3.3.1 Accumulated Current Quantities
The metrology module generates the following accumulated current (I2) quantities: I_A, I_B, I_C, I_Ni, I_Nm, I_Nmi, I_A_F, I_B_F, I_C_F and I_Nm_F.
I_x, I_x_F, I_Nm and I_Nm_F
These accumulators are in units of [Amp2samp scaled] in format [uQ24.40] and represent the accumulated scaled current quantities in the integration period. They are calculated according to the following formula:
Where, I_x_samplei is ith sampled current value of phase x in the present integration period; x = [A, B, C]; and N is the number of samples in the last measurement interval.
I_Ni, I_Nmi
These neutral currents are unscaled in units of [Amp2samp] and are computed directly from DSP-filtered baseband current channel data streams. These neutral currents are unscaled (not normalized by the K_Ix current sensor scale factors); therefore, these accumulators are all in units of (Amp2samples) in format [uQ44.20].
I_Nm is the accumulator for measured neutral current.
In the case of being multiplexed with temperature measurement acquisition, such as when using the PIC32CXMTC with an external ATSense-301, slightly less performance may be expected than DSP-filtered full bandwidth data, calculated according to the following formula:
Where, I_Nm_samplei is ith sampled measured neutral current value from current input I0 in the last integration period; and N is the number of samples in the last measurement interval.
I_Ni is the accumulator for imputed neutral current using full bandwidth (fundamental + harmonics) DSP-filtered baseband current channel data calculated according to the following formulas:
Where, I_Ni_samplei is ith sampled imputed neutral current value computed from the sum of all active current phase currents in the present integration period, and N is the number of samples in the last measurement interval.
I_Nmi is the accumulator for the difference between the sample-by-sample measured and imputed neutral currents. This integration is sensitive to both magnitude and/or phase differences between the measured and imputed neutral currents, calculated according to the following formula:
Where, I_Nm_samplei is ith sampled measured neutral current, I_Ni_samplei is ith sampled imputed neutral current value computed from the sum of all active current phase inputs in the present integration period, and N is the number of samples in the last measurement interval.
| Name: | I_A/I_B/I_C/I_Ni/I_Nm/I_Nmi/I_A_F/I_B_F/I_C_F/I_Nm_F |
| Offset: | Metrology_Acc_Out[0-9] |
| Property: | Read |
| Bit | 63 | 62 | 61 | 60 | 59 | 58 | 57 | 56 | |
| I_x/I_x_F[63:56] | |||||||||
| Access | R | R | R | R | R | R | R | R | |
| Reset | |||||||||
| Bit | 55 | 54 | 53 | 52 | 51 | 50 | 49 | 48 | |
| I_x/I_x_F[55:48] | |||||||||
| Access | R | R | R | R | R | R | R | R | |
| Reset | |||||||||
| Bit | 47 | 46 | 45 | 44 | 43 | 42 | 41 | 40 | |
| I_x/I_x_F[47:40] | |||||||||
| Access | R | R | R | R | R | R | R | R | |
| Reset | |||||||||
| Bit | 39 | 38 | 37 | 36 | 35 | 34 | 33 | 32 | |
| I_x/I_x_F[39:32] | |||||||||
| Access | R | R | R | R | R | R | R | R | |
| Reset | |||||||||
| Bit | 31 | 30 | 29 | 28 | 27 | 26 | 25 | 24 | |
| I_x/I_x_F[31:24] | |||||||||
| Access | R | R | R | R | R | R | R | R | |
| Reset | |||||||||
| Bit | 23 | 22 | 21 | 20 | 19 | 18 | 17 | 16 | |
| I_x/I_x_F[23:16] | |||||||||
| Access | R | R | R | R | R | R | R | R | |
| Reset | |||||||||
| Bit | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | |
| I_x/I_x_F[15:8] | |||||||||
| Access | R | R | R | R | R | R | R | R | |
| Reset | |||||||||
| Bit | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | |
| I_x/I_x_F[7:0] | |||||||||
| Access | R | R | R | R | R | R | R | R | |
| Reset | |||||||||