Floating power supply and method of using the same

Description

FIELD OF THE INVENTION

The present invention generally relates to a power supply and more particularly, to a floating direct current (DC) power supply for use in a system providing data communications through a power line and method of using the same.

BACKGROUND OF THE INVENTION

Well-established power distribution systems exist throughout most of the United States, and other countries, that provide power to customers via power lines. With some modification, the infrastructure of the existing power distribution systems can be used to provide data communication in addition to power delivery, thereby forming a power distribution communication system. In other words, existing power lines, that already have been run to many homes and offices, can be used to carry data signals to and from the homes and offices. These data signals are communicated on and off the power lines at various points in the power distribution communication system, such as, for example, near homes, offices, Internet service providers, and the like.

While the concept may sound simple, there are many challenges to overcome in order to use power lines for data communication. Power distribution systems include numerous sections, which transmit power at different voltages. The transition from one section to another typically is accomplished with a transformer. The sections of the power line distribution system that are connected to the customers typically are low voltage (LV) sections having a voltage between 100 volts and 240 volts, depending on the system. In the United States, the low voltage section typically is about 120 volts (120V). The sections of the power distribution system that provide the power to the low voltage sections are referred to as the medium voltage (MV) sections. The voltage of the MV section is in the range of 1,000 volts to 100,000 volts. The transition from the MV section to the LV section of the power distribution system typically is accomplished with a distribution transformer, which converts the higher voltage of the MV section to the lower voltage of the LV section.

Power system transformers are one obstacle to using power distribution lines for data communication. Transformers act as a low-pass filter, passing the low frequency signals (e.g., the 50 or 60 Hz power signals) and impeding high frequency signals (e.g., frequencies typically used for data communication) from passing through the transformer. As such, power distribution communication systems face the challenge of passing the data signals around, or through, the distribution transformers.

As discussed, medium voltage power lines can operate from about 1000 V to about 100 kV, and often have high current flows. The transformer bypass devices couple data to and from the medium voltage power line—often processing the data signals with conventional signal processing circuitry that is typically powered by voltages in the range of 3.3 volts to 5 volts direct current (DC).

FIG. 1 is a schematic representation illustrating an example of a bypass system having a power line coupler 10 that couples data to and/or from the medium voltage power line. From the power line coupler 10 the data signals are coupled to a signal processor 15, an electrically non-conductive path 50a, a medium voltage modem 20, a data router 30, a low voltage modem 40, a second electrically non-conductive path 50b, a low voltage power line coupler 60, and on to a low voltage power line. Data flow from the low voltage power line to the medium voltage power line may pass through the same components in the opposite order as will be evident to those skilled in the art. This example bypass device includes two non-electrically conductive paths 50a and 50b, which permit the flow of data signals, but provide electrical isolation between the medium voltage power line and the low voltage power line. Thus, the non-electrically conductive paths 50a and 50b prevent the high voltages of the medium voltage power line from reaching the low voltage power lines and the customer premises while permitting the bi-directional communication of data signals around the transformer. Such isolation is a very important component of such systems as it ensures the safety of individuals and property, and prevents damage of equipment, using the low voltage power lines by preventing the medium voltage power from reaching the low voltage power lines.

The power line coupler 10 and/or the signal processor 15 of the bypass device may require a direct current power supply to power the electronics of these functional components. The voltage output of such a power supply typically is on the order of 3.3 volts to 5 volts DC. It would be undesirable, however, to directly connect the low voltage power line to a power supply for powering the circuitry comprising these components (the power line coupler 10 and the signal processor 15) because such a connection would not provide the necessary isolation between the low voltage and medium voltage power lines.

Prior art solutions to this problem include extracting power from the medium voltage power line and using this power to power the electronics on the medium voltage side of the electrical non-conductive paths. Some of the existing means of drawing power from the medium voltage power line include inductively or capacitively coupling power from the power line. However, the inductive method is difficult to implement due to the varying current on the medium voltage power line, which may vary from less than 1 amp to 500 amps. Similarly, capacitive coupling may require extremely large capacitors (e.g., a 10,000 volt rating) and face other technical challenges.

The power supply of the present invention provides a technique for supplying power to the medium voltage side of an isolation device, while maintaining the electrical isolation between the low voltage and medium voltage power lines. These and other advantages are provided by various embodiments of the present invention.

SUMMARY OF THE INVENTION

One embodiment of a power supply of the present invention comprises a transducer having a transducer output and a voltage regulator. The transducer is in communication with an electrically non-conductive medium, which may be a light pipe. The electrically non-conductive medium is in communication with a non-electrical energy source such as a light source, and the non-electrical energy source communicates energy to the transducer via the electrically non-conductive medium. The transducer converts the received light energy to electrical energy, which is supplied to the input of a voltage regulator. The regulator ground is coupled to a live conductor of a medium voltage power line. The regulator output therefore provides an output voltage that is ground referenced to the live conductor of the power line.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is further described in the detailed description that follows, by reference to the noted drawings by way of non-limiting illustrative embodiments of the invention, in which like reference numerals represent similar parts throughout the drawings. As should be understood, however, the invention is not limited to the precise arrangements and instrumentalities shown. In the drawings:

FIG. 1 is a schematic representation illustrating an example transformer bypass device with which the present invention may be used.

FIG. 2 is a schematic representation illustrating an example transformer bypass device using an embodiment of the present invention.

FIG. 3 is a schematic representation illustrating an example embodiment of the present invention.

FIG. 4 is a schematic representation of an example embodiment of a coupling device and signal processor that are powered by an embodiment of the present invention.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

One application of the present invention is for use in a transformer bypass device, which is used to communicate data signals around a transformer that would otherwise filter such data signals, preventing them from passing through the transformer. FIG. 2 is a schematic representation illustrating such an example bypass system having a power line coupler 10 that couples data to and/or from the medium voltage power line and low voltage power line. From the power line coupler 10 the data signals are coupled to the signal processor 15, the electrically non-conductive path 50a, the medium voltage modem 20, the data router 30, the low voltage modem 40, the second electrically non-conductive path 50b, the low voltage power line coupler 60, and on to the low voltage power line. Data flow from the low voltage power line to the medium voltage power line may pass through the same components in the opposite order as will be evident to those skilled in the art.

This example bypass device includes two electrically non-conductive paths 50a and 50b, which permit the flow of data signals, but provide electrical isolation between the medium voltage power line and the low voltage power line. Thus, the non-electrically conductive paths 50a and 50b prevent the high voltages of the medium voltage power line from reaching the low voltage power lines and the customer premises while permitting the bi-directional communication of data signals around the transformer.

The power line coupler 10 and/or the signal processor 15 of the bypass device may require a direct current power supply to power the circuitry of these functional components. Similarly, the medium voltage modem 20, data router 30, and low voltage modem 40 may also require a low voltage direct current power supply. Typically, the voltage requirements of these types of circuitry are on the order of 3.3 volts to 5 volts DC. Other bypass devices may power these components (modem 20, data router 30, and modem 40) with a power supply that utilizes a low voltage isolating device, which may be a transformer.

As shown schematically in FIG. 2, a power supply 100 of the present invention provides a means of supplying power to the medium voltage side of an isolation device (e.g., non-electrically conductive paths 50a and/or 50b), which thereby maintains the isolation between the low voltage and medium voltage power lines. While this example bypass device includes two non-electrically conductive paths (50a and 50b) other bypass devices may employ only one. Likewise, the present invention may be used in other devices where electrical power supply isolation is desirable or necessary such as in a backhaul point used to communicate data between a medium voltage power line and a conventional telecommunications network.

Referring to FIG. 3, one example of the present invention includes a transducer 110, which, for example, may be a solar cell array or other means of converting non-electrical energy to electrical energy. For example, another example of a suitable transducer would be a thermocoupler for converting thermal energy to electrical energy. While the example embodiment below employs a light-to-electricity transducer such as a solar cell array providing a 5 volt output (referenced to its ground), any suitable transducer may be used, which may have any suitable output voltage.

The transducer 110 includes a ground 115 and a voltage output 120. When the 5 volt transducer 110 is transducing, the transducer 110 will maintain approximately a 5 volt potential between its voltage output 120 and its ground 115. In this embodiment, the ground 115 of the transducer 110 is electrically coupled to a ground reference 300, which, for example, may be a medium voltage power line. The voltage output 120 of the transducer 110 is connected to an input 210 of a voltage regulator 200.

In this embodiment, the voltage regulator 200 is a 3.3 volt voltage regulator. In other words, when enough power is supplied to its input, the voltage regulator 200 maintains a 3.3 volt potential between its voltage output 220 and its ground 215. The ground 215 of the voltage regulator 200 is connected to the ground reference 300. Consequently, the output of the voltage regulator 200 at its output 220 will be 3.3 volts referenced to the ground reference 300, which as discussed above may be a medium voltage power line. Thus, an output 102 of the power supply 100 referenced to its ground 101 will be 3.3 volts and “float” or ride on any voltage present on the ground reference 300. In this example, the ground reference 300 is a medium voltage power line having a voltage at 10 kilovolts (referenced to earth ground) at 60 Hz (the power signal) so the output of the power supply 100 will float or ride on the power signal—or in other words remain a substantially constant 3.3 volts relative to the power signal.

The ground connection of the power supply 100 to the medium voltage power line may be explicit or implicit. With respect to an explicit coupling, the ground 215 of the voltage regulator 200 and ground 115 of the transducer 110 may be directly connected (e.g., through a conductor) to the medium voltage power line or connected through a resistor. With respect to an implicit coupling, the ground 215 of the voltage regulator 200 and ground 115 of the transducer 110 is not coupled to the medium voltage power line through a conductor or an explicit conductive pathway. Specifically, with the implicit connection there is no “conductor” or wire coupling the ground 215 of the voltage regulator 200 and ground 115 of the transducer 110 to the medium voltage power line. Instead, the grounds 115 and 215 are connected to a local ground that is not connected to earth ground (or the medium voltage power line) and is shared by the components processing data signals received (or transmitted) through the medium voltage power line. This local ground will float. Due to leakage currents in the components processing the data on the medium voltage power line, the local ground will float to the potential of the medium voltage power line thereby providing an implicit connection. Because these components share the local ground with the voltage regulator 200 and transducer 110, the grounds 115 and 215 of the components will also float to the potential of the medium voltage line through this implicit connection.

The transducer 110 is in communication with a non-electrical energy source—an energy source that generates non-electrical energy (although the energy source may use electrical energy to do so. In this embodiment, the non-electrical energy source is a light source 401 that emits photons and may be a light bulb, a light emitting diode (LED), a laser, or other light emitting device or source. The transducer 110 is coupled to the non-electrically energy source 401 through a electrically non-conductive path 410, which in this embodiment may be a light tube, light pipe, fiber optic cable, or other suitable medium for conducting light energy from the light source 401.

The non-electrical energy source or light source 401 may be powered from the low voltage power line as indicated in the FIG. 3. For example, in this embodiment, the low voltage power line coupler 60 of the bypass device is coupled the low voltage power lines (e.g., conductively, capacitively, or inductively coupled), which includes a 120 volt power signal (and an associated ground, which may be earth ground) for powering the light source 401 or other non-electrical energy source. Thus, the non-electrical energy source or light source 401 is powered by a power source with a first voltage potential relative to earth ground (e.g., 120 volts) and the ground reference or medium voltage power line is at a second voltage potential relative to earth ground (e.g., 10,000 volts).

As indicated by the jagged edges of the electrically non-conductive path 410 shown in FIG. 3, the light source 401 may be remote from the transducer 110 and regulator 200 of the power supply 100. Keeping the light source 401 remote from the power supply 100 also allows the light source 401 to be remote from the medium voltage power line. Thus, the electrically non-conductive path 410 supplies energy to the power supply 100 and provides electrical isolation between the low voltage power line (that is supplying power to the light source 401) and the medium voltage power line.

In operation, power from the low voltage power line powers the light source 401, which emits light. The emitted light travels along the electrically non-conductive path 410 to the transducer 110 to which the electrically non-conductive path 410 is coupled. The transducer 110 converts the non-electrical energy to electrical energy, which in this embodiment results in an output voltage that is referenced to the medium voltage power line. The output voltage of the transducer 110 is supplied to the voltage regulator 200, which provides an output voltage 102 that is referenced to the medium voltage power line 300 or other ground reference.

One example of the power line coupling device 10, the signal processor 15, and the electrically non-conductive path 50a with which an embodiment of the present invention may be used is shown in FIG. 4. From an electrical perspective the coupling device 10 includes a radio frequency (RF) filter or RF choke 705 in series with the medium voltage power line 120 and disposed between the connection nodes 706 and 707. The RF choke 705 may be an impedance provided by ferrite inductors that are toroidal in shape and extend substantially around the medium voltage power line 120.

The RF choke 705 operates as a low pass filter. In other words, low frequency signals (e.g., a power signal having a frequency of 50 or 60 Hz) pass through the RF choke 705 relatively unimpeded (i.e., RF choke 705 can be modeled as a short circuit to low frequency signals). High frequency signals (e.g., a data signal), however, do not pass through the RF choke 705; rather, they are blocked by the RF choke 705 (i.e., the RF choke 705 can be modeled as a high impedance path to high frequency signals). As such, the voltage across the RF choke 705 includes data signals but substantially no power signals. This voltage (i.e., the voltage across the RF choke 705) is applied to a transformer 720 via capacitors 710 to receive data signals from the medium voltage power line 120. To transmit data signals to the medium voltage power line 120, the data signal is applied to the transformer 720, which in turn communicates the data signal to medium voltage power line 120 through the capacitors 710.

The transformer 720 may operate as a differential transceiver. The transformer 720 may operate to repeat data signals received from the MV power line to a receive circuitry 612 and to repeat data signals received from a transmit circuitry 610 to the MV power line. The transformer 720 and capacitors 710 also provide some electrical isolation between the medium voltage power line 120 and the low voltage power line. The transformer 720 and capacitors 710 also permit RF signals, such as data signals, to pass through and travel down the power line.

FIG. 4 also shows other components of the power line coupler 10 and signal processor 15 including the transmit circuitry 610, the receive circuitry 612, a transmit optoelectronic device 620 (e.g., a light emitting diode), and a receive optoelectronic device 622 (e.g., a photo detector).

The capacitors 606 are electrically connected between the transmit circuitry 610 and the receive circuitry 612 and the transformer 720. The transmit circuitry 610 and the receive circuitry 612 are electrically connected to the transmit optoelectronic device 620 and the receive optoelectronic device 622, respectively. The transmit optoelectronic device 620 and the receive optoelectronic device 622 are in communication with a data communication medium 630, which is an electrically non-conductive path for the communication of data signals and is an example of the electrically non-conductive path 50a shown in FIGS. 1 and 2.

In the embodiment illustrated in FIG. 4, the data communication medium 630 is a fiber optic cable that provides electrical power isolation between the medium voltage power line and low voltage power line. Other communication media may be used to provide such electrical power isolation such as wireless electrically non-conductive path or multiple fiber optic conductors.

As discussed above and as shown in FIG. 4, the power supply 100 ground may be explicitly coupled to the medium voltage power line 120 (in this embodiment through a resistor). The power supply 100 receives energy via the electrically non-conductive path 410 from a non-electrical energy source (not shown in FIG. 4) that may be remote from the medium voltage power line 120. Thus, the circuitry of the power coupling device 10, the signal processor 15, and any other circuitry on the medium voltage side of the data communication medium 30 (indicated by 800) are powered by the output voltage (Vout) of the power supply 100 and referenced to the ground of the power supply 100. For example, the output voltage (Vout) of the power supply provides an input voltage (Vin) to the transmit circuitry 610 and receive circuitry 612. Likewise, the power supply 100, as well as the transmit circuitry 610 and the receive circuitry 612 may be ground referenced to the medium voltage power line 120. Thus, the components shown in FIG. 4 are electrically isolated from the low voltage power line via the electrically non-conductive path 410 and the data communication medium 630.

As discussed above, the power supply 100 ground also may be implicitly coupled to the medium voltage power line 120 in which case conductor 708 (including its resistor) would not be necessary. Instead, only a local ground that floats would exist. Leakage currents through the components processing the data signal such as transformer 720, capacitors 710, capacitors 606, transmit circuitry 610, and/or receive circuitry 612 may float the local ground substantially to the potential of the medium voltage power line 120. As a result, the grounds of the transducer 110 and voltage regulator 200 will also float to the same potential (since these local grounds are connected) so that the output 220 of the voltage regulator 200 (and transducer 120) will be relative to the potential of the medium voltage power line. In still other embodiments, the local ground may not float to the potential of the medium voltage power line and may remain isolated therefrom.

While the above embodiment employs a light source powered from the low voltage power line as the non-electrical energy source, other embodiments may use other sources. For example, another embodiment may use solar cell arrays to collect solar energy from the sun. In this alternate embodiment, the solar cell arrays, which act as the transducer, may be positioned on the outside of the power line coupling device and be electrically coupled to the voltage regulator positioned on the inside of the coupling device. Alternately, heat energy may be converted to electrical energy via a thermocoupler to provide energy to the power supply.

It will be understood to those skilled in the art that other components that are often incorporated as part of a power supply may be included in embodiments of the present invention, such as surge protectors and filters, which may be between the voltage regulator and transducer, on the output of the power supply, or between the ground reference 300 and the ground of the power supply 100. In addition, depending on the circuitry powered by the power supply and other factors, the voltage regulator may be omitted in some embodiments. Furthermore, some embodiments of the power supply may not supply a direct current, but may be a fluctuating power source (such as an alternating current (AC) source), which may be achieved, for example, through the addition of circuitry for converting a DC signal (e.g., from the output of the regulator or transducer) to an AC signal, which circuitry is well-known in the art.

It is to be understood that the foregoing illustrative embodiments have been provided merely for the purpose of explanation and are in no way to be construed as limiting of the invention. Words used herein are words of description and illustration, rather than words of limitation. In addition, the advantages and objectives described herein may not be realized by each and every embodiment practicing the present invention. Further, although the invention has been described herein with reference to particular structure, materials and/or embodiments, the invention is not intended to be limited to the particulars disclosed herein. Rather, the invention extends to all functionally equivalent structures, methods and uses, such as are within the scope of the appended claims. Those skilled in the art, having the benefit of the teachings of this specification, may affect numerous modifications thereto and changes may be made without departing from the scope and spirit of the invention.