TITLE:
Development of Battery-Less Wireless Current Sensor Node Utilizing Charging Time of Capacitors with Wide Measurement Range
AUTHORS:
Hironao Okada, Toshihiro Itoh
KEYWORDS:
Battery-Less; Wireless Current Sensor Node; Power Monitoring
JOURNAL NAME:
Wireless Sensor Network,
Vol.5 No.11,
November
26,
2013
ABSTRACT: We report a novel battery-less wireless current sensor node without
an analog to digital converter (ADC). If a capacitor is charged using a current
transformer (CT) and a rectifying circuit, the charging time depends on the
current flowing through a power line. In the case that the node transmits data
every time when voltage of the capacitor exceeds a threshold voltage, we can
indirectly measure the current by measuring the transmission intervals. In this
method, the circuit of the node can be simplified and power consumption for the
wireless transmission can be decreased because the measured current data does
not need to be included in the transmitted packet. However, the measurable
range is about single digit because the transmission interval decreases
suddenly as the current increases. In this work, we have ex- panded
the range using one CT, one wireless transmission module, and two charging
circuits that include different load resistors connected in series. The results
indicated that the measurable range was from 0.5 A to 50 A.