MS student Raya Mahony with Advisor P. Krein

Implementing convenient, cost-effective public charging infrastructure for passenger electric vehicles is critical to enable widespread adoption. We propose a simple smart-meter design for conventional 120V or 240V electrical receptacles to support sufficient energy transfer to meet the needs of 95% of daily driving. Generously funded by the Grainger CEME, this research focuses on increasing the accessibility of these level-one charge points by addressing issues of safety, accurate charging data, payment protocols, and data security/privacy.
The prototype design (shown in Figure 1) employs on/off control with TRIACs (triode for alternating current and isolated optical drivers) isolated voltage and current-sensing support data collection for telemetry. Data is transferred utilizing 2.4 GHz radio XBee modules mimicking standard residential metering protocols. An external real-time clock IC is employed to monitor usage, charge duration, real-time pricing, and to provide detailed data for utility analytics. The design incorporates code-compliant ground-fault protection, line-voltage surge protection, and over-current protection.

Figure 1. Smart-meter prototype for conventional 120V or 240V electrical receptacles to meet need of 95% of daily driving