STPMC1 ST Microelectronics, STPMC1 Datasheet - Page 70

• Manufacturer Part Number: STPMC1
• Description: Programmable poly-phase energy calculator IC
• Manufacturer: ST Microelectronics

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Energy calculation algorithm
10.5
70/76
Equation 52
k
k
k
The DSP performs also an integration of powers (P, Q) into energies:
Equation 53
AW = U
Equation 54
AW = U
These integrators are implemented as up/down counters and they can roll over.
20-bit output buses of the counters are assigned as the most significant part of the energy
data records. It is a responsibility of the application to read the counters at least every
second so as not to miss any rollover. The integration of power can be suspended due to
detected error on the source signals or due to no load condition. From AW, stepper output
signals are generated.
Fundamental power calculation
The fact that integration suppresses all but fundamental components of signals is used to
compute the fundamental active power, which is in case of Rogowski coil:
Equation 55
F
Equation 56
F
Equation 57
F = (F
Similar result are found in case of non Rogowski sensor:
Equation 58
F
Equation 59
F
Equation 60
F = (F
The fundamental reactive power in case of a Rogowski coil is:
INT
UD
DIF
) k
1
2
1
2
= v
= v
= v
= v
P
= 2 f
= 2 f
= M
uic
iic
2
dic
sic
2
RMS
RMS
- F
- F
DIF
v
MCLK
v
v
v
MCLK
uiic
diic
iiic
siic
1
1
) / 2 = (AB cos ) k
) / 2 = - AC cos (2
/ 2 f
I
I
= - ABk
= - ABk
RMS
RMS
= - AC sin ( t) sin ( t + ) = - AC [cos
= - ACk
/ M
/ M
MCLK
UD
cos
sin
INT
INT
INT
= 2
DIF
= 2
= 2
k
k
cos ( t) cos ( t + ) = - ABk
sin ( t) sin ( t + ) = ABk
11
k
P
-8
8
P
INT
k
k
UD
UD
cos ( t) cos ( t + ) = - AC [cos
INT
Doc ID 15728 Rev 1
t + ) = Uk
/ 2 = (Uk
D
D
Ik
Ik
L
s
cos ) k
cos (2
INT
INT
[cos
INT
- cos (2
t + ) / 2 = U
[cos
/ 2 = U
- cos (2
+ cos (2
+ cos (2
RMS
t + )] / 2
RMS
I
RMS
t + )] / 2
I
RMS
t + )] / 2
cos
t + )] / 2
cos (2
k
P
STPMC1
t +