TIDM-1000: A debugging issue

Chen Jiang ti : Can you please answer this question?

Hi Katherine,

Katherine Wang said:

1. When the load is 200 ohms, the input phase voltage is 120V, and the output DC voltage is 400V. When the BUILD2 current loop is established, ilref=0.2, the measured phase current waveform is as shown in the picture, and the reference voltage cannot reach 400V. What is the reason for the current fluctuation? 

Are all the ADC sensing correct in build 1? for build 2, you will start from ilref=0.05. Is everything ok at that time? is this issue only happen when you increase ilref to 0.2?

Can you also attach a pic to show the expression window when you see this issue?

Katherine Wang said:

2. Overcurrent protection occurs during the test, and what is the reason for this?

We need to know the above info to debug the issue.

Katherine Wang said:

3. Can the powerstageoff in line 174 be changed to powerstageon? What is the function of this line?

Those are just some values to show the system status. I don't think that will impact your performance.

Regards,

Chen

Hi Chen,

1. All ADC sensing values ​​in build1 are correct, but in build2, no matter what the reference value of the current is, the bus voltage cannot be stablized at 400V, and there will also be problems with current fluctuations.

2. Because the official program does not mention where to modify the value of ilref, it is not clear what caused the triggering of the overcurrent protection.

Regards,

Katherine

Hi Katherine,

Katherine Wang said:

2. Because the official program does not mention where to modify the value of ilref, it is not clear what caused the triggering of the overcurrent protection.

The initial value is set in vienna.c. And you should be able to tune this value for build 2 current loop.

VIENNA_iLRef_pu = 0.05f;

Katherine Wang said:

1. All ADC sensing values ​​in build1 are correct, but in build2, no matter what the reference value of the current is, the bus voltage cannot be stablized at 400V, and there will also be problems with current fluctuations.

If the ADC values are correct. you can then check the current ref and may plot it if needed. If the ref is also correct, check the control function for build 2.

Regards,

Chen

Hi Chen,

This value can be adjusted for the current loop. The problem is, no matter what the customer adjusts, the current will fluctuate and the output voltage will be less than 400V.

Thanks,

Annie

Hi Chen,

May I know is there any suggestion for this request?

Thanks,

Annie

Hi Annie,

Sorry for the late reply. Is the issue still exist? 

It is really related to three parts: Sensing/control loop/PWM from software side but it could be be h/w issue(if they have another EVM or power supply). Pls check my below question last time. 

"If the ADC values are correct. you can then check the current ref and may plot it if needed. If the ref is also correct, check the control function for build 2."

Regards,

Chen