This design is ideal for applications like utility metering and street lighting, offering reliable, accurate, and cost-effective energy measurement solutions.
Single/Dual-Phase Isolated Electricity Measurement plays a crucial role in modern power management systems, ensuring accurate, safe, and efficient monitoring of electrical energy. This design enables precise measurement of voltage, current, and power parameters in both single and dual-phase systems, making it ideal for smart meters, industrial automation, and renewable energy applications. The isolated measurement ensures electrical safety by separating the sensing and control circuits, protecting both equipment and personnel from potential high-voltage hazards.
This design TIDM-TWOPHASEMETER-I2040, by Texas Instruments offers a low-cost solution for single- or dual-phase electricity measurement. It incorporates a small metrology microcontroller unit (MCU) that operates independently from the host MCU, ensuring protection from AC mains and isolating the energy measurement function from interference caused by other software. The compact metrology MCU achieves IEC/ANSI Class 1 accuracy and computes both active and reactive power and energy. This solution uses Current Transformer (CT) sensors for single- and dual-phase measurements but can be easily adapted to use shunt resistor sensors for single-phase applications.
Its ability to provide accurate power measurement while maintaining cost efficiency is its important aspect. The system offers a 4kV peak isolation between the metrology and host MCUs, ensuring the metrology subsystem is insulated from other subsystems connected to the AC mains. This design uses a small 28-pin TSSOP package for the metrology MCU, reducing board space and simplifying the layout to minimize PCB complexity. It calculates all critical parameters, such as active and reactive power, RMS current and voltage, power factor, and line frequency. The low power consumption of the metrology MCU helps reduce the cost of the power supply, making the overall design more efficient.
At the core of the metrology subsystem is the MSP430i2041 MCU, a device within the 16-bit MSP430i2xx platform, which is well-suited for power and energy measurement applications. These MCUs feature an internal 16.384 MHz digitally controlled oscillator (DCO) to generate system clocks without needing an external crystal. The ADCs support differential inputs, can operate independently, and allow simultaneous sampling of voltage and current signals.
The MSP430i20xx family also includes a 16-bit by 16-bit hardware multiplier, which accelerates math-intensive operations during metrology calculations. Key parameters calculated by the system include RMS current and voltage, active and reactive power, energy, power factor, and frequency. The MSP430 microcontrollers offer multiple low-power modes, ensuring low power consumption even when performing measurements. Since the meter is always connected to the AC mains, the required DC power can be derived through AC-to-DC conversion.
TI has tested this reference design. It comes with a bill of materials (BOM), schematics, assembly drawing, printed circuit board (PCB) layout, and more. The company’s website has additional data about the reference design. To read more about this reference design, click here.
