TMS320F28069F: Motorware 17 Default VsRef

For lab 16&17, please refer to user.h which a description about USER_MAX_VS_MAG_PU. The maximum USER_MAX_VS_MAG_PU is 0.6666 ( means 2/3). Often, we set the maximum USER_MAX_VS_MAG_PU to 0.5 for a pure sine waveform control, and set gMotorVars.VsRef to _IQ(0.8 * USER_MAX_VS_MAG_PU) for leaving a margin to enable field weakening control. You can set USER_MAX_VS_MAG_PU to other value which is less than 0.5.

Yanming,

Thanks for your reply.  I understand the use of overmodulation for the most part, but what I wanted to know specifically is the importance of the 0.8 multiplier.

As an example, could I run Lab 4 (which has no overmodulation), setting my USER_MAX_VS_MAG_PU to 0.5, but could I then change my gMotorVars.VsRef to _IQ(1.0* USER_MAX_VS_MAG_PU) if I don't plan to use field weakening?

You are right. You can set to any value is less than or equal to 0.5 if you didn't use field weakening as Lab09. The 0.8*USER_MAX_VS_MAG_PU value means the threshold of Vs for field weakening in lab09.

Yanming,

Thanks for all of your useful feedback. Since in this current application I will not be using field weakening or overmodulation, I will set my Vsref to 0.5.

However, I do have another test I want to do where I will use field weakening.  Can you explain why 0.8*USER_MAX_VS_MAG_PU is necessary for field weakening?  Couldn't I still use a 0.5 Vsref maximum even during field weakening?

Thanks!

Chris

Thanks so much for all your help Yanming!

Hi,Yanming:
If you wants to use FWC algorithm in motorWare, you have to set the VsRef<0.5 to enable a delta between VsRef and Vs to implement FWC.
As you sad,is there any reference about the VsRef ?why VsRef <0.5?how to calculate the VsRef?

Hi,Luo yanming:
You can set USER_MAX_VS_MAG_PU to other value which is less than 0.5.
In my motorware. the user.h define the USER_MAX_VS_MAG_PU to 1.0. not 0.6666 ,not 0.5.
In the main.h set gMotorVars.VsRef to _IQ(0.9 * USER_MAX_VS_MAG_PU). now I want to use FW control.which one should I change?change USER_MAX_VS_MAG_PU?or change gMotorVars.VsRef ?

Below is motorware user.h code:
//! \brief Set USER_MAX_VS_MAG = 1.0 for a pure sinewave with a peak at SQRT(3)/2 = 86.6% duty cycle. No current reconstruction is needed for this scenario.
//! \brief Set USER_MAX_VS_MAG = 2/SQRT(3) = 1.1547 for a pure sinewave with a peak at 100% duty cycle. Current reconstruction will be needed for this scenario (Lab10a-x).
//! \brief Set USER_MAX_VS_MAG = 4/3 = 1.3333 to create a trapezoidal voltage waveform. Current reconstruction will be needed for this scenario (Lab10a-x).
//! \brief For space vector over-modulation, see lab 10 for details on system requirements that will allow the SVM generator to go all the way to trapezoidal.
#define USER_MAX_VS_MAG_PU (1.0) // Set to 1.0 if a current reconstruction technique is not used. Look at the module svgen_current in lab10a-x for more info.