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TMS320F28035: Clark1.As

Part Number: TMS320F28035
Other Parts Discussed in Thread: TIDA-00366

I have designed my own PCB similar to TIDA-00366 using the F28035 microcontroller instead of the F28027.  I've run through all the levels in HVACI_Scalar completing Level3.  I've started running through the levels in HVACI_Sensored and currently have an issue with the current feedback reading for Phase U.  (Chips for Phase V and W feedback circuits haven't been populated yet.)   Originally I was using 0.005 ohm shunt resistors but I wasn't able to detect any voltage across it using a 1HP induction motor.  I swapped the 0.005 ohm resistors out for 0.100 ohm resistors and now have a detectable sine wave on my oscilloscope that seems to behave as I would expect oscillating around 1.65V.  When I plot the Clark1. As data on a graph in CCS, I get the following graph:

What would cause this oscillation offset?  

  • Hello, thanks for reaching on this design. I have asked someone from the C2K team to take a look and get back to you. Please give a couple of days.

    Thanks,

    Robert 

  • I think I figured it out.  I changed the DSP data type in graphs from 16 bit unsigned integer to 16 bit signed integer.  That change generated the following graph:

    Then to shift it down, so the sine wave oscillates y=0, I modified the code from:

    clarke1.As = _IQmpy2(_IQ12toIQ(AdcResult.ADCRESULT1)-offsetA) to

    clarke1.As = _IQmpy2(_IQ12toIQ(AdcResult.ADCRESULT1)-offsetA+_IQ(.5))

    This generated the following graph with the sine wave oscillating about y=0:

    I have a feeling the polarity on my ADC is reversed.  How is the code for phase currents calibrated in HVACI_Sensored?  Does:

    1) 0V to 1.65V equat4e -10amps to 0 amps and

    2)1.65V to 3.3V equate 0amps to 10amps?

  • I have figured out the phase current calibrations.  

    My next question is regarding Level 2B - Adjusting PI Limits in HVACI_Sensored, specifically the line;

    "Run the system with default VdTesting, VqTesting and SpeedRef and gradually increase VdTesting and VqTesting values. Meanwhile, watch the current waveforms in the graph window. Keep increasing until you notice distorted current waveforms and write down the maximum allowed VdTesting and VqTesting values."

    Does this imply increasing VdTesting and VqTesting together until I notice a distorted current waveform or individually until I notice a distorted waveform by each variable while keeping the other variable constant at 0.2?

  • How is the code for phase currents calibrated in HVACI_Sensored?  Does:

    1) 0V to 1.65V equate -10amps to 0 amps and

    2)1.65V to 3.3V equate 0amps to 10amps?