TIDM-1000: Single phase and two phase failure recovery

Hi Joseph, 

In TIDM-1000 the trips are for board protection. Any unbalance in a phase will bring high inrush currents into the system. Ideally, there's risk involved if PWMs continue after the trip which you are expecting.

Is there a specific scenario you are wanting this? without trips enabled and expecting an unbalance is not an ideal case.

Thanks & Regards,

Uttam

I don't want to generate PWM during single phase failure. I just want to generate the PWM once the input was recovered from single phase failure (all phase applied).

Just to be clear.

Once the trip occurs (irrespective of CBC/OST) which sets the clear-tripflags, You are looking to clear the tripflags automatically (which brings up the PWM operation) after validating if your inputs are recovered or not? Is that the correct interpretation

If thats the case, you can create a custom logic. 

1. separate the tripflags for EPWMs then use below

keep the counter limit & condition to validate the inputs is ok.

Thanks 

Uttam

Thanks for your reply.

I using the logic by sensing the V1meas_rms. If any of the RMS voltage is less than 70V, I am tripping the PWM and in else condition i am giving vienna_clear trip=1.

The logic is working. But the problem is once recovered from single phase failure I probed the inductor current and PWM duty, the PWM generating is close to 80-100% so within 8 PWM pulses the inductor current increases rapidly and getting current limit.

I just want to know whether anything we need to consider in PWM duty calculation while recovering from single phase failure condition. (Since the logic is working (i.e PMW generating) but the duty was seems to be abnormal since within 6 PWM pulses the current increases above the current limit).

Another observation I found it is if I power on with only two phases applied the PWM is not generating ( as I am expecting) and when I give all the three phases PWM is generating the output voltage is stable (As I am expecting). But when make a single phase 0 voltage in live condition and giving 115Vrms in live condition the current trip is happening as I explained above.

Can you please suggest whether any other parameters we need to consider while giving clear trip once it recovered from single phase failure.

Hi Joseph, 

Currently we dont have AC drop feature enabled for TIDM1000 which is what you need. so, increase in inductor current is expected. Please refer to AC drop test of PMP23069 (single phase system) design which uses state machines for implementation. 

power on with only two phases applied the PWM is not generating: Existing control code checks if all phases are enabled or not in the software then clears the trip flag for all PMWs. 

You need to implement for three phase system as per your needs.

Thanks & Regards,

Uttam

Thanks for your reply.

Can you please let me know how the code is checking all phases are enabled. By sensing the voltage or current or frequency.

Because I dont see anything like that in code. There is initialization as all phase enabled equals to 1 and nowhere else the variable was used in the code.

Hi Joseph,

Sorry there a mistake from my end. the s/w doesnt validate if its enabled or not, its the user who needs to define it. 

 assuming all_phase_enabled =1; clear the EPWM trips 1/2/3.

In else case: there is no s/w defined for check phase which is needed.

Since the s/w is made assuming 3 phase balance supply. Incase of any faults (your case 1ph is lost) > current trip happens since there is large amount of current drawn across the phase which is seen in your case. so you need to modify/add some line of code which serves the purpose.

Another observation I found it is if I power on with only two phases applied the PWM is not generating ( as I am expecting) and when I give all the three phases PWM is generating the output voltage is stable (As I am expecting). But when make a single phase 0 voltage in live condition and giving 115Vrms in live condition the current trip is happening as I explained above.

Thanks & Regards,

Uttam

Hi Joseph, 

Closing this thread due to inactivity, Please create another thread for futures queries. 

BR,

Uttam