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TMS320F28054M: USER_SYSTEM_BANDWIDTH issue

Gb Adesiyun
Prodigy 40 points

Part Number: TMS320F28054M
Other Parts Discussed in Thread: TMS320F28069M, TMS320F28068M

Hi,

I'm working on a project where I need to increase the stiffness of the motor to improve the stability of the system. I came across the variable, USER_SYSTEM_BANDWIDTH while reading through the InstaSpin Labs and I can see that this variable directly controls the stiffness so I increased the value for my project from 80.0 in small increments until 160.0 where the system is more stable. 

 

Could you explain what this term means exactly and could you explain the implications of changing this term so that I can understand how my system would respond to the increase in bandwidth? I'd also appreciate it if you can provide resources to read to undestand the impact of changing the bandwidth. What parameters in the PID control loop are directlty affected by changing the bandwidth? What is the the unit for bandwidth and what is the explanation behind that?

 

Thanks,

GB

  • 0
    TI__Mastermind 24871 points

    Hi,

    This bandwidth variable is measured in rad/s. You can find more information about this in the TMS320F28069M, TMS320F28068M InstaSPIN-MOTIONTm Software User's Guide. This bandwidth is for single-variable tuning of the control loop. The control loop feedback gains are backwards calculated from mechanical plant model such that the control loop behaves like single-pole/dual-pole LP system. When you increase the bandwidth, the derived Kp/Ki are also increased so the controller reacts faster and resists disturbances more.

    Regards,

    Peter