AC Current Sensing Hardware
Sensing the current from the AC output load is conceptually similar to sensing the DC input current, but includes an additional intermediate step. Instead of directly providing analog voltage samples that correspond to a current reading from the TMCS1108 to the ATMEGA328P, the samples are first delivered to the second input channel of the ADC122S021.
The ADC122S021 offers higher levels of resolution and better sampling performance compared to the ATMEGA328P’s built-in ADC channels. This improvement is particularly beneficial for monitoring the AC output current signal, which carries greater importance for waveform control and feedback than the DC input current. The control loop feedback, which is to be implemented in future iterations of the board, is fundamentally reliant on an accurate and high-resolution output current sampling mechanism. Ultimately, by leveraging a higher-performance ADC, the system will be better equipped to support real-time control decisions and more precise actuation of the inverter output.
To gain more insight into how the algorithm for computing the AC load current is performed using the ADC122S021, please refer to the AC V/I Sensing Library Feature section.