TIDA-01606: TIDA-01606 Issues

Jiahui,

1.

on the control card, you can set the VREF option to 3.3V using the SW2 and SW3.  check out the C2000 control card user's guide. If you use the 3.0V option, you will need more modifications.

i believe 3.3V vref will make your life easier as the the default design was really intended for 3.3V operation.   After that you can determine the full scale value for a max ADC input in terms of voltage. For example, given a 3.3V at the ADC input, you expect to have 1000V at the VBUS.  you need to figure out this by looking at the circuit.

Put that max value into the main.syscfg.  TINV_VBUS_MAX_SENSE_VOLTS will be automatically updated in the tinv_settings.h.

in the code tinv.h the conversion from filtered ADC value to voltage:

TINV_vBus_sensed_Volts =TINV_vBus_sensed_Filtered_pu *
TINV_VBUS_MAX_SENSE_VOLTS;

as you can see, the TINV_VBUS_MAX_SENSE_VOLTS will affect your final value.

2.  the SW has thresholds for the frequencies, you can change it in the tinv_user_settings.h:

#define TINV_UNIVERSAL_GRID_MAX_FREQ 65
#define TINV_UNIVERSAL_GRID_MIN_FREQ 45

-kelvin

Hi kevin，

Thanks for your quick reply.

as in the previous question
What we are asking is not how to set it to 3.3v and adjust SW.
But in the settings of the SDK, there are these two lines in tinc_user_dettings. h
#Define TINV-ADCP_PU_SCALE_FACTOR (float32_t 0.000244140625) This 0.000244140625 is derived from 1v/2 ^ 12, but aren't we using 3.0v (or 3.3v)? Why use 1V?
#Define TINV_SD32pU_SCALEFACTOR ((float32ut) (1.0/((float32ut) TINV_SDFM-OSR * TINV_SDFM-OSR * TINV_SDFM-OSR), which is also based on 1V? Where did this 1V come from?
2. The setting TINV-UNIVERSAL_GRID-MAX-FREQ has been effective in our initial use.
May I ask, what is the maximum upper limit that can be set for him?

Thank you very much for your help.
Additionally, we previously mentioned the issue of inaccurate measurements, and I would like to consult with you regarding the current section in tinv-user_settings. h
#define TINV_IGRID_MAX_SENSE_AMPS ((float32_t)21.3)
How did this value of 21.3 come about? Because we were unable to purchase the R47 2M resistor in the original schematic, we replaced it with a 1M resistor.
So should the value of 21.3 be modified to be larger? Is inaccurate current measurement related to this issue?

Hi expert，

Any updates？

Hi Jiahui,

Apologies for the delay.  The AMC1306M05 has a maximum input measurement range of +/-64mV before clipping (The recommended input range is +/-50mV).

If we have a 2mohm current sense resistor, the max current before clipping is +/-64mV/2mohm = +/-32A.

So you will have to update TINV_IGRID_MAX_SENSE_AMPS to 32 or else there would be a gain error.

Now if you have 1mohm resistor instead, TINV_IGRID_MAX_SENSE_AMPS = 64A.  However, the 1606 reference design was only designed to support up to 16Arms of current.  you have to keep that in mind.

this is the 2mohm part I"m using for my new design: WSKW06122L000FEA.  I would recommend you use a shunt that optimize for full input range 16Arms*1.41 = 22.5A.  So a 2mohm would be good to give you some margin on top of the peak current.

-Kelvin

1.

TINV_ADC_PU_SCALE_FACTOR basically normalizes the 12-bit ADC reading to a fraction of 1 (full scale).  The idea is to make the code modular.  you can always convert a normalized value to an absolute voltage or current reading with the max_sense_amps or max_sense_volts scaling factor.

2.  I think if you want to go higher, it will depends on what Vripple, THD, etc. you want.  right now, if you have 50khz fpwm and 50hz grid freq, the ratio is 1000:1.  higher inverter output freq, will require higher fpwm.  higher fpwm will impact the design (inductors, capacitors etc.)   remember that you're trying to produce a nice sine wave from switching pwm.  so the resolution of the sine wave will be affected by how fast you switch.

-Kelvin

Hi, Thank you very much for your help.
What is the maximum upper limit that can be set for TINV_UNIVERSAL_GRID-MAX-FREQ?
I didn't make it clear before that we are not going to output frequencies exceeding 60Hz, as this is a bidirectional system,
We have a generator that outputs 3-way AC power at 100~380Hz, so we use tida-01606 to convert this input power into DC power.
So when you want to know as input, What is the maximum frequency of TINV_UNIVERSAL_GRID-MAX-FREQ? 

The design was only rated & validated for 50 to 60 Hz.  But I think you can probably get away with 100 Hz.  You can try it.  The only concern is the increased reactive load / capacitive current.  you will need to make sure that the system can handle the increased current.

-Kelvin