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Does the TI InstaSPIN current sensing method support LEM current sensor at U/V/W of motor?

Neo Chang1
Prodigy 10 points
Other Parts Discussed in Thread: MOTORWARE

Dear Chris:

             Our IGBT module is 3 in1 function module(include rectifier,brake IGBT and inverter IGBT*6),and Emitter of 3 low side IGBT are shorted together in module inside,so we cannot apply 3 shunt current method to measure phase current.

    It's seem that we only can measure 3 phase current at U/V/W phase directly ! So now we apply Hall sensor (LEM current sensor) method to measure current.

Could you tell us does the TI InstaSPIN current sensing method support LEM current sensor at U/V/W of motor? or we can modify S/W to support it and where should we modify it?

Thanks

  • 0
    TI__Guru** 119580 points

    Neo Chang1 said:
    Could you tell us does the TI InstaSPIN current sensing method support LEM current sensor at U/V/W of motor?

    Yes.

    Neo Chang1 said:
    or we can modify S/W to support it and where should we modify it?

    There are only a couple things to modify

    1. With phase current sensing, you only need 2 (U, V) as the 3rd can always be deduced from U + V + W = 0, and you can always measure the 2 currents.
      1. in user.h set #define USER_NUM_CURRENT_SENSORS            (2)
      2. If you want to use the 3rd you can...no harm
    2. You still need to take the output of your current sensor and create a signal between 0 and 3.3V, centered at 1.65V for the input to the ADC channels
    3. You need to tell the software if the current is negative or positive, see SPRUHJI chapter 5.2
      1. this mentions the drv.h file, in MotorWare _12 we renamed this to hal.h
    4. You obviously need to modifty the user.h current scaling to the values you are able to measure
      1. #define USER_ADC_FULL_SCALE_CURRENT_A        (82.5)   // this measure +/- 41.25A
      2. #define USER_IQ_FULL_SCALE_CURRENT_A          (41.25) // set to > 0.5 * USER_ADC_FULL_SCALE_CURRENT_A

    That's it.  Works great!  If you want to use full modulation see chapter 10 of the InstaSPIN Labs document on changing the modulation limit.

    Also, there are serveral posts on this topic if you search:

    http://e2e.ti.com/support/microcontrollers/c2000/f/902/p/287319/1017434.aspx