Smart Meter Technology Facilitates Energy Efficiency
Smart meter technology uses microcontrollers, wireless communication modules, and other electronic components to realize electricity, gas, and water consumption monitoring in real-time. After recording the meter readings, smart meters can transmit these data to the cloud by using wireless communication techniques for users, suppliers, or the government to check and analyze.
In a broad sense, smart meters are part of the smart grid and smart city. They have the advantage of getting real-time accurate readings, and users can save more energy by better understanding the details of power consumption.
However, it is impossible to ask people to replace their traditional meters with smart meters immediately. Hence, the market has come out with some power monitoring products specifically for traditional meters to become “smart”, and the home power monitoring system from 3Egreen Technology Inc. is one of them.
3Egreen Technology uses the power monitoring meters to read the data from traditional meter systems and send them to the local or system integration servers. The power monitoring system can solve the problem of high electricity fees and equipment management difficulties. It can also find the suspected abnormal conditions or leakage in homes and send alert notifications.
Components at TECHDesign that can be implemented into smart meters
Microcontrollers and wireless communication units are the two main units to comprise a smart meter. Other than that, memory ICs and passive components need to be used as well. A microcontroller can communicate with wireless modules and the flash through UART and SPI interfaces, respectively.
Microcontrollers
With Armv8-M TrustZone architecture, Nuvoton NuMicro M2351 microcontrollers are designed for IoT security applications. Without the need for any additional secure element (SE), the secure boot and the key manager are already in the secure world to protect the hardware and the private information from smart meters. To ensure the security capability, the M2351 microcontrollers pass an independent IoT security certification, PSA (Arm Platform Security Architecture) Certified Level 1.
Operating at 64 MHz, the M2351 microcontrollers are equipped with 512 KB dual bank flash, 96 KB SRAM, and abundant interfaces, such as SPI Quad mode and USB OTG 1.1. The hardware crypto accelerators are also implemented in the M2351 series to intensify the cryptographic computing operations. Moreover, multiple power modes are designed in the M2351 microcontrollers to realize more efficient power management.
| Mode | CPU Operating Maximum Speed (MHz) | LDO CAP (V) | Clock Disable |
|---|---|---|---|
| Normal mode | 48MHz | 1.2 | All clocks are disabled by control register. |
| Turbo mode | 64MHz | 1.26 | All clocks are disabled by control register. |
| Idle mode | CPU enter Sleep mode | keep | Only CPU clock is disabled. |
| Power-down mode (CPD) | CPU enters Deep Sleep mode | keep | Most clocks are disabled except LIRC/LXT, and only RTC/WDT/Timer/UART peripheral clocks stil enable if their clock sources are selected as LIR/LXT. |
| Fast Wake-up Power-down mode (FWPD) | CPU enters Deep Sleep mode | keep | Most clocks are disabled except LIRC/LXT, and only RTC/WDT/Timer/UART peripheral clocks stil enable if their clock sources are selected as LIR/LXT. |
| Low leakage Power-down mode (LLPD) | CPU enters Deep Sleep mode | 0.96 | Most clocks are disabled except LIRC/LXT, and only RTC/WDT/Timer/UART peripheral clocks stil enable if their clock sources are selected as LIR/LXT. |
| Ultra Low leakage Power-down mode (ULLPD) | CPU enters Deep Sleep mode | 0.9 | Most clocks are disabled except LIRC/LXT, and only RTC/WDT/Timer/UART peripheral clocks stil enable if their clock sources are selected as LIR/LXT. |
| Standby Power-down mode (SPD) | Power off | Floating | only LIRC/LXT still enable for RTC function and wake-up timer usage. |
| Deep Power-down mode (DPD) | Power off | Floating | only LIRC/LXT still enable for RTC function and wake-up timer usage. |
Overall, the NuMicro M2351 microcontroller provides high performance and secure function with low cost and flexible implementation, which is suitable for smart meter applications.
LoRa Modules
A wireless communication module transmits the smart meter readings to the cloud and lets users or suppliers read, collect, and analyze these data. Multiple wireless modules can be implemented into smart meter systems, and a LoRa module is one great option.
Operating at 868/915 MHz, with Nuvoton M031FB0AE microcontroller and Semtech LoRa engine built-in, REYAX RYLR998 has already been applied in smart water meters. Compared to other LoRa modules, RYLR998 features the smart receiving power saving mode to save more power, which means it enters the power saving mode when it temporarily doesn’t need to work.
| Item | Min. | Typical | Max. | Unit | Condition |
|---|---|---|---|---|---|
| Transmit mode current | 140 | mA | RFOP = +22dBm | ||
| Receive mode current | 17.5 | mA | |||
| Sleep mode current | 15 | uA | AT + MODE =1 | ||
| Smart receiving power saving mode average current | 0.02 | 2.7 | 5.5 | mA | AT + MODE =2,3000,3000 |
Not only that, but RYLR998 can also transmit as long as 20 km in an interference-free environment with high RX sensitivity (-129 dBm), high interference immunity, and low receive current.
Memory ICs: Flash memories
Winbond SLC NAND flash W29N memory provides a storage solution with low-density availability, from 1Gb to 8Gb. With 29/40 MHz operating frequency, 1.8V/3V operating voltage, -40°C～85°C (or even higher) operating temperature, and corresponding to the standard ONFI (Open NAND Flash Interface) 1.0 protocol, these high-quality NAND flash products can be applied into smart meter applications.
As cyber security issues are getting serious, more secure memory ICs are provided by Winbond, and the W77Q TrustME secure flash memory is one of them. The W77Q series offers the secure boot, secure storage, secure root of trust (RoT), secure code updated with rollback protection, etc. If you want a more secure solution for your smart meter project, choose W77Q then.
Passive Components: Inductors
Inductors may not be the main part of a smart meter design, but they are indispensable. Being RoHS compliant and certified with ISO 9001, ISO 14001, and ISO 45001, Arlitech ATNR series is used by Hangzhou Hexing Electrical Co., Ltd already. Operating temperature ranges from -40°C to +125°C (including self-temperature rise), the ATNR series is designed in low profile, multiple sizes, medium current, and dropping impact prevention. The cost-effective and stable supply characteristics make Arlitech ATNR series a great choice for customers.
Conclusion
Smart meter systems are the future of power management in homes and industrial spaces. Currently, some suppliers even offer prepayment services for their customers to choose from. Here at TECHDesign, multiple solutions including component level and product level can be found to realize smart meter applications, which comprise the home power monitoring smart meter systems from 3Egreen Technology, Nuvoton M2351 microcontrollers, REYAX RYLR998 LoRa modules, Winbond W29N/W77Q NAND flash memories, and Arlitech ATNR inductor series.
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