Why is the load torque greater than the motor torque for a single phase asynchronous machine in SimPowerSystems 4.1.1 (R14SP3)?

I use a capacitor-start run single phase asynchronous machine to study the effects of an applied load torque of 0.25N and find the input motor torque to be less than this value. I would expect the output torque to be less than its input.

Answer 1

[MathWorks Support Team]

This enhancement has been incorporated in Release 2006b (R2006b). For previous product releases, read below for any possible workarounds:

There is a bug in the Single Phase Asynchronous Machine block in SimPowerSystems 4.1.1 (R14SP3) in the way that it handles the load torque and the motor torque.

To work around this issue, download the attached M,P files from the zip file and perform the following installation instructions:

1. Copy and replace the first four P-coded files into your $MATLAB/toolbox/physmod/powersys/powersys/private/ directory.

(where $MATLAB is the MATLAB root directory on your machine, as returned by typing

matlabroot

at the MATLAB Command Prompt.)

2. Copy and replace the file named getSPSMaskValues.p into your $MATLAB/toolbox/physmod/powersys/powersys/ directory.

3. Open the NewSPASMBlockForPowerlib.mdl model and follow the instruction provided inside the model.

4. Open the NewBlocksForPowerlibModels.mdl model and follow the instructions provided inside the model.