1 Introduction

As we move toward a more sustainable energy grid with sources such as solar and wind power, the need arises for energy metering devices to obtain detailed insights into individual power consumption in order to identify areas for improvement, optimize usage, and reduce costs. The types of electronic end equipment that require an energy metering subsystem include smart electrical meters, electric vehicles (EVs) charging stations, power supplies and power distribution units, smart appliances, street lightning, and building automation components. The sheer number of these products drives the need for the lowest possible cost for energy metering solutions, while regional metering standards such as American National Standards Institute C12 (in the U.S.) or Measuring Instruments Directive (in Europe) impose strict accuracy and safety requirements [1], [2].

Figure 1 illustrates a typical signal chain inside an energy metering application, showing only one phase for simplicity. An analog-to-digital converter (ADC) simultaneously measures and digitizes voltage and current for each phase. Subsequently, digital signal processing extracts metrology parameters such as active and reactive power and energy, line-to-line voltages, fundamental power and energy, and harmonics [3].

The fundamental buildings blocks of the signal chain are:

• Line voltage sensing front end (A in Figure 1).
• Current measurement sensor (B).
• Front-end and signal conditioner between the current sensor and the ADC (C).
• ADC (D).
• Digital signal processing hardware (E).
• Galvanic isolation (F).

While the line voltage sensing front end is in most cases implemented using simple resistor-dividers [3], various options exist for the choice of every other building block. For each of these signal-chain components, performance, size and cost trade-offs exist. This article focuses on the performance vs. cost trade-offs for the current measurement sensor and signal conditioning, as well as the ADC.