Patent Application
20170229886
This invention relates to power distribution system safety protection devices—for example, power distribution systems with electronic monitoring to detect and disconnect power in the event of an electrical fault or safety hazard, particularly where an individual has come in contact with exposed conductors. This invention is applicable to general power distribution, or more specifically to, e.g., electric vehicle charging, telecommunications or alternative energy power systems.
Digital electric power, or digital electricity, can be characterized as any power format where electrical power is distributed in discrete, controllable units of energy. Packet energy transfer (PET) is a new type of digital electric power protocol disclosed in U.S. Pat. No. 8,781,637 (Eaves 2012).
The primary discerning factor in a digital power transmission system compared to traditional, analog power systems is that the electrical energy is separated into discrete units; and individual units of energy can be associated with analog and/or digital information that can be used for the purposes of optimizing safety, efficiency, resiliency, control or routing.
As described by Eaves 2012, a source controller and a load controller are connected by power transmission lines. The source controller of Eaves 2012 periodically isolates (disconnects) the power transmission lines from the power source and analyzes, at a minimum, the voltage characteristics present at the source controller terminals directly before and after the lines are isolated. The time period when the power lines are isolated was referred to by Eaves 2012 as the “sample period”, and the time period when the source is connected is referred to as the “transfer period”. The rate of rise and decay of the voltage on the lines before, during and after the sample period reveal if a fault condition is present on the power transmission lines. Measurable faults include, but are not limited to, short circuit, high line resistance or the presence of an individual who has improperly come in contact with the lines.
Eaves 2012 also describes digital information that may be sent between the source and load controllers over the power transmission lines to further enhance safety or provide general characteristics of the energy transfer, such as total energy or the voltage at the load controller terminals. Since the energy in a PET system is transferred as discrete quantities, or quanta, it can be referred to as “digital power” or “digital electricity”.
A power distribution system regulates transfer of energy from a source on a source side to a load on a load side, wherein the source and load each include terminals. A source controller on the source side is in communication with and responsive to a source sensor that provides feedback to the source controller that includes at least a signal indicative of electric current through the source terminals. A source switching bridge is electrically coupled with the source controller and is responsive to control signals from the source controller for electrically disconnecting the source from the source terminals and for applying a source voltage in either a forward-polarity or reverse-polarity state relative to the source terminals. A load disconnect device is configured to electrically decouple the load from the load terminal. A logic device is implemented in at least the source controller and configured to place the source switching bridge into a reverse-polarity state and to perform at least one current measurement on the current passing through the source terminals when the source switching bridge is in the reverse-polarity state, wherein a current measurement outside of predetermined high or low limits indicates that there is a foreign object or living organism making contact with the source or load terminals or a failure in the power distribution system, and to electrically disconnect the source from the source terminals if the current measurement falls outside the predetermined high and low limits.
In the transfer of energy from a source to a load, a power distribution system is configured to detect unsafe conditions that include electrically conducting foreign objects or individuals that have come in contact with exposed conductors in the power distribution system. A responsive signal is generated in a source controller including source terminals. The responsive signal reverses a voltage on the source terminals. With the voltage on the source terminals reversed, a measurement of electrical current flowing through the source terminals is acquired; and the source controller generates signals to electrically disconnect the source from the source terminals if and when the electrical current falls outside of high or low limits indicating that there is a conducting foreign object or living organism making electrical contact with the source or load terminals or a failure in power distribution system hardware.
The apparatus and methods described herein offer an alternative form of PET using the method of periodically reversing the polarity of the transmission lines. Since the most common forms of electrical faults are polarity independent, the method allows for detection of a fault based on the load device being equipped with a uni-directional switch, such as a diode. When the polarity of the transmission lines are reversed, the flow of electrical current is inhibited by the uni-directional switch. If there is a fault on the transmission lines, such as due to a person touching the lines, electrical current will continue to flow into the fault when the transmission lines are reversed and can be detected by the source controller.
The foregoing and other features and advantages of various aspects of the invention(s) will be apparent from the following, more-particular description of various concepts and specific embodiments within the broader bounds of the invention(s). Various aspects of the subject matter introduced above and discussed in greater detail below may be implemented in any of numerous ways, as the subject matter is not limited to any particular manner of implementation. Examples of specific implementations and applications are provided primarily for illustrative purposes.
Unless otherwise defined, used or characterized herein, terms that are used herein (including technical and scientific terms) are to be interpreted as having a meaning that is consistent with their accepted meaning in the context of the relevant art and are not to be interpreted in an idealized or overly formal sense unless expressly so defined herein.
The terminology used herein is for the purpose of describing particular embodiments and is not intended to be limiting of exemplary embodiments. As used herein, singular forms, such as “a” and “an,” are intended to include the plural forms as well, unless the context indicates otherwise. Additionally, the terms, “includes,” “including,” “comprises” and “comprising,” specify the presence of the stated elements or steps but do not preclude the presence or addition of one or more other elements or steps.
A block diagram of an embodiment of the power distribution system is shown in
The normal resistance between the source terminals 31a and 31b is represented by Rsrc. In a particular embodiment, Rsrc has a value greater than 1 million Ohms. During normal conditions, when the polarity of the transmission lines is reversed, the current, as sensed by current sensor 8, would be less than 1 milliamp for a source voltage of 380V. However, during a cross-line fault, as depicted in
If no fault conditions are detected, the switching bridge 7 is again commanded to a forward-polarity state. Energy is then transferred between the source 1 and the load 3 until the next sample period. The conducting period between sample periods is referred to as the “transfer period”.
An additional check for the in-line fault is where the source and load controllers 5 and 9 acquire their respective terminal voltages at sensing points 34 and 35, as shown in
An alternative method to measure in-line resistance without a communications link 11 to the load 3 is where the source controller 5 measures the source terminal voltage at sensing point 34 and measures the electrical current passing through the source terminals 31a and 31b using the current sensor 8. The voltage and current samples are made nearly simultaneously during the same energy transfer period. The switching bridge 7 is then placed in a non-conducting state, and the source controller 5 immediately takes another voltage sample at sensing point 34. The difference in magnitude between the first and second voltage samples is proportional to the line resistance. Explained differently, as the transmission line resistance increases, more voltage is dropped across the length of the line for a given current. Since the voltage on the line capacitor 4 is equal to the source voltage minus the voltage drop on the line, measuring the voltage of the transmission lines without current flowing sets the line voltage drop to zero allowing an independent measurement of the voltage across the line capacitor 4. Once the voltage of the line capacitor 4 is known, the voltage drop on the transmission lines can be calculated by subtracting the earlier measurement at point 34 made when line current was present.
Referring to
The switching bridge 7 has three states applicable to the present invention: non-conducting, forward-polarity (causes current to flow from the source 1 to the load 3) and reverse-polarity (where no current flows to the load 3 under normal operation).
There are a number of industry standard methods for constructing the disconnect device 13 of
The transistor type used for the internal switch 38 is chosen based on the voltage and current requirements. Industry standard transistors that can be used include FETs, IGBTs or IGCTs. The electrical implementation of the control signal 41 for controlling the conduction of the internal switch 38 is dependent on the type of transistor but is well known to those skilled in the art of power electronics.
As shown in
Referring to
The source controller 5 and the load controller 9 can include a logic device, such as a microprocessor, microcontroller, programmable logic device or other suitable digital circuitry for executing the control algorithm. The load controller 9 may take the form of a simple sensor node that collects data relevant to the load side of the system. It does not necessarily require a microprocessor.
The controllers 5 and 9 can be computing devices and the systems and methods of this disclosure can be implemented in a computing system environment. Examples of well-known computing system environments and components thereof that may be suitable for use with the systems and methods include, but are not limited to, personal computers, server computers, hand-held or laptop devices, tablet devices, smart phones, multiprocessor systems, microprocessor-based systems, set top boxes, programmable consumer electronics, network PCs, minicomputers, mainframe computers, distributed computing environments that include any of the above systems or devices, and the like. Typical computing system environments and their operations and components are described in many existing patents (e.g., U.S. Pat. No. 7,191,467, owned by Microsoft Corp.).
The methods may be carried out via non-transitory computer-executable instructions, such as program modules. Generally, program modules include routines, programs, objects, components, data structures, and so forth, that perform particular tasks or implement particular types of data. The methods may also be practiced in distributed computing environments where tasks are performed by remote processing devices that are linked through a communications network. In a distributed computing environment, program modules may be located in both local and remote computer storage media including memory storage devices.
The processes and functions described herein can be non-transitorially stored in the form of software instructions in the computer. Components of the computer may include, but are not limited to, a computer processor, a computer storage medium serving as memory, and a system bus that couples various system components including the memory to the computer processor. The system bus can be of any of several types of bus structures including a memory bus or memory controller, a peripheral bus, and a local bus using any of a variety of bus architectures.
The computer typically includes one or more a variety of computer-readable media accessible by the processor and including both volatile and nonvolatile media and removable and non-removable media. By way of example, computer-readable media can comprise computer-storage media and communication media.
The computer storage media can store the software and data in a non-transitory state and includes both volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of software and data, such as computer-readable instructions, data structures, program modules or other data. Computer-storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disks (DVD) or other optical disk storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to store the desired information and that can accessed and executed by the processor.
The memory includes computer-storage media in the form of volatile and/or nonvolatile memory such as read only memory (ROM) and random access memory (RAM). A basic input/output system (BIOS), containing the basic routines that help to transfer information between elements within the computer, such as during start-up, is typically stored in the ROM. The RAM typically contains data and/or program modules that are immediately accessible to and/or presently being operated on by the processor.
The computer may also include other removable/non-removable, volatile/nonvolatile computer-storage media, such as (a) a hard disk drive that reads from or writes to non-removable, nonvolatile magnetic media; (b) a magnetic disk drive that reads from or writes to a removable, nonvolatile magnetic disk; and (c) an optical disk drive that reads from or writes to a removable, nonvolatile optical disk such as a CD ROM or other optical medium. The computer-storage medium can be coupled with the system bus by a communication interface, wherein the interface can include, e.g., electrically conductive wires and/or fiber-optic pathways for transmitting digital or optical signals between components. Other removable/non-removable, volatile/nonvolatile computer storage media that can be used in the exemplary operating environment include magnetic tape cassettes, flash memory cards, digital versatile disks, digital video tape, solid state RAM, solid state ROM, and the like.
The drives and their associated computer-storage media provide storage of computer-readable instructions, data structures, program modules and other data for the computer. For example, a hard disk drive inside or external to the computer can store an operating system, application programs, and program data.
The source and load controllers 5 and 9 can be used to meter energy transfer and communicate the information back to the user or to a remote location. For example, the disclosed methods and system can be implemented on a public charging station for electric vehicles and can be utilized to send electricity consumption data back to a central credit card processor. The transfer of information can be through an outside communication link 15, as depicted in
The source switching bridge 7 can be supplemented by the addition of an electromechanical relay or “contactor” providing a redundant method to disconnect the source 1 from the source terminals so as to provide a back-up in the case of a failure of the source switching bridge 7. The load disconnect device 13 can be supplemented by an electromechanical relay or contactor in the same fashion. The electromechanical contactor activation coils can be powered by what is known to those skilled in the art as a “watchdog circuit”. The watchdog circuit continually communicates with the source or load controllers 5 and 9; otherwise, the contactor will automatically open, providing a fail-safe measure against “frozen” software or damaged circuitry in the controllers 5 and 9.
Referring to
An alternative embodiment of a combined load and load disconnect device 13 is shown in
The data communication link 11 and/or external communication link 15 can be implemented using various methods and protocols well known to those skilled in the art. Communication hardware and protocols can include RS-232, RS-485, CAN bus, Firewire and others. The communication link 11 can be established using copper conductors, fiber optics or wirelessly over any area of the electromagnetic spectrum allowed by regulators, such as the Federal Communications Commission (FCC), as set forth in Part 18 of the FCC rules—for example, the 2.4 GHz, 3.6 GHz, 4.9 GHz, 5 GHz, and 5.9 GHz frequencies allocated for WiFi or the 915 Mhz frequency allocated for ZigBee. Wireless communication can be established using any of a number of protocols well known to those skilled in the art, including Wi-Fi, ZigBee, IRDa, Wi-Max and others. The data communication link 11 and/or external communication link 15 of
To allow simultaneous power transfer and user-data communications, the system can be configured as depicted in
Thus the scope of the disclosed invention should be determined by the appended claims and their legal equivalents, rather than the examples given. In describing embodiments of the invention, specific terminology is used for the sake of clarity. For the purpose of description, specific terms are intended to at least include technical and functional equivalents that operate in a similar manner to accomplish a similar result. Additionally, in some instances where a particular embodiment of the invention includes a plurality of system elements or method steps, those elements or steps may be replaced with a single element or step; likewise, a single element or step may be replaced with a plurality of elements or steps that serve the same purpose. Moreover, while this invention has been shown and described with references to particular embodiments thereof, those skilled in the art will understand that various substitutions and alterations in form and details may be made therein without departing from the scope of the invention. Further still, other aspects, functions and advantages are also within the scope of the invention; and all embodiments of the invention need not necessarily achieve all of the advantages or possess all of the characteristics described above. Additionally, steps, elements and features discussed herein in connection with one embodiment can likewise be used in conjunction with other embodiments. Still further, the components, steps and features identified in the Background section are integral to this disclosure and can be used in conjunction with or substituted for components and steps described elsewhere in the disclosure within the scope of the invention. In method claims, where stages are recited in a particular order—with or without sequenced prefacing characters added for ease of reference—the stages are not to be interpreted as being temporally limited to the order in which they are recited unless otherwise specified or implied by the terms and phrasing.
This application claims the benefit of U.S. Provisional Application No. 62/292,596, filed 8 Feb. 2016, the entire content of which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 62292596 | Feb 2016 | US |
