Power output mismatch in simulating electric drivetrain, where expected power flow is Pbatt>Pdcd​c>Pdcac>Pm​otor,. I dont see that in my simulation.

Hi All,

I am simulating an electric drivetrain for marine application , where after designing the models I need to export the models to FMU . I am using the simscape electrical models, however , since I need to export , I have packaged them as susbsytem (using voltage and current measurement outputs as output and input signals)before connecting them to the other models in the drive train rather than directly connecting them in the electrical sense.

I have noticed that , when I directly connect the simscape models I/Os of say motor, converters etc , I see that the drivetrain works as expected in the sense, power flow is as expected i;e.,Pbatt>Pdcdc>Pdcac>Pmotor . However, If I use the subsystems to connect the models and run the simulation , I see a different behavious in the start and also the values of the Power outputs from each block , current etc mismatch.

Initially , I thought should be some intial value setting . But after I made sure the inital values are keyed in correctly , still I wasnt getting the results properly.

I need some help to resolve this issue from the community who has dealt with similar issues or can help me identify where it is going wrong.

I have attached my simulatio and parameters file , with screen shots of the scopes to look at.

Thanks in advance.

[Yasho Bharat]

@MathWorks Support Team, can you give any insights on this ?

Answer 1

[S@m]

Hi Bharat,

When Simscape components are packaged as subsystem and connected via I/O ports, the physical connections are replaced with signal-based connections. This breaks the physical continuity of the model. So, physical laws like Kirchhoff’s law are no longer consistent over the entire Simscape network. Instead, consider using network couplers to split the model, with retaining the physical connections. This would resolve the different behaviour issue. For more information on network couplers, refer the below link.

https://www.mathworks.com/help/releases/R2024b/simscape/ug/using-network-couplers-to-split-physical-networks.html

Secondly, exporting individual subsystems of a network to FMU is currently not supported in Simscape. The whole Simscape network can be exported.