STEVAL-IPE012V1 STMicroelectronics, STEVAL-IPE012V1 Datasheet - Page 39

• Manufacturer Part Number: STEVAL-IPE012V1
• Description: EVAL BOARD ENERGY METER
• Manufacturer: STMicroelectronics
• Series: -r

Specifications of STEVAL-IPE012V1

• Design Resources: STEVAL-IPE012V1 Schematic STEVAL-IPE012V1 BOM
• Main Purpose: Power Management, Energy/Power Meter
• Embedded: Yes, MCU, 8-Bit
• Utilized Ic / Part: STPM10BTR, STM8L152
• Primary Attributes: Single Phase with 1 Current Transformer & Shunt
• Secondary Attributes: Tamper Detection
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 497-11462

STPM10
7.23.2
Equation 13
[see
In this way, the AC part V•I•cos(2
power.
The absence of any AC component allows for a very fast calibration procedure. It requires
only the setting of (using the internal device programming registers) the voltage and current
sensor conversion constants, using the effective voltage and current (V
provided by the device’s built-in communication port, avoiding the time-averaged readings of
the active power or the need for line synchronization.
Reactive power
The reactive power is produced using the previously-computed signals. In case of shunt
sensor the voltage signal is derived while the current signal is not. A first computation is to
multiply the DS value of the integrated voltage channel with the value of the integrated
current channel, which yields:
Equation 14
The second is to multiply the filtered DS value of the voltage channel with the value of the
filtered current channel:
Equation 15
From the above results, Q1(t) is proportional to 1/
correct reactive power would result from the following formula:
Equation 16
Since the above computation would need significant additional circuitry, the reactive power
in the STPM10 is calculated using only the Q1(t) multiplied by
Equation 17
Q
Q
p
Q
) t (
1
2
=
) t (
(
) t
Figure 26
=
1
2
=
=
⋅
p (
Q
∫
/
v
v
2
1
′
(
) t (
′
) t (
) t (
) t
⋅
⋅
dt
2
−
( i
ω
- 11]
) t
p
⋅
/
+
I
1
) t (
=
Q
(
)) t
V
2
=
) t (
ω
v
) t (
=
cos
⋅
V
ω
⋅
1
I
) t (
⋅
ω
=
I
t
⋅
=
Doc ID 17728 Rev 3
VI
2
⋅
2
cos
I
V (
sin(
ω
sin
sin
t +
ϕ
ϕ
ω
ω
ϕ
t
+
) t
)/2 has been removed from the instantaneous
ϕ
⋅
⎛
⎜
⎝
)
−
=
ω
I
VI
2
cos(
ω,
⋅
ω
ω
⋅
while Q2(t) is proportional to
(
t
sin
+
ϕ
ϕ
⎞
⎟
⎠
+
=
sin(
ω
2
VI
ω
, which means:
2
⋅
(
ω
sin
t
+
Theory of operation
ϕ
rms
ϕ
−
)
, I
)
sin(
rms
2
) readings
ω
t
ω
+
. The
ϕ
)
39/51
)