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TIDA-1007: phase shedding control details

Aki Li
Genius 9805 points

My customer wants to understand the details about the phase shedding control in TIDA-1007. Could you please help check the below questions?

1)  Did we implement the phase shedding and adding control during the zero crossing point? If so, if the load changes from light load to high load, how can it support fast transient response if it needs to wait for the zero crossing point?

2) Does it need to adjust the duty cycle during the phase shedding or adding? For example, if we change from 1 PH to 2 PHs, do we use the same duty cycle from the current loop for the both phases? 

Thank you.

  • 0
    TI__Mastermind 43730 points

    1. No we do not wait for zero crossing point, phases are added or removed based on the current command demanded from the voltage loop. This was a novel method we developed. 

    2. Currently, the control is not adjusted, hence in a single phase and 2 phase mode we do not have enough bandwidth for optimal performance. However, it did not impact the iTHD spec hence we did not spend time optimizing it. 

  • 0 in reply to Manish Bhardwaj
    TI__Genius 9805 points

    Manish,

    Thank you for the clarification. For the duty cycle adjustment during phase shedding or adding, do you know what the common optimization method is? Just want to share with customer the general idea for this.

  • 0 in reply to Aki Li
    TI__Mastermind 43730 points

    Aki 

    Given the loop is closed the compensator will take care of the duty adjustments as needed. 

    The issues is the compensator tuning is not ideal for the single-phase or two-phase mode because we assume the plant as equation 3, page 9 (notice the multiply by 3)

    Hence when we go in phase shedding the loop gain is lower in 1 phase and 2 phase mode. Some corrections can be provided for the same. Though is not implemented in the design. 

    -Manish