WO2023175371A1

WO2023175371A1 - Multi-circuit energy harvesting

Info

Publication number: WO2023175371A1
Application number: PCT/IB2022/052301
Authority: WO
Inventors: Ragnar Einarsson; Karl PÁLSSON; Kristján GUÐMUNDSSON
Original assignee: Etactica Ehf.
Priority date: 2022-03-15
Filing date: 2022-03-15
Publication date: 2023-09-21

Abstract

An energy harvesting system includes two or more power harvesting subsystems respectively coupled to different conductors of an electrical circuit, such as multiple legs of a multi-phase electrical circuit. Each energy harvesting subsystem includes a current transformer configured to be coupled around a conductor carrying current and having an alternating current (AC) output. Each power harvesting transformer also includes a rectifier coupled to the AC output and a first direct current (DC) to DC converter to generate a DC output at a predetermined voltage. A current-summing circuit is coupled to the DC outputs of the power harvesting subsystems to create a summed DC output which provides current to an energy storage device.

Description

MULTI CIRCUIT ENERGY HARVESTING

Background

Technical Field

The present subject matter relates to harvesting electrical power from a circuit using inductive coupling, and more specifically, to harvesting power from individual legs of a multiphase electrical circuit.

Background Art

Electrical power is typically distributed to individual circuits of a building in a service panel. The service panel commonly includes a circuit-breaker for each circuit that provides overcurrent protection for the circuit. The circuit-breakers are typically arranged at regular intervals along a bus which provides the electrical power from the main power meter for the building. In some cases, a multi-phase electrical circuit may be created with ganged circuit-breakers having one circuit-breaker per leg of the multi-phase electrical circuit. Sensors, which require power, may be used to monitor certain aspects of the circuits in the service panel.

Brief Description of the Drawings

The accompanying drawings, which are incorporated in and constitute part of the specification, illustrate various embodiments. Together with the general description, the drawings serve to explain various principles. In the drawings:

FIG. l is a block diagram of an embodiment of an electrical distribution system;

FIG. 2A, 2B, and 2C show different views of an embodiment of a ganged multi-circuit sensor;

FIG. 3 is a block diagram of the embodiment of the ganged multi-circuit sensor with an energy harvesting system;

FIG. 4A and 4B show alternative embodiments of a rectifier;

FIG. 5A, 5B, 5C, and 5D show alternative embodiments of a DC-to-DC converter;

FIG. 6 shows an implementation of a rectifier and DC-to-DC converter using an integrated circuit;

FIG. 7A and FIG. 7B show alternative embodiments of a current-summing circuit; and i FIG. 8 is a flow chart of a method for energy harvesting.

Detailed Description

In the following detailed description, numerous specific details are set forth by way of examples in order to provide a thorough understanding of the relevant teachings. However, it should be apparent to those skilled in the art that the present teachings may be practiced without such details. In other instances, well known methods, procedures, and components have been described at a relatively high-level, without detail, in order to avoid unnecessarily obscuring aspects of the present concepts. A number of descriptive terms and phrases are used in describing the various embodiments of this disclosure. These descriptive terms and phrases are used to convey a generally agreed upon meaning to those skilled in the art unless a different definition is given in this specification.

Traditionally, power is delivered to a premises from an electrical power utility through an electrical meter that is used to monitor the amount of power delivered to the premises. The utility can then access the meter to determine an amount of energy (power over time) used so that the utility can then charge their customer based on the amount of energy that was actually used. But in traditional systems, the amount of power delivered to individual loads, or individual circuits, cannot be separately determined or reported by the single electrical meter used for billing purposes.

A submetering system that may be separate from the traditional power meter can be used to measure power and/or energy used by individual loads or individual circuits. A submetering system may use sensors to measure electrical parameters of the load/circuit and report the measurements over a network to a user. The sensors of a submetering system often require power for their operation. A sensor may include electronics, such as a processor to manage the measurement of the parameters, and a network interface to send the measurements to another computer where they can be analyzed and or reported to the user. In traditional systems, the submetering system may have been powered by a physical connection to power in the service panel.

In systems that place sensors inside the service panel on the conductors near the circuit breakers, space may be limited due to the spacing of the circuit breakers. Some sensors, such as the Power Bar EB from eTactica provide ganged sensors which can monitor multiple conductors separately by providing multiple openings for individual conductors. The openings are designed to match the pitch of circuit breakers in a service panel to allow for many sensors to be installed in a minimum amount of space. If the Power Bar EB is retrofitted in an existing service panel, the conductors need to be removed from the breakers to allow the current sensors to be installed because the conductors must be inserted through the openings in the Power Bar EB sensors before they are reinserted into their respective circuit breakers. This can be time consuming and disruptive due to the need to turn off the circuit breakers which turns off power to the circuits. The sensors in the Power Bar EB send signals to a gateway device, such as the Gateway EG from eTactica which connects to the rails of the service panel to receive power which it provides through a wired connection to the Power Bar EB. eTactica and other companies also provide split core current transformers that provide a stepped-down AC current that can then be measured by a separate device, such as the Power Meter EM from eTactica, which can then send the measurement data to the Gateway EG over a wire. While this design may make it easier to retrofit existing service panels, it takes more space than the Power Bar EB and it may be difficult to install on every circuit within a service panel. It also requires multiple positions on the rail in the service panel, limiting the number of circuitbreakers that may be supported.

Power may be harvested from a conductor passing through a current transformer, but a sensor monitoring a circuit which is off for extended periods of time may not allow enough energy to be harvested to power the sensor through the extended off time. Disclosed herein is a ganged sensor that harvests energy from multiple legs of an electrical circuit to charge an energy storage device which can power the sensor. By harvesting power from multiple legs or a circuit, which may have different currents flowing at different times, including different periods when the load may not be drawing any current at all. Because a current transformer cannot harvest any power if no current is flowing in the conductor, having multiple energy harvesting subsystems connected to different conductors allows current harvested from one conductor to be used by a sensor that may be monitoring a parameter that is unrelated to that conductor. Using energy harvested from multiple conductors and storing the energy from each conductor in a common energy storage device can provide a more reliable power source for a sensor than harvesting energy from a single conductor.

The ganged sensor includes an energy harvesting system having two or more energy harvesting subsystems that are respectively coupled to conductors carrying alternating current (AC) for different loads. That is, they may be different legs of an electrical circuit. The different legs of the electrical circuit may be different phases in a multi-phase electrical circuit, such as two legs that are 180 degrees out of phase, or three legs of a 3-phase circuit where the legs are 120 degrees out of phase with each other. In addition, or alternatively, the conductors may be different branches of a single-phase circuit and may be protected by separate circuit-breakers.

Each energy harvesting subsystem includes a current transformer that is inductively coupled to the conductor carrying current. The current transformer can be any type of current transformer, including a bar-type current transformer, a toroidal current transformer, a ring-type current transformer, a split-ring current transformer, or a fixed or flexible Rogowski coil. Some current transformers may include a core, such as an iron core or a ferrite core. At least one implementation uses a split ferrite core to allow the current transformer to be placed around a conductor without disconnecting the conductor from its source or load. Because the current transformer is being used for energy harvesting, and not for making accurate measurements of the current flowing in the coupled conductor, the response of the current transformer need not be linear, although the current transformer may have a linear response over an operating range in some implementations. In other implementation, the response of the current transformer may be non-linear and/or the current transformer may saturate at a current level that is less than the maximum operating current.

Energy harvesting subsystems also include a rectifier to convert the AC output of the current transformer to a direct current (DC) and a DC-to-DC converter to generate a voltage- regulated current source. The energy harvesting subsystems may operate over a wide range of currents flowing in the conductor to which they are coupled. In some implementations, the energy harvesting subsystem may maintain the voltage regulation of its output over current range having an order of magnitude difference between the minimum operating current and the maximum operating current (i.e. a lOx range). In other implementations, the ratio of maximum to minimum operating current may be 50, 57, 90, 100 120 or greater. The maximum operating current may be any level, including common breaker values, such as 15 Amperes (A), 20 A, 30 A, 40 A, 50 A, or 63 A. The minimum operating current defines the lowest current level in the coupled conductor where the energy harvesting subsystem is able to maintain the voltage regulation of its output, and may be at any level, depending on the implementation. But in some implementations, the minimum operating current may be 1 A, 0.7 A, 0.5 A, or less.

Some implementations of the ganged sensor include a first component and a second component shaped to fit together to create a combined unit with multiple openings through the combined unit that can each surround an electrical conductor. The openings may have the same pitch as that between circuit-breakers in a service panel. The two components may be held together using clips, latches, screws, straps, or other fasteners. The openings are each bounded on a first side by the first component and on a second side by the second component. The first component includes split ferrite core halves respectively proximal the first side of the openings. The second component includes split ferrite core halves respectively proximal the second side of the openings with rectifiers coupled to their output. The first component and the second component may be installed in the service panel with conductors passing through the holes in the combined unit without disconnecting the conductors from the circuit-breakers or from their loads. Some implementations may have an energy harvesting subsystem for each opening through the ganged sensor, so a ganged sensor having 3 openings through the combined unit may include three energy harvesting subsystems and a ganged sensor with 6 openings through the combined unit may include 6 energy harvesting subsystems, although another implementation with 6 opening may have fewer than 6 energy harvesting subsystems.

The energy harvesting system also includes a current-summing circuit coupled to the voltage-regulated DC outputs of the energy harvesting subsystems to provide current from the two or more energy harvesting subsystems on a single electrical node which can then be provided to an energy storage device, such as a rechargeable battery or a capacitor. The energy harvesting system may include a sensor powered by the energy storage device in some cases. The sensor may communicate with a gateway device using wired or wireless communication. In at least one embodiment, the sensor utilizes a Bluetooth® network to communicate with the gateway device and can communicate at least one measurement to the gateway device in near real-time.

The use of the two components each having half of the current transformers makes installation easier and cheaper as up to half of project costs may be related to installation, including wiring, networking, and power disruption planning. In some cases, the disruption to the network and power distribution caused with prior solutions may be enough to completely halt a project or delay it for long periods of time. The embodiments described herein avoid those problems as installation can occur with no disruption to the networking and power distribution infrastructure of the premises because the ganged sensors described herein allow the current transformers of the energy harvesting system to be installed without disconnecting power for individual circuits at the breaker. Different implementations may be configured to have any number of openings in the combined unit capable of surrounding current-carrying conductors, and implementations having two, three, four, five, and six openings are explicitly envisioned. Embodiments having 8, 10, 12, and 16 openings are also envisioned.

Reference now is made in detail to the examples illustrated in the accompanying drawings and discussed below.

FIG. 1 is a block diagram of an embodiment of an electrical distribution system 100. Electrical power is provided from a power source, such as the electrical power gird 101, to a service panel 120 of a premises or building. The electrical power grid 101 may provide multiphase power, such as single phase 220 Volts (V) which may be split into two 110 V circuits that are 180 degrees out of phase, or 3-phase power which has three legs that are 120 degrees out of phase. An electrical meter 102 may measure the amount of electrical power delivered to the service panel 120. The electrical power is distributed within the service panel 120 by one or more bus bars 122 to circuit breakers 124 which each provide over-current protection for one of the circuits 126 which feed electrical power to the various loads on the premises. The service panel 120 may also include a master circuit breaker (not shown) that can disconnect the electrical power from the bus bars 122. In the implementation shown, the electrical power grid 101 provides 3-phase power and the ganged circuit-breaker 124 controls power to three conductors 126 A carrying power from the three legs of the 3-phase power. The service panel 120 may also have additional circuit-breakers protecting additional circuits. For example, conductor 126 A receives its electrical power though circuit breaker 124 A which provides over-current protection for the circuit fed by conductor 126 A.

The electrical distribution system 100 includes a ganged sensor 130 that has a sensor 132 and an energy harvesting system coupled to three conductors 126A that pass through three holes 133 in the ganged sensor 130. As mentioned above, other implementations may have a different number of holes to harvest energy from a different number of conductors carrying AC current.

The ganged sensor 130 also includes an energy storage device, which is charged by energy harvesting subsystems associated with each of the three holes 133, which provides power to the sensor 132. The sensor 132 may measure any type of parameter associated with the service panel 120, the circuit breakers 124, or the conductors 126, depending on the implementation.

FIG. 2A shows a front, top, right perspective view of the ganged multi-circuit sensor 200 and FIG. 2B shows a top, left, front perspective view of the ganged multi-circuit sensor 200. FIG. 2C shows a rear elevation view of the ganged multi-circuit sensor 200. The ganged multicircuit sensor 200 includes an energy harvesting system and has a first component 201 and a second component 202. The two components are shaped to fit together with the first component 201 positioned below the second component to create a combined unit which is the ganged multi-circuit sensor 200. A mechanism to hold the two components 201/202 together may be included such as the bump 203 and latch 204 on one side. Some embodiments may include an additional clip 205 (not shown in FIG. 2A and 2B) on the other side although other embodiments may use other mechanisms to hold the first component 201 together with the second component 202, including, but not limited to, snaps, straps, screws, magnets, latches, or hook and loop fasteners.

The current sensor 200 includes two or more openings 210, 220, 230 through the combined unit 200 suitable to surround a conductor for a circuit in a service panel. The openings 210, 220, 230 are created by putting the two components 201, 202 together. While three openings 210, 220, 230 are shown, other embodiments may have any number of openings. The first opening 210, the second opening 220, and the third opening 230 are bounded on the bottom side by the first component 201 and on the top side by the second component 202. The openings 210, 220, 230 are spaced at a pitch (i.e. distance apart) designed to match a particular brand or model of circuit breaker as installed in a service panel. In some embodiments, the pitch may be 1 DIN unit (i.e. 17.5 mm), 27 mm, or any other pitch to match a particular brand or model of circuit breaker. The openings 210, 220, 230 are sized to easily allow a conductor to fit into the openings, such as a 14 AWG (American Wire Gauge) wire for a 15 A circuit, a 12 AWG wire for a 20 A circuit, a 10 AWG wire for a 30 A circuit, or an 8 AWG wire for a 50 A circuit. In at least one embodiment, the openings are about 8 mm in diameter to allow an insulated wire between 14 AWG and 6 AWG (inclusive) to fit through the opening. Other embodiments may have different sized openings, depending on the gauge of wire around which they are intended to be installed.

The current sensor 200 may be installed into a service panel by sliding the first component 201 under conductors to be monitored and then attaching the second component 202 above the conductors to mate with the first portion 201 and individually surround each conductor in one of the openings 210, 220, 230. The clips 204, 205 may be used to attach the first component 201 to the second component 202.

FIG. 3 is a block diagram of the embodiment of the ganged multi-circuit sensor 200 with an energy harvesting system. The ganged multi-circuit sensor 200 includes the first component 201 and the second component 202 shaped to fit together to create a combined unit with multiple openings through the combined unit. The energy harvesting system includes a first energy harvesting subsystem 310 and a second energy harvesting subsystem 320. Some implementations include a third energy harvesting subsystem 330 configured to couple to a third conductor passing through the third hole 230.

The first energy harvesting subsystem 310 includes a first current transformer 311 configured to be coupled to a first conductor passing through the first hole 210 and having a first alternating current (AC) output 315, a first rectifier 316 coupled to the first AC output 315 and having a first rectified voltage output 317, and a first direct current (DC) to DC converter 318 coupled to the first rectified voltage output 317 and having a first DC output 319 at a predetermined voltage. The second energy harvesting subsystem 320 includes a second current transformer 321 configured to be coupled to a second conductor passing through the second hole 220 and having a second AC output 325, a second rectifier 326 coupled to the second AC output 325 and having a second rectified voltage output 327, and a second DC-to-DC converter 328 coupled to the second rectified voltage output 327 and having a second DC output 329 at the predetermined voltage. The third energy harvesting subsystem 330 includes a third current transformer 331 configured to be coupled to a third conductor passing through the third hold 230 and having a third AC output 335, a third rectifier 336 coupled to the third AC output 335 and having a third rectified voltage output 337, and a third DC-to-DC converter 338 coupled to the third rectified voltage output 337 and having a third DC output 339 at the predetermined voltage.

Different implementations can use different types of current transformers, but the example implementation shown in FIG. 3 uses split-ring current transformer using split ferrite core halves. The first current transformer 311 includes a first split ferrite core half 312 in the first component 201 proximal to the first opening 210, and a second split ferrite core half 313 positioned in the second component 202 proximal to the first opening 210. A first coil 314 is wrapped around the second split ferrite core half 313 to provide the first AC output 315. The second current transformer 321 includes a third split ferrite core half 322 positioned in the first component 201 proximal to the second opening 220 and a fourth split ferrite core half 323 positioned in the second component 202 proximal to the second opening 220. A second coil 324 is wrapped around the fourth split ferrite core half 323 to provide the second AC output 325. The third current transformer 331 includes a fifth split ferrite core half 332 positioned in the first component 201 proximal to a third opening 230 and a sixth split ferrite core half 333 positioned in the second component 202 proximal to the third opening 230. A third coil 334 is wrapped around the sixth split ferrite core half 333 to provide the third AC output 335.

In some implementations the ferrite core halves 312, 322, 332 are completely encased in an enclosure for the first component 201 and/or the ferrite core halves 313, 323, 333 are completely encased in the enclosure for the second component 202. But in other implementations, structures of the first component 201 and second component 202 may expose some portion of the ferrite core halves 312, 322, 332, 313, 323, 333 such as the outer surfaces facing the other component, to allow for physical contact between the core halves 312, 322, 332 of the first component 201 and the core halves 313, 323, 333 of the second component 202. This can improve the efficiency of the current transformers 311, 321, 331.

Because the current transformers are used to harvest energy and may not be used to take measurements of the current flowing through the conductor in at least some implementations, the current transformers may not need to be calibrated or even match other current transformers in the energy harvesting system. So, in some implementations the first current transformer is operable to provide a first power output on the first AC output with a first level of current flowing in the first conductor and the second current transformer is operable to provide a second power output on the second AC output with the first level of current flowing in the second conductor, wherein the first power output differs from the second power output by at least 10%.

The second component 202 can include first rectifier 316, the second rectifier 326, the third rectifier 336 the first DC-to-DC converter 318, the second DC-to-DC converter 328, and the third DC-to-DC converter 328. The second component 202 can also include a currentsumming circuit 340 coupled to the first DC output 319, the second DC output 329, and the third DC output 339. The current summing circuit 340 has a summed DC output 349 to provide current from the first DC output 319, the second DC output 329, and the third DC output 339 to an energy storage device 350 that is coupled to the summed DC output 349. Any appropriate energy storage device may be used including one or more rechargeable battery cells, such as lithium-ion battery cells or nickel-metal hydride battery cells, or one or more capacitors, such as a supercapacitor. In at least one implementation, a 5 Farad (F) DGH505Q5R5 supercapacitor from Cornell Dubilier is used, but other implementations may provide two or more supercapacitors of higher or lower capacitance, depending on the application.

The second component 202 also includes a sensor 390 powered by the energy storage device 350. The sensor 390 may measure any applicable parameter, depending on the implementation, including, but not limited to, a temperature, a current, a voltage, or a power. The energy storage device 350 may be sized to provide a target current draw of the sensor 390 for a targeted period of time. In at least one implementation, the 5 F energy storage device 350 charged to full capacity at 1.8 V can theoretically provide 1 milli-Amp of current at 1.8 volts (using a secondary DC-to-DC converter) for up to 5000 seconds and realistically for over one hour.

FIG. 4A and 4B show alternative embodiments of a rectifier suitable for use in the energy harvesting subsystems 310, 320, 330. FIG. 4A shows a half-wave rectifier 410 that receives an AC input 411, which may be provided by a current transformer, and uses a single diode 412 to provide a rectified output 417. Note that a half-wave rectifier 410 blocks half of the energy provided at the input 411.

FIG. 4B shows a full-wave bridge rectifier 420. The full-wave bride rectifier 420 receives an AC input 421 and uses a set of four diodes arranged in a bridge configuration 422 to pass both the positive-going portion of waveform received on the AC input 421 and an inverted version of the negative-going portion of waveform received on the AC input 421 to the rectified output 425. A full-wave bridge rectifier 420 is more efficient than the half-wave rectifier 410 shown in FIG. 4A.

FIG. 5A, 5B, 5C, and 5D show alternative embodiments of a DC-to-DC converter that may be used in an energy harvesting subsystem 310, 320, 330 shown in FIG. 3. Each of the diagrams provides a simplified view of the various DC-to-DC converters and omit many details and components that may be included in a final design, such as capacitors and resistors that are not necessary to understand the basic operation of the DC-to-DC converters.

FIG. 5 A shows a DC-to-DC converter 510 that receives a rectified input 517 and uses a three-terminal linear regulator 511 to generate the output 519 at a predetermined regulated voltage level. Note that the voltage of the output 519 cannot exceed the voltage at the input 517.

FIG. 5B shows a DC-to-DC converter 520 known as a buck converter or step-down converter. The DC-to-DC converter 520 receives a rectified input 527 and uses a transistor 522 as an electronic switch under the control of the controller 521 to provide current into the inductor 523 and out through the voltage regulated output 529 while the transistor 522 is conducting. When the transistor 522 shuts off, the current flowing in the inductor 523 continues by drawing current through the diode 524. As the current flowing in the inductor 523 begins to decrease, the controller 521 turns the transistor 522 back on to provide more current into the inductor 523. The capacitor 525 helps to maintain a steady voltage at the output 529. Like the linear regulator 510, the voltage of the output 529 cannot exceed the voltage at the input 527.

FIG. 5C shows a DC-to-DC converter 530 known as a boost converter. The DC-to-DC converter 530 receives current through a rectified input 517 which then flows through the inductor 533. A controller 531 controls a transistor 532 to determine whether to send the current from the inductor 533 to ground, increasing the current flow, by turning the transistor 532 on, or to direct the current from the inductor 533 through the diode 534 to the output 539. The capacitor 535 helps to maintain a steady voltage at the output 539. This DC-to-DC converter 530 generates a higher voltage at the output 539 than that at the input 537. FIG. 5D shows a DC-to-DC converter 540 known as an inverting buck-boost converter. Because the converter 540 provides an output 549 with an opposite polarity from its input 547, a rectifier used with this DC-to-DC converter 540 may provide a negative rectified input 547 so that the output 549 can be a positive voltage. The DC-to-DC converter 540 receives the negative rectified input 547 and uses a transistor 542 controlled by a controller 541 to selective pull current through the inductor 543. When the transistor 542 turns off, the inductor 543 drives its current through the diode 544 to the output 549, increasing the voltage across the capacitor 545. As the current begins to fall, the controller 541 can turn the transistor 542 back on, increasing the current flow in the inductor 542 so that when the transistor 542 turns off again, more current is provided through the diode 544 to the output 549.

FIG. 6 shows an implementation of a rectifier and DC-to-DC converter using an integrated circuit (IC) 610 that may be used in an energy harvesting subsystem 310, 320, 330 shown in FIG. 3. In the example shown, the IC 610 is a LTC3588-1 Nanopower Energy Harvesting Power Supply from Linear Technologies. Other devices from other manufacturers may be used in other implementations. The IC 610 includes a full-wave rectifier coupled to the PZ1 and PZ2 pins which are connected to the AC input 611. A capacitor 612 provides a reservoir of energy for the IC 610. The DO and DI pins are used to set the output voltage, such as setting a 1.8 V regulated output when both pins are tied to ground. The IC 610 acts as a buck converter with an external inductor 613 to provide the regulated voltage output 619. The capacitor 615 helps to maintain a steady voltage at the output 619.

FIG. 7A and FIG. 7B show alternative embodiments of a current-summing circuit that may be useful for the energy harvesting system shown in FIG. 3. FIG. 7A shows a first current summing circuit 710 that takes in three voltage regulated inputs 711, 712, 713 and provides each input 712, 712, 713 to respective diodes 714, 715, 716. The outputs of the diodes 714, 715, 716 are connected at a summing node 718 which is then fed to the output 719. As long as the inputs 711, 712, 713 are regulated to the same voltage level, they can equally contribute current to the output 719. The diodes 714, 715, 716 keep current from flowing back into an input 711, 712, 713 should it fall out of regulation, which may happen if the current flowing in its coupled conductor should fall below the minimum operating current level.

FIG. 7B shows a second current summing circuit 720 that simply joins the three inputs 721, 722, 723 at the summing node 728 which is then fed to the output 729. For this simplified summing circuit 720 to work, the sources of the inputs 721, 722, 723 are configured to disallow any current to flow back into the source which allows the three inputs to equally contribute current to the output 729.

Implementations of the energy harvesting subsystems can operate over a wide range of operating current in the conductor to which they are inductively coupled. This allows energy to be successfully harvested over a wide range of loads on a circuit, as some circuits may be connected to loads that are operating near a maximum current allowed by their circuit breaker and other circuits may have much lighter loads such as a few light-emitting diode (LED) luminaires. Providing a wide range of operating currents can be done by having a high efficiency at low operating currents and a lower efficiency at high operating currents to avoid overloading components of the energy harvesting subsystem.

One characteristic that can help to do this is to select current transformers with a nonlinear response curve. That is to say that the current transformers 311, 321, 331 used in the energy harvesting subsystems 310, 320, 330 provide a higher efficiency at low current levels than at high current levels. So, for example if the current transformer provides 1 mA of current output with 1 A of current flowing through the coupled conductor, a linear response curve would provide 40 mA of output when 40 A of current flows through the coupled conductor, but a current transformer with a non-linear response curve may provide less current, such as only 20 mA when 40 A flows through the coupled conductor. In some implementations the current transformers 311, 321, 331 have a non-linear response curve.

One thing that can cause a non-linear response if to have the core of the current transformer 311, 321, 331 become saturated with a current level in the coupled conductor that is less than the maximum operating current. In some implementations the current transformers 311, 321, 331 become saturated with a current level in their respective coupled conductor that is less than the maximum operating current.

Different implementations may be operable to generate the DC outputs of the energy harvesting subsystems at the predetermined voltage over different ranges of operating current flowing in their respective coupled conductor, where a range is defined by a minimum operating current and a maximum operating current. In some implementations, the maximum operating current may be at least 57 time greater than the minimum operating current, although other implementations may have different ratios of maximum to minimum operating currents that may be greater or lesser. Different implementations may have different maximum operating currents. At least one implementation of an energy harvesting subsystem may have a maximum operating current of at least 40 A. In another implementation, an energy harvesting subsystem may have a minimum operating current no greater than 0.7 A and a maximum operating current of at least 63 A.

Aspects of various embodiments are described with reference to flowchart illustrations and/or block diagrams of methods, apparatus, and systems according to various embodiments disclosed herein. It will be understood that various blocks of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by various circuits and or actions of an individual performing a physical task.

The flowchart and/or block diagrams in the figures help to illustrate the architecture, functionality, and operation of possible implementations of systems and methods of various embodiments. In this regard, each block in the flowchart or block diagrams may represent a physical device, such as a block of circuitry, for implementing the specified logical function(s), or a task performed by the physical device or a user. It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved.

FIG. 8 is a flow chart 800 of a method for multi-circuit energy harvesting 810. The method includes producing 811 a first alternating current (AC) output using a first current transformer, which may use a split ferrite core, coupled around a first conductor of an electrical circuit. The first AC output is rectified 812 to produce a first rectified voltage output and a first direct current (DC) output regulated to a predetermined voltage is generated 813 using the first rectified voltage output.

A second AC output is produced 814 using a second current transformer, which may use a split ferrite core, coupled around a second conductor of the electrical circuit and the second AC output is rectified 815 to produce a second rectified voltage output. A second DC output regulated to the predetermined voltage is generated 816 using the second rectified voltage output. Note that the first current transformer/rectifier/DC-to-DC converter may operate simultaneously with the second current transformer/rectifier/DC-to-DC converter if currents are simultaneously flowing in the first conductor and the second conductor. But if current is only flowing in one of the conductors at a particular time, only its coupled current transformer will harvest energy at that particular time.

Current is provided 817 from both the first DC output and the second DC output to an energy storage device. Depending on the currents flowing in the coupled first and second conductor, the amount of current provided from the first DC output and the second DC output may vary and could be zero if current less than the minimum operating current is flowing a conductor. In some implementations a sensor may be powered 818 with energy from the energy storage device.

Implementations with more than two energy harvesting subsystems may, for one or more additional energy harvesting subsystems, produce an additional AC output using an additional current transformer coupled around another conductor of the electrical circuit and rectify that AC output to product another rectified output which is converted using another DC-to-DC converter to generate another DC output regulated to the predetermined voltage. Current from the additional DC output(s) can then be provided to the energy storage device.

In some cases, the first conductor carries a first AC current of a first leg of a multi-phase electrical circuit and the second conductor carries a second AC current of a second leg of the multi-phase electrical circuit. In such cases, the first AC current may have a first phase angle that differs from a second phase angle of the second AC current by more than 100 degrees. In some cases, the multi-phase electrical circuit may be a 3 -phase electrical circuit where the legs are 120 degrees out of phase with each other. The method may include producing a third AC output using a third current transformer, rectifying the third AC output to produce a third rectified voltage output, and generating a third DC output regulated to the predetermined voltage using the third rectified voltage output. Current from the third DC output is then provided to the energy storage device along with current from the first DC output and the second DC output.

The method may also include providing a first component and a second component shaped to fit together to create a combined unit with a plurality of openings through the combined unit, including a first opening and a second opening respectively bounded on a first side by the first component and on a second side by the second component. The first component and the second component are configured to be fitted together with the first conductor passing through the first opening and the second conductor passing through the second opening.

The first current transformer includes a first split ferrite core half positioned in the first component proximal to the first opening and a second split ferrite core half positioned in the second component proximal to the first opening. The second current transformer includes a third split ferrite core half positioned in the first component proximal to the second opening and a fourth split ferrite core half positioned in the second component proximal to the second opening.

The first component and the second component are then installed in a service panel with the first conductor passing through the first opening and the second conductor passing through the second opening.

Examples of various implementations are described in the following paragraphs:

Implementation 1. An energy harvesting system comprising: a first energy harvesting subsystem including a first current transformer configured to be coupled to a first conductor and having a first alternating current (AC) output, a first rectifier coupled to the first AC output and having a first rectified voltage output, and a first direct current (DC) to DC converter coupled to the first rectified voltage output and having a first DC output at a predetermined voltage; a second energy harvesting subsystem that includes a second current transformer configured to be coupled to a second conductor and having a second AC output, a second rectifier coupled to the second AC output and having a second rectified voltage output, and a second DC-to-DC converter coupled to the second rectified voltage output and having a second DC output at the predetermined voltage; a current-summing circuit coupled to the first DC output and the second DC output and having a summed DC output to provide current from both the first DC output and the second DC output; and an energy storage device, coupled to the summed DC output.

Implementation 2. The energy harvesting system of implementation 1, wherein: the first current transformer comprises a first split ferrite core; and the second current transformer comprises a second split ferrite core.

Implementation 3. The energy harvesting system of any one of the preceding implementations, wherein: the first current transformer is operable to provide a first power output on the first AC output with a first level of current flowing in the first conductor; and the second current transformer is operable to provide a second power output on the second AC output with the first level of current flowing in the second conductor, wherein the first power output differs from the second power output by at least 10%.

Implementation 4. The energy harvesting system of any one of the preceding implementations, wherein: the first rectifier and the first DC-to-DC converter are included in a first integrated circuit (IC); and the second rectifier and the second DC-to-DC converter are included in a second IC.

Implementation 5. The energy harvesting system of any one of the preceding implementations, wherein: the first energy harvesting subsystem is operable to generate the first DC output at the predetermined voltage over a range of operating current flowing in the first conductor; the second energy harvesting subsystem is operable to generate the second DC output at the predetermined voltage over the range of operating current flowing in the second conductor; and the range of operating current has a minimum operating current and a maximum operating current that is at least 57 times greater than the minimum operating current.

Implementation 6. The energy harvesting system of implementation 5, wherein the maximum operating current is at least 40 A.

Implementation 7. The energy harvesting system of implementation 5, wherein the minimum operating current is no greater than 0.7 A and the maximum operating current is at least 63 A.

Implementation 8. The energy harvesting system of any one of implementations 5 through 7, wherein the first current transformer and the second current transformer each become saturated with a current level in their respective coupled conductor that is less than the maximum operating current.

Implementation 9. The energy harvesting system of any one of implementations 5 through 8, wherein the first current transformer and the second current transformer each have a non-linear response curve over the range of operating current.

Implementation 10. The energy harvesting system of any one of the preceding implementations, further comprising: a first component and a second component shaped to fit together to create a combined unit with multiple openings through the combined unit, including a first opening and a second opening, that each are bounded on a first side by the first component and on a second side by the second component, wherein the first component and the second component are configured to be fitted together with the first conductor passing through the first opening and the second conductor passing through the second opening; the first current transformer comprising a first split ferrite core half positioned in the first component proximal to the first opening and a second split ferrite core half positioned in the second component proximal to the first opening; the second current transformer comprising a third split ferrite core half positioned in the first component proximal to the second opening and a fourth split ferrite core half positioned in the second component proximal to the second opening; and the second component comprising the first rectifier, the second rectifier, the first DC-to-DC converter, the second DC-to-DC converter, and the current summing circuit.

Implementation 11. The energy harvesting system of implementation 10, the first opening, the second opening, and the third opening in the combined unit arranged to match a pitch between circuit-breakers in a service panel.

Implementation 12. The energy harvesting system of implementation 10 or implementation 11, the second component further comprising the energy storage device. Implementation 13. The energy harvesting system of any one of implementations 10 through 12, further comprising a sensor, powered by the energy storage device.

Implementation 14. The energy harvesting system of any one of implementations 10 through 13, further comprising: a third energy harvesting subsystem including a third current transformer configured to be coupled to a third conductor and having a third AC output, a third rectifier coupled to the third AC output and having a third rectified voltage output, and a third DC-to-DC converter coupled to the third rectified voltage output and having a third DC output at the predetermined voltage; the third current transformer comprising a fifth split ferrite core half positioned in the first component proximal to a third opening in the combined unit and a sixth split ferrite core half positioned in the second component proximal to the third opening; the current-summing circuit coupled to the third DC output to provide current from the third DC output in the summed DC output; and the second component further comprising the third rectifier and the third DC-to-DC converter.

Implementation 15. A method for harvesting energy from an electrical circuit, the method comprising: producing a first alternating current (AC) output using a first current transformer coupled around a first conductor of an electrical circuit; rectifying the first AC output to produce a first rectified voltage output; generating a first direct current (DC) output regulated to a predetermined voltage using the first rectified voltage output; producing a second AC output using a second current transformer coupled around a second conductor of the electrical circuit; rectifying the second AC output to produce a second rectified voltage output; generating a second DC output regulated to the predetermined voltage using the second rectified voltage output; provide current from both the first DC output and the second DC output to an energy storage device.

Implementation 16. The method of implementation 15, wherein the first current transformer and the second current transformer each comprises a split ferrite core.

Implementation 17. The method of implementation 15 or implementation 16, wherein the first conductor carries a first AC current of a first leg of a multi-phase electrical circuit and the second conductor carries a second AC current of a second leg of the multi-phase electrical circuit, the first AC current having a first phase angle that differs from a second phase angle of the second AC current by more than 100 degrees.

Implementation 18. The method of any one of implementations 15 through 17, further comprising: providing a first power output on the first AC output with a first level of current flowing in the first conductor; and providing a second power output on the second AC output with the first level of current flowing in the second conductor, wherein the first power output differs from the second power output by at least 10%.

Implementation 19. The method of any one of implementations 15 through 18, further comprising: maintaining regulation of the first DC output to the predetermined voltage over a range of operating current flowing in the first conductor; and maintaining regulation of the second DC output to the predetermined voltage over the range of operating current flowing in the second conductor; wherein the range of operating current has a minimum operating current and a maximum operating current that is at least 57 times greater than the minimum operating current.

Implementation 20. The method of implementation 19, wherein the maximum operating current is at least 40 A.

Implementation 21. The method of implementation 19, wherein the minimum operating current is no greater than 0.7 A and the maximum operating current is at least 63 A.

Implementation 22. The method of any one of implementations 19 through 21, further comprising: saturating the first current transformer with a first current flowing in the first conductor; and saturating the second current transformer with a second current flowing in the second conductor; wherein both the first current and the second current are less than the maximum operating current.

Implementation 23. The method of any one of implementations 19 through 22, wherein the first current transformer and the second current transformer each have a non-linear response curve over the range of operating current.

Implementation 24. The method of any one of implementations 15 through 23, further comprising: providing a first component and a second component shaped to fit together to create a combined unit with a plurality of openings through the combined unit, including a first opening and a second opening respectively bounded on a first side by the first component and on a second side by the second component, wherein the first component and the second component are configured to be fitted together with the first conductor passing through the first opening and the second conductor passing through the second opening; and installing the first component and the second component in a service panel with the first conductor passing through the first opening and the second conductor passing through the second opening; wherein the first current transformer comprises a first split ferrite core half positioned in the first component proximal to the first opening and a second split ferrite core half positioned in the second component proximal to the first opening; and the second current transformer comprises a third split ferrite core half positioned in the first component proximal to the second opening and a fourth split ferrite core half positioned in the second component proximal to the second opening.

Implementation 25. The method of any one of implementations 15 through 24, further comprising: powering a sensor with energy from the energy storage device.

Implementation 26. The method of any one of implementations 15 through 25, further comprising: producing a third AC output using a third current transformer coupled around a third conductor of the electrical circuit, wherein the electrical circuit is a 3-phase electrical circuit, and the first conductor, the second conductor, and the third conductor are respectively coupled to individual legs of the 3-phase electrical circuit; rectifying the third AC output to produce a third rectified voltage output; generating a third DC output regulated to the predetermined voltage using the third rectified voltage output; and providing current from the third DC output to the energy storage device.

Unless otherwise indicated, all numbers expressing quantities, properties, measurements, and so forth, used in the specification and claims are to be understood as being modified in all instances by the term “about.” The recitation of numerical ranges by endpoints includes all numbers subsumed within that range, including the endpoints (e.g. 1 to 5 includes 1, 2.78, 7t, 3.33, 4, and 5). Values referring to an AC measurement, such as Volts or Amperes, should be interpreted as a root mean squared (RMS) value unless otherwise noted.

As used in this specification and the appended claims, the singular forms “a”, “an”, and “the” include plural referents unless the content clearly dictates otherwise. Furthermore, as used in this specification and the appended claims, the term “or” is generally employed in its sense including “and/or” unless the content clearly dictates otherwise. As used herein, the term “coupled” includes direct and indirect connections. Moreover, where first and second devices are coupled, intervening devices including active devices may be located there between.

The description of the various embodiments provided above is illustrative in nature and is not intended to limit this disclosure, its application, or uses. Thus, different variations beyond those described herein are intended to be within the scope of embodiments. Such variations are not to be regarded as a departure from the intended scope of this disclosure. As such, the breadth and scope of the present disclosure should not be limited by the above-described exemplary embodiments but should be defined only in accordance with the following claims and equivalents thereof.

Claims

What is claimed is:

1. An energy harvesting system comprising: a first energy harvesting subsystem including a first current transformer configured to be coupled to a first conductor and having a first alternating current (AC) output, a first rectifier coupled to the first AC output and having a first rectified voltage output, and a first direct current (DC) to DC converter coupled to the first rectified voltage output and having a first DC output at a predetermined voltage; a second energy harvesting subsystem that includes a second current transformer configured to be coupled to a second conductor and having a second AC output, a second rectifier coupled to the second AC output and having a second rectified voltage output, and a second DC-to-DC converter coupled to the second rectified voltage output and having a second DC output at the predetermined voltage; a current-summing circuit coupled to the first DC output and the second DC output and having a summed DC output to provide current from both the first DC output and the second DC output; and an energy storage device, coupled to the summed DC output.

2. The energy harvesting system of claim 1, wherein: the first current transformer comprises a first split ferrite core; and the second current transformer comprises a second split ferrite core.

3. The energy harvesting system of any one of the preceding claims, wherein: the first current transformer is operable to provide a first power output on the first AC output with a first level of current flowing in the first conductor; and the second current transformer is operable to provide a second power output on the second AC output with the first level of current flowing in the second conductor, wherein the first power output differs from the second power output by at least 10%.

4. The energy harvesting system of any one of the preceding claims, wherein: the first rectifier and the first DC-to-DC converter are included in a first integrated circuit (IC); and the second rectifier and the second DC-to-DC converter are included in a second IC.

5. The energy harvesting system of any one of the preceding claims, wherein: the first energy harvesting subsystem is operable to generate the first DC output at the predetermined voltage over a range of operating current flowing in the first conductor; the second energy harvesting subsystem is operable to generate the second DC output at the predetermined voltage over the range of operating current flowing in the second conductor; and the range of operating current has a minimum operating current and a maximum operating current that is at least 57 times greater than the minimum operating current.

6. The energy harvesting system of claim 5, wherein the maximum operating current is at least 40 A.

7. The energy harvesting system of claim 5, wherein the minimum operating current is no greater than 0.7 A and the maximum operating current is at least 63 A.

8. The energy harvesting system of any one of claims 5 through 7, wherein the first current transformer and the second current transformer each become saturated with a current level in their respective coupled conductor that is less than the maximum operating current.

9. The energy harvesting system of any one of claims 5 through 8, wherein the first current transformer and the second current transformer each have a non-linear response curve over the range of operating current.

10. The energy harvesting system of any one of the preceding claims, further comprising: a first component and a second component shaped to fit together to create a combined unit with multiple openings through the combined unit, including a first opening and a second opening, that each are bounded on a first side by the first component and on a second side by the second component, wherein the first component and the second component are configured to be fitted together with the first conductor passing through the first opening and the second conductor passing through the second opening; the first current transformer comprising a first split ferrite core half positioned in the first component proximal to the first opening and a second split ferrite core half positioned in the second component proximal to the first opening; the second current transformer comprising a third split ferrite core half positioned in the first component proximal to the second opening and a fourth split ferrite core half positioned in the second component proximal to the second opening; and the second component comprising the first rectifier, the second rectifier, the first DC-to- DC converter, the second DC-to-DC converter, and the current-summing circuit.

11. The energy harvesting system of claim 10, the first opening, the second opening, and the third opening in the combined unit arranged to match a pitch between circuit-breakers in a service panel.

12. The energy harvesting system of claim 10 or claim 11, the second component further comprising the energy storage device.

13. The energy harvesting system of any one of claims 10 through 12, further comprising a sensor, powered by the energy storage device.

14. The energy harvesting system of any one of claims 10 through 13, further comprising: a third energy harvesting subsystem including a third current transformer configured to be coupled to a third conductor and having a third AC output, a third rectifier coupled to the third AC output and having a third rectified voltage output, and a third DC-to-DC converter coupled to the third rectified voltage output and having a third DC output at the predetermined voltage; the third current transformer comprising a fifth split ferrite core half positioned in the first component proximal to a third opening in the combined unit and a sixth split ferrite core half positioned in the second component proximal to the third opening; the current-summing circuit coupled to the third DC output to provide current from the third DC output in the summed DC output; and the second component further comprising the third rectifier and the third DC-to-DC converter.

15. A method for harvesting energy from an electrical circuit, the method comprising: producing a first alternating current (AC) output using a first current transformer coupled around a first conductor of an electrical circuit; and rectifying the first AC output to produce a first rectified voltage output; generating a first direct current (DC) output regulated to a predetermined voltage using the first rectified voltage output; producing a second AC output using a second current transformer coupled around a second conductor of the electrical circuit; rectifying the second AC output to produce a second rectified voltage output; generating a second DC output regulated to the predetermined voltage using the second rectified voltage output; provide current from both the first DC output and the second DC output to an energy storage device.

16. The method of claim 15, wherein the first current transformer and the second current transformer each comprises a split ferrite core.

17. The method of claim 15 or claim 16, wherein the first conductor carries a first AC current of a first leg of a multi-phase electrical circuit and the second conductor carries a second AC current of a second leg of the multi-phase electrical circuit, the first AC current having a first phase angle that differs from a second phase angle of the second AC current by more than 100 degrees.

18. The method of any one of claims 15 through 17, further comprising: providing a first power output on the first AC output with a first level of current flowing in the first conductor; and providing a second power output on the second AC output with the first level of current flowing in the second conductor, wherein the first power output differs from the second power output by at least 10%.

19. The method of any one of claims 15 through 18, further comprising: maintaining regulation of the first DC output to the predetermined voltage over a range of operating current flowing in the first conductor; and maintaining regulation of the second DC output to the predetermined voltage over the range of operating current flowing in the second conductor; wherein the range of operating current has a minimum operating current and a maximum operating current that is at least 57 times greater than the minimum operating current.

20. The method of claim 19, wherein the maximum operating current is at least 40 A.

21. The method of claim 19, wherein the minimum operating current is no greater than 0.7 A and the maximum operating current is at least 63 A.

22. The method of any one of claims 19 through 21, further comprising: saturating the first current transformer with a first current flowing in the first conductor; and saturating the second current transformer with a second current flowing in the second conductor; wherein both the first current and the second current are less than the maximum operating current.

23. The method of any one of claims 19 through 22, wherein the first current transformer and the second current transformer each have a non-linear response curve over the range of operating current.

24. The method of any one of claims 15 through 23, further comprising: providing a first component and a second component shaped to fit together to create a combined unit with a plurality of openings through the combined unit, including a first opening and a second opening respectively bounded on a first side by the first component and on a second side by the second component, wherein the first component and the second component are configured to be fitted together with the first conductor passing through the first opening and the second conductor passing through the second opening; and installing the first component and the second component in a service panel with the first conductor passing through the first opening and the second conductor passing through the second opening; wherein the first current transformer comprises a first split ferrite core half positioned in the first component proximal to the first opening and a second split ferrite core half positioned in the second component proximal to the first opening; and the second current transformer comprises a third split ferrite core half positioned in the first component proximal to the second opening and a fourth split ferrite core half positioned in the second component proximal to the second opening.

25. The method of any one of claims 15 through 24, further comprising: powering a sensor with energy from the energy storage device.

26. The method of any one of claims 15 through 25, further comprising: producing a third AC output using a third current transformer coupled around a third conductor of the electrical circuit, wherein the electrical circuit is a 3-phase electrical circuit, and the first conductor, the second conductor, and the third conductor are respectively coupled to individual legs of the 3-phase electrical circuit; rectifying the third AC output to produce a third rectified voltage output; generating a third DC output regulated to the predetermined voltage using the third rectified voltage output; and providing current from the third DC output to the energy storage device.