SPRAD32 May   2022 AM2631 , AM2631-Q1 , AM2632 , AM2632-Q1 , AM2634 , AM2634-Q1

 

  1.   Trademarks
  2. 1Introduction
  3. 2AM26x FOC ISR Benchmarks
  4. 3Typical Application Scenarios for Traction Inverters
    1. 3.1 Sample ADC in Cycle 0 and Update PWM in Cycle 1
    2. 3.2 Sample ADC in First Half of Cycle 0 and Update PWM in Second Half of Cycle 0
  5. 4Summary
  6. 5References

3.2 Sample ADC in First Half of Cycle 0 and Update PWM in Second Half of Cycle 0

In this case, feedbacks can be collected at 20 kHz with 10 kHz PWM. For the 10 kHz resolver, both peak and valley can be sampled and used after processing. The 3.9 µs excution time is about 7.8% of half PWM period, 50 µs. Similar to Figure 3-1, there is still more than 50% time from a single core left for customized operations if it is preferred to keep the time on the FOC ISR less than 60% of single core usage.

Figure 3-2 Sample ADC in First Half of Cycle 0 and Update PWM in Second Half of Cycle 0

On the other hand, in another case, 20 kHz PWM and 20 kHz resolver, the interrupt service routine will be operated at 40 kHz. 3.9 µs is about 16% of half PWM period, 25 µs. There is still more than 40% time if the ISR is limited by 60% of single core usage. If there is 40 kHz resolver, with 40 kHz PWM, the numbers can simply be scaled to 32% on basic control loop and 28% for customized operations. If it is 20 kHz resolver and 40 kHz PWM, the percentile on basic control loop should be reduced slightly by distributing resolver and speed loop among two cycles of current loop.