Patent Application
20160028324
Power over Ethernet (PoE) systems are generally configured to transmit electrical power along with data on Ethernet cabling. This allows a single cable to provide both data and electrical power. The power may be applied to an Ethernet cable by a power source equipment (PSE) device for use by a powered device (PD). Examples of PDs may include wireless network access points, routers, IP cameras, or other such devices. Power may be carried on the same Ethernet conductors as the data, or it may be carried on dedicated conductors in the same Ethernet cable.
There are several common techniques for transmitting power over Ethernet cabling. A first technique involves utilizing a subset of conductors in an Ethernet cable for data transmission (e.g., 10BASE-T or 10BASE-TX data transmission), and the other conductors of the Ethernet cable for power transmission. In a second technique, power may be transmitted on the data conductors of the Ethernet cable by applying a common-mode voltage to each pair of these conductors. Because Ethernet uses differential signaling, this technique of applying a common-mode voltage does not interfere with data transmission.
However, such PoE transmitted power is typically characterized by a direct current (DC) voltage substantially below 60V. Accordingly, PDs are generally configured to include power inputs for receiving such a voltage.
Embodiments disclosed herein may be configured to boost and then invert DC voltage received from a PSE device to produce a standard AC voltage output (e.g., 120 VAC or 240 VAC), thus enabling a PoE cable to power an external device via a standard AC voltage input.
In one example, an apparatus may include a data management assembly and a DC to AC inverter assembly. The data management assembly may include a data input, a data output, and a power port. The data management assembly may be configured to receive in combination a data signal and a variable DC input voltage on the data input, to separate the received data signal from the input voltage, to output the data signal on the data output, and to output the input voltage on the power port. The DC to AC inverter assembly may be configured to receive the input voltage from the power port, to boost the input voltage to a predetermined DC stepped-up voltage that is constant for different input voltages, to convert the stepped-up voltage to an AC voltage, and to output the AC voltage on a power output.
In another example, an apparatus may include a data management assembly, a boost converter, a controller circuit, an inductor assembly, first and second switches, a driver assembly, and an opto-coupler. The data management assembly may include a data input, a data output, and a power port. The data management assembly may be configured to receive in combination a data signal and a variable DC input voltage on the data input, to separate the data signal and the input voltage, to output the data signal on the data output, and to output the separated input voltage on the power port. The boost converter may be configured to receive the input voltage on the power port, and to boost the input voltage to a DC stepped-up voltage determined by a voltage-control signal. The controller circuit may be configured to receive an input voltage signal representative of the received input voltage, and to generate the voltage-control signal appropriate to cause the boost converter to boost the input voltage to a predetermined stepped-up voltage that is constant for different input voltages. The inductor assembly may be configured to receive the predetermined stepped-up voltage from the boost converter, and to produce therefrom positive and negative stepped-up voltages. The first and second switches may be configured to apply the respective positive and negative stepped-up voltages from the inductor assembly to a first output node, in response to received switch drive signals. The driver assembly may be electrically connected to the first and second switches. The driver assembly may produce the switch drive signals in response to received switch control signals. The opto-coupler may convey the switch control signals output by the controller circuit to the driver assembly, and may electrically isolate the controller circuit from the driver assembly. The controller circuit may be configured to generate switch control signals to operate the first and second switches via the opto-coupler and the driver assembly to alternatingly apply the positive and negative stepped-up voltages on the first output node to produce an AC voltage output between the first output node and a second output node.
In some embodiments, system 100 may include a source device 300 from which data input 212 may receive in combination data signal 224 and variable DC input voltage 228. For example, device 300 may be a PSE device similar to that described in U.S. Pat. No. 8,386,088, which is hereby incorporated by reference. In particular, device 300 may include a switch 304 (e.g., an Ethernet switch, a USB switch, or other switch configured to produce a data signal), a power supply 308, a power injector 312, and an interface 316. Switch 304, power supply 308, and power injector 312 may be coupled to interface 316 to inject power and data onto wires of a network cable 320 (e.g., a twisted pair CAT5e Ethernet cable, a USB cable, or other cable or medium suitable for transmission of data and power), which may connect interface 316 to data input 212. More specifically, switch 304 may be configured to supply data signal 224 (e.g., an Ethernet data signal, a USB signal, or other suitable data signal) to interface 316.
Power supply 308 may be configured to supply a DC voltage output to interface 316 via power injector 312. Interface 316 may be configured to output the supplied data signal and DC voltage output on network cable 320.
System 100 may utilize active PoE. For example, apparatus 200 (e.g., assembly 204) and/or device 300 may include circuitry for modulating power and data for transmission over cable 320 to apparatus 200. In particular, the circuitry may include one or more components and/or functionalities, such as those described in U.S. Pat. No. 8,386,088, which may enable system 100 to detect when apparatus 200 is connected to cable 320, determine (or detect) whether a configuration of apparatus 200 is suitable for receiving power from device 300, and/or determine how much power to transmit over cable 320 based on the configuration of apparatus 200. While device 300 may be configured to output a substantially constant and/or predetermined DC voltage output (e.g., 56 VDC) on cable 320, varying cable lengths and loads, among other factors, may result in the DC voltage received by apparatus 200 being a substantially variable DC voltage, such as voltage 228, which may vary in a range of about 32 VDC to about 56 VDC when received at input 212.
As shown in
Accordingly, apparatus 200 may be (or be included in) an adapter that enables device 400 to receive both data and power from device 300. In particular, assembly 204 may be configured to pass the data signal from device 300 to device 400, and assembly 208 in conjunction with assembly 204 may be configured to receive power for device 300, to boost and invert that power (as described above) to a suitable AC voltage level for powering device 400 via input 408.
Examples of suitable switches include field-effect transistors (FETs), and in particular metal-oxide-semiconductor FETs (MOSFETs). An example of a suitable opto-coupler is a multi-channel and bi-directional 15 MBd digital logic gate opto-coupler (e.g., model number ACSL-6400-50TE) available from Avago Technologies of San Jose, Calif., U.S.A. An example of a suitable differential driver is a high-voltage high/low-side driver (e.g., model number L6390DTR) available through STMicroelectronics of Geneva, Switzerland. An example of a suitable power switch is an OPTIMOS™ 3 power-transistor (e.g., model number BSC900N2ONS3 G) available from Infineon Technologies AG of Neubiberg, Germany. An example of a suitable potentiometer is a digital rheostat model number AD5272 or AD5274) available from Analog Devices, Inc. of Norwood, Mass., U.S.A. An example of a suitable boost circuit is model number LT3758A available from Linear Technology Corporation of Milpitas, Calif.
Boost converter 504 may be configured to receive input voltage 228 (e.g., from power port 220), and to step input voltage 228 up to a DC stepped-up voltage, which may be determined by a voltage-control signal 560. Signal 560 may be appropriate to cause boost converter 504 to boost input voltage 228 to a predetermined DC stepped-up voltage 562 (e.g., 120 VDC, or in some embodiments 60 VDC) that may be constant for different input voltages. For example, controller circuit 508 may be configured to receive an input-voltage signal 564 (e.g., from and/or produced by boost circuit 544). Signal 564 may be representative of input voltage 228 received by boost converter 504. Controller circuit 508 may be responsive to signal 564 to produce (or generate) signal 560, and to transmit signal 560 to potentiometer 540. Potentiometer 540 may be configured to produce a resistance based on received signal 560, and booster circuit 544 may be connected to potentiometer 540 for stepping up input voltage 228 (to stepped-up voltage 562) based on the produced resistance of potentiometer 540. Inductor assembly 512 may be configured to receive stepped-up voltage 562 from boost converter 504 (e.g., from boost circuit 544) and to produce therefrom a positive stepped-up voltage 572 (e.g., +120 VDC, or in some cases +60V DC) and a negative stepped-up voltage 576 (e.g., −120 VDC, or in some cases −60V DC). In some embodiments, voltage 572 may be within 10 percent of +120 VDC, and voltage 576 may be within 10 percent of −120 VDC. For example, though not shown, inductor assembly 512 may include mutually coupled inductors, with one inductor configured to provide a positive output voltage and another inductor configured to provide a negative output voltage. Energy output from the inductors may be stored on a capacitor assembly disposed between each respective output and a circuit ground reference. Other conventional circuits may also be used to produce the positive and negative stepped-up voltages.
Switches 516, 520 may be configured to receive a respective one of voltages 572, 576, and to selectively apply a first voltage output to node 530. Similarly, switches 524, 528 may be configured to receive a respective one of voltages 572, 576, and to selectively apply a second voltage output to node 532. In particular, switches 516, 524 may receive voltage 572, and may selectively apply voltage 572 on respective nodes 530, 532. Similarly, switches 520, 528 may receive voltage 576, and may selectively apply voltage 576 on respective nodes 530, 532.
Controller circuit 508 may be configured to operate switches 516, 520 (e.g., via opto-coupler 536 and driver 548) to alternatingly output voltages 572, 576 to node 530 to produce a first AC output voltage relative to output node 532, such as a first AC voltage output between nodes 530, 532 (e.g., as depicted in
In some embodiments, controller circuit 508 may be configured to operate switches 524, 528 (e.g., via opto-coupler 536 and driver 548) in combination with switches 516, 520 (via opto-coupler 536 and driver 552) to produce the AC voltage output (e.g., a second AC voltage output) by alternatingly outputting a combination of voltage 572 on node 530 and voltage 576 on node 532, and a combination of voltage 576 on node 530 and voltage 572 on node 532 (e.g., as depicted in
For example, controller circuit 508 may be configured to generate and output one or more switch control signals, such as switch control signals 584, 586, 588, and/or 590. Opto-coupler 536 may be configured to communicate one or more of signals 584, 586, 588, 590 to switch-driver assembly 534. For example, opto-coupler 536 may be configured to convey signals 584, 586 to driver 548, and/or may be configured to convey signals 588, 590 to driver 552. Driver 548 may be electrically connected to switches 516, 520, and may be configured to produce switch drive signals 592, 594 in response to received signals 584, 586. In particular, driver 548 may be configured to produce signal 592 in response to received signal 584, and to produce signal 594 in response to received signal 586. Similarly, driver 552 may be electrically connected to switches 524, 528, and may be configured to produce switch drive signals 596, 598 in response to received signals 588, 590. In particular, driver 552 may be configured to produce signal 596 in response to received signal 588, and to produce signal 598 in response to received signal 590. Switches 516, 520 may be configured to apply respective voltages 572, 576 to node 530 in response to respective signals 592, 594. Similarly, switches 524, 528 may be configured to apply respective voltages 572, 576 to node 532 in response to respective signals 596, 598.
While signals 584, 586 may be on separate channels (e.g., each of signals 584, 586 may include generated high and low signals carried over separate conductors), in other embodiments these signals may be on the same channel. For example, signals 584, 586 may be respective high and low signals transmitted over the same conductor. Similarly, signals 588, 590 may be on the same or separate channels. If signals 584, 586 (and/or signals 588, 590) are on the same channel, then, for example, the associated switches may be configured to operate in the off state in the absence of a corresponding switch drive signal, or the associated driver may be configured to generate a switch drive signal corresponding (or for operation) to the off state in the absence of a corresponding switch control signal.
As can be inferred from the upper portion of
In particular, during durations T1, T3, T5, T7, corresponding signals 584, 592 may be configured to operate switch 516 in the off state to prevent the positive stepped-up voltage from being applied to node 530 when switch 520 is in the on state. Similarly, signal 586 may be configured to operate switch 520 in the off state to prevent the negative stepped-up voltage from being applied to node 530 when switch 516 is in the on state. During durations T2, T6, corresponding signals 584, 592 may be configured to operate switch 516 in the on state to apply the positive stepped-up voltage to node 530, and corresponding signals 586, 594 may be configured to operate switch 520 in the off state to prevent the negative stepped-up voltage from being applied to node 530. Similarly, during duration T4 and subsequent corresponding periods, corresponding signals 584, 592 may be configured to operate switch 516 in the off state to prevent the positive stepped-up voltage from being applied to node 530 and corresponding signals 586, 594 may be configured to operate switch 520 in the on state to apply the negative stepped-up voltage to node 530. In this example, switches 524 and 528 are continuously maintained in the off state. It will be appreciated that the positive and negative voltages producing an AC output may also be applied to node 532 by selective operation of switches 524, 528 while continuously maintaining switches 516 and 520 in the off state.
In some embodiments, in addition to the control of the operating states of the switches by the control signals, differential drivers 548, 552 may not be able to be operated concurrently in an on state. This may result in a short time delay when the operating state of complementary pairs of switches 516, 520 and 524, 528 are transitioning between opposite operating states. For example, control signal 584 may be configured to change switch 516 from an off state to an on state at the end of duration T4 when control signal 586 is configured to change switch 520 from an on state to an off state. The result is a short duration, represented by time duration T5, when switches 516, 520 are off. This transition period during which both complementary switches are in a non-conducting (off) state may provide a further increased level of safety (e.g., by ensuring that both of voltages 572, 576 are not applied to the same node at the same time).
Specifically, the alternating voltage level on node 530, as described above with reference to
During durations T2′, T6′, corresponding signals 588, 596 may be configured to operate switch 524 in the off state to prevent the positive stepped-up voltage from being applied to node 532. During duration T4′, corresponding signals 590, 598 may be configured to operate switch 528 in the off state and corresponding signals 588, 596 may be configured to operate switch 524 in the on state to apply the positive stepped-up voltage to node 532. Concurrently, corresponding signals 590, 598 may be configured to operate switch 528 in the off state to prevent the negative stepped-up voltage from being applied to node 532.
During durations T1′, T3′, T5′, T7′, respectively corresponding signals 588, 596 and 590, 598 may be configured to respectively operate switches 524, 528 in the off state to prevent either of the positive or negative stepped-up voltages from being applied to node 532, which in conjunction with the concurrent off state of switches 516, 520 as produced by the control signals from controller circuit 508 and/or the time delay of driver 548, may result in the second AC voltage also better approximating a sinusoidal waveform than if these quiescent periods did not exist
While the positive and negative stepped-up voltages are respectively shown in
Referring back to
In response to a second operator input selecting the second AC voltage (e.g., 240 VAC), controller circuit 508 may produce control signals 584, 586, 588, 590 to alternatingly output the positive and negative stepped-up voltages on node 530, and alternatingly output the opposite positive and negative stepped-up voltages on node 532, in a manner similar to that shown in
In some embodiments, in response to the first operator input, the controller circuit 508 may be configured to produce potentiometer control signal 560 appropriate for causing the boost converter to produce positive and negative stepped-up voltages of +60V and −60V. In this case, the switch control signals 584, 586, 588, 590 may be generated by controller circuit 508 to control switches 516, 520, 524, 528 to produce 120 VAC as in a manner similar to that shown in
In some embodiments, in response to the second operator input, the controller circuit 508 may be configured to produce potentiometer control signal 560 appropriate for causing the boost converter to produce positive and negative stepped-up voltages of +240V and −240V. In this case, the switch control signals 584, 586, 588, 590 generated by controller circuit 508 to control switches 516, 520, 524, 528 may produce 240 VAC in a manner similar to that shown in
The above description is intended to be illustrative and not restrictive. Many other embodiments will be apparent to those skilled in the art, upon reviewing the above description. The scope of the inventions should therefore be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. This disclosure may include one or more independent or interdependent inventions directed to various combinations of features, functions, elements and/or properties, one or more of which may be defined in the following claims. Other combinations and sub-combinations of features, functions, elements and/or properties may be claimed later in this or a related application. Such variations, whether they are directed to different combinations or directed to the same combinations, whether different, broader, narrower or equal in scope, are also regarded as included within the subject matter of the present disclosure.
An appreciation of the availability or significance of claims not presently claimed may not be presently realized. Accordingly, the foregoing embodiments are illustrative, and no single feature or element, or combination thereof, is essential to all possible combinations that may be claimed in this or a later application. Each claim defines an invention disclosed in the foregoing disclosure, but any one claim does not necessarily encompass all features or combinations that may be claimed. Where the claims recite “a” or “a first” element or the equivalent thereof, such claims include one or more such elements, neither requiring nor excluding two or more such elements. Further, ordinal indicators, such as first, second or third, for identified elements are used to distinguish between the elements, and do not indicate a required or limited number of such elements, and do not indicate a particular position or order of such elements unless otherwise specifically stated. Ordinal indicators may be applied to associated elements in the order in which they are introduced in a given context, and the ordinal indicators for such elements may be different in different contexts.
