: Control Parameters
Note
The “Save File” under Scope Parameters allows the student to give different file names for data acquisition, while the “Switch (50 Hz/60 Hz)” allows to select a reference frequency for power, THD and RMS computation.
It is possible to save up to eleven .mat files with the name “FileSavedcurrents_X (where X can be anywhere from 0 to 10).
The student can give X values via the “Save File”, and press “Data Acq.” for acquiring data.
The data acquired can be used for offline harmonic studies.
The saved data are in the following folder:
C:\OPAL-RT\TestDrive\v2.9.0.16\Models\Package4_CPU\package4_cpu_sm_master\OpNTtarget
Control Buttons | Associated functions | |
Trigger |
| The waveforms are not triggered. They “move” |
| The waveforms are triggered with respect to a reference signal. | |
This button is accessible and enabled in all scenarios | ||
SYNCHRONIZE |
| The reference frequency is fixed to 60 Hz (or 50 Hz). |
| The reference frequency used for the PWM generator is dictated by the AC-source frequency. | |
This button is disabled in Rectifier Mode scenario | ||
Apply Deadtime |
| The dead-time is not applied in the control of the switches. |
| The dead-time is applied in the control of the switches. | |
This button is disabled in Rectifier Mode scenario | ||
Connect Filter |
| The capacitors mounted in delta configuration are disconnected from the circuit. |
| The capacitors mounted in delta configuration are connected to the circuit, thus enabling the LC filter. | |
This button is accessible in LC Filter and Rectifier Mode scenarios | ||
PWM_DISABLE |
| The PWM generator is enabled, and the commands are sent to the IGBTs. |
| The PWM generator is disabled; the diodes are the sole conducting elements. | |
This button is accessible in Rectifier Mode scenario only | ||
APPLY_RECT_LOAD |
| The resistive load is disconnected at the output of the rectifier, on the DC side. |
| The resistive load is connected at the output of the rectifier, on the DC side. | |
This button is accessible in Rectifier Mode scenario only | ||
Data Acq. |
| Data acquisition is disabled. |
| Data acquisition is activated and allows to record .mat files for offline studies, in particular harmonic analysis. | |
This button is disabled in Rectifier Mode scenario | ||
Reset |
| The reset push button is disabled. |
| The reset push button is activated and simulates replacement of fuses after a fault. | |
This button is accessible and enabled in all scenarios | ||
HELP / BACK |
| Open the Help page associated to the scenario currently running. |
| Close the Help page and go back to the simulations. | |
This button is accessible and enabled in all scenarios | ||
Fuse |
| The protection fuse is blown. |
| The protection fuse is intact. | |
Switch |
| Reference frequency for PWM generation, 50 Hz or 60 Hz. |
Table 4: Control Buttons and LED fuse status indicators
On scope localization, the indices used will be like those of matrix elements.
Hence, the scope located in the upper left corner (first row, first column) is denoted Scope11, while the scope in the upper right corner (first row, second column) is Scope12.
By the same token, the scope in the lower left corner is Scope21 while the scope in the lower right corner is Scope22.
Table 5: Content of Scopes and Displayed Waveforms
Three power displays are available in all the scenarios.
They are located below the scopes in the observation section.
From left to right they are identified as Display1, Display2 and Display3.
They refer to the power measurements described in Section 2.7.
Additionally, two RMS voltage displays and two THD (related to inverter and load currents) displays, referred to as Display4 to Display7, are located below the scopes of Inverter mode and LC Filter scenarios.
Finally, an extra display, referred to as Display8, is available for RMS filter current in the LC Filter scenario.
Scenario | Display | Content of Displays |
|---|---|---|
LC Filter | Display1 | DC Power released by the DC source at the input of the inverter |
Display2 | AC Power at the output of the inverter | |
Display3 | AC Power absorbed by the three-phase AC load | |
Display4 | RMS of fundamental inverter voltage (line-to-line) | |
Display5 | RMS of fundamental load voltage (line-to-line) | |
Display6 | THD of inverter current | |
Display7 | THD of load current | |
Display8 | RMS of fundamental filter current | |
Rectifier Mode | Display1 | AC Power released by the AC source |
Display2 | AC Power at the input of the rectifier | |
Display3 | DC Power absorbed by the DC Load |
Table 6: Content of Displays
Consequently, the power dissipated in the LC Filter and the converter bridge can be deduced as shown in Table 7 below.
Scenario | Difference | Description |
|---|---|---|
LC Filter | Display1 - Display2 | Power dissipated in the inverter bridge (IGBT/Diodes) |
Display2 - Display3 | Power dissipated in the LC Filter | |
Rectifier Mode | Display1 - Display2 | Power dissipated in the LC Filter |
Display2 - Display3 | Power dissipated in the rectifier bridge (diodes only) |
Table 7: Power Dissipated in LC Filter and Converter Bridge
3.2. First Scenario - Inverter Mode With Load: R, L, Back-EMF
When starting the demo, the panel corresponding to the Inverter Mode scenario opens by default as shown in Figure 10.
A concise scheme of the circuit is given below the tabs in the scenario selection area.
More details on the circuit, the control parameters, and buttons, as well as the observed waveforms are available when clicking the Help button.
The student can directly start exercises related to the Inverter Mode, available in Section 4.2.
3.3. Second Scenario - Adding LC Filter at the Inverter Output
When clicking on the “LC Filter” tab, the panel in Figure 11 below is displayed.
Figure 11: Second Panel - LC Filter Scenario
By clicking the Connect Filter button, the student activates the LC filtering and can start the exercises of Section 4.3 that are associated with this scenario.
3.4. Third Scenario - Rectifier Mode
When clicking on the “Rectifier Mode” tab, the panel of Figure 12 below is displayed.
Figure 12: Third Panel - Rectifier Mode Scenario
Note that by clicking the PWM_Disable button, the DC Source is disconnected and the PWM generator is disabled.
Consequently, the first category of control parameters, namely, “DC Source and PWM parameters” is automatically disabled.
The same applies to the buttons SYNCHRONIZE and Apply Deadtime.
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