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How the "base phase frequency" of SMOPOS module in Hercules Motorware foc_encoder_speed ?

Hiroyasu Matsubara
Expert 1405 points
Other Parts Discussed in Thread: MOTORWAREHello, I'm wondering about a parameter , that is included in Hercules Motorware solution "foc_encoder_speed". The place of the "foc_encoder_speed" is "C:\ti\Hercules\MotorWare\v1.0.3.03\sw\solutions\foc_encoder_speed\boards\drv8301kit_revD\hercules\src". The definition of the parameter I would like to know is , "base phase current " of the function "SMO_POS_Init". It is written in line 165 of "drv.c". That is : " drv->smoPosHandle = SMO_POS_init((void *)&drv->smoPos, sizeof(drv->smoPos), 0.36, 0.0002, 38.29, 10.3125, period);" In this sentence ,the value "10.3125" is the "base phase frequency". I tried to know how it is decided with teknic motor data sheet,but I couldn't understand. Is anyone could tell me how the "base phase frequency" of the SMO_POS_Init is defined ? I would appriciate if someone could reply. Regards, Hiroyasu
  • 0
    TI__Guru 59540 points

    Hello Hiroyasu,

    I have forwarded your question to our motoware expert. They get back with you shortly.

  • 0
    TI__Genius 13810 points

    No, it is not the base Frequency. It is the "base current", we use this number to normalize the measured phase current.

    10.3 is defined becasue: if the ADC measures a phase shunt current 0 or 3.3v (dynamic range of the plug in control card), it represents -10.3A or 10.3A.

    The base frequency of this setup is 230, which means 230*60/4 = 3450RPM. The motor itself can run 6000rpm or higher. But, the power supply in the kit is only 24v. The back EMF of the motor is 4.6v/1000rpm, once running at 4000rpm, the back EMF will be 18.4v, we still need to reserve some voltage to generate the toque. That is why we define 230 as the base frequency. If you want a higher base frequency, you can:

    1. use other power supply, e.g a 36v DC power supply, or

    2. use field weakening to increase the current consumption but reducing the back EMF. Then, be care for of hitting the current limit of the power supply.

    Regards,

    Haixiao

  • 0 in reply to Haixiao Weng
    Expert 1405 points
    Dear Haixiao, Thanks for your reply. I'm sorry to mistype the parameter name. As you said,the correct parameter name is "base phase current." I would like to ask additional quetion about the function parameter "SMO_POS_init". How the "base phase voltage".in the avobe example, the value "38.29" is defined ? If it is concerned with the "DC Bus Voltage" ? I'll appriciate if you could reply to my quetion. Regards, Hiroyasu
  • 0 in reply to Hiroyasu Matsubara
    TI__Genius 13810 points

    Hiroyasu,

    it is the maximum ADC measurable DC Bus(66.32V)/sqrt(3).

    Regards,

    Haixiao

  • 0 in reply to Haixiao Weng
    Expert 1405 points

    Haixiao,

    Thanks for your reply.

    I could understand.

    Regards,

    Hiroyasu