I doing student project about electric power meter. Hardware and micro controller board are work fine but I have accuracy problem.
This my hardware.
Use hall effect current sensor and divider network + c coupling for current front end. (In datasheet hall effect have nonlinear error at 1.5%)
Use voltage transformer and divider network
This settting about ADE7753
PGA = 1 for both analog input (Current sensor and Voltage sensor)
Sampling rate at default. I not set.
This method to read electric variable.
1. I read Vrms and Irms synchronous with zero crossing interrupt and take average 100 times.
2. I read AEnergy and VAEnergy with timer interrupt and find diff of energy (this mean watt , right ? , dE/dT) Setting timer interrupt every 2.097152 Sec with timer 16 bit , but i assume don't care dT
And calibrate with external factor which store in micro controller. Use slope and offset correct (y = mx + c). I assume it 's should be linear because my load is incandescent lamp which pf = 1. This caribrate parameter with imin = 0.5A and ibase = 5A I found max percentage error about 5.4% in current section. and voltage error max at 0.2%
How to optimize it. For best accuracy. i hope it should less than about 2% for all range.