STEVAL-IPE012V1 STMicroelectronics, STEVAL-IPE012V1 Datasheet - Page 22

• 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

Theory of operation
Figure 19. Timings of tamper module - Secondary channel selected
7.10
7.11
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When the secondary channel is selected to be integrated by the final energy integrator, the
MUX and INH signals change according to
This means that energy of four periods from secondary channel followed by energy of four
periods from primary channel is sampled within the tamper module. From these two
samples, called B and A respectively, the criteria of tamper is calculated and the channel
with higher current is selected, resulting in a new tamper state. If four consecutive new
results of criteria happen, i.e. after elapsed 5.12 s at 50 Hz, the meter will enter into tamper
state. Thus, the channel with the higher current will be selected for the energy calculation. If
samples of power A and B would have different signs, the Tamper would be on all the time
but, the channel with bigger power would be still selected for the final integration of energy.
If a tamper status has been detected, the multiplex ratio will be 56:8 if the primary channel
energy is greater than the secondary one, otherwise it will be 8:56.
The detected tamper condition is stored in the BIT status bit. If BIT = 0 tamper is not
detected, if BIT = 1 a tamper condition has been detected. In standalone mode the BIT flag
is also available in the SDATD pin.
Phase compensation
The STPM10 does not introduce any phase shift between the voltage and current channel.
However, the voltage and current signals come from transducers, which could have inherent
phase errors. For example, a phase error of 0.1° to 0.3° is not uncommon for a current
transformer (CT). These phase errors can vary from part to part, and they must be corrected
in order to perform accurate power calculations. The errors associated with phase mismatch
are particularly noticeable at low power factors. The STPM10 provides a means of digitally
calibrating these small phase errors by introducing delays on the voltage or current signal.
The amount of phase compensation can be set using the 4 bits of the phase calibration
register (CPH).
The default value of this register is at a value of 0, which gives 0° phase compensation.
When the 4 bits give a CPH of 15 (1111) the compensation introduced is +0.576°. This
compensates the phase shift usually introduced by the current sensor, while the voltage
sensor, normally a resistor divider, does not introduce any delay. The resolution step of the
phase compensation is 0.038°.
Clock generator
All the internal timing of the STPM10 is based on the CLKOUT signal. This signal can be
generated in three different ways:
Doc ID 17728 Rev 3
Figure 19
below.
STPM10