STPMC1 ST Microelectronics, STPMC1 Datasheet - Page 65

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

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STPMC1
10
Energy calculation algorithm
For the purpose of simplicity the energy computation shown below is relative to only one
phase.
Given line voltage and current as:
Equation 11
u = U sin ( t)
The voltage divider, AD converter and calibrator produce the value:
Equation 12
v
The Rogowski coil preamplifier, AD converter and calibrator produce the value:
Equation 13
v
The 2
Equation 14
v
Equation 15
vii = ∫ v
From signs of v
Equation 16
This result is used to compensate Eq. 41, Eq. 44, Eq. 45 and Eq. 54.
The frequency compensated values are:
Equation 17
v
Equation 18
v
The 3
Equation 19
v
Equation 20
v
u
i
ui
uic
iic
uiic
iiic
= - L (di/dt) (A
/ k
= u (R
= ∫ v
=
= ∫ v
=
= ∫ v
INT
nd
rd
i
u
dt = - B sin ( t + ) k
/ k
stage internal integrations and DC cancellations produce the values:
= k / T
/ k
iic
stage internal integrations produce the values:
dt = - (A / ) cos ( t) k
uic
2
/(R
INT
dt = B cos ( t + ) k
INT
dt = - (A / ) sin ( t) k
1
v
+R
v
ii
ui
u
I
= - B
/V
2
and v
= - A cos ( t)
) (A
REF
U
) k
ui
/V
sin ( t + )
the base frequency of line can be produced:
I
REF
= - I k
) k
INT
Doc ID 15728 Rev 1
INT
U
L
INT
= u k
INT
cos ( t + ) = - B
i = I sin( t + )
D
= A sin ( t)
cos ( t + )
Energy calculation algorithm
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