Modular Multilevel Converter
Figure 3: Scheduling task in the Coder Options
Multi-tasking
If the
Tasking mode
is configured as
Multi-tasking
the physical model is split into
three different tasks and those tasks are associated with the three available CPU cores of the RT Box
2/3, as shown in Fig. 3.
The physical model is split as follows:
• Core 0: AC Grid and phase inductance/resistance and DC bus
• Core 1: All high-side sub-cells and DC-link capacitors
• Core 2: All low-side sub-cells and DC-link capacitors
To allow this system splitting, the physical model has to be split at strategic locations by using a
coupling circuit. To do so, a controlled current source is placed in one part of the model and a con-
trolled voltage source in the other part. Both sources are controlled by the respectively measured volt-
age/current state variables from the other part of the model. To avoid state/source dependence, one
measured signal has to be delayed by one discretization step. This approach is shown in Fig. 4.
A
z
-1
V
1
2
3
4
Figure 4: Circuit to allow physical system splitting
The individual CPU load for each core becomes smaller and due to this, the average execution time
can be reduced considerably. A reduced discretization step size leads to a better frequency resolution,
3
