US 2018/0003739 A1 · PLUG-THROUGH POWER METER WITH PLANAR PROFILE

Abstract

An improved energy meter is presented that achieves a vastly smaller form factor than prior systems. The energy meter occupies an unobtrusive and essentially two-dimensional volume, 1″×1″× 1/16″, and meters loads plugged through it and into an outlet. Despite its small size, the energy meter is a wireless true power meter, capable of metering real, reactive, and apparent power at kHz frequencies, aggregating these measurements into cumulative energy, and transmitting these data several times per second using a Bluetooth Low Energy (BLE) radio to a nearby smart phone or gateway. At a cost of $11 in modest quantities of 1,000 units, the energy meter is the smallest and lowest cost AC plug-load meter with 1.13% accuracy over a 2-1200 W range for unity power factor loads, and slightly worse for non-linear and reactive loads. This small form factor, coupled with easy access to and transport of the meter data, enables new applications.

Claims20

Dependent claims

An energy meter for use with a device having a power cord, comprising:

a circuit board having a set of holes configured for prongs of an electric plug to pass therethrough;
a current sense circuit mounted onto the circuit board, the current sense circuit includes an inductor that is disposed proximate to a given hole in the set of holes and configured to measure magnetic field generated by current flowing through a prong passing through the given hole;
a voltage sense circuit mounted onto the circuit board and configured to measure voltage between two specific prongs passing through the set of holes, where the voltage sense circuit includes input terminals that physically contact the two specific prongs and electrically couples the two specific prongs to the voltage sense circuit;
and
a microcontroller mounted onto the circuit board and is electrically coupled to the current sense circuit and the voltage sense circuit, wherein the microcontroller computes electrical power of load supplied by the electric plug from the measured magnetic field and the measured voltage.

2 more elements

An energy meter for use with a device having a power cord, comprising:

a circuit board having a set of cutouts configured for prongs of an electric plug to pass therethrough;
a power supply circuit mounted to the circuit board, where the power supply circuit is configured to receive AC voltage from a specified prong passing through one of the cutouts in the set of cutouts and operates to rectify and down convert the AC voltage to a lower DC voltage;
a current sense circuit mounted onto the circuit board, the current sense circuit includes an inductor that is disposed proximate to a given cutout in the set of cutouts and configured to measure magnetic field generated by current flowing through a prong passing through the given cutout;
a voltage sense circuit mounted onto the circuit board and configured to measure voltage between two specific prongs passing through the set of cutouts, where the voltage sense circuit includes input terminals that physically contacts the two specific prongs and electrically couples the two specific prongs to the voltage sense circuit;
a microcontroller mounted onto the circuit board and is electrically coupled to the current sense circuit and the voltage sense circuit, wherein the microcontroller computes electrical power of load supplied by the electric plug from the measured magnetic field and the measured voltage;
and
a wireless transmitter mounted to the circuit board and interfaced with the microcontroller to transmit the computed electrical power.

4 more elements

Dependencies are inferred from the claim text.

Plug-through power meter with planar profile

Life of this patent

Plug-through power meter with planar profile

Life of this patent

Abstract

Claims20