ST推出误差仅为0.1%的单相电表解决方案

中心议题：
    *  ST STPM1X系列单相计量芯片的功能介绍
    *  基于STPM1X计量芯片的单相电能表设计方案

ST的STPM11/12/13/14单相电表IC集成脉冲输出和数字校准,具有无波纹的有用功率脉冲输出,直接的步进计数器驱动器,可以采用并联,电流变压器和Rogowsky线圈传感器.该器件还集成了线性VREGS,支持50÷60 HZ - IEC62052-11, IEC62053-2X规范,误差小于0.1%.本文介绍了STPM11/12/13/14的主要性能和方框图,电表中有功能量计算图, 电荷泵电路图以及应用电路图.

概述

The STPM1x family is designed for effective measurement of active energy in a power line system using a Rogowski Coil, Current Transformer and Shunt sensors. This device isspecifically designed to provide all the necessary features to implement a single phase energy
meter without any other active component. The STPM1x device family consists, essentially, of two parts: the analog part and the digital part. The former, is composed of a preamplifier and first order A/D converter blocks, band gap voltage reference, low drop voltage regulator. The digital part is composed of a system control, oscillator, hard wired DSP and interface for
calibration and configuration.

The calibration and configuration are done by OTP cells, that can be programmed through aserial interface. The configured bits are used for testing, configuration and calibration purposes.

From two output signals coming from the analog section, a DSP unit computes the amount of consumed active energy. The active energy is available as a pulse frequency output and directly driven by a stepper counter. In the STPM1X an output signal with pulse frequency proportional to energy is generated. This signal is used in the calibration phase of the energy meter application allowing a very easy approach. When the device is fully configured and calibrated, a dedicated bit of OTP block can be written permanently in order to prevent accidental entry into test mode or changing any configuration bit.

主要性能

Ripple free active energy pulsed output

Direct stepper counter drivers

Shunt, current transformer, Rogowsky coil sensors

Live and neutral monitoring (STPM13/14)

Easy and fast digital calibration at only one load point

No-load, negative power and tamper indicators

Integrated linear VREGS

RC (STPM11/13) or crystal oscillator (STPM12/14)

Support 50÷60 HZ - IEC62052-11, IEC62053-2X specification

Less than 0.1% error

图1.方框图

 

图2. 有功能量计算图

图3. 电荷泵电路图

图4. 应用电路图