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MOTORWARE: Variable switching frequency

Javier Vara
Expert 1595 points
Part Number: MOTORWARE
Other Parts Discussed in Thread: TMS320F28069, C2000WARE, CONTROLSUITE, POWERSUITE

Hello,

We are currently running an inverter based on Motorware 18 and TMS320F28069. We would like to know if it is possible to vary the switching frequency in real time and if it is, how? I am aware that the switching frequency macro in user.h is used in many places around the code for things like the interrupt service routine and so on which makes me worry about the effect of trying to vary that in real time.

The reason to change the switching frequency in real time is to reduce the switching losses of the inverter when the motor is running at low speeds and increase the switching frequency only when it is necessary to run higher speeds.

Regards

  • 0
    Guru 26200 points
    Hello Javier,
    I have no experience with MOTORWARE,
    however I think you should check this link: e2e.ti.com/.../319433
  • 0 in reply to Tomasz Kocon
    Expert 1595 points

    Hi Tom,

    Thanks for the answer but I am afraid it doesn't answer the question. The question is not about how to choose the switching frequency but rather about how, if possible, to vary that value during runtime.

    I hope someone else can help me here.

    Regards,

  • 0 in reply to Javier Vara
    TI__Genius 17175 points
    Javier

    The feature you are asking about is not offered by default for Motorware 18. The reason is, as you alluded to, that the ISR and CTRL frequencies are intrinsically tied to the PWM frequency when it is set during initialization. We will be releasing an example of how to change PWM frequency during run-time with the Motor Control SDK release in 2019. Until then, my recommendation for you would be to take the following approach - tie the CTRL frequency to an independent timer module instead of the PWM timer. You will need to do some experimentation on your end as we do not have a reference code available today.

    Sean
  • 0 in reply to Sean Bigley
    Expert 1595 points

    Sean,

    Thanks for the answer. Can I ask, how does the Motor Control SDK relate to Motorware? Are they the same thing? Compatible?

    Also, where can I find this SDK? I have tried to look for it and I couldn't find it.

  • 0 in reply to Javier Vara
    TI__Genius 17175 points
    Motor Control SDK is the successor to Motorware. C2000 is moving away from the traditional software packages (ControlSUITE, PowerSuite, Motorware) to a new format known as C2000Ware. C2000Ware is available today, as is the Digital Power SDK. Motor Control SDK is not available yet, it will be released at the end of the first quarter of 2019. One major change that precipitated a need for a new software development kit was that the InstaSPIN estimator ROM will move from fixed point to floating point format. As a result, Motor Control SDK examples will not be compatible with existing InstaSPIN devices (F2802x, F2805x and F2806x families). The F28004x family of devices will be the first InstaSPIN devices supported by Motor Control SDK. Motorware is frozen at version 18 and will not receive any additional updates.

    Sean
  • 0 in reply to Sean Bigley
    Expert 1595 points

    That makes things clear. Thanks for the answer Sean.

    Regards,