Week 10
Current and Speed Sensing
I use my PSIM report and PI calculation file to revisit the DC-motor model, cascaded current-speed loops, and field weakening.
What I connect in this unit
A current sensor converts shunt or magnetic sensing into an ADC value, while an encoder derives speed from pulse count over an interval or time between edges. Filtering reduces noise but adds delay, so it follows scaling and offset correction and must fit control bandwidth.
Concept map
- Current sensors
- Encoders
- Filtering
- Scaling
Technical anchor
Current scaling can be checked with i = (ADC_count - offset) V_ref/(ADC_fullscale G R_shunt), and encoder speed with omega = 2 pi Delta count/(N_pulse T_s).
How I review it
Create test vectors for zero-current offset, positive-negative polarity, encoder wraparound, and low-speed quantization, then check filter cutoff against current- and speed-loop phase margin.
Connection to the full course
Unit 10 of 12. Unit numbers follow the control structure in the saved design files and do not claim attendance weeks.